Guest guest Posted October 14, 2010 Report Share Posted October 14, 2010 Fascinating research not just for autism, but helps explain the rise in other disorders including metabolic and immune. . Also interesting to note the diet once again is mentioned as playing a role for helping rid the body of " Protozoan Parasites " . Diet; a possibly more important than previously thought, under-appreciated possible simple solution? Here's a clip Volume 5, Issue 1, January-March 2011, Pages 14-59 Review Metabolic, immune, epigenetic, endocrine and phenotypic abnormalities found in individuals with autism spectrum disorders, Down syndrome and Alzheimer disease may be caused by congenital and/or acquired chronic cerebral toxoplasmosis Department of Social Pediatrics, Faculty of Health Sciences, University Medical School, 5 Bartla Street, 51-618 Wroclaw, Poland Received 19 January 2010; revised 17 March 2010; accepted 18 March 2010. Available online 28 April 2010. Abstract Toxoplasma gondii is a protozoan parasite that infects about a third of human population. It is generally believed that in immunocompetent hosts, the parasite infection takes usually asymptomatic course and induces self-limiting disease, but in immunocompromised individuals may cause significant morbidity and mortality. T. gondii uses sulfated proteoglycans for host cell invasion and sulfated sugars on the surface of host cells may functions as key parasite receptors. Patients with autism spectrum disorders (ASD) have many inborn or acquired abnormalities of metabolism, including impaired sulfation and sulfoxidation. The impaired sulfation of dehydroepiandrosterone (DHEA) to DHEA-S affected normal development of various brain functions because DHEA-S inhibited vascular neuroinflammation in ASD individuals probably caused by cerebral toxoplasmosis (CT). Treatment of endothelial cells with DHEA-S dramatically inhibited the TNF- & #945;-induced activation of NF- & #954;B, an inflammatory transcription factor, and increased protein levels of the NF- & #954;B inhibitor, I & #954;B- & #945;. A significant decrease in sulfation capacity found during pregnancy compared with post partum probably reflect a defense reaction of the host due to increased production of proinflammatory cytokines associated with frequent and widespread infection with this parasite. This suggestion may be supported by the finding that TNF and IL-1 mediated inhibitory effect of lipopolysaccharide on DHEA sulfotransferase mRNA level in Hep3B human hepatoma cells. It seems however that the impaired sulfation and sulfonation may be also beneficial for the host because lack or a markedly diminished anionic charge of the host cells associated with this event did not promote binding to the negatively charged outer leaflet of T. gondii plasma membranes. Phosphorylation of the parasite and/or host proteins is also of great importance in the process of T. gondii–host cell interaction. Furthermore, the increased male to female ratio characteristic for autistic participants most likely resulted from significantly increased testosterone levels associated with congenital T. gondii infection. It was demonstrated that the parasite, aging and dietary restriction have been able to induce DNA breakage, therefore one may suggest that such an epigenetic mechanism play an important role in development of Down syndrome (DS). Several data may support this notion: (a) autism occurs 10 times more often in children with trisomy 21 than in the general population, ( the parasite can be transmitted by semen and ovum, © autistic children exhibit impaired DNA methylation capacity, and (d) T. gondii affect chromatin structure and may cause dysregulation of the host cell cycle. Alzheimer disease (AD) also may be caused by CT because this abnormality is more prevalent in women, characterizes with a skewed capacity for xenobiotic metabolism especially of compounds containing sulfur that manifest as a decreased plasma levels of DHEA-S, and has marked immune irregularies in part due to aging. Moreover, chronic neuroinflammation characteristic for AD and DS individuals is associated with vascular lesions, patients with AD have increased levels of DNA breaks in the cerebral cortex, markedly enhanced production of proinflammatory cytokines, reactive oxygen species, and lipid peroxidation, disturbances in glucose metabolism, and irregularities in hypothalamic–pituitary axis. It must be noted that similar metabolic and endocrine disturbances have been reported also in humans and mice with chronic toxoplasmosis. Overproduction of IFN- & #947; and other proinflammatory cytokines associated with persistent neuroinflammation resulted in neurodegeneration and induced amyloid- & #946; production also in DS, as well as accounted for cognitive impairment. Because bradyzoites and sporozoites throughout their life cycle accumulate large amounts of crystalline storage polysaccharide granules analogous to amylopectin within the cytoplasm and are able to build more complex macromolecules, they may be at least in part responsible for the production of amyloid- & #946; senile plaques. Moreover, it seems that the accumulation of iron in senile plaques reflect a defense of the host against T. gondii because this transition metallic ion is necessary for proliferation of tachyzoites. Finally, the beneficial effects of ibuprofen in the patients with AD that restored cellular immunity, decreased production of proinflammatory cytokines, NO, amyloid- & #946;, reduced lipid peroxidation and free radical generation, were consistent with the suggestion that congenital and/or acquired chronic latent CT play an important role in development of these types of neurodegeneration. Keywords: Autism spectrum disorders; Alzheimer disease; Down syndrome; Metabolism disturbances; Immune changes; Epigenetic irregularities; Carbohydrate metabolism; Phenotypic abnormalities; Testosterone levels; Amyloid- & #946; plaques Article Outline 1. Introduction 2. Abnormalities in transsulfuration and transmethylation metabolism and DNA hypomethylation in children with ASD and their parents 2.1. Impaired sulfation and sulfoxidation metabolism 2.1.1. Patients with ASD 2.1.2. T. gondii infection 2.2. Impaired methylation capacity 2.2.1. Patients with ASD 2.2.2. Effect of growth factors, copper, and dopamine on methylation ability 2.2.2.1. Growth factors 2.2.2.2. Divalent copper 2.2.2.3. Dopamine and other catecholamines 3. T. gondii affects host cell chromatin structure which may, at least in part, participate in development of DS 3.1. Chromosomal disturbances in ASD 3.2. Chromosomal abnormalities in DS 3.3. Effects of T. gondii infection on mitosis and cell proliferation 3.4. Epigenetic chromosomal changes 4. Disturbances in phosphorylation 4.1. Hypophosphorylation of salivary peptidome in ASD individuals 5. Host cell manipulation by T. gondii 6. Neuroinflammation and other molecular abnormalities in AD participants 7. Dysregulated brain carbohydrate metabolism in patients with ASD, DS, and AD 7.1. Abnormal glucose metabolism in DS participants 8. T. gondii infection causes marked disturbances in carbohydrate metabolism 9. Pathophysiological role of amyloid- & #946; plaques 9.1. Patients with AD 9.2. T. gondii infection and possible generation of amyloid plaques 9.2.1. Crystalline storage polysaccharide analogous to amylopectin produced by T. gondii bradyzoites may be, at least in part, responsible for development of amyloid- & #946; containing plaques in ASD, DS, AD, and other neurodegenerative diseases 10. Increased activation of tryptophan metabolic pathway in AD individuals 11. A patient with AD and concomitant T. gondii infection 12. Disturbances of fatty acid profiles in ASD participants may, at least in part, be due to T. gondii infection 13. Increased phospholipase A2 (PLA2) levels in ASD/Asperger's syndrome individuals may enhance host cells invasion by T. gondii through increasing their penetration 14. T. gondii requires polyamines for proper growth, and heparan sulfate facilitates salvage of extracellular polyamines. Inhibitory effects of polyamines on lipid peroxidation 15. Disturbances of aminoacids levels in ASD participants 16. Important role of vasoactive intestinal peptide (VIP) in development of DS and ASD 17. Disturbances of sulfation of sugars on the surface of the host cells and irregularities of T. gondii and/or host proteins phosphorylation are important for invasion of the parasite to the host cells 18. Impaired sulfation of dehydroepiandrosterone (DHEA) to DHEA-S may reflect a defense reaction of ASD patients against T. gondii infection. Deficiency of DHEA-S affects however normal development of various brain functions and decreases efficiency of inhibition of vascular inflammation 18.1. T. gondii infection 19. Possible causes of the increased male to female ratio in ASD individuals 19.1. Increased testosterone and other androgens serum levels in patients with ASD 19.2. Women infected with T. gondii have more sons. Increased saliva testosterone concentrations in men with T. gondii infection 19.3. Effect of T. gondii infection on personality profiles of men and women 19.4. Correlation between T. gondii infection, salivary testosterone levels and lower left hand 2D:4D ratios 19.5. Handwriting impairments in children with ASD and shorter life span of left handed than right handed men 20. Abnormalities of steroid and hypothalamo–pituitary hormone levels and endocrinologic disturbances reported in patients with ASD, DS, and revealed during congenital or chronic T. gondii infection 20.1. ASD individuals 20.2. Patients with DS 20.3. Congenital toxoplasmosis 20.4. Acute toxoplasmosis 20.5. Mice 21. Important effects of the increased testosterone levels on the host References Thumbnail image Fig. 1. Various pathways of the essential amino acid tryptophan metabolism. About 99% of the dietary tryptophan is metabolized along the kynurenine pathway. Alternative pathways are the conversion of tryptophan to 5-hydroxytryptamine (5-HT) and then to melatonin, or to tryptamine and then to the kynuramines (or kynurenamines). 3-HAO, 3-Hydroxyanthranilate oxidase; IDO, indoleamine 2,3-dioxygenase; KAT, kynurenine aminotransferase; MAO, monoamine oxidase; QPRT, quinolinic-acid phosphoribosyl transferase; TDO, tryptophan 2,3-dioxygenase. Reproduced and modified with permission from Nature Reviews Drug Discovery (Stone & Darlington, 2002) copyright (2002) Macmillan Magazines Ltd. View Within Article Thumbnail image Fig. 2. Interrelationships between indoleamine 2,3-dioxygenase (IDO) and nitric oxide synthase (NOS) in macrophages or glial cells, and the potential interactions with neurons by means of N-methyl-d-aspartate (NMDA)-receptor-induced nitric-oxide (NO) formation. Arg, Arginine; 3-HAA, 3-hydroxyanthranilic acid; 3-HK, 3-hydroxykynurenine; IFN- & #947;, interferon- & #947;; IL, interleukin; Kyn, kynurenine; KynA, kynurenic acid; LPS, lipopolysaccharide; mRNA, messenger RNA; iNOS, inducible nitric-oxide synthase; TGF- & #946;, transforming growth factor- & #946;; TNF- & #945;, tumor necrosis factor- & #945;; Trp, tryptophan; xA, xanthurenic acid. The broken lines represent possible reactions. Reproduced with permission from Nature Reviews Drug Discovery (Stone & Darlington, 2002) copyright (2002) Macmillan Magazines Ltd. View Within Article Thumbnail image Fig. 3. Possible model for NO-mediated regulation of IDO in IFN- & #947;-primed mononuclear phagocytes. NOS, Nitric-oxide synthase; IDO, indoleamine 2,3-dehydrogenase, l-Arg, l-arginine; l-Trp, l-tryptophan; IFN- & #947;, interferon- & #947;; NO, nitric oxide; Kyn, kynurenine; 3-HAA, 3-hydroxyanthranilic acid; QA, quinolinic acid; SNP, sodium nitroprusside; GTN, glyceryl trinitrate; SNAP, S-nitroso-N-acetylpenicillamine; DEANO, diethylaminodinitric oxide. SNP, DEANO, and SNAP release NO extracellularly, while GTN is thought to release NO intracellularly. Nitric Oxide Inhibits Indoleamine 2,3-Dioxygenase Activity in Interferon- & #947; Primed Mononuclear Phagocytes, vol. 269, pp. 14457–14464/The Journal of Biological Chemistry by SR, Mohr D, Stockert R. Copyright [1994] by The American Society for Biochemistry and Molecular Biology. Reprinted by permission of The American Society for Biochemistry and Molecular Biology via the Copyright Clearance Center. View Within Article Table 1. Glycolytic enzymes identified in T. gondii (Fleige et al., 2007; with own modification). View table in article View Within Article Table 1A. Selected modifications in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in metabolism (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression ( & #8595;), upregulated ( & #8593;), or modulated (M). Modulated proteins had expression altered across several isoforms on the same gel using the Amersham difference gel electrophoresis, and this probably indicated a posttranslational modification event ( et al., 2008). a The host cell proteins, which also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). View Within Article Table 1B. Selected modifications in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in glycolysis (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression ( & #8595;), upregulated ( & #8593;), or modulated (M). a These host cell proteins also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). It must be noted that T. gondii tachyzoites are thought to rely upon both glycolysis and the tricarboxylic acid cycle, while bradyzoites are largely dependent upon glycolysis (Tomavo et al., 2001; Xia et al., 2008). Although tachyzoites utilize both glycolysis and oxidative phosphorylation to obtain energy, glycolysis seems to be the predominant pathway for ATP synthesis in the bradyzoite ([Coppin et al., 2003] and [Denton et al., 1996]). Moreover, ENO2 and lactate dehydrogenase1 are only found in tachyzoites while ENO1 and lactate dehydrogenase 2 are exclusively expressed in bradyzoites ([Dzierszinski et al., 2001] and [Ferguson et al., 2002]). Silencing of tachyzoite ENO2 altered nuclear targeting of bradyzoite ENO1 in T. gondii (Holmes et al., 2009). View Within Article Table 1C. Selected changes in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in cell cycle, transcription, and translation (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression ( & #8595;), upregulated ( & #8593;), or modulated (M). View Within Article Table 1D. Selected proteins modulated in the parasite-modified parasitophorous vacuole-associated organelles from T. gondii infected and noninfected cells (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression ( & #8595;), upregulated ( & #8593;), or modulated (M). a These host cell proteins also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). Interestingly, host cell invasion and egress induce marked relocations of glycolytic enzymes in T. gondii tachyzoites and this ability allows the parasite to optimize ATP delivery to those cellular processes that are important for survival outside host cells and those required for growth and multiplication (Pomel, Luk, & Beckers, 2008). On the other hand, treatment of macrophages with ATP activates ROS-dependent oxidative stress response and secretion of proinflammatory cytokines (Cruz et al., 2007), characteristic for neuroinflammation and neurodegeneration processes in ASD, DS, and AD. View Within Article Table 1E. Selected changes in the proteomes of human foreskin fibroblasts by T. gondii infection: various proteins (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression ( & #8595;), upregulated ( & #8593;), or modulated (M). a The host cell proteins changed expression also in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). View Within Article Table 2. Immune system abnormalities in autistic individuals (acc. to Ashwood, Wills, & de Water, 2006, with own modification). View table in article PDD, pervasive developmental disorder; TLR2, toll-like receptor 2 (lipoteichoic acid); TLR4, lipopolysaccharide; TLR9, synthetic oligonucleotides containing CpG-B motifs, GM-CSF, granulocyte/macrophage colony stimulating factor. It must be noted that IL-6 promoted innate NK cell production of IL-17 during toxoplasmosis (Passos et al., 2010). aLeptin has the structure similar to that of IL-2 and may activate the innate immune system and shift the cognate immune system toward a predominance of a proinflammatory TH1 T cell population while reducing the regulatory TH2 phenotype. bIt is interesting that antibodies raised against T. gondii predominantly belonged to the IgG2a subclass, an isotype of which production is usually mostly controlled by TH1 cytokines, and especially IFN- & #947; ([Nguyen et al., 2003] and [Markine-Goriaynoff et al., 2000]). c,dThe complement system proteins are involved in the lysis and removal of infectious organisms in blood, and may be involved in cellular apoptosis in brain ([Chauhan et al., 2005] and [Chauhan and Chauhan, 2006]).These increases may therefore reflect immune defense of the host because complement has membrane lytic activity directed against the extracellular stage of T. gondii (Seeber, 2000). It must be noted that reduced serum levels of transferrin in autism (Chauhan, Chauhan, Cohen et al., 2004) affect normal early T-cell differentiation (Macedo et al., 2004). View Within Article Table 3. Partial downregulation of cell-mediated immune responses after infection with T. gondii (Lang et al., 2007, with own modification). View table in article CIITA, master regulator of major histocompatibility complex class II transcription; CCR5, CC chemokine receptor; DCs, dendritic cells; iNOS, inducible nitric oxide synthase; IRF-1, interferon regulatory factor-1; LXA4, lipoxin A4; MHC, major histocompatibility complex molecules; PGE2, prostaglandin E2; TGF- & #946;, transforming growth factor- & #946;. Proliferation of T. gondii in inflammatory macrophages was associated with diminished ROS production in host cells (Shrestha, Tomita, Weiss, & Orlofsky, 2006). In young children with congenital toxoplasmosis specific T cell response to the parasite antigens was impaired and such hyporesponsiveness has been restored during childhood. The acquisition of functional T cell response was disease-unrelated and indistinguishable in terms of strength, epitope specificity, and cytokine profile from the corresponding responses in immunocompetent adults with asymptomatic acquired T. gondii infection (Guglietta et al., 2007). In pregnant mice, T. gondii infection caused a decrease of CD4+CD25+-regulatory T cells (Ge et al., 2008). It must be noted that peripheral blood leukocytes (PBL) from healthy children older than 36 months responded to several stimuli at levels comparable to those of PBL from adults, but surprisingly, cord blood leukocytes appeared to be more efficient in antigen-presenting function than PBL from children younger than 13 months (Clerici, Depalma, Roilides, Baker, & Shearer, 1993). View Within Article Table 3A. Suppression of immune responses to T. gondii by parasite-triggered modulation of host cell apoptosis (acc. to Lang et al., 2007; with own modification). View table in article CTL, Cytotoxic T lymphocyte; Fas, receptor; FasL, Fas ligand (a cell surface molecule belonging to TNF family and death factor, which binds to its receptor Fas, thus inducing apoptosis of Fas-bearing cells); NK, natural killer cells; PARP, poly(ADP-ribose) polymerase. a T. gondii delayed neutrophil apoptosis by inducing granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor secretion by the parasite-infected human fibroblasts. Although neutrophils are unable to kill T. gondii, this can retard their division time from the usual 6-8 hrs cycle to a 24 hrs cycle and this enhanced neutrophil survival may contribute to the robust proinflammatory response elicited in the pathogen-infected host cells (Channon, Miselis, Minns, Dutta, & Kasper, 2002). View Within Article Table 4. Biomolecules of T. gondii regulating the host innate immune responses (Pollard et al., 2009; with own modification). View table in article CCR5, CC-chemokine family receptor; GPI, glycosyl-phosphatidylinositol; HSP70, heat shock protein 70; ROP, T. gondii rhoptry; TLR, toll-like receptor ligands, TLR2, lipoteichoic acid; TLR4, LPS; TLR11, is one of three mouse TLRs activated specifically by uropathogenic bacteria. View Within Article Table 5. Proteins undergoing a change in phosphorylation state following T. gondii infection (acc. to et al., 2008; with own modification). View table in article T. gondii kinase activity is involved in phosphorylation of host I & #954;B & #945; and this unusual mechanism can be utilized in manipulating the NF- & #954;B pathway (Molestina & Sinai, 2005). It must be noted that in DS, T cell activation deficiency was associated with an aberrant pattern of protein tyrosine phosphorylation after CD3 perturbation (Scotese et al., 1998). Abnormal hyperphosphorylation of tau and abberrant tau aggregation has been also found in AD ([Avila, 2000] and [Avila, 2006]). It must be noted that psudohyperphosphorylated tau was toxic to cells and was associated with induction of apoptotic cell death (Shimura et al., 2004). View Within Article Table 6. Bradyzoite and tachyzoite stage-specifically expressed genes coding the enzymes involved in T. gondii amylopectin metabolism (acc. to Coppin et al., 2005; with own modification). View table in article & #8593; & #8593; & #8593;, Markedly increased gene expression; & #8593; & #8593;, increased expression; & #8593;, weak expression; 0, no gene present. T. gondii enzymes were identified at the genome Web site: htttp://www.toxodb.org. The parasite genome encodes two fructose 1,6-biphosphatase isoenzymes, a single pyruvate-carboxylase, and two PEP-carboxykinases. The conversion from glucose-6-phosphate into glucose-1-phosphate, which forms the link between amylopectin metabolism and gluconeogenesis, is catalysed by two isoforms of glucosephosphate-mutase (Fleige, Pfaff, Gross, & Bohne, 2008). The following soluble tachyzoite antigenic proteins have been identified: a putative protein disulfide isomerase, Hsp60, Hsp70, a pyruvate kinase, a putative glutamate dehydrogenase, a coronin, a protein kinase C receptor 1, a malate dehydrogenase, a major surface antigen 1, an uridine phosphorylase, and a peroxiredoxin (Ma et al., 2009). View Within Article Table 7. Drugs tested for in vitro activity against T. gondii (acc. to -Brando et al., 2003; with own modification). View table in article DMSO: dimethylsulfoxide; Toxo CGM: Toxoplasma cell growth medium. Valproic acid at a concentration of 1 & #956;g/ml inhibited 7% of the tachyzoites and trimethoprim at 3.2 & #956;g/ml produced 2% inhibition, but the combination of these two compounds at those concentrations resulted in a potentiating effect inhibiting 55% of the tachyzoites. a Median inhibitory dose, a measure of tachyzoite inhibition. b Median toxicity dose, a measure of cytotoxicity. c Therapeutic index, a measure of efficacy determined by TD50/ID50 ratio. View Within Article Table 8. Hypoxia inducible gene expressiona (acc. to Prandota, 2004). View table in article a T. gondii activates hypoxia-inducible factor 1 (HIF1) already at physiologically relevant oxygen levels and requires HIF1 for growth and survival (Spear et al., 2006). View Within Article Corresponding Author Contact InformationTel.: +48 071 348 42 10; fax: +48 71 345 93 24. Research in Autism Spectrum Disorders Volume 5, Issue 1, January-March 2011, Pages 14-59 http://www.sciencedirect.com/science?_ob=ArticleURL & _udi=B83X1-4YYGYT6-1 & _user=1\ 0 & _coverDate=03%2F31%2F2011 & _rdoc=1 & _fmt=high & _orig=search & _origin=search & _sort=\ d & _docanchor= & view=c & _searchStrId=1498218513 & _rerunOrigin=google & _acct=C00005022\ 1 & _version=1 & _urlVersion=0 & _userid=10 & md5=659362a17808d2bfb1763a4cba210090 & searc\ htype=a For more on why whole food may help http://pursuitofresearch.org/science.html ===== Quote Link to comment Share on other sites More sharing options...
Guest guest Posted October 14, 2010 Report Share Posted October 14, 2010 Yes--fascianting research for sure --Thank you for posting it. it is well known in the reseearch literature that environemntal toxins weaken the immune system and predispose it to opportunistic infections---viruses--bacteria--parasites, fungi etc. The honey bees are experiencing a similar thing-----fungi infection it seems in their case---but toxic exposure caused the fungi to take hold over entire bee colonies and we all know what the demise of bees means for the rest of the ecosystem. http://www.naturalnews.com/030027_colony_collapse_disorder_Bayer.html All the best, Elena From: kiddietalk <kiddietalk@...> Subject: [ ] Fascinating new research for autism and many other disorders on the rise Date: Thursday, October 14, 2010, 12:02 PM Fascinating research not just for autism, but helps explain the rise in other disorders including metabolic and immune. . Also interesting to note the diet once again is mentioned as playing a role for helping rid the body of " Protozoan Parasites " . Diet; a possibly more important than previously thought, under-appreciated possible simple solution? Here's a clip Volume 5, Issue 1, January-March 2011, Pages 14-59 Review Metabolic, immune, epigenetic, endocrine and phenotypic abnormalities found in individuals with autism spectrum disorders, Down syndrome and Alzheimer disease may be caused by congenital and/or acquired chronic cerebral toxoplasmosis Department of Social Pediatrics, Faculty of Health Sciences, University Medical School, 5 Bartla Street, 51-618 Wroclaw, Poland Received 19 January 2010; revised 17 March 2010; accepted 18 March 2010. Available online 28 April 2010. Abstract Toxoplasma gondii is a protozoan parasite that infects about a third of human population. It is generally believed that in immunocompetent hosts, the parasite infection takes usually asymptomatic course and induces self-limiting disease, but in immunocompromised individuals may cause significant morbidity and mortality. T. gondii uses sulfated proteoglycans for host cell invasion and sulfated sugars on the surface of host cells may functions as key parasite receptors. Patients with autism spectrum disorders (ASD) have many inborn or acquired abnormalities of metabolism, including impaired sulfation and sulfoxidation. The impaired sulfation of dehydroepiandrosterone (DHEA) to DHEA-S affected normal development of various brain functions because DHEA-S inhibited vascular neuroinflammation in ASD individuals probably caused by cerebral toxoplasmosis (CT). Treatment of endothelial cells with DHEA-S dramatically inhibited the TNF-α-induced activation of NF-κB, an inflammatory transcription factor, and increased protein levels of the NF-κB inhibitor, IκB-α. A significant decrease in sulfation capacity found during pregnancy compared with post partum probably reflect a defense reaction of the host due to increased production of proinflammatory cytokines associated with frequent and widespread infection with this parasite. This suggestion may be supported by the finding that TNF and IL-1 mediated inhibitory effect of lipopolysaccharide on DHEA sulfotransferase mRNA level in Hep3B human hepatoma cells. It seems however that the impaired sulfation and sulfonation may be also beneficial for the host because lack or a markedly diminished anionic charge of the host cells associated with this event did not promote binding to the negatively charged outer leaflet of T. gondii plasma membranes. Phosphorylation of the parasite and/or host proteins is also of great importance in the process of T. gondii–host cell interaction. Furthermore, the increased male to female ratio characteristic for autistic participants most likely resulted from significantly increased testosterone levels associated with congenital T. gondii infection. It was demonstrated that the parasite, aging and dietary restriction have been able to induce DNA breakage, therefore one may suggest that such an epigenetic mechanism play an important role in development of Down syndrome (DS). Several data may support this notion: (a) autism occurs 10 times more often in children with trisomy 21 than in the general population, ( the parasite can be transmitted by semen and ovum, © autistic children exhibit impaired DNA methylation capacity, and (d) T. gondii affect chromatin structure and may cause dysregulation of the host cell cycle. Alzheimer disease (AD) also may be caused by CT because this abnormality is more prevalent in women, characterizes with a skewed capacity for xenobiotic metabolism especially of compounds containing sulfur that manifest as a decreased plasma levels of DHEA-S, and has marked immune irregularies in part due to aging. Moreover, chronic neuroinflammation characteristic for AD and DS individuals is associated with vascular lesions, patients with AD have increased levels of DNA breaks in the cerebral cortex, markedly enhanced production of proinflammatory cytokines, reactive oxygen species, and lipid peroxidation, disturbances in glucose metabolism, and irregularities in hypothalamic–pituitary axis. It must be noted that similar metabolic and endocrine disturbances have been reported also in humans and mice with chronic toxoplasmosis. Overproduction of IFN-γ and other proinflammatory cytokines associated with persistent neuroinflammation resulted in neurodegeneration and induced amyloid-β production also in DS, as well as accounted for cognitive impairment. Because bradyzoites and sporozoites throughout their life cycle accumulate large amounts of crystalline storage polysaccharide granules analogous to amylopectin within the cytoplasm and are able to build more complex macromolecules, they may be at least in part responsible for the production of amyloid-β senile plaques. Moreover, it seems that the accumulation of iron in senile plaques reflect a defense of the host against T. gondii because this transition metallic ion is necessary for proliferation of tachyzoites. Finally, the beneficial effects of ibuprofen in the patients with AD that restored cellular immunity, decreased production of proinflammatory cytokines, NO, amyloid-β, reduced lipid peroxidation and free radical generation, were consistent with the suggestion that congenital and/or acquired chronic latent CT play an important role in development of these types of neurodegeneration. Keywords: Autism spectrum disorders; Alzheimer disease; Down syndrome; Metabolism disturbances; Immune changes; Epigenetic irregularities; Carbohydrate metabolism; Phenotypic abnormalities; Testosterone levels; Amyloid-β plaques Article Outline 1. Introduction 2. Abnormalities in transsulfuration and transmethylation metabolism and DNA hypomethylation in children with ASD and their parents   2.1. Impaired sulfation and sulfoxidation metabolism     2.1.1. Patients with ASD     2.1.2. T. gondii infection   2.2. Impaired methylation capacity     2.2.1. Patients with ASD     2.2.2. Effect of growth factors, copper, and dopamine on methylation ability   2.2.2.1. Growth factors   2.2.2.2. Divalent copper   2.2.2.3. Dopamine and other catecholamines 3. T. gondii affects host cell chromatin structure which may, at least in part, participate in development of DS   3.1. Chromosomal disturbances in ASD   3.2. Chromosomal abnormalities in DS   3.3. Effects of T. gondii infection on mitosis and cell proliferation   3.4. Epigenetic chromosomal changes 4. Disturbances in phosphorylation   4.1. Hypophosphorylation of salivary peptidome in ASD individuals 5. Host cell manipulation by T. gondii 6. Neuroinflammation and other molecular abnormalities in AD participants 7. Dysregulated brain carbohydrate metabolism in patients with ASD, DS, and AD   7.1. Abnormal glucose metabolism in DS participants 8. T. gondii infection causes marked disturbances in carbohydrate metabolism 9. Pathophysiological role of amyloid-β plaques   9.1. Patients with AD   9.2. T. gondii infection and possible generation of amyloid plaques     9.2.1. Crystalline storage polysaccharide analogous to amylopectin produced by T. gondii bradyzoites may be, at least in part, responsible for development of amyloid-β containing plaques in ASD, DS, AD, and other neurodegenerative diseases 10. Increased activation of tryptophan metabolic pathway in AD individuals 11. A patient with AD and concomitant T. gondii infection 12. Disturbances of fatty acid profiles in ASD participants may, at least in part, be due to T. gondii infection 13. Increased phospholipase A2 (PLA2) levels in ASD/Asperger's syndrome individuals may enhance host cells invasion by T. gondii through increasing their penetration 14. T. gondii requires polyamines for proper growth, and heparan sulfate facilitates salvage of extracellular polyamines. Inhibitory effects of polyamines on lipid peroxidation 15. Disturbances of aminoacids levels in ASD participants 16. Important role of vasoactive intestinal peptide (VIP) in development of DS and ASD 17. Disturbances of sulfation of sugars on the surface of the host cells and irregularities of T. gondii and/or host proteins phosphorylation are important for invasion of the parasite to the host cells 18. Impaired sulfation of dehydroepiandrosterone (DHEA) to DHEA-S may reflect a defense reaction of ASD patients against T. gondii infection. Deficiency of DHEA-S affects however normal development of various brain functions and decreases efficiency of inhibition of vascular inflammation   18.1. T. gondii infection 19. Possible causes of the increased male to female ratio in ASD individuals   19.1. Increased testosterone and other androgens serum levels in patients with ASD   19.2. Women infected with T. gondii have more sons. Increased saliva testosterone concentrations in men with T. gondii infection   19.3. Effect of T. gondii infection on personality profiles of men and women   19.4. Correlation between T. gondii infection, salivary testosterone levels and lower left hand 2D:4D ratios   19.5. Handwriting impairments in children with ASD and shorter life span of left handed than right handed men 20. Abnormalities of steroid and hypothalamo–pituitary hormone levels and endocrinologic disturbances reported in patients with ASD, DS, and revealed during congenital or chronic T. gondii infection   20.1. ASD individuals   20.2. Patients with DS   20.3. Congenital toxoplasmosis   20.4. Acute toxoplasmosis   20.5. Mice 21. Important effects of the increased testosterone levels on the host References Thumbnail image Fig. 1. Various pathways of the essential amino acid tryptophan metabolism. About 99% of the dietary tryptophan is metabolized along the kynurenine pathway. Alternative pathways are the conversion of tryptophan to 5-hydroxytryptamine (5-HT) and then to melatonin, or to tryptamine and then to the kynuramines (or kynurenamines). 3-HAO, 3-Hydroxyanthranilate oxidase; IDO, indoleamine 2,3-dioxygenase; KAT, kynurenine aminotransferase; MAO, monoamine oxidase; QPRT, quinolinic-acid phosphoribosyl transferase; TDO, tryptophan 2,3-dioxygenase. Reproduced and modified with permission from Nature Reviews Drug Discovery (Stone & Darlington, 2002) copyright (2002) Macmillan Magazines Ltd. View Within Article Thumbnail image Fig. 2. Interrelationships between indoleamine 2,3-dioxygenase (IDO) and nitric oxide synthase (NOS) in macrophages or glial cells, and the potential interactions with neurons by means of N-methyl-d-aspartate (NMDA)-receptor-induced nitric-oxide (NO) formation. Arg, Arginine; 3-HAA, 3-hydroxyanthranilic acid; 3-HK, 3-hydroxykynurenine; IFN-γ, interferon-γ; IL, interleukin; Kyn, kynurenine; KynA, kynurenic acid; LPS, lipopolysaccharide; mRNA, messenger RNA; iNOS, inducible nitric-oxide synthase; TGF-β, transforming growth factor-β; TNF-α, tumor necrosis factor-α; Trp, tryptophan; xA, xanthurenic acid. The broken lines represent possible reactions. Reproduced with permission from Nature Reviews Drug Discovery (Stone & Darlington, 2002) copyright (2002) Macmillan Magazines Ltd. View Within Article Thumbnail image Fig. 3. Possible model for NO-mediated regulation of IDO in IFN-γ-primed mononuclear phagocytes. NOS, Nitric-oxide synthase; IDO, indoleamine 2,3-dehydrogenase, l-Arg, l-arginine; l-Trp, l-tryptophan; IFN-γ, interferon-γ; NO, nitric oxide; Kyn, kynurenine; 3-HAA, 3-hydroxyanthranilic acid; QA, quinolinic acid; SNP, sodium nitroprusside; GTN, glyceryl trinitrate; SNAP, S-nitroso-N-acetylpenicillamine; DEANO, diethylaminodinitric oxide. SNP, DEANO, and SNAP release NO extracellularly, while GTN is thought to release NO intracellularly. Nitric Oxide Inhibits Indoleamine 2,3-Dioxygenase Activity in Interferon-γ Primed Mononuclear Phagocytes, vol. 269, pp. 14457–14464/The Journal of Biological Chemistry by SR, Mohr D, Stockert R. Copyright [1994] by The American Society for Biochemistry and Molecular Biology. Reprinted by permission of The American Society for Biochemistry and Molecular Biology via the Copyright Clearance Center. View Within Article Table 1. Glycolytic enzymes identified in T. gondii (Fleige et al., 2007; with own modification). View table in article View Within Article Table 1A. Selected modifications in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in metabolism (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression (↓), upregulated (↑), or modulated (M). Modulated proteins had expression altered across several isoforms on the same gel using the Amersham difference gel electrophoresis, and this probably indicated a posttranslational modification event ( et al., 2008). a The host cell proteins, which also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). View Within Article Table 1B. Selected modifications in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in glycolysis (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression (↓), upregulated (↑), or modulated (M). a These host cell proteins also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). It must be noted that T. gondii tachyzoites are thought to rely upon both glycolysis and the tricarboxylic acid cycle, while bradyzoites are largely dependent upon glycolysis (Tomavo et al., 2001; Xia et al., 2008). Although tachyzoites utilize both glycolysis and oxidative phosphorylation to obtain energy, glycolysis seems to be the predominant pathway for ATP synthesis in the bradyzoite ([Coppin et al., 2003] and [Denton et al., 1996]). Moreover, ENO2 and lactate dehydrogenase1 are only found in tachyzoites while ENO1 and lactate dehydrogenase 2 are exclusively expressed in bradyzoites ([Dzierszinski et al., 2001] and [Ferguson et al., 2002]). Silencing of tachyzoite ENO2 altered nuclear targeting of bradyzoite ENO1 in T. gondii (Holmes et al., 2009). View Within Article Table 1C. Selected changes in the proteomes of human foreskin fibroblasts infected with T. gondii: proteins implicated in cell cycle, transcription, and translation (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression (↓), upregulated (↑), or modulated (M). View Within Article Table 1D. Selected proteins modulated in the parasite-modified parasitophorous vacuole-associated organelles from T. gondii infected and noninfected cells (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression (↓), upregulated (↑), or modulated (M). a These host cell proteins also changed expression in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). Interestingly, host cell invasion and egress induce marked relocations of glycolytic enzymes in T. gondii tachyzoites and this ability allows the parasite to optimize ATP delivery to those cellular processes that are important for survival outside host cells and those required for growth and multiplication (Pomel, Luk, & Beckers, 2008). On the other hand, treatment of macrophages with ATP activates ROS-dependent oxidative stress response and secretion of proinflammatory cytokines (Cruz et al., 2007), characteristic for neuroinflammation and neurodegeneration processes in ASD, DS, and AD. View Within Article Table 1E. Selected changes in the proteomes of human foreskin fibroblasts by T. gondii infection: various proteins (acc. to et al., 2008; with own modification). View table in article Host cell proteins were designated as being downregulated in expression (↓), upregulated (↑), or modulated (M). a The host cell proteins changed expression also in the brains of patients with mild cognitive impairement, early AD, or AD (Butterfield and Lange, 2009). View Within Article Table 2. Immune system abnormalities in autistic individuals (acc. to Ashwood, Wills, & de Water, 2006, with own modification). View table in article PDD, pervasive developmental disorder; TLR2, toll-like receptor 2 (lipoteichoic acid); TLR4, lipopolysaccharide; TLR9, synthetic oligonucleotides containing CpG-B motifs, GM-CSF, granulocyte/macrophage colony stimulating factor. It must be noted that IL-6 promoted innate NK cell production of IL-17 during toxoplasmosis (Passos et al., 2010). aLeptin has the structure similar to that of IL-2 and may activate the innate immune system and shift the cognate immune system toward a predominance of a proinflammatory TH1 T cell population while reducing the regulatory TH2 phenotype. bIt is interesting that antibodies raised against T. gondii predominantly belonged to the IgG2a subclass, an isotype of which production is usually mostly controlled by TH1 cytokines, and especially IFN-γ ([Nguyen et al., 2003] and [Markine-Goriaynoff et al., 2000]). c,dThe complement system proteins are involved in the lysis and removal of infectious organisms in blood, and may be involved in cellular apoptosis in brain ([Chauhan et al., 2005] and [Chauhan and Chauhan, 2006]).These increases may therefore reflect immune defense of the host because complement has membrane lytic activity directed against the extracellular stage of T. gondii (Seeber, 2000). It must be noted that reduced serum levels of transferrin in autism (Chauhan, Chauhan, Cohen et al., 2004) affect normal early T-cell differentiation (Macedo et al., 2004). View Within Article Table 3. Partial downregulation of cell-mediated immune responses after infection with T. gondii (Lang et al., 2007, with own modification). View table in article CIITA, master regulator of major histocompatibility complex class II transcription; CCR5, CC chemokine receptor; DCs, dendritic cells; iNOS, inducible nitric oxide synthase; IRF-1, interferon regulatory factor-1; LXA4, lipoxin A4; MHC, major histocompatibility complex molecules; PGE2, prostaglandin E2; TGF-β, transforming growth factor-β. Proliferation of T. gondii in inflammatory macrophages was associated with diminished ROS production in host cells (Shrestha, Tomita, Weiss, & Orlofsky, 2006). In young children with congenital toxoplasmosis specific T cell response to the parasite antigens was impaired and such hyporesponsiveness has been restored during childhood. The acquisition of functional T cell response was disease-unrelated and indistinguishable in terms of strength, epitope specificity, and cytokine profile from the corresponding responses in immunocompetent adults with asymptomatic acquired T. gondii infection (Guglietta et al., 2007). In pregnant mice, T. gondii infection caused a decrease of CD4+CD25+-regulatory T cells (Ge et al., 2008). It must be noted that peripheral blood leukocytes (PBL) from healthy children older than 36 months responded to several stimuli at levels comparable to those of PBL from adults, but surprisingly, cord blood leukocytes appeared to be more efficient in antigen-presenting function than PBL from children younger than 13 months (Clerici, Depalma, Roilides, Baker, & Shearer, 1993). View Within Article Table 3A. Suppression of immune responses to T. gondii by parasite-triggered modulation of host cell apoptosis (acc. to Lang et al., 2007; with own modification). View table in article CTL, Cytotoxic T lymphocyte; Fas, receptor; FasL, Fas ligand (a cell surface molecule belonging to TNF family and death factor, which binds to its receptor Fas, thus inducing apoptosis of Fas-bearing cells); NK, natural killer cells; PARP, poly(ADP-ribose) polymerase. a T. gondii delayed neutrophil apoptosis by inducing granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor secretion by the parasite-infected human fibroblasts. Although neutrophils are unable to kill T. gondii, this can retard their division time from the usual 6-8 hrs cycle to a 24 hrs cycle and this enhanced neutrophil survival may contribute to the robust proinflammatory response elicited in the pathogen-infected host cells (Channon, Miselis, Minns, Dutta, & Kasper, 2002). View Within Article Table 4. Biomolecules of T. gondii regulating the host innate immune responses (Pollard et al., 2009; with own modification). View table in article CCR5, CC-chemokine family receptor; GPI, glycosyl-phosphatidylinositol; HSP70, heat shock protein 70; ROP, T. gondii rhoptry; TLR, toll-like receptor ligands, TLR2, lipoteichoic acid; TLR4, LPS; TLR11, is one of three mouse TLRs activated specifically by uropathogenic bacteria. View Within Article Table 5. Proteins undergoing a change in phosphorylation state following T. gondii infection (acc. to et al., 2008; with own modification). View table in article T. gondii kinase activity is involved in phosphorylation of host IκBα and this unusual mechanism can be utilized in manipulating the NF-κB pathway (Molestina & Sinai, 2005). It must be noted that in DS, T cell activation deficiency was associated with an aberrant pattern of protein tyrosine phosphorylation after CD3 perturbation (Scotese et al., 1998). Abnormal hyperphosphorylation of tau and abberrant tau aggregation has been also found in AD ([Avila, 2000] and [Avila, 2006]). It must be noted that psudohyperphosphorylated tau was toxic to cells and was associated with induction of apoptotic cell death (Shimura et al., 2004). View Within Article Table 6. Bradyzoite and tachyzoite stage-specifically expressed genes coding the enzymes involved in T. gondii amylopectin metabolism (acc. to Coppin et al., 2005; with own modification). View table in article ↑↑↑, Markedly increased gene expression; ↑↑, increased expression; ↑, weak expression; 0, no gene present. T. gondii enzymes were identified at the genome Web site: htttp://www.toxodb.org. The parasite genome encodes two fructose 1,6-biphosphatase isoenzymes, a single pyruvate-carboxylase, and two PEP-carboxykinases. The conversion from glucose-6-phosphate into glucose-1-phosphate, which forms the link between amylopectin metabolism and gluconeogenesis, is catalysed by two isoforms of glucosephosphate-mutase (Fleige, Pfaff, Gross, & Bohne, 2008). The following soluble tachyzoite antigenic proteins have been identified: a putative protein disulfide isomerase, Hsp60, Hsp70, a pyruvate kinase, a putative glutamate dehydrogenase, a coronin, a protein kinase C receptor 1, a malate dehydrogenase, a major surface antigen 1, an uridine phosphorylase, and a peroxiredoxin (Ma et al., 2009). View Within Article Table 7. Drugs tested for in vitro activity against T. gondii (acc. to -Brando et al., 2003; with own modification). View table in article DMSO: dimethylsulfoxide; Toxo CGM: Toxoplasma cell growth medium. Valproic acid at a concentration of 1 μg/ml inhibited 7% of the tachyzoites and trimethoprim at 3.2 μg/ml produced 2% inhibition, but the combination of these two compounds at those concentrations resulted in a potentiating effect inhibiting 55% of the tachyzoites. a Median inhibitory dose, a measure of tachyzoite inhibition. b Median toxicity dose, a measure of cytotoxicity. c Therapeutic index, a measure of efficacy determined by TD50/ID50 ratio. View Within Article Table 8. Hypoxia inducible gene expressiona (acc. to Prandota, 2004). View table in article a T. gondii activates hypoxia-inducible factor 1 (HIF1) already at physiologically relevant oxygen levels and requires HIF1 for growth and survival (Spear et al., 2006). View Within Article Corresponding Author Contact InformationTel.: +48 071 348 42 10; fax: +48 71 345 93 24. Research in Autism Spectrum Disorders Volume 5, Issue 1, January-March 2011, Pages 14-59 http://www.sciencedirect.com/science?_ob=ArticleURL & _udi=B83X1-4YYGYT6-1 & _user=1\ 0 & _coverDate=03%2F31%2F2011 & _rdoc=1 & _fmt=high & _orig=search & _origin=search & _sort=\ d & _docanchor= & view=c & _searchStrId=1498218513 & _rerunOrigin=google & _acct=C00005022\ 1 & _version=1 & _urlVersion=0 & _userid=10 & md5=659362a17808d2bfb1763a4cba210090 & searc\ htype=a For more on why whole food may help http://pursuitofresearch.org/science.html ===== Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.