Text of study of ARBs for arthritis, effects on TH1 & TH2.

[Guest guest]

Back in June, the study of ARBs on arthritis was discussed, but I

don't think anyone had access to the actual text of the study (at

least no one posted it here, that I could find). Having just read it,

I think it might be of interest to other people. Here is the

conclusions section of it. Especially note the following quotes:

" We chose olmesartan (Benicar) from among the ARBs because it

suppressed Th1 responses in vivo more potently than did the other ARBs

tested. "

" mean arthritis scores were only slightly improved when olmesartan was

administered every other day but were extremely improved when

olmesartan was administered daily. Thus, for more effective

suppression, the means of administration and the doses of ARB need to

be modified. "

Arthritis Rheum. 2005 Jun;52(6):1920-8.

Angiotensin receptor blockers suppress antigen-specific T cell

responses and ameliorate collagen-induced arthritis in mice.

Sagawa K, Nagatani K, Komagata Y, Yamamoto K.

University of Tokyo, Tokyo, Japan.

n this study, we examined the influence of ARBs on antigen-specific

Th1 and Th2 responses in vivo. Furthermore, we assessed the

immunosuppressive effects of ARBs on the development of the murine CIA

model, which is a Th1-driven animal model of human RA. Naive CD4+ T

cells differentiate into 2 distinct subpopulations, Th1 cells and Th2

cells, each of which produces its own panel of cytokines and mediates

separate functions ([16]). Th1 cells secrete IFN, IL-2, and tumor

necrosis factor ([16]), thereby activating macrophages, inducing

delayed-type hypersensitivity responses, and helping in the

immunoglobulin isotype switch from IgM to IgG2a ([17]). In contrast,

Th2 cells secrete IL-4, IL-5, and IL-10 in response to extracellular

bacterial pathogens and help in the immunoglobulin isotype switch from

IgM to IgG1 and IgE ([16][17]).

In our study, the proliferation of antigen-specific Th1 cells and the

production of IFN in vitro were suppressed by ARB administration in

vivo (Figures 1 and 2), although the suppressive effect of telmisartan

was smaller than that of the other ARBs, olmesartan and candesartan

(data not shown). However, production of the Th1-dependent IgG

antibody (IgG2a) was not suppressed (Figure 1C). In addition, ARBs

also reduced antigen-specific Th2 cell proliferation, although the

level of suppression of Th2 responses was lower than that of Th1

responses (Figure 4). As in the case of Th1, production of

Th2-dependent IgG antibody (IgG1) was not significantly different

between ARB-treated mice and controls (data not shown). Generally, the

proliferation of Th1 cells prevents the generation of Th2 cells,

whereas the proliferation of Th2 cells prevents the generation of Th1

cells ([18]). In a continuous Ang II infusion model of rats, Shao et

al ([5]) showed that Ang II polarized CD4+ T cells into Th1

lymphocytes, and that the polarization was normalized by ARBs.

Interestingly, in our study ARBs suppressed not only Th1 responses but

also Th2 responses in vivo without enhancing the production of Th2 or

Th1 cytokines. It is possible that ARBs suppress both Th1 and Th2

responses in cases in which CD4+ T cells are extremely polarized into

Th1 or Th2 cells.

Several recent studies have demonstrated the protective effects of RAS

antagonists in immunologically mediated conditions such as

myocarditis, chronic allograft rejection, and antiglomerular basement

membrane nephritis ([9-12][14][19-21]). However, the mechanism

underlying the beneficial actions of RAS inhibitors in preventing

immunologic injury in these models is still unclear. To analyze the

immunosuppressive effect of ARBs on Th1 responses in a disease model,

we administered olmesartan orally in a murine CIA model. We chose

olmesartan from among the ARBs because it suppressed Th1 responses in

vivo more potently than did the other ARBs tested. There were no signs

that blood pressure was reduced in any of the mice throughout this

study. In our study, the development and progression of CIA appeared

to be blocked in the olmesartan-treated group (Figure 5). Furthermore,

not only the clinical scores but also results of the histologic

analysis of olmesartan-treated mice revealed that their joints had

much milder inflammation compared with control mice (Table 1).

Importantly, olmesartan was effective even when it was introduced

after the onset of arthritis (Figures 5D-F). These data suggest that

ARBs may be useful therapeutically in RA, and that Ang II may be

involved in the development of CIA.

CIA is associated with a Th1-polarized immune response, rendering it

an excellent model in which to explore the effect of olmesartan in

vivo. To confirm the relationship between the CII-specific immune

responses in vitro and CIA in vivo, we examined CII-specific

proliferation and cytokine production by draining lymph node cells

obtained from mice belonging to the same strain, DBA/1 (Figure 3).

According to our data, CII-specific proliferation and IFN production

were suppressed in vitro (Figures 3A and . Moreover, in order to

make sure that the suppressive effects of olmesartan were

antigen-specific, we examined the response of lymphocytes to a mitogen

(Figures 3A and . Concanavalin A-induced proliferation and IFN

production were similar between the olmesartan-treated and control

groups, indicating that olmesartan suppresses only antigen-specific

responses. During the acute phase (day 9), the levels of CII-specific

IgG2a were also similar between the olmesartan and control groups, but

during a later phase (day 88) the levels in the olmesartan group were

significantly suppressed (Figure 6). These data suggest that

olmesartan can effectively suppress anti-collagen B cell responses

during a later phase of CIA.

It has been reported that immunocompetent cells, including T cells,

macrophages, and dendritic cells, are equipped with components of the

RAS, and that they can participate in the production of Ang II

([22-24]). It has also been reported that AT1 receptors are expressed

in human synovium ([25]), and that ACE activity in synovial fluid is

increased in patients with arthritis ([26-28]). It has been

demonstrated that both AT1 and AT2 receptors activate the NF-B pathway

and up-regulate the NF-B gene ([6-8][29-32]). The constitutive

activation of the NF-B pathway is often associated with inflammatory

diseases such as RA, inflammatory bowel diseases, multiple sclerosis,

and asthma ([33]). In our study, ARB administration attenuated the

development of CIA clinically and pathologically, suggesting that Ang

II, which in the CIA model is locally generated in the synovium,

exacerbates inflammation of the synovium in articular muscle via the

up-regulation of NF-B. Alternatively, it has been speculated that

another mechanism allows ARBs to directly suppress Th1 responses,

because the AT1 receptor is present on T cells ([34-36]).

Ang II acts via AT1 and/or AT2 receptors. AT1 receptors are involved

in cell proliferation as well as in the production of cytokines and

extracellular matrix proteins by cultured cells ([4][32][37][38]). AT2

receptors regulate blood pressure control and renal natriuresis, and,

after vascular injury, inhibit both cell proliferation and neointimal

formation. Because Ang II activates NF-B via both AT1 and AT2

receptors, and because Esteban et al ([31]) showed that only combined

treatment with AT1 and AT2 antagonists completely blocked renal

inflammatory infiltration and NF-B activation in Ang II-infused mice,

therapy combining AT1 and AT2 antagonists may be more effective than

therapy using AT1 antagonist alone in reducing the inflammation of

arthritis. In this study, we administered a relatively high dose of

olmesartan to mice. This approach was used because Shao et al

demonstrated an increase in the level of IFN and a decrease in the

level of IL-4 in Ang II-infused rats and showed that this imbalance in

T cell subsets was reversed by olmesartan, in a dose-dependent manner

([5]). Furthermore, in the CIA model, mean arthritis scores were only

slightly improved when olmesartan was administered every other day but

were extremely improved when olmesartan was administered daily. Thus,

for more effective suppression, the means of administration and the

doses of ARB need to be modified.

In conclusion, our findings suggest that ARBs restrain exacerbation of

arthritis in the CIA model. It was previously reported that the ACE

inhibitor captopril improved arthritis symptoms and laboratory values

in patients with active arthritis ([13]). However, it has never been

reported that ARBs may be of therapeutic benefit to patients with

arthritis. It has become clear that several serine proteases,

including kallikrein, cathepsin G, and chymase, are related to

ACE-independent Ang II formation in vivo ([39][40]); in particular,

chymase is responsible for most Ang II formation in humans ([41]). The

ARBs have much greater potential than ACE inhibitors for blocking

angiotensin II production, and they may be better drugs for patients

with arthritis and hypertension.

[Guest guest]

Mark, the quotes you lead off with, are those meant to suggest an

analogy with the very high doses of ARBs used in the MP?

If so, it might be helpful to know what the authors mean, in terms

of actual doses used, when they say below:

" In this study, we administered a relatively high dose of olmesartan

to mice. "

You seem to have the full text, in which the authors will have

specified the actual dose or ratio to body weight used, which would

tell us if we are seeing something analagous to the MP or not.

Have you looked at comparable studies on DBA/1 mice and collagen-

induced arthritis? A number of substances can completely prevent

this 'experimental model' of RA in these mice.

I'm not sure how valid a model CIA is, but the points I would want

to compare would be:

1) Effective suppression of collagen-specific antibodies

2) Clinical and histopathological improvement measures

3) Ability of agent to leave most or all non CIA immune responses

and body systems undisturbed (no side effects).

1,25-D (and analogues which have less potential for causing

hypercalcemia) have been shown to completely prevent CIA when DBA/1

mice are pre-treated and reduce inflammation dramatically when DBA/1

mice are post-treated.

If we put full-length studies side-by-side, we might be able to make

a comparison by the three criteria I suggest. We might be able to

gather, for example, whether this result reported in the Pub Med

abstract of your study:

" ARBs severely suppressed lymphocyte proliferation and interferon-

gamma production in mice immunized with OVA or type II collagen in

CFA. "

....is really necessary, in order to resolve symptoms, or whether

less immunosuppressive agents can accomplish the same result.

I think with a little time I can dig up a nice, detailed, full-text

study on one or two alternative agents, and provide them to you.

Perhaps if you get time you could see how levels of

immunosuppression and disease resolution compare.

In the meantime, it shouldn't take more than a minute to find the

actual dose or mg/kg ratio of Olmesartan used in this experiment.

Could you provide that?

Thanks,

S.

> Back in June, the study of ARBs on arthritis was discussed, but I

> don't think anyone had access to the actual text of the study (at

> least no one posted it here, that I could find). Having just read

it,

> I think it might be of interest to other people. Here is the

> conclusions section of it. Especially note the following quotes:

>

> " We chose olmesartan (Benicar) from among the ARBs because it

> suppressed Th1 responses in vivo more potently than did the other

ARBs

> tested. "

>

> " mean arthritis scores were only slightly improved when olmesartan

was

> administered every other day but were extremely improved when

> olmesartan was administered daily. Thus, for more effective

> suppression, the means of administration and the doses of ARB need

to

> be modified. "

>

>

> Arthritis Rheum. 2005 Jun;52(6):1920-8.

>

> Angiotensin receptor blockers suppress antigen-specific T cell

> responses and ameliorate collagen-induced arthritis in mice.

>

> Sagawa K, Nagatani K, Komagata Y, Yamamoto K.

> University of Tokyo, Tokyo, Japan.

>

> n this study, we examined the influence of ARBs on antigen-specific

> Th1 and Th2 responses in vivo. Furthermore, we assessed the

> immunosuppressive effects of ARBs on the development of the murine

CIA

> model, which is a Th1-driven animal model of human RA. Naive CD4+ T

> cells differentiate into 2 distinct subpopulations, Th1 cells and

Th2

> cells, each of which produces its own panel of cytokines and

mediates

> separate functions ([16]). Th1 cells secrete IFN, IL-2, and tumor

> necrosis factor ([16]), thereby activating macrophages, inducing

> delayed-type hypersensitivity responses, and helping in the

> immunoglobulin isotype switch from IgM to IgG2a ([17]). In

contrast,

> Th2 cells secrete IL-4, IL-5, and IL-10 in response to

extracellular

> bacterial pathogens and help in the immunoglobulin isotype switch

from

> IgM to IgG1 and IgE ([16][17]).

>

> In our study, the proliferation of antigen-specific Th1 cells and

the

> production of IFN in vitro were suppressed by ARB administration in

> vivo (Figures 1 and 2), although the suppressive effect of

telmisartan

> was smaller than that of the other ARBs, olmesartan and candesartan

> (data not shown). However, production of the Th1-dependent IgG

> antibody (IgG2a) was not suppressed (Figure 1C). In addition, ARBs

> also reduced antigen-specific Th2 cell proliferation, although the

> level of suppression of Th2 responses was lower than that of Th1

> responses (Figure 4). As in the case of Th1, production of

> Th2-dependent IgG antibody (IgG1) was not significantly different

> between ARB-treated mice and controls (data not shown). Generally,

the

> proliferation of Th1 cells prevents the generation of Th2 cells,

> whereas the proliferation of Th2 cells prevents the generation of

Th1

> cells ([18]). In a continuous Ang II infusion model of rats, Shao

et

> al ([5]) showed that Ang II polarized CD4+ T cells into Th1

> lymphocytes, and that the polarization was normalized by ARBs.

> Interestingly, in our study ARBs suppressed not only Th1 responses

but

> also Th2 responses in vivo without enhancing the production of Th2

or

> Th1 cytokines. It is possible that ARBs suppress both Th1 and Th2

> responses in cases in which CD4+ T cells are extremely polarized

into

> Th1 or Th2 cells.

>

> Several recent studies have demonstrated the protective effects of

RAS

> antagonists in immunologically mediated conditions such as

> myocarditis, chronic allograft rejection, and antiglomerular

basement

> membrane nephritis ([9-12][14][19-21]). However, the mechanism

> underlying the beneficial actions of RAS inhibitors in preventing

> immunologic injury in these models is still unclear. To analyze the

> immunosuppressive effect of ARBs on Th1 responses in a disease

model,

> we administered olmesartan orally in a murine CIA model. We chose

> olmesartan from among the ARBs because it suppressed Th1 responses

in

> vivo more potently than did the other ARBs tested. There were no

signs

> that blood pressure was reduced in any of the mice throughout this

> study. In our study, the development and progression of CIA

appeared

> to be blocked in the olmesartan-treated group (Figure 5).

Furthermore,

> not only the clinical scores but also results of the histologic

> analysis of olmesartan-treated mice revealed that their joints had

> much milder inflammation compared with control mice (Table 1).

> Importantly, olmesartan was effective even when it was introduced

> after the onset of arthritis (Figures 5D-F). These data suggest

that

> ARBs may be useful therapeutically in RA, and that Ang II may be

> involved in the development of CIA.

>

> CIA is associated with a Th1-polarized immune response, rendering

it

> an excellent model in which to explore the effect of olmesartan in

> vivo. To confirm the relationship between the CII-specific immune

> responses in vitro and CIA in vivo, we examined CII-specific

> proliferation and cytokine production by draining lymph node cells

> obtained from mice belonging to the same strain, DBA/1 (Figure 3).

> According to our data, CII-specific proliferation and IFN

production

> were suppressed in vitro (Figures 3A and . Moreover, in order to

> make sure that the suppressive effects of olmesartan were

> antigen-specific, we examined the response of lymphocytes to a

mitogen

> (Figures 3A and . Concanavalin A-induced proliferation and IFN

> production were similar between the olmesartan-treated and control

> groups, indicating that olmesartan suppresses only antigen-specific

> responses. During the acute phase (day 9), the levels of CII-

specific

> IgG2a were also similar between the olmesartan and control groups,

but

> during a later phase (day 88) the levels in the olmesartan group

were

> significantly suppressed (Figure 6). These data suggest that

> olmesartan can effectively suppress anti-collagen B cell responses

> during a later phase of CIA.

>

> It has been reported that immunocompetent cells, including T cells,

> macrophages, and dendritic cells, are equipped with components of

the

> RAS, and that they can participate in the production of Ang II

> ([22-24]). It has also been reported that AT1 receptors are

expressed

> in human synovium ([25]), and that ACE activity in synovial fluid

is

> increased in patients with arthritis ([26-28]). It has been

> demonstrated that both AT1 and AT2 receptors activate the NF-B

pathway

> and up-regulate the NF-B gene ([6-8][29-32]). The constitutive

> activation of the NF-B pathway is often associated with

inflammatory

> diseases such as RA, inflammatory bowel diseases, multiple

sclerosis,

> and asthma ([33]). In our study, ARB administration attenuated the

> development of CIA clinically and pathologically, suggesting that

Ang

> II, which in the CIA model is locally generated in the synovium,

> exacerbates inflammation of the synovium in articular muscle via

the

> up-regulation of NF-B. Alternatively, it has been speculated that

> another mechanism allows ARBs to directly suppress Th1 responses,

> because the AT1 receptor is present on T cells ([34-36]).

>

> Ang II acts via AT1 and/or AT2 receptors. AT1 receptors are

involved

> in cell proliferation as well as in the production of cytokines and

> extracellular matrix proteins by cultured cells ([4][32][37][38]).

AT2

> receptors regulate blood pressure control and renal natriuresis,

and,

> after vascular injury, inhibit both cell proliferation and

neointimal

> formation. Because Ang II activates NF-B via both AT1 and AT2

> receptors, and because Esteban et al ([31]) showed that only

combined

> treatment with AT1 and AT2 antagonists completely blocked renal

> inflammatory infiltration and NF-B activation in Ang II-infused

mice,

> therapy combining AT1 and AT2 antagonists may be more effective

than

> therapy using AT1 antagonist alone in reducing the inflammation of

> arthritis. In this study, we administered a relatively high dose of

> olmesartan to mice. This approach was used because Shao et al

> demonstrated an increase in the level of IFN and a decrease in the

> level of IL-4 in Ang II-infused rats and showed that this

imbalance in

> T cell subsets was reversed by olmesartan, in a dose-dependent

manner

> ([5]). Furthermore, in the CIA model, mean arthritis scores were

only

> slightly improved when olmesartan was administered every other day

but

> were extremely improved when olmesartan was administered daily.

Thus,

> for more effective suppression, the means of administration and the

> doses of ARB need to be modified.

>

> In conclusion, our findings suggest that ARBs restrain

exacerbation of

> arthritis in the CIA model. It was previously reported that the ACE

> inhibitor captopril improved arthritis symptoms and laboratory

values

> in patients with active arthritis ([13]). However, it has never

been

> reported that ARBs may be of therapeutic benefit to patients with

> arthritis. It has become clear that several serine proteases,

> including kallikrein, cathepsin G, and chymase, are related to

> ACE-independent Ang II formation in vivo ([39][40]); in particular,

> chymase is responsible for most Ang II formation in humans ([41]).

The

> ARBs have much greater potential than ACE inhibitors for blocking

> angiotensin II production, and they may be better drugs for

patients

> with arthritis and hypertension.

[Guest guest]

> Mark, the quotes you lead off with, are those meant to suggest an

> analogy with the very high doses of ARBs used in the MP?

>

> If so, it might be helpful to know what the authors mean, in terms

> of actual doses used, when they say below:

Probably not, because the dose they used, seems to be a standard

dose used in other ARB studies, i.e. 10 mg/kg There was no attempt

in the study to see if lower doses were as useful.

> Have you looked at comparable studies on DBA/1 mice and collagen-

> induced arthritis? A number of substances can completely prevent

> this 'experimental model' of RA in these mice.

Yes. There seems to be a lot of recent studies that attempt to

increase IL-4 levels.

But my real point of bringing up this study, is that there is no

need (or rational) to believe that Benicar has " antibiotic " or " anti-

vitamin d " effect, when significant anti-inflammtory and immune

effects have been well documented. Plus, it shows that Benicar is

better at doing that. Of course, it makes sense, i.e. the ARB that

binds the strongest to AT1 receptors SHOULD be the best. There is

no need to have to believe that Benicar is binding to some form of

bacteria. And this study also explains the need for constantly high

doses.

> 1,25-D (and analogues which have less potential for causing

> hypercalcemia) have been shown to completely prevent CIA when DBA/1

> mice are pre-treated and reduce inflammation dramatically when

DBA/1

> mice are post-treated.

I assume you are referring to this study:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=9822288 & query_hl=14

I can't find any study on CIA and 1,25-D itself. And it's hard to

compare the 2, since " in inhibiting allogeneic T cell activation, MC

1288 is about 300 times more potent than 1alpha,25(OH)2D3 " Since

that study was done back in 1998, one would have thought that that

analogue (or another one) would now be in use for RA. I don't know

of any yet (do you)? My impression is that they are still looking

for one that doesn't have hypercalcemia or other side effects.

> " ARBs severely suppressed lymphocyte proliferation and interferon-

> gamma production in mice immunized with OVA or type II collagen in

> CFA. "

>

> ...is really necessary, in order to resolve symptoms, or whether

> less immunosuppressive agents can accomplish the same result.

ARBs cause a lot less suppression than vitamin D does, because

vitamin D (or it's analogues) not only suppress lymphocyte

proliferation, but also affects cytokine levels.

Angiotensin II simply is not that impressive in terms of any

positive effects on the immune system. For a good study on it's

effects, see:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=10606623 & query_hl=27

It is hard to believe that something the body creates is actually

bad for a lot of health conditions. However, a lot of people

theorize that Angiotensin II is something that the body might have

had a greater need for in the past, like for wound repair, which is

of much less of a problem in modern humans.

Mark

[Guest guest]

Hi Mark,

You say the study used a dosing ratio of 10mg/kg. A person of

average body weight, say 140 pounds, would weigh 63.5 kg. At

10mg/kg, that would make for a dose of 635 milligrams of Benicar a

day, yes?

This article show the results using 1,25-D in the same mice, with

the same collagen induced arthritis, at a dose that did not disturb

serum calcium levels.

It also includes an experiement that used a model of Lyme arthritis

(different mice, a necessity I think because most don't develop Lyme

arthritis from Bb). It might offer an interesting comparison:

http://xrl.us/ehh5

S.

> > Mark, the quotes you lead off with, are those meant to suggest an

> > analogy with the very high doses of ARBs used in the MP?

> >

> > If so, it might be helpful to know what the authors mean, in

terms

> > of actual doses used, when they say below:

>

> Probably not, because the dose they used, seems to be a standard

> dose used in other ARB studies, i.e. 10 mg/kg There was no

attempt

> in the study to see if lower doses were as useful.

>

> > Have you looked at comparable studies on DBA/1 mice and collagen-

> > induced arthritis? A number of substances can completely prevent

> > this 'experimental model' of RA in these mice.

>

> Yes. There seems to be a lot of recent studies that attempt to

> increase IL-4 levels.

>

> But my real point of bringing up this study, is that there is no

> need (or rational) to believe that Benicar has " antibiotic "

or " anti-

> vitamin d " effect, when significant anti-inflammtory and immune

> effects have been well documented. Plus, it shows that Benicar is

> better at doing that. Of course, it makes sense, i.e. the ARB

that

> binds the strongest to AT1 receptors SHOULD be the best. There is

> no need to have to believe that Benicar is binding to some form of

> bacteria. And this study also explains the need for constantly

high

> doses.

>

> > 1,25-D (and analogues which have less potential for causing

> > hypercalcemia) have been shown to completely prevent CIA when

DBA/1

> > mice are pre-treated and reduce inflammation dramatically when

> DBA/1

> > mice are post-treated.

>

> I assume you are referring to this study:

>

> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

> cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=9822288 & query_hl=14

>

> I can't find any study on CIA and 1,25-D itself. And it's hard to

> compare the 2, since " in inhibiting allogeneic T cell activation,

MC

> 1288 is about 300 times more potent than 1alpha,25(OH)2D3 " Since

> that study was done back in 1998, one would have thought that that

> analogue (or another one) would now be in use for RA. I don't

know

> of any yet (do you)? My impression is that they are still looking

> for one that doesn't have hypercalcemia or other side effects.

>

> > " ARBs severely suppressed lymphocyte proliferation and

interferon-

> > gamma production in mice immunized with OVA or type II collagen

in

> > CFA. "

> >

> > ...is really necessary, in order to resolve symptoms, or whether

> > less immunosuppressive agents can accomplish the same result.

>

> ARBs cause a lot less suppression than vitamin D does, because

> vitamin D (or it's analogues) not only suppress lymphocyte

> proliferation, but also affects cytokine levels.

>

> Angiotensin II simply is not that impressive in terms of any

> positive effects on the immune system. For a good study on it's

> effects, see:

>

> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

> cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=10606623 & query_hl=27

>

> It is hard to believe that something the body creates is actually

> bad for a lot of health conditions. However, a lot of people

> theorize that Angiotensin II is something that the body might have

> had a greater need for in the past, like for wound repair, which

is

> of much less of a problem in modern humans.

>

> Mark