Kofi
Guest
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 Posted: Thu Oct 02, 2008 11:11 am Post subject: Mycobacterium - kill the bacteria or induce tolerance? |
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I had an enlightening conversation this week with my doctor about
theoretical models of Crohn>s. Off the top of my head, I mentioned that
many of the agents used to treat Crohn>s turned out to be anti-MAP
antibodies. That>s wrong, I know, but it was a long conversation and I
don>t have perfect recall of thousands of research results off the top
of my head. But it was one of those felicitous mistakes. What>s
interesting is what he said in response. He said, have you ever
considered that maybe these treatments are inducing tolerance to MAP
similar to low-dose allergen therapies?
It made a kind of sense when I thought they were antibodies. Well, that
made me go back to the original paper and I realized the agents were
antiMAP *antibiotics*, not antibodies. However, the antibody search I
ran to find it turned up the possibility of an anti-OCTN1 antibody
response in Crohn>s triggered by genetic overlap with Campylobacter
jejuni and Mycobacterium paratuberculosis. That lead me to think that
maybe what you have going wrong in Crohns/IBD/colitis is not just an
infection but also cross-reactive antibodies to the infection. Maybe in
some individuals, the MAP infection isn>t even severe in the first place
(at least until the autoimmune problem gets going).
So what are we looking at here? Do we not only have to treat the
bacterial overgrowth (or perhaps fungal in the case of Candida albicans)
but once that is done do we also have to prime the immune system to be
*more* and not less tolerant of these same organisms we just set out to
kill?
For a discussion of the importance of OCTN1/OCTN2, look at my recent
post on CMV and my discussion of what might happen metabolically if the
body tried to downregulate carnitine uptake to fight an infection.
PLoS ONE. 2008 Jul 2;3(7):e2537.
On the prevalence of M. avium subspecies paratuberculosis DNA in the
blood of healthy individuals and patients with inflammatory bowel
disease.
Juste RA, Elguezabal N, Garrido JM, Pavon A, Geijo MV, Sevilla I,
Cabriada JL, Tejada A, Garcia-Campos F, Casado R, Ochotorena I, Izeta A,
Greenstein RJ.
Departamento de Produccion y Sanidad Animal, Instituto Vasco de
Investigacion y Desarrollo Agrario (NEIKER-Tecnalia), Derio, Bizkaia,
Spain.
BACKGROUND: Mycobacteria, such as M. leprae and M. tuberculosis infect
billions of humans. However, because of appropriate immune responses and
antibiotic therapy, overt mycobacterial diseases occur far less
frequently. M. avium subspecies paratuberculosis (MAP) causes Johne>s
disease in ruminants, an affliction evocative of inflammatory bowel
disease (IBD). Several agents used to treat IBD (5-ASA, methotrexate,
azathioprine and its metabolite 6-MP) have recently been shown to be
antiMAP antibiotics. We herein evaluate the prevalence of MAP DNA in
healthy individuals and compare them with IBD patients on antiMAP
antibiotics. METHODS: We studied 100 healthy individuals (90 blood
donors) and 246 patients with IBD. IS900 MAP DNA was identified using a
nested primer PCR in the buffy coat of blood. Positive signal was
confirmed as MAP by DNA sequence analysis. PCR positive results
frequencies were compared according to medications used. Significance
was accepted at p<0.05. RESULTS: 47% (47/100) healthy controls and 16%
(40/246) IBD patients were IS900 positive (p<0.0001). MAP DNA was
identified in 17% of 143 patients receiving mesalamine and 6% of 16
receiving sulfasalazine. None of the IBD patients receiving methotrexate
(n = 9), 6-MP (n = 3), ciprofloxacin (n = 5) or Tacrolimus (n = 3) had
MAP DNA detectable in their blood. DISCUSSION: We found a disquietingly
large percentage of healthy individuals have MAP DNA in their blood, the
significance of which remains to be determined. Counter-intuitively, the
incidence of MAP DNA was significantly lower in patients with IBD.
Agents with the most potent in vitro antiMAP activity were associated
with clearance of blood MAP DNA. We posit that the use antiMAP
antibiotics was responsible for the decreased prevalence of MAP DNA in
patients with IBD.
Publication Types:
* Research Support, Non-U.S. Gov>t
PMID: 18596984
Gastroenterology. 2006 Jul;131(1):85-96.
Comment in:
* Gastroenterology. 2006 Jul;131(1):312-4.
Does cross-reactivity between mycobacterium avium paratuberculosis and
human intestinal antigens characterize Crohn>s disease?
Polymeros D, Bogdanos DP, Day R, Arioli D, Vergani D, Forbes A.
University College London, London, United Kindgom.
BACKGROUND & AIMS: Most Crohn>s disease (CD) patients show
seroreactivity against Mycobacterium avium paratuberculosis (MAP),
suggesting a pathogenic role for this organism. Our aim was to seek
amino acid similarities between MAP and intestinal proteins that,
through molecular mimicry, could serve as targets for cross-reactive
immunity in CD. METHODS: Fifty-three peptides comprising 23 sets of
MAP/human intestinal peptidyl mimics chosen for maximal homology were
constructed and tested for immunologic cross-reactivity by enzyme-linked
immunosorbent assay in 50 patients with CD, 50 with ulcerative colitis,
and 38 healthy controls. RESULTS: Antibody reactivity was present in
only 7 of 23 peptide sets. MAP/self-reactivity in at least 1 of the 7
reactive sets was present in 21 (42%) CD patients but was virtually
absent in the controls. Significant double-reactivity was found against
MAP glycosyl transferase d (gsd)(230-244)/human gastrointestinal
glutathione peroxidase (GPg)(111-125) homologues in 15 of 50 (30%) CD
patients; MAP alkylohydroperoxidase C (ahpC)(20-34)/human tumor
overexpressed protein (TOG)(637-651) double-reactivity was present in 10
(20%) CD patients, but in none of the controls. Inhibition studies
confirmed that simultaneous reactivity to mimics was caused by
cross-reactivity. Three-dimensional modeling predicts GPg(111-125) will
be exposed in a solvent-accessible surface region of the protein
compatible with antibody recognition. Antibody affinity was greater for
the MAP mimics than for the self-sequences, suggesting that reactivity
to the mycobacterial sequences precedes that against self-sequences.
CONCLUSIONS: We describe MAP/self-mimics as targets of cross-reactive
antibody responses characterizing patients with CD. Our findings
indicate gastrointestinal glutathione peroxidase as a novel autoantigen
in CD.
Publication Types:
* Comparative Study
* Research Support, Non-U.S. Gov>t
PMID: 16831593
Biochem Biophys Res Commun. 2005 Dec 2;337(4):1165-75. Epub 2005 Oct 6.
Epitope shared by functional variant of organic cation/carnitine
transporter, OCTN1, Campylobacter jejuni and Mycobacterium
paratuberculosis may underlie susceptibility to Crohn>s disease at 5q31.
Lamhonwah AM, Ackerley C, Onizuka R, Tilups A, Lamhonwah D, Chung C, Tao
KS, Tellier R, Tein I.
Division of Neurology, Department of Pediatrics, The Hospital for Sick
Children, Toronto, Ont., Canada.
Campylobacter jejuni and Mycobacterium paratuberculosis have been
implicated in the pathogenesis of Crohn>s disease. The presence of
bacterial metabolites in the colonic lumen causing a specific breakdown
of fatty acid oxidation in colonic epithelial cells has been suggested
as an initiating event in inflammatory bowel disease (IBD). l-Carnitine
is a small highly polar zwitterion that plays an essential role in fatty
acid oxidation and ATP generation in intestinal bioenergetic metabolism.
The organic cation/carnitine transporters, OCTN1 and OCTN2, function
primarily in the transport of l-carnitine and elimination of cationic
drugs in the intestine. High-resolution linkage disequilibrium mapping
has identified a region of about 250kb in size at 5q31 (IBD5)
encompassing the OCTN1 and -2 genes, to confer susceptibility to Crohn>s
disease. Recently, two variants in the OCTN1 and OCTN2 genes have been
shown to form a haplotype which is associated with susceptibility to
Crohn>s. We show that OCTN1 and OCTN2 are strongly expressed in target
areas for IBD such as ileum and colon. Further, we have now identified a
nine amino acid epitope shared by this functional variant of OCTN1
(Leu503Phe) (which decreases the efficiency of carnitine transport), and
by C. jejuni (9 aa) and M. paratuberculosis (6 aa). The prevalence of
this variant of OCTN1 (Phe503:Leu503) is 3-fold lower in unaffected
individuals of Jewish origin (1:3.44) compared to unaffected individuals
of non-Jewish origin (1:1). We hypothesize that a specific antibody
raised to this epitope during C. jejuni or M. paratuberculosis
enterocolitis would cross-react with the intestinal epithelial cell
functional variant of OCTN1, an already less efficient carnitine
transporter, leading to an impairment of mitochondrial beta-oxidation
which may then serve as an initiating event in IBD. This impairment of
l-carnitine transport by OCTN1 may respond to high-dose l-carnitine
therapy.
Publication Types:
* Research Support, Non-U.S. Gov>t
PMID: 16246312
Antimicrob Agents Chemother. 2008 Feb;52(2):418-26. Epub 2007 Dec 10.
Related Articles, Cited Articles, Free in PMC, Cited in PMC, LinkOut
Erratum in:
* Antimicrob Agents Chemother. 2008 Mar;52(3):1208.
Thiopurine drugs azathioprine and 6-mercaptopurine inhibit Mycobacterium
paratuberculosis growth in vitro.
Shin SJ, Collins MT.
Department of Pathobiological Sciences, School of Veterinary Medicine,
University of Wisconsin-Madison, Madison, WI 53706-1102, USA.
The in vitro susceptibility of human- and bovine-origin Mycobacterium
paratuberculosis to the thioupurine drugs 6-mercaptopurine (6-MP) and
azathioprine (AZA) was established using conventional plate counting
methods and the MGIT 960 ParaTB culture system. Both 6-MP and AZA had
antibacterial activity against M. paratuberculosis; isolates from
Crohn>s disease patients tended to be more susceptible than were
bovine-origin isolates. Isolates of Mycobacterium avium, used as
controls, were generally resistant to both AZA and 6-MP, even at high
concentrations (> or =64.0 microg/ml). Among rapidly growing
mycobacteria, Mycobacterium phlei was susceptible to 6-MP and AZA
whereas Mycobacterium smegmatis strains were not. AZA and 6-MP limited
the growth of, but did not kill, M. paratuberculosis in a dose-dependent
manner. Anti-inflammatory drugs in the sulfonamide family
(sulfapyridine, sulfasalazine, and 5-aminosalycilic acid [mesalamine])
had little or no antibacterial activity against M. paratuberculosis. The
conventional antibiotics azithromycin and ciprofloxacin, used as control
drugs, were bactericidal for M. paratuberculosis, exerting their killing
effects on the organism relatively quickly. Simultaneous exposure of M.
paratuberculosis to 6-MP and ciprofloxacin resulted in significantly
higher CFU than use of ciprofloxacin alone. These data may partially
explain the paradoxical response of Crohn>s disease patients infected
with M. paratuberculosis to treatment with immunosuppressive thiopurine
drugs, i.e., they do not worsen with anti-inflammatory treatment as
would be expected with a microbiological etiologic pathogen. These
findings also should influence the design of therapeutic trials to
evaluate antibiotic treatments of Crohn>s disease: AZA drugs may
confound interpretation of data on therapeutic responses for both
antibiotic-treated and control groups.
Publication Types:
* Research Support, Non-U.S. Gov>t
PMID: 18070971
PLoS ONE. 2008 Jun 25;3(6):e2496.
On the action of cyclosporine A, rapamycin and tacrolimus on M. avium
including subspecies paratuberculosis.
Greenstein RJ, Su L, Juste RA, Brown ST.
Department of Surgery, Veterans Affairs Medical Center, Bronx, New York,
United States of America.
BACKGROUND: Mycobacterium avium subspecies paratuberculosis (MAP) may be
zoonotic. Recently the "immuno-modulators" methotrexate, azathioprine
and 6-MP and the "anti-inflammatory" 5-ASA have been shown to inhibit
MAP growth in vitro. We concluded that their most plausible mechanism of
action is as antiMAP antibiotics. The "immunosuppressants" Cyclosporine
A, Rapamycin and Tacrolimus (FK 506) treat a variety of "autoimmune" and
"inflammatory" diseases. Rapamycin and Tacrolimus are macrolides. We
hypothesized that their mode of action may simply be to inhibit MAP
growth. METHODOLOGY: The effect on radiometric MAP (14)CO(2) growth
kinetics of Cyclosporine A, Rapamycin and Tacrolimus on MAP cultured
from humans (Dominic & UCF 4) or ruminants (ATCC 19698 & 303) and M.
avium subspecies avium (ATCC 25291 & 101) are presented as "percent
decrease in cumulative GI" (%-DeltacGI.) PRINCIPAL FINDINGS: The
positive control clofazimine has 99%-DeltacGI at 0.5 microg/ml
(Dominic). Phthalimide, a negative control has no dose dependent
inhibition on any strain. Against MAP there is dose dependent inhibition
by the immunosuppressants. Cyclosporine has 97%-DeltacGI by 32 microg/ml
(Dominic), Rapamycin has 74%-DeltacGI by 64 microg/ml (UCF 4) and
Tacrolimus 43%-DeltacGI by 64 microg/ml (UCF 4) CONCLUSIONS: We show
heretofore-undescribed inhibition of MAP growth in vitro by
"immunosuppressants;" the cyclic undecapeptide Cyclosporine A, and the
macrolides Rapamycin and Tacrolimus. These data are compatible with our
thesis that, unknowingly, the medical profession has been treating MAP
infections since 1942 when 5-ASA and subsequently azathioprine, 6-MP and
methotrexate were introduced in the therapy of some "autoimmune" and
"inflammatory" diseases.
PMID: 18575598
1: Curr Opin Gastroenterol. 2008 Jul;24(4):440-7.
Pathogenic agents in inflammatory bowel diseases.
Pineton de Chambrun G, Colombel JF, Poulain D, Darfeuille-Michaud A.
Clinic of Digestive Disorders and Nutrition, Hopital Claude Huriez, CHRU
Lille, France.
PURPOSE OF REVIEW: Infectious agents are still thought to be involved in
the origin of inflammatory bowel disease. The focus in recent years has
been more on Mycobacterium avium subsp paratuberculosis,
adherent-invasive Escherichia coli or yeasts. RECENT FINDINGS: A
metaanalysis has shown a significant association of M. avium subsp
paratuberculosis and Crohn>s disease and a large randomized
placebo-controlled trial reported an absence of sustained beneficial
effects of combined antibiotic therapy on remission of active Crohn>s
disease. Adherent-invasive E. coli adhere via type 1 pili to
carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6),
abnormally expressed by intestinal epithelial cells in Crohn>s disease
patients. Both colonization of the ileal mucosa and stimulation of ileal
epithelial cells by tumour necrosis factor-alpha induce overexpression
of CEACAM6, leading to an amplification loop of colonization and
inflammation. Anti-Saccharomyces cerevisiae mannan antibodies are the
most prevalent serologic marker in Crohn>s disease. Major oligomannose
epitopes supporting antibody formation are expressed by Candida albicans
in human tissues, suggesting that a loss of tolerance to C. albicans
could lead to antibody formation in a subset of Crohn>s disease patients
who are genetically predisposed. SUMMARY: M. avium subsp
paratuberculosis, adherent-invasive E. coli and Candida are good
candidates for an infectious aetiology of Crohn>s disease on the basis
of genetic susceptibility, which relates to impaired function in the
defence against intracellular bacteria.
PMID: 18622157 [PubMed - in process] |
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Kofi
Guest
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| Posted: Thu Oct 02, 2008 11:26 am Post subject: Re: Mycobacterium - kill the bacteria or induce tolerance? |
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I forgot to highlight an important supporting fact. There were plenty
of healthy individuals positive for MAP DNA in their blood but far fewer
IBD patients were positive for MAP. This suggests eradicating the
bacteria doesn>t produce a cure and it further suggests plenty of people
are able to live in peace with MAP.
[quote]PLoS ONE. 2008 Jul 2;3(7):e2537.
On the prevalence of M. avium subspecies paratuberculosis DNA in the
blood of healthy individuals and patients with inflammatory bowel
disease.
Juste RA, Elguezabal N, Garrido JM, Pavon A, Geijo MV, Sevilla I,
Cabriada JL, Tejada A, Garcia-Campos F, Casado R, Ochotorena I, Izeta A,
Greenstein RJ.
Departamento de Produccion y Sanidad Animal, Instituto Vasco de
Investigacion y Desarrollo Agrario (NEIKER-Tecnalia), Derio, Bizkaia,
Spain.
BACKGROUND: Mycobacteria, such as M. leprae and M. tuberculosis infect
billions of humans. However, because of appropriate immune responses and
antibiotic therapy, overt mycobacterial diseases occur far less
frequently. M. avium subspecies paratuberculosis (MAP) causes Johne>s
disease in ruminants, an affliction evocative of inflammatory bowel
disease (IBD). Several agents used to treat IBD (5-ASA, methotrexate,
azathioprine and its metabolite 6-MP) have recently been shown to be
antiMAP antibiotics. We herein evaluate the prevalence of MAP DNA in
healthy individuals and compare them with IBD patients on antiMAP
antibiotics. METHODS: We studied 100 healthy individuals (90 blood
donors) and 246 patients with IBD. IS900 MAP DNA was identified using a
nested primer PCR in the buffy coat of blood. Positive signal was
confirmed as MAP by DNA sequence analysis. PCR positive results
frequencies were compared according to medications used. Significance
was accepted at p<0.05. RESULTS: 47% (47/100) healthy controls and 16%
(40/246) IBD patients were IS900 positive (p<0.0001). MAP DNA was
identified in 17% of 143 patients receiving mesalamine and 6% of 16
receiving sulfasalazine. None of the IBD patients receiving methotrexate
(n = 9), 6-MP (n = 3), ciprofloxacin (n = 5) or Tacrolimus (n = 3) had
MAP DNA detectable in their blood. DISCUSSION: We found a disquietingly
large percentage of healthy individuals have MAP DNA in their blood, the
significance of which remains to be determined. Counter-intuitively, the
incidence of MAP DNA was significantly lower in patients with IBD.
Agents with the most potent in vitro antiMAP activity were associated
with clearance of blood MAP DNA. We posit that the use antiMAP
antibiotics was responsible for the decreased prevalence of MAP DNA in
patients with IBD.
Publication Types:
* Research Support, Non-U.S. Gov>t
PMID: 18596984[/quote] |
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