Notes

Outline

Microscopic Colitis Syndrome Chronic, watery, non-bloody diarrhea Normal colonoscopic appearance Histopathology: LP inflamm, intraepithelial                                                                                                                                                                                                                   lymphocytosis, surface epithelial flattening, +/- thick subepithelial collagen band Etiology unknown      Pathogen, antigen, autoimmunity

Treatment of MC Published Experience Mainly case reports; retrospective series   Corticosteroids, 5-ASA, antimicrobials 1 prospective trial   prednisilone  3 - 12 weeks Decreased fecal frequency  43% No change in colonic histopathology Diarrhea recurred rapidly after dc’d (Sloth et al.  J Int Med  1991)

Bismuth Subsalicylate Pharmacological Properties Anti-diarrheal Stimulates fluid/electrolyte absorption,      decreases secretion Binds bacterial toxins and bile salts Anti-bacterial Bactericidal and inhibits metabolism Anti-inflammatory

Previous Experience With Bismuth Compounds in UC 9 of 15 refractory patients improved                                                                                                                                                                                                                     with bismuth subsalicylate enemas (Ryder, et al.  Aliment Pharmacol Ther 1990) 12 of 31 patients improved with                                                                                                                                                                                         bismuth citrate enemas (=  5-ASA) (Pullan, et al.  Gut 1993)

Initial Pilot Study of Bismuth Subsalicylate (Pepto Bismol, Procter and Gamble)

Hypothesis    Because of its antidiarrheal, antibacterial, and anti-inflammatory properties, bismuth subsalicylate will resolve both the diarrhea and the histopathology of microscopic colitis.

Patients Studied Nine consecutively diagnosed patients with microscopic colitis 4 - Thick subepithelial collagen band 5 - Normal subepithelial collagen band All female, 37-71 years old Duration of diarrhea  4 mos - 21 yrs

Bismuth Subsalicylate Treatment Eight 262 mg chewable tablets per                                                                                                                                                                                                                              day for eight weeks Pilot study - open label, no placebo Feasibility and safety of 8 weeks of Rx Determine open label response rates Help plan placebo-controlled trial

Measured Parameters CBC, chem, ANA, bismuth, salicylate Fecal consistency and weight 48-Hour stool collection Fecal frequency recorded daily Histology of 24 Bx’s from left colon Flexible sigmoidoscopy

Interpretation of Colonic Biopsies Lamina propria cellularity - magnitude, type Thickness of subepithelial collagen layer Number of intraepithelial lymphocytes Integrity of surface epithelium Crypt architecture

Definition of Response Clinical   < 2 formed or semi-formed BM per day Histological   > 50% decrease in histopathology score

Summary: Bismuth Subsalicylate Rx for Microscopic Colitis Treated 12 patients for 8wks with open-label Pepto-Bismol (8 chewable tabs/day) Resolution of diarrhea in 11 patients Resolution of colitis in 9 patients No toxicity or side-effects (constipation in 2) Patients without celiac sprue-no recurrence Patients with celiac sprue - some required retreatment at 3-6 month intervals

Effect of Bismuth Subsalicylate on Colonic Histopathology Score

Relation of ANA Titer to Response

Safety of Bismuth Subsalicylate No side effects (constipation in 2) CBC, chemistries, liver enzymes - Nl Bismuth levels  5-34 µg/L  (safe <100) Salicylate levels - undetectable

Follow-up (8 - 21 Months) Well, no further treatment     7of 9  (78%) Well, required retreatment 1of 9   (11%) Continued diarrhea 1of 9    (11%)

Response of MC to BSS in 3 Patients with Celiac Sprue Treated celiac sprue       1 responded            ANA  negative       1 no response         ANA  1:640 Untreated, newly dx’d celiac sprue                                                                                                                                                                                                                                     1 responded           ANA  negative

Hypothesis   Bismuth subsalicylate can improve both the diarrhea and the histopathology of microscopic colitis, and will be superior to placebo in a randomized, double-blind, placebo-controlled trial.

Randomized, Double-Blind Study Protocol Treatment - 3 tablets three times a day x 8 weeks Bismuth subsalicylate 262 mg  chewable tablets Identically colored and flavored sucrose-placebo tablets Measured parameters Fecal consistency and weight - 48-Hour stool collection Fecal frequency recorded daily Histology of 16 Bx’s from left colon - flex sig Placebo crossed over to active drug

Patients Studied 20 patients with microscopic colitis 13- Thick subepithelial collagen band   7 - Normal subepithelial collagen band 16 female, 4 male; age 35-78 years old Duration of diarrhea  4 mos - 18 yrs

Interpretation of Colonic Biopsies Lamina propria cellularity - magnitude, type Thickness of subepithelial collagen layer Number of intraepithelial lymphocytes Integrity of surface epithelium Crypt architecture

Effect of Bismuth Subsalicylate on Frequency of Bowel Movements

Effect of Bismuth Subsalicylate  on Fecal Consistency

Effect of Bismuth Subsalicylate on Fecal Weight

Slide 25

Effect of Bismuth Subsalicylate on Colonic Histopathology

Follow-up (4 - 43 Months) Well, no further treatment   16 of 22  (73%) Well, required retreatment 5 of 22  (23%) Continued diarrhea 1 of 22   (4%)

Follow-up* of 40 Patients with MC Treated with Bismuth Subsalicylate Well, no further treatment                 25   (62%) Well, required retreatment                  5   (13%) Well, required adjuvant treatment       8   (20%) Continued diarrhea               2     (5%) * 10 - 50 months

Summary of Effect of Bismuth Subsalicylate for MC Following 8-weeks of treatment : 93% of patients with microscopic colitis                                                                                                                                                                                                                         resolve diarrhea 74% resolve or have less histologic colitis No side effects 60-70% require no further treatment

Conclusions Bismuth subsalicylate is an effective treatment of  microscopic colitis Retreatment is sometimes necessary but usually successful Apparent predictors of relapse or no response: Gluten sensitivity, signs of autoimmunity, NSAID use

Potential Mechanisms of Action of Bismuth Subsalicylate for MC Bismuth                             Calcium Antibacterial                             Binding of bile acids Binding of enterotoxins            Binding of fatty acids Binding of bile acids                 Antidiarrheal Antiinflammatory Salicylate                           Mannitol Antiinflammatory                       Alters colonic flora Proabsorptive

Apparent Predictors of Relapse NSAID use Signs of significant autoimmunity Signs of gluten sensitivity

Clinical Overlap of MC with Celiac and Refractory Sprue Microscopic colitis is present  in 5% of treated celiac sprue patients and is the most common cause of diarrhea following treatment with a GFD Present in 67% of patients with refractory sprue Colitis in celiac and refractory sprue histologically identical to that in patients without sprue

HLA-DQ Genes Molecules involved in antigen presentation to     T cells - cell mediated immune processes Typed by serologic method - antigenic structure molecular method - DNA sequence Certain alleles are tightly associated with and involved in pathogenesis of celiac sprue HLA-DQ2  in 90% HLA-DQ8  in most without DQ2

HLA Genes in Celiac Sprue Tightly associated with class II alleles HLA-DQ2   90% HLA-DQ8   most of those without DQ2 HLA-DQ alleles present in patients with MC or refractory sprue not reported previously

Hypothesis    Because of the histopathologic similarities and epidemiologic overlap of microscopic colitis with celiac and refractory sprue, we hypothesized that the HLA-DQ genes of patients with these sprue syndromes and patients with microscopic colitis may be similar, and if so, may shed light on the pathogenesis of the microscopic colitis syndrome.

Methods    HLA-DQ genotype assessed by serologic                                                                                                                                                                                                                   and molecular methods in: patients with celiac sprue patients with refractory sprue and MC patients with the MC syndrome (with and without subepithelial collagen thickening) normal controls

Methods (cont.) Serum antigliadin IgG and IgA antibody,    and antiendomysial IgA antibody measured 37 patients with the microscopic colitis syndrome underwent endoscopic biopsy of mid - distal duodenum Biopsy slides analyzed blindly

HLA-DQ Typing in Celiac Sprue and Microscopic Colitis

HLA-DQ Typing in Microscopic Colitis with or without Thick Subepithelial Collagen

Distribution of DQ1,3 between DQ1,7, DQ1,8, and DQ1,9 in MC

Small Bowel Histology in 37 Patients with Microscopic Colitis

Frequency of Positive Serologic Tests for Celiac Sprue in MC

Titers of Positive Antibody Tests in Celiac Sprue and MC

Fecal Antigliadin Antibody Testing              Group                        Positivty rate Untreated celiac sprue (n=20)   100% Microscopic colitis (n=63)      75% Normals (n=37)     32% Treated celiacs (n=11)       9%

Comparison of Serum and Fecal Antigliadin Ab Positivity

Stratification of HLA, SB Bx, AGA Results in MC by Response to BSS

Summary HLA-DQ2,x or DQ1,3 genotype was seen in 96%   of celiac sprue, 100% of refractory sprue with MC,   and 91% of patients with MC syndrome Serologic tests for celiac sprue are low titer or negative, but fecal antigliadin antibody tests can show that MC patients are gluten sensitive Mild inflammation of small intestine present in 67% of MC; half have mild to moderate villous atrophy

Conclusions 1.   A shared set of predisposing HLA genotypes accounts for the epidemiologic overlap of celiac sprue, refractory sprue, and microscopic colitis. This suggests that microscopic colitis like celiac                                                                                                                   sprue results from an HLA-directed, T cell-mediated   reaction to a luminal antigen. The ability of celiac patients on a gluten-free diet     to develop colitis implies that an antigen other than gliadin is etiologic.

Conclusions (cont.) 2. Patients with microscopic colitis may have  mild yet potentially clinically important gluten sensitivity. Likely due to the presence of an HLA class II genotype capable of mounting an immune  response to gliadin. Speculate gliadin sensitivity is triggered by the colitis, rather than the converse. May cause persistence of symptoms despite successful treatment of the colitis.

Conclusions (cont.) 3. In patients with microscopic colitis genetically capable of gluten-sensitivity, low titers of antigliadin antibodies and mild small intestinal histopathology occur secondarily to the colonic inflammatory response, rather than the converse Serologic tests for celiac sprue are low titer or negative, but fecal antigliadin antibody tests can show that MC patients are gluten sensitive

Speculation Mild gluten sensitivity in microscopic colitis occurs secondarily to colonic inflammatory response rather than the converse “Secondary” gluten sensitivity with MC Serum antigliadin/antiendomysial Ab: found         less often and lower titers than celiac sprue Small intestinal inflammation or villous abnormalities usually mild or absent Steatorrhea minimal or absent

“Secondary” Gluten-Sensitivity in Microscopic Colitis Serum antigliadin Ab: less prevalent and lower titers than celiac sprue;usually IgG or IgA Serum Antiendomysial Ab: less prevalent than CS Fecal antigliadin or antitissue transglutaminase antibody tests are positive Enteropathy usually mild L.P. inflammation +/-  pva or sva Minimal or no steatorrhea

Speculations on the Pathogenesis of Microscopic Colitis HLA-directed T-cell reaction to an antigenic stimulus in the colonic lumen Not gluten or other dietary derivative Related to bacteria or another microorganism Potentiated by NSAID’s and possibly estrogen supplements Antibiotics or other factors related to alteration of colonic flora

Microscopic Colitis Recommendations for Treatment Stool fat - assess for steatorrhea Serum AGA IgG; fecal AGA IgA, ATTA IgA Stop NSAID’s (including aspirin) Bismuth subsalicylate tablets 3 tid for 8 weeks Relapse - small bowel biopsy, re-treat, gluten-free diet No response - small bowel biopsy, gluten-free diet, increase dose of BSS, add or replace with              cholestyramine, new protocol to alter colonic flora

Early Experience with New Approach to Treatment of Microscopic Colitis

Evidence for a Role of Enteric      Bacteria in the Pathogenesis of IBD Intestinal inflammation in murine models of IBD requires an enteric flora for development and is inhibited or attenuated by antibiotics, germ-free conditions, or inoculation with Lactobacillus spp Fecal diversion in animals and humans attenuates or prevents inflammation Primary anatomic areas of intestine in human IBD are those harboring greatest #’s of bacteria

Modulation of Intestinal Contents as Therapy for IBD Reduce or prevent exposure to foodstuffs Bowel rest +/- liquid diets Suppress bacterial growth Antibiotics (anaerobic or broad spectrum) Intestinal lavage Alter intestinal flora Lactobacillus supplements (Probiotic) Poorly absorbed CHO supplements (Prebiotic)

Protocol to Alter Intestinal Flora  for Treatment of MC Intestinal lavage with PEG/electrolyte solution Supplementation with Lactobacillus caseii subspecies rhamnosus (Lactobacillus GG) More adherent to colonic cells than other species, aiding colonization                (Goldin et al, DDS 1992) Low dose lactulose (10-20 gram/day) Lowers colonic pH promoting growth of Lactobacilli                           (Florent et al, JCI 1985)

Fecal Parameters in Three MC Patients Treated with Intestinal Flora Modulation

A Total of Eight Patients Have Completed Protocol Seven are improved One did not complete protocol Further details are forthcoming