A 8 0 4 AGA ABSTRACTS GASTROENTEROLOGY, Vol. 108, No. 4

• A NEWLY SYNTHESIZED COLON-SPECIFIC CORTICOSTEROID PRODRDG DEMONSTRATES ENHANCED MUCOSAL REPAIR AND SPECIFIC ANTIDIARRHEAL EFFECTS IN RAT COLITIS ~ RN Fedorak, DR Friend*, KL Madsen, LR Empey. Division of Gastroenterology, University of Alberta, Edmonton, Canada and *SRI international Menlo Park, CA.

We have recently developed and synthesized a new colon-specific glucocorticoid prodrug, dexomethesone-J3-D-glucoronide. When compared tO its parent drug, dexamethasone, the prodrug had minimal adrenal suppression, and was 14-fold more effective in heagng colitis and improving colonic fluid and electrolyte absorption. The present study examined whether the improvement in colonic fluid absorption seen with the prodrug occurred as a consequence of generalized mucosal healing orwas a consequence of specific upregualtion in sodium and chloride absorption. Methods: The efficacy of the prodrug and parent drug (O.22pmol/kg/d) were tested in acetic acid-induced rat pancolitis. Treatment groups were: (1) control + vehicle, (2) control+prodrug, (3) colitis+vehicle, (4) colitis+parent drug or (5) colitis + prodrug. Healing of colitis was assessed by measuring in viva net colonic fluid absorptien and surface area ulceration. Specific ion transport was assessed by transmural unidirectional fluxes of Z2Na and ~CI across sheets of colonic mucosa in Ussing chambers. Results: The prodrug delivered 6- fold higher concentrations of luminal dexamethasone to the colon and subsequently accelerated the in vivo healing of colitis relative to the parent drug (p < 0.01). Consistent with a specific effect on ion transport net basal sodium and chloride absorption was sighificantly enhanced by the prodtug in control animals. Furthermore, in colitic animals this specific

Fluxes Control+ Colit is+ (/zEq/cm 2)

vehicle prodrug vehicle parent drug prodrug

Jnet Na basal 3.3±0.7 5.5±0.9 ~0.9±0.8 3.2+0.7 6.1 ±0.8 then -1.8±0.6 1 .0±0 .9 -3.2± 1.4 2.0±0.8 1.6±1.1

Jnet CI basal 3.5±0.6 5.8±0.8 -1.5±0.8 3.8±0.6 5.6±0.9 thee -4.3±0.9 0.8±0.8 -4.2± 1.0 0.8±0.9 1.2±0.9

absorptive effect of the prodrug was approximately 2-fold greater than that of the parent drug (p < 0.02). Both drugs limited theophylline (cAMP),mediated net sodium and chloride secretion (p < 0.05), consistent with the antidiarrheal effect of these drugs; Conclusion: The results suggest that treatment of experimentally-induced colitis with the novel colon-specific prodrug, dexamethasone-~-D-glucuronido, has distinct mucosal repair and antidiarrheal advantages over administration of its parent drug, dexamethasone.

INCREASED PERMEABILITY OCCURS IN RAT ILEUM FOLLOWING INDUCTION OF PANCOLITIS N Cui, RN Fedorak, DR Friend*, KL Madsen LR Empey. Division o f Gastroenterology, University of Alberta, Edmonton, Canada and *SRI International, Menlo Park, CA.

Experimentally-induced pancolitis induces a bystander injury in the ileum characterized by marked reduction in in rive fluid and electrolyte absorption without macroscopic changes (Agents Actions 38:78,1993). The present study thus determined whether this bystander injury occurred as a consequence of either a downregulation in active sodium and chloride transport or an increase in intestinal permeability. Methods: Pancolitis was induced in rats with 4% acetic acid. Previous studies confirmed no backflux of acetic aced into the ileum. 72 hours after induction of colitis the study was carried out. Active ileal sodium and chloride transport was assessed by measuring mucosal-serosal (Jms) and serosal-

22 36 mucosal (Jsm) Na and Cl unidirectional fluxes in vitro on paired intestinal segments mounted in voltage clamped Ussing chambers. Net flux (Jnet)represented the difference between Jms and Jsm: Ileal permeability was assessed by measuring serosal-mucosal fluxes of 3H-mannitol and !H-inulin. Tight junctional morphology was examined by transmission electron microscopy: Results: The reductionin ileal in vivO fluid and electrolyte'absorption during colitis (bystander injury) occurred as a conse( permeability as evidenced by increases in mannitol

< 0.05 vs control)

Jsm Flux (nmol/cmZ/b)

Mannitol Inulin

Control 33.2±2.11 24.3±3.2

Colitis 45.8± 3.1 * 38.8 ± 5,5*

uonce of a marked increase in intestinal inulin, sodium and chloride Jsm fluxes

Jsm (MEqlcmZlh)

Sodium Chloride

10.3+0.7 9.9+0.8

12.2+0.4" 12.2+0.7"

There were no differences in ileal Jms sodium and chloride fluxes, confirming that these specific ion transport processes were not altered with the pancolitis-induced bystander injury. Furthermore, the permeability changes were not accompanied by any morphological alteration at the electron microscopic level. Conclusion: The reduction in fluid and electrolyte absorption seen as a bystander injury in the ileum of acetic-acid induced pancolitis occurs a s . a result of an increased intestinal permeability,

CELLULAR IMMUNE RESPONSE IN CHILDREN W I T H HELICOBACTER PY'LORI ASSOCIATED GASTRITIS AND/OR PEPTIC ULCER. E. Czk'wianiane. K. Zeman, l. Plancta-Malecka, LI B~tk- Romaniszyn, E. Fomalczyk, Depts. of Pediatrics and Immunology, Military Medical Academy; Lodz, Poland.

Colonization of gastric mucosa with theH.pylori is the principal cause of chronic type B gastritis and is associated with duodenal ulceration. Th e mechanism by which H.pyiori causes gastritis and/or ulceration are not y ~ well understood, but it is reasonable to assume that the interaction of the bacterium with cells of the host immune defense system participates in the pathogenesis of this diseases. In the course o f H.pylori infection clear specific immunological response is observed, but bacteria are not eliminated and in majority of children chronic gastritis or/and peptic ulcer disease are developed

While both a local and a humeral immune response toH.pylori is evident in infected patients, little is known about systemic cellular immun e responses to H.pylori in .peptic ulcer disease. We examined subsets of blood lymphocyte (CD3, CD4, CDS, CD3/DR, CDig) and NK cells (CDI6+56+) using monoclonal antibodies and flow ¢ytometry in 12 children with H.pylori associated peptic ulcer, 20 children with H.pyiori associated gastritis, 20 with abdominal pain without infection and 20 healthy control. The mitogen-induced lymphocyte response (PHA) were also evaluated.

We observed that: ( I ) there were no evidences of an altered lymphocyte phenotypes and their activity in children with H.pyiori &qsociated gastritis compare to healthy control or children without infection; (2) in children with 1t. pylori associated peptic ulcer were decreased percentage o f CD8 lymphocytes and NK cells, increased CD4/CD8 ratio and decreased mitogen-induced response.

We conclude that the changes in host immune response may play aa important role in the pathogenesis of peptic ulceration in Children with H.py/or/asociated ulcer peptic disease.

e MODULATION OF NEUTROPHIL (PMN) OXIDATIVE BURST: PRO- INFLAMMATORY UPREGULATION BY ULCERATIVE COLITIS (UC) PLASMA; ANTI-INFLAMMATORY DOWN-REOWL,ATION BY CONTROL PLASMA. F Dude, R Moparty, R Luu, D Winship, J Fields & A Keshavarzian. Depts Med& Pharm, Loyola Med Sch, Maywood IL; Med& Res Svces, VAH, Hines IL

PMN appear to be a major factor in colonic tissue damage in UC. Cirenlctory PMN, the source of colonic PMN, were reported to be normal in UC, suggesting that local colonic factors contribut© to PMN chemotaxis & .activation. But, these studies did not consider the effect of plasma - part o( the .normal PMN environment - on PMN function. It was suggested that normal plasma can inhibit PMN functions, We hypothesized that plasma from patients (Pts) with UC either has lost its inhibitory effect, or has developed a pro-inflammatory effect, or both. Our aim was to assess the effect of plasma from Pts with inactive UC (& Crohn's disease [CD]) on the ability of PMN to produce supercxide anion ('02-). Methods: Circulating PMN were isolated from controls (cPMN), inactive UC (OCPMN), & inactive CD (cdPMN). The.oxidative burst of PMN was estimated by the production of "Oz- spectrophotometrically, Results: fmlp increased "O 2- production by all PMN to similar values: cPMN (6.60_+0.23); ucPMN (5.91_+0.26); cdPMN {8.05+0.15). Control plasma (10 & 35% dilution) significantly & dose dependently inhibited.fmlp-induced "02- production by PMN from normal, UC & CD subjects (Table). In contrast, UC plasma significantly & dose dependently stimulated "O2- production by cPMN & ucPMN CD plasma was similar to controls, significantly inhibiting "O:. Conclusions: l) PMN from UC & CD patients have normal baseline & fMLP-stimulated "02- production. 2) Normal plasma significantly blunts 'O:production by activated PMN while plasma from patients with inactive UC potentiates it. This effect is specific to UC since plasma from inactive CD did not increase "02-. This modulatory effect of UC plasma can have proinflammatory consequences that may either initiate or potentiate an inflammatory cascade leading to tissue damage in UC. Table: Data from fmlp-stimulated PMN in plasma were divided by the value for fmlp- stimulated PMN in buffer & are shown as ratios ~ stun). All values were significantly different from PMN in buffer (paired t-tests). Ratios 3one-el vs UC P lasma 2ontrol vs CD Plasma Plasma :on-10% :on-35% zc-10% zc-35% :on-10% ~on-35% :d-10% cd-35% :PMN 3.63+~04 ).49÷.03 [.034..06 1.28_+.05 ).63'+.03 ).554-.03 ).634..04 0.58+~02 acPMN ~.72+~08 ).614..05 [.094..07 1.45+.07 - zdPMN - ).61_+.02 ).51_+.02 ).70+.03 D.64_+.04