Cystic Fibrosis/Pancreas

INCREASED PLASMA TRANSFORMING GROWTH FACTOR BETA 1 IN PATIENTS WITH SEVERE PULMONARY DISEASE SECONDARY TO CYSTIC FIBROSIS K B Schwarz, J Rosensweig, S Sharma, L Jones, M Durant, C Potter and M R Narkewicz, Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States.

Transforming growth factor beta 1 (TGFβ1) is a major fibrogenic cytokine, the expression of which is increased in the livers of children with cystic fibrosis liver disease (CFLD) and in the bronchoalveolar lavage fluid of patients with cystic fibrosis pulmonary disease(CFPD). The purpose of our study was to investigate the utility of plasma TGFβ1 as a non-invasive marker of CFLD and/or CFPD and to investigate the contribution of platelet-derived TGFβ1 to plasma TGFβ 1 by correlating the latter with Platelet Factor 4 (PF4). Three groups of CF patients were studied: 1)CFLD n = 35, 15+/-3 years of age, alanine aminotransferase (ALT) 79 +/- 13 U/L, Forced expiratory volume in 1 second (FEV1) 80 +/- 4% predicted 2)CF well, n = 19, 12 +/- 1 years of age, ALT 33 +/- 3 U/L, FEV1 86 +/- 3% predicted, and 3)CF patients with advanced pulmonary disease (CFPD) n = 8, 26 +/- 5 y of age, ALT 30 +/- 4 U/L, FEV1 28 +/- 2% predicted. Two groups of healthy volunteers served as age-group controls: healthy teens, n = 10, 13 +/- 1 years of age, and healthy adults, n = 9, 30 +/- 2 years of age. Plasma TGFβ1 was assayed utilizing the R and D Quantikine quantitative sandwich enzyme immunoassay technique and PF4, by the American Bioproducts ELISA kit.

Plasma TGFβ1 was markedly increased in CFPD (15 +/- 3 ng/ml) vs. healthy adults (1 +/- 0), p<0.002. PF4 values followed a similar pattern: 105 +/- 8 in CFPD vs 12 +/- 4 ng/ml), p<0.001. However, within the CFPD group, plasma TGFβ1 values did not correlate with PF4 values, suggesting that the elevated plasma TGFβ1 values were not merely secondary to platelet-derived TGFβ1. Plasma TGFβ1 values in CFLD did not differ from CF well patients of comparable age. Combining data for all groups, despite meticulous efforts to perform venipuncture as atraumatically as possible, plasma TGFβ1 values were strongly correlated with values for PF4: r = 0.691, p<0.0001 Conclusion: Plasma TGFβ1 is not a useful marker of CFLD. The increased plasma TGFβ1 in CFPD patients is of interest in that it could potentially serve as a means of assessing response to pharmocotherapy for pulmonary fibrosis in CFPD as has been shown for other types of pulmonary fibrosis.

THE FATE OF EXOGENOUS ENZYMES IN PATIENTS WITH CYSTIC FIBROSIS (CF) AND PANCREATIC INSUFFICIENCY (PI) A M Butt, W Ip, L Ellis, S Martin, S Beharry, J Pike, E Kelly, M Stormon, E Tullis, P B Pencharz, E P DiMagno and P R Durie, University of Toronto, Toronto; and Mayo Foundation, Rochester, MN, United States.

Introduction: We have evaluated in vivo release and fate of exogenous enzymes (enteric-coated microspheres), to examine why therapy fails to correct maldigestion in most CF patients with PI.

Methods: Postprandial events were studied in the duodenum, jejunum and ileum of 3 CF subjects by a validated multi-lumen intestinal tube and marker perfusion technique (1). After the tube was inserted, marker equilibrated baseline samples were obtained from each intestinal site. Subjects ingested a standard solid meal, fixed dose of enzyme (microspheres) and a gastric marker. Serial intestinal samples aspirated over 7.5 h were evaluated for pH, markers, enzyme activities and bile acids.

Results: Duodenal delivery of the gastric marker and endogenous bile acids peaked within 3 h. Duodenal pH showed considerable inter-individual variation (range-4.5-7.75); mean jejunal (6.69) and ileal (6.97) pH were more alkaline and stable. Sequential activities for each enzyme were similar to that shown for total lipase and colipase (Figure). Postprandial enzyme activities showed: (a) a small rise from baseline in the duodenum throughout the 7.5 h period; (b) a large rise in jejunal activity, peaking at 1-2.5 h; (c) a sustained increase in activity in the ileum after 1.5 h for total lipase but not colipase. After 3 h, the colipase to lipase ratio was markedly reduced in the jejunum and ileum. Conclusions: Unlike normal digestion, in which enzyme activity is highest in the duodenum, very little exogenous enzyme is released proximally. Consequently, peak nutrient and bile acid delivery to the duodenum is asynchronous with enzyme release. Pancreatic colipase may be more susceptible than lipase to intraluminal degradation.

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(1) Am. J. Physiol. 251: G475-480, 1986. Funded by an unrestricted grant from Organon Canada Ltd and Digestive Care Inc.

EVALUATION OF LIPID ASSIMILATION IN PATIENTS WITH CYSTIC FIBROSIS (CF) USING 13CO2 BREATH TESTS OF LABELED LIPID SUBSTRATES WITH DIFFERING CHAIN LENGTH A M Butt, E Kelly, J Pike, M Myilvanasuntharum, K Sequeira, N Morson, A Buchholz, E Tullis, P B Pencharz and P R Durie, University of Toronto, Toronto, ON, Canada.

Introduction: Stable isotope breath tests of lipid substrates have been used to evaluate digestive events in patients with CF. Mixed Triglyceride (MTG), a 1,3-distearyl, 2-octanoyl glycerol, with 13C label on the medium chain moiety, may be more useful for assessing intraluminal lipolysis. In contrast, the Long Chain Triglyceride mixture, Hiolein (LCTG), which resembles dietary fat, should be capable of assessing all phases of lipid assimilation (lipolysis, absorption and metabolism).

Methods: We assessed lipid assimilation in 6 controls and 10 CF subjects with pancreatic insufficiency (PI) by comparing the metabolic fate of MTG and LCTG. Each substrate was ingested on separate occasions with an isotopically neutral meal. CF subjects received each substrate with enzyme and placebo. Breath samples obtained serially over 12 h were analyzed for 13CO2 enrichment by isotope ratio mass spectrometry. VCO2 production, measured by indirect calorimetry, was used to calculate appearance of label (V13CO2= VCO2x enrichment).

Results: Cumulative V13CO2 (Cum %) and peak V13CO2 (Peak %/h) were expressed as a percentage of administered label (Table). In controls, cumulative recovery of label with MTG exceeded that for LCTG (p=0.01). In CF subjects without enzymes, recovery of each substrate was markedly reduced. Peak recovery of label with MTG and LCTG occurred at the same time (8.5-9.5 h) in controls and CF patients receiving enzymes. In CF, enzyme therapy normalized label recovery with MTG, but LCTG peak V13CO2 was reduced in comparison with controls (p<0.05).

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Conclusions: In CF, enzyme therapy normalized assimilation of MTG but LCTG remained impaired. These results provide indirect evidence that enzyme therapy corrects intraluminal lipolysis whereas postlipolytic assimilation of lipids (absorption or metabolism) is impaired.

Unrestricted grant from Solvay Pharma Clinical Inc.

ORNITHINE DECARBOXYLASE IN PRECOCIOUS EXPRESSION OF PANCREATIC AMYLASE INDUCED BY EARLY WEANING IN RATS C Lin, M S Seelbach and R Vijesurier, Wayne State University, Detroit, MI, United States.

Background: Early weaning has been shown to induce precocious expression of pancreatic amylase in rats (J. Nutr. 113:1381-1387,1983). However, the exact mechanism has not been elucidated. Ornithine decarboxylase (ODC) is important during the initial stage of cell proliferation and differentiation. Increased ODC activity plays a critical role in the precocious induction of pancreatic development induced by thyroxine (Biochim. Biophys. Acta 1093:65-71,1991).

Objective: To determine if early weaning would affect the activity of ODC, and functional parameters of exocrine pancreas.

Methods: Suckling rats were prematurely weaned on postnatal day 15 and followed through day 21. Pancreatic tissues were obtained on postnatal days 16 and 21 (day 1 & 6 after early weaning) and assayed for ODC activity, DNA, protein and amylase activity. α-difluoromethyl ornithine (DFMO), a specific ODC inhibitor, was given orally to early-weaned pups and its resultant effects were assessed on day 1 and 6 after early weaning.

Results: Pancreatic amylase activities significantly increased on day 6 after early weaning. ODC activity increased in days 1 and 6 after early weaning, with highest increased (12-fold) in day 1 when compared to controls. The increases of ODC activity, as induced by early weaning were significantly suppressed when pups were exposed to DFMO. However, no suppression of amylase activity was observed.

Conclusion: Our study shows that early weaning induces ODC activity and functional growth of exocrine pancreas. Pancreatic ODC activity is not essential in precocious expression of pancreatic amylase induced by early weaning. The induction of pancreatic ODC may act as an early marker in the growth of exocrine pancreas induced by early weaning in rats.

EXOCRINE PANCREATIC FAILURE FOLLOWING BONE MARROW TRANSPLANTATION IN CHILDREN M H Dirks, B Shuckett, S Calderwood, W Ip and P R Durie, GI/Nutrition, Hospital for Sick Children, Toronto, ON, Canada.

Background:. Diarrhea, malabsorption, and malnourishment commonly follow bone marrow transplantation(BMT). There is an inverse relationship between nutritional status and mortality in this population. These complications are usually attributed to gastrointestinal and hepatic graft versus host disease (GVHD) or enteric infections, except in the cases known to have pre-existing exocrine pancreatic dysfunction, such as children with the Shwachman Diamond syndrome. A previous report has suggested that transient pancreatic insufficiency may also contribute to malabsorption in pediatric post-BMT recipients(1).

Methods: We evaluated whether permanent pancreatic insufficiency contributed to malabsorption following BMT, using CT imaging and serum trypsinogen.

Results: 4/22 children receiving an allogeneic BMT within a 15 month period (followed by GVHD) were found to have significant steatorrhea between 7 and 30 months following transplantation. None of these children had clinical features of the Shwachman Diamond syndrome. In all cases, CT imaging revealed pancreatic atrophy, with features of pancreatic lipomatosis. Serial serum trypsinogen values were less than 7ng/mL (normal range 16.6-46.5 ng/mL), consistent with exocrine pancreatic insufficiency. These findings persisted in follow-up from 7 months to 4 years following BMT. Histology of the pancreas of one child confirmed the radiological interpretation of fatty replacement of the pancreas. All patients experienced significant growth failure and had skin and intestinal manifestations of GVHD which were treated with cyclosporine and prednisone. In three cases, diarrhea, pain, and fat malabsorption improved with pancreatic enzyme supplements. One child was intolerant of all enteral feeding. The etiology of the pancreatic failure is unclear. One child did not receive preparative chemotherapy or irradiation, suggesting that events following BMT, such as GVHD, its treatment with immunosuppressives, or an infectious agent may be responsible.

Conclusion: We provide evidence, for the first time, of irreversible pancreatic atrophy and exocrine pancreatic failure following bone marrow transplantation in childhood. Prospective studies will determine the prevalence of pancreatic insufficiency in this population.

1. Papadopoulou A et al. Arch Dis Child 1996;75:208-13.