BACKGROUND Full recovery is always achieved after caerulein induced pancreatitis. Cyclosporin stimulates transforming growth factor β (TGF-β) and may interfere with pancreatic regeneration.

AIM To investigate the effects of cyclosporin after caerulein induced pancreatitis or after caerulein injury.

RESULTS Protocol A: plasma TGF-β1 and tissue collagenase rose after pancreatitis but decreased towards baseline values on day 15, matching a low collagen content. Morphology disclosed minimal inflammatory infiltration and some interstitial cells immunoreactive for smooth muscle α-actin (SMA). TGF-β1 increased, and remained high in cyclosporin treated groups (cyclosporin alone and cyclosporin plus caerulein). Rats treated with cyclosporin and caerulein showed severe pancreatic weight reduction, abundant inflammatory infiltrates, increased SMA immunoreactive interstitial cells, high collagen content, and delayed collagenase response. No SMA immunoreactive cells were detected in normal rats. Cyclosporin alone also increased SMA immunoreactive cells, despite the absence of inflammatory infiltration and fairly conserved pancreatic structure. Protocol B: the combined pulse treatment induced appreciable collagen deposition and resulted in a smaller pancreas than controls. Morphological examination showed atrophy, fibrosis, fibroblast proliferation, and mononuclear infiltrates.

CONCLUSION Cyclosporin greatly distorts pancreatic repair, transforming caerulein induced pancreatitis into a fibrotic chronic-like disease. The mechanism involves TGF-β, myofibroblasts, and defective collagenase activation.