Cloning and expression of cytokine-inducible nitric oxide synthase cDNA from rat islets of Langerhans.

An inducible nitric oxide (NO) synthase isoform (iNOS) is specifically induced in the beta-cells of interleukin (IL)-1 beta-exposed rat islets, suggesting a role for NO in the pathogenesis of type I diabetes. The aim of this study was to clone and characterize iNOS cDNA from cytokine-exposed islets. Neither NO production nor iNOS transcription could be detected in rat islets or in rat insulinoma RIN-5AH beta-cells cultured in the absence of cytokines. Addition of IL-1 beta alone or in combination with tumor necrosis factor-alpha induced a concentration- and time-dependent expression of the iNOS gene and associated NO production (measured as nitrite) from both islets and RIN cells. iNOS transcripts were cloned by reverse transcriptase-polymerase chain reaction from the cytokine-exposed rat islets and RIN cells, and DNA sequence analysis revealed a near 100% identity to the recently published iNOS cDNA cloned from cytokine-exposed rat hepatocytes and smooth muscle cells. Recombinant rat islet iNOS was transiently and stably expressed in human kidney 293 fibroblasts, and the high enzymatic activity was inhibited by addition of the L-arginine analogs, N omega-nitro-L-arginine methyl ester and aminoguanidine. Two-dimensional gel electrophoresis revealed the recombinant iNOS as a series of spots with the expected molecular mass of 131 kDa and pI values in the range of 6.8 to 7.0. In conclusion, the IL-1 beta-induced iNOS cloned and expressed from rat islets and RIN cells is encoded by the same transcript as the iNOS induced in other cell types.

On the pathogenesis of IDDM.

A model of the pathogenesis of insulin-dependent diabetes mellitus, i.e. the initial phase of beta-cell destruction, is proposed: in a cascade-like fashion efficient antigen presentation, unbalanced cytokine, secretion and poor beta-cell defence result in beta-cell destruction by toxic free radicals (O2- and nitric oxide) produced by the beta cells themselves. This entire process is under polygenetic control.

[Dermatitis herpetiformis vs. celiac disease]. / Dermatitis herpetiforme versus enfermedad celíaca.

Twenty-nine patients affected with dermatitis herpetiformis (HD), all of whom were on a diet including gluten, were investigated for symptoms of enteropathy. Of these patients, 71% presented severe intestinal lesions, indistinguishable from those found in coeliac disease (CD). However, there were little other clinical manifestations of this finding since only three children in this group had weight and height < or = P3. Of the remaining children, 18% had moderate intestinal atrophy and 10% had normal mucosa or mucosa with negligible changes. When changed to a gluten free diet, the intestinal lesions subsided, dermic lesions disappeared in 17 patients, improved in 8 others and remained the same in the other three patients that were still on variable diets. A study of human leukocyte antigens (HLA) class II showed a total association with Dqw2 and 85% association to DR3, which was identical to the coeliac disease control group. These findings lead one to conclude that HD and CD are different clinical expressions of the same sensitivity to gluten which is associated to an immunological disorder with a common genetic base linked to certain HLA molecules.