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Previously, we have shown that primary afferent sensory neurons are necessary for disease activity in T cell-mediated immune hepatitis in mice. In the present study, we analyzed the possible role of substance P (SP), an important proinflammatory neuropeptide of these nerve fibers, in an in vivo mouse model of liver inflammation.

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The association of cyclosporin A (CsA) immunosuppression with inhibition of transcription factor-dependent lymphokine gene activation formed the basis of our decision to investigate nuclear-associated Cyp isoforms. Immunofluorescence microscopy of mouse macrophages cell line with a monoclonal antibody mAb7F1 raised against CypA shows a co-localisation of CypA in the nucleus and in the cytosol. Nuclear CypA binds to DNA in a zinc ion-dependent manner, in contrast to recombinant CypB. Peptidyl-prolyl cisltrans isomerase (PPIase) activity of nuclear CypA is inhibited by zinc ions. The zinc inhibited CypA does not bind cyclosporin A (CsA). We suggest that nuclear Cyp in complex with zinc ions recognizes DNA sequences and is involved in transcription modulating processes.

Previously, we have shown that primary afferent neurons are necessary for disease activity in immune-mediated liver injury in mice. These nerve fibers are detectable by substance P (SP) immunocytochemistry in the portal tract of rodent liver. Antagonists of the neurokinin-1 receptor (NK-1R), which is the prime receptor of SP, prevented liver damage by suppressing the synthesis of proinflammatory cytokines. Here, we investigated the influence of primary afferent nerve fibers, SP, and NK-1 receptor antagonists on hepatocyte apoptosis in vivo induced by administration of activating anti-CD95 monoclonal antibody (mAb) to mice. Depletion of primary afferent nerve fibers by neonatal capsaicin treatment prevented CD95-mediated activation of caspase-3, measured as enzymatic activity in liver homogenates or by demonstration of hepatocellular immunoreactivity for active caspase-3 in liver slices, and liver damage. This effect was reversed by administration of SP to anti-CD95 mAb-treated mice In conclusion, SP, probably by binding to its receptor on hepatocytes, might aggravate apoptotic signals in these cells. Because NK-1 receptor antagonists not only suppress the proinflammatory cytokine response in the liver but also prevent liver cell apoptosis in vivo, they might be suitable drugs for treatment of immunemediated liver disease.

SummaryThe antiparasitic effects of cyclosporin A were examined in leishmanial infection by analysing the role of CsA-binding proteins (cyclophilins) in the host-parasite interaction. We hypothesized that the leishmanicidal effects of CsA on Leishmania major infected macrophages might be mediated through a cyclophilin of either the parasite or the host cell. Two cyclophilins (20 and 22 kDa) were purified from L. major parasites and N-terminally sequenced. Although enzyme activity of these cyclophilins was inhibited by CsA, pretreatment of L. major parasites with CsA did not result in reduction of a subsequent macrophage infection, arguing against a role of L. major cyclophilins as infectivity potentiators. However, host-cell cyclophilin A (CypA) was found to be critically involved in the intracellular replication of L. major parasites in murine macrophages. An antisense oligonucleotide to murine CypA was constructed and added to cultures of peritoneal macrophages prior to infection with L. major parasites. This treatment strongly reduced the expression of CypA in macrophages and resulted in the inhibition of the intracellular replication of L. major amastigotes. These data indicate that interaction of amastigotes with host-cell cyclophilin is an important part of the intracellular replication machinery of L. major and define, for the first time, a direct involvement of a cyclophilin in the survival strategies of an intracellular parasite.