Host‐cell cyclophilin is important for the intracellular replication of Leishmania major

Abstract

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.

Opposite Regulation of Tissue Factor Expression by Calcineurin in Monocytes and Endothelial Cells

“…Moreover, comparable amounts of Cyp40 were present in total cell extracts of monocytes and EC as shown by use of a semiquantitative immunoblot. Using the different methods, a severalfold higher expression level for CypA than for Cyp40 was found in both cells, comparable with other human cell lines and tissues (23). These results indicate that the difference in binding to the CsA resin was possibly attributable to a difference in intracellular interactions of the Cyp from both cells, which are competitive to CsA binding.…”

“…The RII peptide (DLDVPIPGRFDRRSVAAE; Biomol, Hamburg, Germany) was labeled to ϳ600 cpm/pmol and purified on a RP-C2 clean up extraction column (Amchro, Sulzbach, Germany) as previously described (23). The peptide was eluted with 80% acetonitrile and freeze-dried, and reconstituted samples were stored in deionized water at Ϫ80°C.…”

“…Characterization and purification of Cyp isoforms were performed with modifications of our earlier described procedure (23). Cell extract was prepared as described for the Cn assay.…”

Molecular aspects of cyclophilins mediating therapeutic actions of their ligands

“…It has also been suggested that the mammalian host cell CyPA seems to be involved in the intracellular parasite's replication cycle of L. major parasites, as CyPA siRNA interference or CsA reduced the parasite burden [134]. Some of the small cyclophilins from Plasmodium falciparum and Toxoplasma gondii (TgCyP18) have similar inhibitory profiles as those established for the hCyPA (Table 3) [124,[126][127][128][129].…”

Agrobacterium VirD2 protein interacts with plant host cyclophilins

“…The biological role of host CyPs is more intriguing in a number of host-pathogen interactions (41). CyPs are specific targets for the CsA-mediated attenuation of a variety of parasitic infections, including leishmaniasis, malaria and toxoplasmosis (42). Interestingly, human CyPA promotes HIV-1 infectivity by forming a stable complex with the capsid protein in HIV-1 virions and promoting viral uncoating (30).…”