C-C chemokine receptor 5 is essential for conventional NK cell trafficking and liver injury in a murine hepatitis virus-induced fulminant hepatic failure model

BACKGROUND

Previous studies have demonstrated that natural killer (NK) cells migrated into the liver from peripheral organs and exerted cytotoxic effects on hepatocytes in virus-induced liver failure.

AIM

This study aimed to investigate the potential therapeutic role of chemokine receptors in the migration of NK cells in a murine hepatitis  virus strain 3 (MHV-3)-induced fulminant hepatic failure (MHV-3-FHF) model and its mechanism.

RESULTS

By gene array analysis, chemokine (C-C motif) receptor 5 (CCR5) was found to have remarkably elevated expression levels in hepatic NK cells after MHV-3 infection. The number of hepatic CCR5+ conventional NK (cNK) cells increased and peaked at 48 h after MHV-3 infection, while the number of hepatic resident NK (rNK) cells steadily declined. Moreover, the expression of CCR5-related chemokines, including macrophage inflammatory protein (MIP)-1α, MIP-1β and regulated on activation, normal T-cell expressed and secreted (RANTES) was significantly upregulated in MHV-3-infected hepatocytes. In an in vitro Transwell migration assay, CCR5-blocked splenic cNK cells showed decreased migration towards MHV-3-infected hepatocytes, and inhibition of MIP-1β or RANTES but not MIP-1α decreased cNK cell migration. Moreover, CCR5 knockout (KO) mice displayed reduced infiltration of hepatic cNK cells after MHV-3 infection, accompanied by attenuated liver injury and improved mouse survival time. Adoptive transfer of cNK cells from wild-type mice into CCR5 KO mice resulted in the abundant accumulation of hepatic cNK cells and aggravated liver injury. Moreover, pharmacological inhibition of CCR5 by maraviroc reduced cNK cell infiltration in the liver and liver injury in the MHV-3-FHF model.

CONCLUSION

The CCR5-MIP-1β/RANTES axis played a critical role in the recruitment of cNK cells to the liver during MHV-3-induced liver injury. Targeted inhibition of CCR5 provides a therapeutic approach to ameliorate liver damage during virus-induced acute liver injury.

[Comparing gene density and GC content between two large genomic blocks at short arm of chromosome 3]

The present paper is to investigate gene distribution at different genomic region with different local GC content. With shout-gun technology, we sequencing two sequences at 3p25.1 and 3p26.1, at genome size 328 kb and 753 kb respectively. The 328 kb sequence,with an average GC content as high as 47.57%, has high gene density (13.7 gene/100 kb). However, another sequence at 3p26.1 only includes one exon and one intron of large gene GRM7 and the coding sequence size is 11 520 bp only taking a small part (1.31%) of the whole genome region. High percentage distribution of GC-rich repeats of SINEs explain high GC genomic region at 3p25.1 and high concentration of AT-rich repeats of LINEs at 3p26.1 lead to low GC content of the region. Our results suggest isochore structure is the result of coevolution between gene and genome.

[Role of TNF-alpha and ICAM-1 in pathogenesis of cerebral malaria]

OBJECTIVE

To investigate the role of TNF-alpha and ICAM-1 in the pathogenesis of cerebral malaria.

METHODS

Immunohistochemical method and ELISA were employed to examine the expression of ICAM-1 on the brain microvessel endothelium and to detect the production of serum TNF-alpha in P. berghei ANKA strain infected-CBA/J mice.

RESULTS

Serum TNF-alpha levels of mice were apparently higher and the ICAM-1 expression was more evident in P. berghei ANKA infected-CBA/J mice than in control groups. rTNF-alpha i.p. injection could enhance the development of CM and the expression of ICAM-1 on brain endothelial cells(EC).

CONCLUSION

Excessive production of TNF-alpha may mediate the expression of ICAM-1 on brain EC and hence cause the development of CM.