https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.26115

Natural killer cells in liver disease

Acute liver failure (ALF) is a syndrome of diverse aetiology, including hepatic encephalopathy, renal, cardiac and pulmonary failures, which result in a rapid loss of hepatic function. The mechanisms of liver injury contributing to ALF can be summarized into two categories: direct damage and immune-mediated liver injury. This review summarizes current concepts of immune-mediated liver injury from both clinical studies and animal models. We highlight immune responses of ALF from the liver injury perspective, which combines a variety of molecular and cellular mechanisms, particularly, the contribution of cytokines and the innate immune system. Hepatic and circulating inflammatory cytokines play a significant role in the pathophysiology of ALF including hepatocyte necrosis, extrahepatic complications and hepatocyte regeneration. Overproduction of cytokines, if unchecked, is hazardous to the host and may cause severe outcomes. Measuring pro-inflammatory cytokines in ALF may be of value for predictors of outcome. Innate and adaptive immune systems both involved in ALF contribute to immune-mediated liver injury. The innate immune response is activated much more rapidly compared with adaptive immunity, particularly in acute liver injury where the host has little time to trigger an effective adaptive immune response. From this point of view, the innate immune system may make a more profound contribution than the adaptive immune system. Furthermore, immune responses crosstalk with other physiological or pathophysiological factors, for example, coagulation factors which in turn determine the outcome of ALF and these are discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1478-3231.2010.02262.x

Acute liver failure: mechanisms of immune-mediated liver injury.

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.23977

Hypercytolytic Activity of Hepatic Natural Killer Cells Correlates With Liver Injury in Chronic Hepatitis B Patients

The liver represents a frontline immune organ that is constantly exposed to a variety of gut-derived antigens as a result of its unique location and blood supply. With a predominant role in innate immunity, the liver is enriched with various innate immune cells, among which natural killer (NK) cells play important roles in host defense and in maintaining immune balance. Hepatic NK cells were first described as 'pit cells' in the rat liver in the 1970s. Recent studies of NK cells in mouse and human livers have shown that two distinct NK cell subsets, liver-resident NK cells and conventional NK (cNK) cells, are present in this organ. Here, we review liver NK cell subsets in different species, revisiting rat hepatic pit cells and highlighting recent progress related to resident NK cells in mouse and human livers, and also discuss the dual roles of NK cells in liver immunity.

/pdf/liver-natural-killer-cells-subsets-and-roles-in-liver-29evhhbiyy.pdf

Liver natural killer cells: subsets and roles in liver immunity.

Roles of natural killer cells in antiviral immunity

The role of liver NK cells in virus-induced severe viral hepatitis and, subsequently, hepatic failure is not well defined. In this study, we investigated the role of liver NK cells in the development of hepatocyte necrosis in fulminant hepatic failure (FHF) and acute-on-chronic liver failure (ACLF) because of viral infection. A mouse model of FHF induced by murine hepatitis virus strain 3 (MHV-3) was used to study the role of liver NK cells. Samples from patients with hepatitis B virus-related ACLF (HBV-ACLF) were examined. After MHV-3 infection, the number of NK cells in livers of BALB/cJ mice increased markedly, peaked at 48 h postinfection, and remained at a high level until sacrifice. In peripheral blood, spleen, and bone marrow, this number decreased significantly. Expression of CD69, cytotoxic activity, and intracellular IFN-gamma and TNF-alpha production by liver NK cells at 48 h postinfection were all significantly upregulated. Depletion of NK cells 24 h post-MHV-3 infection increased the mice survival from 0 of 18 (0%) to 4 of 18 (22.2%). Highly activated liver NK cells were cytotoxic to MHV-3-infected hepatocytes and this effect was markedly inhibited by anti-Fas ligand (FasL) plus anti-NKG2D mAbs. Furthermore, the accumulation of hepatic NK cells and increased expression of FasL and natural cytotoxicity receptors (NKp30 and NKp46) on the peripheral NK cells from patients with HBV-ACLF were correlated with disease progression. These results indicate NK cells play a pivotal role in the pathogenesis of FHF and HBV-ACLF, in which process Fas/FasL and NKG2D/NKG2D ligand pathway contribute to the liver NK cell-mediated hepatocyte injury.

/pdf/increased-killing-of-liver-nk-cells-by-fas-fas-ligand-and-o69k89m3jv.pdf

Increased Killing of Liver NK Cells by Fas/Fas Ligand and NKG2D/NKG2D Ligand Contributes to Hepatocyte Necrosis in Virus-Induced Liver Failure

This study is to analyze the effect of C-type natriuretic peptide (CNP) on sperm motility of asthenozoospermia and explore the influence mechanism of CNP on the reproductive system and sperm motility. Our results showed that the concentration of CNP in asthenospermia patients’ semen was lower than in normal people’s. The motility of sperm could be improved markedly by CNP and 8-Br-cGMP, while the effect of CNP was inhibited by NPR-B antagonist and KT5823. In the asthenozoospermia mouse model induced by CTX, CNP injection could improve sperm motility in the epididymis, alleviate tissue damage in the testes and epididymis, and increase testosterone levels. The asthenospermia mouse model showed high activity of MDA and proinflammatory factors (TNF-α, IL-6), as well as low expression of antioxidants (SOD, GSH-Px, CAT) in the testis and epididymis, but this situation could be significantly ameliorated after being treated with CNP. Those studies indicated that the concentration of CNP in the semen of asthenospermia patients is lower than in normal people and could significantly promote sperm motility through the NPR-B/cGMP pathway. In the asthenospermia mouse model induced by CTX, CNP can alleviate the damage of cyclophosphamide to the reproductive system and sperm motility. The mechanism may involve increasing testosterone and reducing ROS and proinflammatory factors to damage the tissue and sperm.

/pdf/c-type-natriuretic-peptide-cnp-could-improve-sperm-motility-hk9jm4ah.pdf

Ge Song

Papers

Increased Killing of Liver NK Cells by Fas/Fas Ligand and NKG2D/NKG2D Ligand Contributes to Hepatocyte Necrosis in Virus-Induced Liver Failure

C-Type Natriuretic Peptide (CNP) Could Improve Sperm Motility and Reproductive Function of Asthenozoospermia

Involvement of CXCR3-associated chemokines in MHV-3 induced fulminant hepatic failure