Changes in natural killer cells and exhausted memory regulatory T Cells with corticosteroid therapy in acute autoimmune hepatitis

Abstract

Autoimmune hepatitis (AIH) is an immune‐mediated liver disease currently treated by immunosuppressive medications with significant side effects. Thus, novel mechanistic treatments are greatly needed. We performed prospective deep immunophenotyping of blood immune cells in patients with acute AIH before and after corticosteroid therapy. Blood samples from 26 patients with acute AIH (United Kingdom‐AIH Consortium) were phenotyped by flow cytometry at baseline and 4 months after starting corticosteroids. Pretreatment liver tissues were stained for forkhead box P3‐positive (FOXP3POS) regulatory T cells (Tregs), clusters of differentiation (CD)56POS natural killer (NK) cells, and chemokine (C‐X‐C motif) ligand 10. Chemokine secretion by cultured primary hepatocyte and biliary epithelial cells was measured by enzyme‐linked immunosorbent assay. Functional coculture assays with stimulated NK cells and Tregs were performed. CD161 ligand, lectin‐like transcript‐1 expression by intrahepatic immune cells was demonstrated with flow cytometry. Frequencies of NKbright cells declined with therapy (P < 0.001) and correlated with levels of alanine aminotransferase (P = 0.023). The Treg:NKbright ratio was lower pretreatment, and Tregs had an activated memory phenotype with high levels of CD39, cytotoxic T lymphocyte antigen 4, and FOXP3 but also high programmed death ligand 1, indicating exhaustion. Coculture experiments suggested the Tregs could not efficiently suppress interferon‐γ secretion by NK cells. Both Tregs and NK cells had high expression of liver infiltration and T helper 17 plasticity‐associated marker CD161 (P = 0.04). Pretreatment and CD161pos NK cells expressed high levels of perforin and granzyme B, consistent with an activated effector phenotype (P < 0.05). Lectin‐like transcript 1, a ligand for CD161, is expressed on intrahepatic B cells, monocytes, and neutrophils. Conclusion: Activated effector NK cells, which correlate with biochemical measurements of hepatitis, and exhausted memory Tregs are increased in the blood of patients with treatment‐naive AIH and decline with corticosteroid therapy. Inadequate regulation of NK cells by exhausted FOXP3pos Tregs may play a role in AIH pathogenesis and contribute to liver injury. (Hepatology Communications 2018;2:421‐436)

Dysregulation of Adenosinergic Signaling in Systemic and Organ-Specific Autoimmunity

“…Further, in acutely presenting, untreated AIH patients there is low ratio between Tregs and a specific NK subset with activated effector phenotype [64]. In this same study, Tregs were found to display an activated memory phenotype and exhibit signs of exhaustion, including increased CTLA-4 and PD-1 receptor levels, as well as decreased ability to limit pro-inflammatory responses [64].…”

“…In both AIH and autoimmune sclerosing cholangitis, there is a decrease in CD39 + Th17-cell numbers, associated with impaired overall cell-associated ADPase activity and lower A2AR expression [63]. Further, in acutely presenting, untreated AIH patients there is low ratio between Tregs and a specific NK subset with activated effector phenotype [64]. In this same study, Tregs were found to display an activated memory phenotype and exhibit signs of exhaustion, including increased CTLA-4 and PD-1 receptor levels, as well as decreased ability to limit pro-inflammatory responses [64].…”

Immune checkpoint molecules in natural killer cells as potential targets for cancer immunotherapy

“… 79 – 81 More so, PD-1 contains an extracellular variable immunoglobulin (IgV) domain, a transmembrane region, and an intracellular tail with two phosphorylation sites; one phosphorylation site is in an immunoreceptor tyrosine-based inhibitory motif, and the other is in an immunoreceptor tyrosine-based switch motif. 72 , 82 , 83 To be more specific, Y248 (a PD-1 tyrosine-based switch motif) interacts with SHP-2, which is a requirement of the inhibition of proximal signaling molecules (including ZAP70, PI3K/AKT, C3G, and ERK) that consequently leads to the suppression of immune cell activation. 79 In contrast, the activity of NK cells can be enhanced by histidine-rich glycoprotein, which modulates PD-1 expression via anti-C-type lectin-like receptor 1B.…”

Review article: unanswered clinical and research questions in autoimmune hepatitis‐conclusions of the International Autoimmune Hepatitis Group Research Workshop

“…Current data for the effects of immunosuppression come largely from CD4 cell culture but there is an emerging body of evidence to suggest that an imbalance of effector and regulatory T cells (enhancing T reg function) plays a role, potentially controlling the autoreactive T cells . The natural killer (NK) population (particularly natural killer bright cells that secrete cytokines) may be interesting with high CD161 expression at diagnosis and a significant reduction in blood T regs in the treatment naïve state of acute AIH which recovers by 4 months . However, the local hepatic inflammatory cytokine milieu seems to be a relevant determinant in degree of control by suppressive activity of T reg cells .…”