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Tolerizing CTL by sustained hepatic PD-L1 expression provides a new therapy spproach in mouse sepsis
(2019)
Cytotoxic T lymphocyte (CTL) activation contributes to liver damage during sepsis, but the mechanisms involved are largely unknown. Understanding the underlying principle will permit interference with CTL activation and thus, provide a new therapeutic option.
Methods: To elucidate the mechanism leading to CTL activation we used the Hepa1-6 cell line in vitro and the mouse model of in vivo polymicrobial sepsis, following cecal-ligation and -puncture (CLP) in wildtype, myeloid specific NOX-2, global NOX2 and NOX4 knockout mice, and their survival as a final readout. In this in vivo setting, we also determined hepatic mRNA and protein expression as well as clinical parameters of liver damage - aspartate- and alanine amino-transaminases. Hepatocyte specific overexpression of PD-L1 was achieved in vivo by adenoviral infection and transposon-based gene transfer using hydrodynamic injection.
Results: We observed downregulation of PD-L1 on hepatocytes in the murine sepsis model. Adenoviral and transposon-based gene transfer to restore PD-L1 expression, significantly improved survival and reduced the release of liver damage, as PD-L1 is a co-receptor that negatively regulates T cell function. Similar protection was observed during pharmacological intervention using recombinant PD-L1-Fc. N-acetylcysteine blocked the downregulation of PD-L1 suggesting the involvement of reactive oxygen species. This was confirmed in vivo, as we observed significant upregulation of PD-L1 expression in NOX4 knockout mice, following sham operation, whereas its expression in global as well as myeloid lineage NOX2 knockout mice was comparable to that in the wild type animals. PD-L1 expression remained high following CLP only in total NOX2 knockouts, resulting in significantly reduced release of liver damage markers.
Conclusion: These results suggest that, contrary to common assumption, maintaining PD-L1 expression on hepatocytes improves liver damage and survival of mice during sepsis. We conclude that administering recombinant PD-L1 or inhibiting NOX2 activity might offer a new therapeutic option in sepsis.
Background and aims: Expression of carbonic anhydrase IX (CA9), an enzyme expressed in response to hypoxia, acidosis and oncogenic alterations, is reported to be a prognostic factor in HCC patients. Here we evaluated serum CA9 levels in HCC and cirrhosis patients.
Methods: HCC and cirrhosis patients were prospectively recruited and CA9 levels were determined. CA9 levels were compared to stages of cirrhosis and HCC stages. The association of the CA9 levels and overall survival (OS) was assessed. Furthermore, immunohistochemical CA9 expression in HCC and cirrhosis was evaluated.
Results: 215 patients with HCC were included. The median serum CA9 concentration in patients with HCC was 370 pg/ml and significantly higher than in a healthy cohort. Patients with advanced cancer stages (BCLC and ALBI score) had hid significant higher levels of CA9 in the serum. HCC patients with high serum CA9 concentrations (>400 pg/ml) had an increased mortality risk (hazard ratio (HR) 1.690, 95% confidence interval (CI) 1.017–2.809, P = 0.043). Serum CA9 concentration in cirrhotic patients did not differ significantly from HCC patients. Higher CA9 levels in cirrhotic patients correlated with portal hypertension and esophageal varices. Patients with ethanol induced cirrhosis had the highest CA9 levels in both cohorts. Levels of CA9 did not correlate with immunohistochemical expression.
Conclusions: We conclude that a high CA9 level is a possible prognostic indicator for a poor outcome in HCC patients. The high CA9 levels are probably mainly associated with portal hypertension. Ductular reactions might be a possible source of serum CA9.