ImportanceNonalcoholic steatohepatitis (NASH) is the inflammatory subtype of nonalcoholic fatty liver disease (NAFLD) and is associated with disease progression, development of cirrhosis, and need for liver transplant. Despite its importance, NASH is underrecognized in clinical practice.ObservationsNASH affects an estimated 3% to 6% of the US population and the prevalence is increasing. NASH is strongly associated with obesity, dyslipidemia, type 2 diabetes, and metabolic syndrome. Although a number of noninvasive tests and scoring systems exist to characterize NAFLD and NASH, liver biopsy is the only accepted method for diagnosis of NASH. Currently, no NASH-specific therapies are approved by the US Food and Drug Administration. Lifestyle modification is the mainstay of treatment, including dietary changes and exercise, with the primary goal being weight loss. Substantial improvement in histologic outcomes, including fibrosis, is directly correlated with increasing weight loss. In some cases, bariatric surgery may be indicated to achieve and maintain the necessary degree of weight loss required for therapeutic effect. An estimated 20% of patients with NASH will develop cirrhosis, and NASH is predicted to become the leading indication for liver transplants in the US. The mortality rate among patients with NASH is substantially higher than the general population or patients without this inflammatory subtype of NAFLD, with annual all-cause mortality rate of 25.56 per 1000 person-years and a liver-specific mortality rate of 11.77 per 1000 person-years.Conclusions and RelevanceNonalcoholic steatohepatitis affects 3% to 6% of the US population, is more prevalent in patients with metabolic disease and obesity, progresses to cirrhosis in approximately 20% of cases, and is associated with increased rates of liver-specific and overall mortality. Early identification and targeted treatment of patients with nonalcoholic steatohepatitis are needed to improve patient outcomes, including directing patients toward intensive lifestyle modification to promote weight loss and referral for bariatric surgery as indicated for management of obesity and metabolic disease.

BaCKgRoUND aND aIMS: Nonalcoholic steatohepatitis is rapidly becoming the leading cause of liver failure and indication for liver transplantation. Hepatic inflammation is a key feature of NASH but the immune pathways involved in this process are poorly understood. B lymphocytes are cells of the adaptive immune system that are critical regulators of immune responses. However, the role of B cells in the pathogenesis of NASH and the potential mechanisms leading to their activation in the liver are unclear.appRoaCH aND ReSUltS: In this study, we report that NASH livers accumulate B cells with elevated proinflammatory cytokine secretion and antigen-presentation ability. Single-cell and bulk RNA sequencing of intrahepatic B cells from mice with NASH unveiled a transcriptional landscape that reflects their pro-inflammatory function. Accordingly, B-cell deficiency ameliorated NASH progression, and adoptively transferring B cells from NASH livers recapitulates the disease. Mechanistically, B-cell activation during NASH involves signaling through the innate adaptor myeloid differentiation primary response protein 88 (MyD88) as B cell-specific deletion of MyD88 reduced hepatic T cell-mediated inflammation and fibrosis, but not steatosis. In addition, activation of intrahepatic B cells implicates B cellreceptor signaling, delineating a synergy between innate and adaptive mechanisms of antigen recognition. Furthermore, fecal microbiota transplantation of human NAFLD gut microbiotas into recipient mice promoted the progression of NASH by increasing the accumulation and activation of intrahepatic B cells, suggesting that gut microbial factors drive the pathogenic function of B cells during NASH. CoNClUSIoN:Our findings reveal that a gut microbiotadriven activation of intrahepatic B cells leads to hepatic inflammation and fibrosis during the progression of NASH through innate and adaptive immune mechanisms. (Hepatology 2021;74:704-722). NAFLD is estimated to affect 30% of the population and is now recognized as the most prevalent chronic liver disease worldwide. (1) The disease covers a wide spectrum of liver pathology, ranging from simple lipid accumulation to the development of NASH, defined by hepatic steatosis, local inflammation, hepatocellular injury, and fibrosis. (2) NASH-associated inflammation is driven by innate and adaptive immune mechanisms comprising macrophages, dendritic cells, neutrophils, and lymphocytes. (3) Recent single-cell transcriptome analyses have uncovered the heterogeneity of intrahepatic

Obesity-related insulin resistance is driven by low-grade chronic inflammation of metabolic tissues. In the liver, non-alcoholic fatty liver disease (NAFLD) is associated with hepatic insulin resistance and systemic glucose dysregulation. However, the immunological factors supporting these processes are poorly understood. We found that the liver accumulates pathogenic CD8+ T cell subsets which control hepatic insulin sensitivity and gluconeogenesis during diet-induced obesity in mice. In a cohort of human patients, CD8+ T cells represent a dominant intrahepatic immune cell population which links to glucose dysregulation. Accumulation and activation of these cells are largely supported by type I interferon (IFN-I) responses in the liver. Livers from obese mice upregulate critical interferon regulatory factors (IRFs), interferon stimulatory genes (ISGs), and IFNα protein, while IFNαR1−/− mice, or CD8-specific IFNαR1−/− chimeric mice are protected from disease. IFNαR1 inhibitors improve metabolic parameters in mice, while CD8+ T cells and IFN-I responses correlate with NAFLD activity in human patients. Thus, IFN-I responses represent a central immunological axis that governs intrahepatic T cell pathogenicity during metabolic disease.

Purpose: To expand clinical-grade healthy donor-derived double-negative T cells (DNT) to a therapeutically relevant number and characterize their potential to be used as an "offthe-shelf" adoptive cellular therapy (ACT) against cancers.Experimental Design: We developed methods to expand DNTs under GMP conditions and characterized their surface molecule expression pattern using flow cytometry-based high-throughput screening. We investigated the off-the-shelf potential of clinical-grade DNTs by assessing their cytotoxicity against various cancer types and their off-tumor toxicity in vitro and in xenograft models and determining the effect of cryopreservation under GMP conditions on cell viability and cytotoxicity. Further, we determined the susceptibility of DNTs to conventional allogeneic T cells in vitro and in vivo.Results: Clinical-grade DNTs expanded 1,558 AE 795.5-fold in 17 days with >90% purity. Expanded DNTs showed potent in vitro cytotoxic activity against various cancer types in a donor-unrestricted manner. DNTs enhanced the survival of mice infused with a lethal dose of EBV-LCL and significantly reduced leukemia engraftment in xenograft models. Expanded DNTs cryopreserved using GMP-compliant reagents maintained viability and anticancer functions for at least 600 days. Live allogeneic DNTs did not induce cytotoxicity of alloreactive CD8 þ T cells in vitro, and coinfusion of DNTs with peripheral blood mononuclear cells (PBMC) from a different donor into mice resulted in coengraftment of DNTs and PBMC-derived allogeneic conventional T cells in the absence of cytotoxicity toward DNTs, suggesting the lack of hostversus-graft reaction.Conclusions: We have established a method to generate therapeutic numbers of clinical-grade DNTs that fulfill the requirements of an off-the-shelf ACT.