Granulocyte–macrophage colony-stimulating factor (GM-CSF) has emerged as a crucial cytokine that activates myeloid cells to initiate tissue inflammation. However, the molecular actions of GM-CSF against innate immunity are still poorly characterized. Here, we investigated the in vitro effects of GM-CSF on the activation of human myeloid lineages, neutrophils, and the underlying intracellular signaling mechanism, including inflammasome activation. Human neutrophils were stimulated with GM-CSF in the presence or absence of tofacitinib. The cellular supernatants were analyzed for interleukin-1 beta (IL-1β) and caspase-1 by enzyme-linked immunosorbent assay (ELISA) methods. Pro-IL-1β mRNA expressions in human neutrophils were analyzed by real-time polymerase chain reaction. Protein phosphorylation of neutrophils was assessed by Western blot using phospho-specific antibodies. Stimulation with GM-CSF alone, but not tumor necrosis factor-alpha, was shown to increase the release of IL-1β and cleaved caspase-1 (p20) from human neutrophils. Tofacitinib, which inhibits GM-CSF–induced Janus kinase 2 (Jak2)-mediated signal transduction, completely abrogated GM-CSF–induced IL-1β and caspase-1 (p20) secretion from neutrophils. GM-CSF stimulation also induced pro-IL-1β mRNA expression in neutrophils and induced NLR family pyrin domain-containing 3 (NLRP3) protein expression. Although tofacitinib pretreatment marginally inhibited GM-CSF–induced pro-IL-1β mRNA expression, tofacitinib completely abrogated NLRP3 protein expression in neutrophils. These results indicate that GM-CSF signaling induces NLRP3 expression and subsequent IL-1β production by affecting neutrophils, which may cause the activation of innate immunity. Therefore, GM-CSF is a key regulator of the NLRP3 inflammasome and IL-1β production by activating innate immune cells. This process can be blocked by tofacitinib, which interferes with JAK/STAT signaling pathways.

Recently, the number of follicular helper T (Tfh) cells expressing interleukin (IL)-21 was found to increase in peripheral blood of human and murine models of autoimmune hepatitis (AIH). IL-21, the most recently discovered member of the type-I cytokine family, exerts various effects on the immune system, including B cell activation, plasma cell differentiation, and immunoglobulin production. We aimed to assess the relationship of serum IL-21 levels in patients with type I AIH with clinical and laboratory parameters and histology. Ninety-two Japanese patients with liver disease (22 AIH, 20 primary biliary cholangitis, 19 drug-induced liver injury, 8 acute hepatitis B, 8 chronic hepatitis C, 10 non-alcoholic steatohepatitis, 5 viral hepatitis) and 10 healthy volunteers were recruited. Serum IL-21 levels were detected by enzyme-linked immunosorbent assay. Real-time polymerase chain reaction measured mRNA levels of Bcl-6, IL-21, and CXCR5 (Tfh-related factors) in peripheral mononuclear cells. Mean age at diagnosis of AIH was 58.6 years, male-to-female ratio was 4:18, 18.2 % of participants had cirrhosis, and 22.7 % had severe disease. IL-21 levels were significantly increased in the serum of patients with AIH compared to those with other liver diseases and controls (p < 0.0001). Particularly, serum IL-21 levels were significantly increased in severe AIH cases compared to non-severe cases (p < 0.05). Serum IL-21 levels correlated positively with total serum bilirubin levels (r = 0.46, p < 0.05), grading of necroinflammatory activity (r = 0.68, p < 0.005) and negatively with serum albumin levels in patients with AIH (r = −0.49, p < 0.05). In patients with biochemical remission of AIH, serum IL-21 levels remained elevated and correlated positively with serum IgG levels (r = 0.84, p < 0.01). Expression of Tfh-related factors, such as Bcl-6 and IL-21, in peripheral blood mononuclear cells of patients with AIH was significantly higher than that in healthy volunteers. IL-21 may play an important role in the pathogenesis and severity of AIH, and may present a promising target for AIH therapy.

Health-related quality of life is impaired in patients with autoimmune hepatitis, but the association between health-related quality of life and patients’ backgrounds remains unknown. We assessed health-related quality of life in patients with autoimmune hepatitis and identified factors associated with its impairment. We assessed health-related quality of life in patients with autoimmune hepatitis, patients with chronic hepatitis C, and healthy subjects using the Japanese version of the Chronic Liver Disease Questionnaire and the 36-Item Short Form Survey. We compared health-related quality of life in patients with autoimmune hepatitis with that of patients with chronic hepatitis C and healthy subjects. A total of 265 patients with autoimmune hepatitis, 88 patients with chronic hepatitis C, and 97 healthy subjects were enrolled; most patients were women. The median ages of patients were 65, 66, and 57 years, respectively. Of these patients with autoimmune hepatitis, 10.6% and 57.0% had cirrhosis and comorbid diseases, respectively. The overall Chronic Liver Disease Questionnaire scores (5.5 vs. 6.2, P < 0.001) and physical (48.1 vs. 54.2, P < 0.001) and mental (51.8 vs. 55.0, P = 0.004) component summaries of 36-Item Short Form Survey were significantly lower in patients with autoimmune hepatitis than in healthy subjects, and similar to scores in patients with chronic hepatitis C. Having cirrhosis, comorbid diseases, and treatment for autoimmune hepatitis were associated with impaired health-related quality of life among patients with autoimmune hepatitis. In particular, prednisolone use was associated with lower scores on the worry domain of the Chronic Liver Disease Questionnaire. Patients with autoimmune hepatitis showed impairment in health-related quality of life, which was associated with not only disease progression, but also comorbid diseases and treatment. Ways to improve health-related quality of life should be considered in patients with AIH when disease outcome is not favorable and when using prednisolone.