Inflammatory Phenotype of Intrahepatic Sulfatide-Reactive Type II NKT Cells in Humans With Autoimmune Hepatitis

Background: Natural Killer T (NKT) cells are CD1d-restricted innate-like T cells that can rapidly release stored cytokines upon recognition of lipid antigens. In mice, type I NKT cells seem to promote liver inflammation, whereas type II NKT cells seem to restrict hepatitis. Here, we aimed at characterizing the role of human type I and type II NKT in patients with autoimmune hepatitis (AIH).Methods: NKT cells were analyzed by flow cytometry in peripheral blood and liver of AIH patients and control groups. α-galactosylceramide-loaded or sulfatide-loaded tetramers were used to detect type I or II NKT cells, respectively. Hepatic CD1d was stained by in situ-hybridization of liver biopsies.Results and Conclusions: Type II NKT cells were more prevalent in human peripheral blood and liver than type I NKT cells. In AIH patients, the frequency of sulfatide-reactive type II NKT cells was significantly increased in peripheral blood (0.11% of peripheral blood leukocytes) and liver (3.78% of intrahepatic leukocytes) compared to healthy individuals (0.05% and 1.82%) and patients with drug-induced liver injury (0.06% and 2.03%; p < 0.05). Intrahepatic type II NKT cells of AIH patients had a different cytokine profile than healthy subjects with an increased frequency of TNFα (77.8% vs. 59.1%, p < 0.05), decreased IFNγ (32.7% vs. 63.0%, p < 0.05) and a complete lack of IL-4 expressing cells (0% vs. 2.1%, p < 0.05). T cells in portal tracts expressed significantly more CD1d-RNA in AIH livers compared to controls. This study supports that in contrast to their assumed protective role in mice, human intrahepatic, sulfatide-reactive type II NKT cells displayed a proinflammatory cytokine profile in patients with AIH. Infiltrating T cells in portal areas of AIH patients overexpressed CD1d and could thereby activate type II NKT cells

Natural history and outcomes in drug induced autoimmune hepatitis

Aim: Drug-induced autoimmune hepatitis (DIAIH) remains poorly characterized. Our aim was to assess natural history and outcomes in DIAIH. Methods: This was a retrospective cohort study. Results: Eighty-two patients with autoimmune hepatitis (AIH) were identified, 11 (13.4%) with DIAIH, implicated drugs being nitrofurantoin (n = 4), statins (n = 4), herbal remedies (n = 2) and diclofenac (n = 1). Female sex, acute onset, elevated serum globulins/immunoglobulin G, fibrosis stage (Ishak), cirrhosis at onset, moderate–severe portal inflammation, interface and lobular hepatitis, remission, relapse and poor outcome were similar in those with DIAIH and AIH (P > 0.05). The former were however more likely to be aged 60 years or more and take longer to relapse on immunosuppression discontinuation (P = <0.05). On Kaplan–Meier analysis, probability of poor outcome was similar in those with DIAIH and AIH (log–rank test, 0.339). On comparing those with (n = 4) and without nitrofurantoin (n = 7) DIAIH, the former were older, had longer duration of drug use prior to DIAIH diagnosis, higher fibrosis stage and were less likely to relapse upon immunosuppression discontinuation. Conclusion: Approximately 15% of patients with AIH have DIAIH with similar outcomes, although the latter are older with a propensity for late relapse, mandating long-term follow up

Hepatitis C Virus (HCV)-Specific Immune Responses of Long‐Term Injection Drug Users Frequently Exposed to HCV

BACKGROUND: Injection drug users (IDUs) who successfully clear hepatitis C virus (HCV) have a reduced risk of developing chronic reinfection, despite their continuing exposure to the virus. To identify immunological correlates for this apparent protection, we studied HCV-specific immune responses in long-term IDUs (duration, >10 years). METHODS: HCV-specific T cell responses were assessed in proliferation, enzyme-linked immunospot (ELISPOT), interferon (IFN)–γ secretion, and cytotoxicity assays, whereas HCV-specific antibodies were assessed in enzyme immunoassays (EIAs), chemiluminescent assays, and in vitro neutralization assays. RESULTS: HCV-specific T cell proliferation and IFN-γ production were more common in nonviremic EIA-positive IDUs (16 [94%] of 17 IDUs) than in viremic EIA-positive IDUs (9 [45%] of 20 IDUs) (P = .003). They were also noted in 16 (62%) of 26 nonviremic EIA-negative IDUs. In contrast, 19 (90%) of 21 viremic IDUs displayed neutralizing antibodies (nAbs), compared with 9 (56%) of 16 nonviremic EIA-positive IDUs (P = .04) and 0 of 24 nonviremic EIA-negative IDUs. Nonviremic IDUs with nAbs were older (P = .0115) than those without nAbs, but these groups did not differ in terms of either injection drug use duration or HCV-specific T cell responses. CONCLUSION: The reduced risk of HCV persistence in IDUs previously recovered from HCV infection correlated with T cell responses, and prolonged antigenic stimulation appears to be required to maintain humoral responses

Intrinsiccone adaptation modulates feedback efficiency from horizontal cells to cones

Processing of visual stimuli by the retina changes strongly during light/dark adaptation. These changes are due to both local photoreceptor-based processes and to changes in the retinal network. The feedback pathway from horizontal cells to cones is known to be one of the pathways that is modulated strongly during adaptation. Although this phenomenon is well described, the mechanism for this change is poorly characterized. The aim of this paper is to describe the mechanism for the increase in efficiency of the feedback synapse from horizontal cells to cones. We show that a train of flashes can increase the feedback response from the horizontal cells, as measured in the cones, up to threefold. This process has a time constant of ∼3 s and can be attributed to processes intrinsic to the cones. It does not require dopamine, is not the result of changes in the kinetics of the cone light response and is not due to changes in horizontal cells themselves. During a flash train, cones adapt to the mean light intensity, resulting in a slight (4 mV) depolarization of the cones. The time constant of this depolarization is ∼3 s. We will show that at this depolarized membrane potential, a light-induced change of the cone membrane potential induces a larger change in the calcium current than in the unadapted condition. Furthermore, we will show that negative feedback from horizontal cells to cones can modulate the calcium current more efficiently at this depolarized cone membrane potential. The change in horizontal cell response properties during the train of flashes can be fully attributed to these changes in the synaptic efficiency. Since feedback has major consequences for the dynamic, spatial, and spectral processing, the described mechanism might be very important to optimize the retina for ambient light conditions

Key Terms and Definitions in Acute Porphyrias: Results of an International Delphi Consensus Led by the European Porphyria Network

Background: Acute porphyrias are a group of rare inherited disorders causing acute neurovisceral attacks. Many terms used frequently in the literature and in clinical practice are ambiguous, which can lead to confusion in the way patients are managed, studied, and reported in clinical studies. Agreed definitions are a necessary first step in developing management guidelines and will facilitate communication of results of future clinical research. Methods: The Delphi method was used to generate consensus on key terms and definitions in acute porphyria. The process started with a brainstorming phase offered to all members of the European Porphyria Network followed by 2 Delphi rounds among international experts in the field of porphyria (the Acute Porphyria Expert Panel). A consensus of 75% or more was defined as the agreement threshold. Results: 63 respondents from 26 countries participated in the brainstorming phase, leading to the choice of 9 terms and definitions. 34 experts were invited to take part in the Delphi rounds. 7 of the initial 9 terms and definitions which entered the first Delphi round achieved the threshold for agreement. Following a second Delphi round, all 9 definitions achieved agreement. Conclusion: Agreement on the definitions for 9 important terms describing acute porphyrias represents a significant step forward for the porphyria community. It will facilitate more accurate comparison of outcomes among porphyria centres and in clinical trials and provide a strong framework for developing evidence based clinical guidelines.Background: Acute porphyrias are a group of rare inherited disorders causing acute neurovisceral attacks. Many terms used frequently in the literature and in clinical practice are ambiguous, which can lead to confusion in the way patients are managed, studied, and reported in clinical studies. Agreed definitions are a necessary first step in developing management guidelines and will facilitate communication of results of future clinical research. Methods: The Delphi method was used to generate consensus on key terms and definitions in acute porphyria. The process started with a brainstorming phase offered to all members of the European Porphyria Network followed by 2 Delphi rounds among international experts in the field of porphyria (the Acute Porphyria Expert Panel). A consensus of 75% or more was defined as the agreement threshold. Results: 63 respondents from 26 countries participated in the brainstorming phase, leading to the choice of 9 terms and definitions. 34 experts were invited to take part in the Delphi rounds. 7 of the initial 9 terms and definitions which entered the first Delphi round achieved the threshold for agreement. Following a second Delphi round, all 9 definitions achieved agreement. Conclusion: Agreement on the definitions for 9 important terms describing acute porphyrias represents a significant step forward for the porphyria community. It will facilitate more accurate comparison of outcomes among porphyria centres and in clinical trials and provide a strong framework for developing evidence based clinical guidelines

Functional Contribution of Elevated Circulating and Hepatic Non-Classical CD14+CD16+ Monocytes to Inflammation and Human Liver Fibrosis

BACKGROUND: Monocyte-derived macrophages critically perpetuate inflammatory responses after liver injury as a prerequisite for organ fibrosis. Experimental murine models identified an essential role for the CCR2-dependent infiltration of classical Gr1/Ly6C(+) monocytes in hepatic fibrosis. Moreover, the monocyte-related chemokine receptors CCR1 and CCR5 were recently recognized as important fibrosis modulators in mice. In humans, monocytes consist of classical CD14(+)CD16(-) and non-classical CD14(+)CD16(+) cells. We aimed at investigating the relevance of monocyte subpopulations for human liver fibrosis, and hypothesized that 'non-classical' monocytes critically exert inflammatory as well as profibrogenic functions in patients during liver disease progression. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed circulating monocyte subsets from freshly drawn blood samples of 226 patients with chronic liver disease (CLD) and 184 healthy controls by FACS analysis. Circulating monocytes were significantly expanded in CLD-patients compared to controls with a marked increase of the non-classical CD14(+)CD16(+) subset that showed an activated phenotype in patients and correlated with proinflammatory cytokines and clinical progression. Correspondingly, CD14(+)CD16(+) macrophages massively accumulated in fibrotic/cirrhotic livers, as evidenced by immunofluorescence and FACS. Ligands of monocyte-related chemokine receptors CCR2, CCR1 and CCR5 were expressed at higher levels in fibrotic and cirrhotic livers, while CCL3 and CCL4 were also systemically elevated in CLD-patients. Isolated monocyte/macrophage subpopulations were functionally characterized regarding cytokine/chemokine expression and interactions with primary human hepatic stellate cells (HSC) in vitro. CD14(+)CD16(+) monocytes released abundant proinflammatory cytokines. Furthermore, CD14(+)CD16(+), but not CD14(+)CD16(-) monocytes could directly activate collagen-producing HSC. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate the expansion of CD14(+)CD16(+) monocytes in the circulation and liver of CLD-patients upon disease progression and suggest their functional contribution to the perpetuation of intrahepatic inflammation and profibrogenic HSC activation in liver cirrhosis. The modulation of monocyte-subset recruitment into the liver via chemokines/chemokine receptors and their subsequent differentiation may represent promising approaches for therapeutic interventions in human liver fibrosis