A Sensitive Whole Blood Assay Detects Antigen-Stimulated Cytokine Release From CD4+ T Cells and Facilitates Immunomonitoring in a Phase 2 Clinical Trial of Nexvax2 in Coeliac Disease.

Improved blood tests assessing the functional status of rare gluten-specific CD4+ T cells are needed to effectively monitor experimental therapies for coeliac disease (CD). Our aim was to develop a simple, but highly sensitive cytokine release assay (CRA) for gluten-specific CD4+ T cells that did not require patients to undergo a prior gluten challenge, and would be practical in large, multi-centre clinical trials. We developed an enhanced CRA and used it in a phase 2 clinical trial ("RESET CeD") of Nexvax2, a peptide-based immunotherapy for CD. Two participants with treated CD were assessed in a pilot study prior to and six days after a 3-day gluten challenge. Dye-dilution proliferation in peripheral blood mononuclear cells (PBMC) was assessed, and IL-2, IFN-γ and IL-10 were measured by multiplex electrochemiluminescence immunoassay (ECL) after 24-hour gluten-peptide stimulation of whole blood or matched PBMC. Subsequently, gluten-specific CD4+ T cells in blood were assessed in a subgroup of the RESET CeD Study participants who received Nexvax2 (maintenance dose 900 µg, n = 12) or placebo (n = 9). The pilot study showed that gluten peptides induced IL-2, IFN-γ and IL-10 release from PBMCs attributable to CD4+ T cells, but the PBMC CRA was substantially less sensitive than whole blood CRA. Only modest gluten peptide-stimulated IL-2 release could be detected without prior gluten challenge using PBMC. In contrast, whole blood CRA enabled detection of IL-2 and IFN-γ before and after gluten challenge. IL-2 and IFN-γ release in whole blood required more than 6 hours incubation. Delay in whole blood incubation of more than three hours from collection substantially reduced antigen-stimulated IL-2 and IFN-γ secretion. Nexvax2, but not placebo treatment in the RESET CeD Study was associated with significant reductions in gluten peptide-stimulated whole blood IL-2 and IFN-γ release, and CD4+ T cell proliferation. We conclude that using fresh whole blood instead of PBMC substantially enhances cytokine secretion stimulated by gluten peptides, and enables assessment of rare gluten-specific CD4+ T cells without requiring CD patients to undertake a gluten challenge. Whole blood assessment coupled with ultra-sensitive cytokine detection shows promise in the monitoring of rare antigen-specific T cells in clinical studies.

Sustained virological response halts fibrosis progression: A long-term follow-up study of people with chronic hepatitis C infection.

BACKGROUND/AIMS: Long-term follow-up studies validating the clinical benefit of sustained virological response (SVR) in people with chronic hepatitis C (CHC) infection are lacking. Our aim was to identify rates and predictors of liver fibrosis progression in a large, well characterized cohort of CHC patients in whom paired liver fibrosis assessments were performed more than 10 years apart. METHODS: CHC patients who had undergone a baseline liver biopsy pre-2004 and a follow up liver fibrosis assessment more than 10 years later (biopsy or liver stiffness measurement (LSM) using transient elastography [FibroScan]) were identified. Subjects who had undergone a baseline liver biopsy but had no follow up fibrosis assessment were recalled for LSM. Fibrosis was categorised as mild-moderate (METAVIR F0-2 / LSM result of ≤ 9.5 kPa) or advanced (METAVIR F3-4/ LSM >9.5 kPa). The primary objective was to assess the association between SVR and the rate of liver fibrosis progression over at least 10 years, defined as an increase from mild-moderate fibrosis at baseline liver biopsy (METAVIR F0-2) to advanced fibrosis at follow-up liver fibrosis assessment. RESULTS: 131 subjects were included in this analysis: 69% male, 82% Caucasian, 60% G1 HCV, 25% G3 HCV. The median age at F/U fibrosis staging was 57 (IQR 54-62) years with median estimated duration of infection 33-years (IQR 29-38). At F/U, liver fibrosis assessment was performed by LSM in 86% and liver biopsy in 14%. The median period between fibrosis assessments was 14-years (IQR 12-17). 109 (83%) participants had received interferon-based antiviral therapy. 40% attained SVR. At F/U, there was a significant increase in the proportion of subjects with advanced liver fibrosis: 27% at baseline vs. 46% at F/U (p = 0.002). The prevalence of advanced fibrosis did not change among subjects who attained SVR, 30% at B/L vs 25% at F/U (p = 0.343). However, advanced fibrosis became more common at F/U among subjects with persistent viremia: 10% at B/L vs 31% at F/U (p = 0.0001). SVR was independently associated with protection from liver fibrosis progression after adjustment for other variables including baseline ALT (p = 0.011), duration of HCV infection and mode of acquisition. CONCLUSION: HCV eradication is associated with lower rates of liver fibrosis progression. The data support early treatment to prevent long-term liver complications of HCV infection.

Toll-like Receptor Expression and Signaling in Peripheral Blood Mononuclear Cells Correlate With Clinical Outcomes in Acute Hepatitis C Virus Infection.

BACKGROUND: Mechanisms by which spontaneous clearance of acute hepatitis C occurs are unclear. A critical role for the innate immune system and IFNL4 polymorphisms has been proposed. This study investigates whether Toll-like receptor (TLR) expression and signaling during acute hepatitis C correlates with clinical outcomes. METHODS: Participants identified from the Australian Trial in Acute Hepatitis C and the Networks study were followed longitudinally from the time of diagnosis of acute hepatitis C. Peripheral blood mononuclear cells (PBMCs) and plasma were collected at and 2 time points after diagnosis. At each time point, TLR2, TLR4, and CD86 expression on peripheral blood monocytes, natural killer (NK) cells, and NK T cells was measured, as well as the response of PBMCs to stimulation with TLR ligands. Cytokine and chemokine levels were measured in stimulated PBMCs and plasma. RESULTS: We identified 20 participants with acute hepatitis C (10 with hepatitis C virus [HCV] monoinfection and 10 with HCV and human immunodeficiency virus coinfection). Eleven participants (55%) spontaneously cleared HCV. Acute hepatitis C and spontaneous clearance was associated with lower TLR4 expression on monocytes (P = .009) and NK cells (P = .029). Acute hepatitis C and spontaneous clearance was also associated with a reduced interferon γ response to TLR4 (P = .038) and TLR7/8 stimulation (P = .035), a reduced interleukin 6 response to TLR7/8 stimulation (P = .037), and reduced IFN-γ-inducible protein 10 (IP-10) response to TLR2 stimulation (P = .042). Lower plasma IP-10 levels were associated with spontaneous clearance (P = .001). CONCLUSIONS: These findings implicate TLR4 signaling as playing a critical role in the outcome of acute hepatitis C.