Jessica Nyström

Arming of MAIT Cell Cytolytic Antimicrobial Activity Is Induced by IL-7 and Defective in HIV-1 Infection

Mucosa-associated invariant T (MAIT) cells represent a large innate-like evolutionarily conserved antimicrobial T-cell subset in humans. MAIT cells recognize microbial riboflavin metabolites from a range of microbes presented by MR1 molecules. MAIT cells are impaired in several chronic diseases including HIV-1 infection, where they show signs of exhaustion and decline numerically. Here, we examined the broader effector functions of MAIT cells in this context and strategies to rescue their functions. Residual MAIT cells from HIV-infected patients displayed aberrant baseline levels of cytolytic proteins, and failed to mobilize cytolytic molecules in response to bacterial antigen. In particular, the induction of granzyme B (GrzB) expression was profoundly defective. The functionally impaired MAIT cell population exhibited abnormal T-bet and Eomes expression patterns that correlated with the deficiency in cytotoxic capacity and cytokine production. Effective antiretroviral therapy (ART) did not fully restore these aberrations. Interestingly, IL-7 was capable of arming resting MAIT cells from healthy donors into cytotoxic GrzB+ effector T cells capable of killing bacteria-infected cells and producing high levels of pro-inflammatory cytokines in an MR1-dependent fashion. Furthermore, IL-7 treatment enhanced the sensitivity of MAIT cells to detect low levels of bacteria. In HIV-infected patients, plasma IL-7 levels were positively correlated with MAIT cell numbers and function, and IL-7 treatment in vitro significantly restored MAIT cell effector functions even in the absence of ART. These results indicate that the cytolytic capacity in MAIT cells is severely defective in HIV-1 infected patients, and that the broad-based functional defect in these cells is associated with deficiency in critical transcription factors. Furthermore, IL-7 induces the arming of effector functions and enhances the sensitivity of MAIT cells, and may be considered in immunotherapeutic approaches to restore MAIT cells.

Elevated plasma levels of lipopolysaccharide and high mobility group box-1 protein are associated with high viral load in HIV-1 infection : reduction by 2-year antiretroviral therapy

Objective:To investigate plasma levels of high mobility group box-1 protein (HMGB1), a marker of tissue necrosis and immune activation, as well as lipopolysaccharide (LPS), a marker of bacterial translocation, in HIV-1-infected patients. Design:We studied 32 HIV-1-positive patients who had responded to antiretroviral therapy with undetectable viremia after 2 years, 10 nonresponders and 19 healthy controls. Methods:HMGB1 was analyzed by ELISA, and LPS by Lamilus colometric assay. Nonparametric statistics were applied. Results:In naive HIV-1 patients, HMGB1 and LPS were elevated as compared with controls (P < 0.001). LPS levels were higher in African and Oriental patients compared with whites (P = 0.007). Notably, viral load was two-fold higher in patients with LPS, and HMGB1 was above median as compared with other patients (P = 0.005). This association was largely driven by African patients, who had a five-fold increased viral load in the presence of elevated LPS and HMGB1. After 2 years of effective antiretroviral therapy, LPS was reduced to the same median level as in the control group (P < 0.001), and HMGB1 was also reduced (P = 0.001), whereas no reductions were seen in nonresponders. Conclusion:The new findings are the association of elevated plasma levels of LPS and HMGB1 with high viral load, as well as the normalized levels of LPS, and the reduction of HMGB1 after 2 years of effective antiretroviral therapy. As LPS and HMGB1 tend to form immunologically active complexes in vitro, we propose that such complexes may be involved in the immune activation and pathogenesis of HIV-1 infection.

In Vivo Clearance of Hepatitis C Virus Nonstructural 3/4A–Expressing Hepatocytes by DNA Vaccine–Primed Cytotoxic T Lymphocytes

A key question in the development of a therapeutic vaccine against hepatitis C virus (HCV) is whether vaccine-primed T cells enter the liver and eliminate HCV-expressing hepatocytes. In the absence of an infectious small-animal model, we evaluated liver homing of vaccine-primed T cells in mice with transient hepatic transgene expression of the HCV nonstructural 3/4A (NS3/4A) protein. We found that T cells primed by transdermal DNA-based vaccination entered the liver and cleared NS3/4A-expressing hepatocytes in transiently transgenic CD8(+/+) mice but not in CD8(-/-) mice. Hence, peripherally primed NS3/4A-specific CD8(+) T cells home to the liver and clear HCV protein-expressing hepatocytes.

Increased serum levels of lipopolysaccharide and antiflagellin antibodies in patients with diarrhea‐predominant irritable bowel syndrome

Innate immune responses to conserved microbial products such as lipopolysaccharide (LPS) and flagellin are likely important in microbial–host interactions and intestinal homeostasis. We hypothesized that bacterial translocation and activation of mucosal immunity against common microbial antigens might be involved in the development of irritable bowel syndrome (IBS). We therefore compared serum levels of LPS, soluble CD14 (sCD14), and flagellin antibodies between patients with different subtypes of IBS and healthy controls.

Improved cell mediated immune responses after successful re-vaccination of non-responders to the hepatitis B virus surface antigen (HBsAg) vaccine using the combined hepatitis A and B vaccine

We successfully re-vaccinated hepatitis B virus (HBV) vaccine non-responders using a double dose of the combined hepatitis A virus (HAV) and HBV vaccine. The hope was to improve priming of hepatitis B surface antigen (HBsAg)-specific cell mediated immune response (CMI) by an increased antigen dose and a theoretical adjuvant-effect from the local presence of a HAV-specific CMI. A few non-responders had a detectable HBsAg-specific CMI before re-vaccination. An in vitro detectable HBsAg-specific CMI was primed equally effective in non-responders (58%) as in first time vaccine recipients (68%). After the third dose a weak, albeit significant, association was observed between the magnitude of HBsAg-specific proliferation and anti-HBs levels. This regimen improves the priming of HBsAg-specific CMIs and antibodies.

Kinetics of microbial translocation markers in patients on efavirenz or lopinavir/r based antiretroviral therapy.

Objectives We investigated whether there are differences in the effects on microbial translocation (MT) and enterocyte damage by different antiretroviral therapy (ART) regimens after 1.5 years and whether antibiotic use has impact on MT. In a randomized clinical trial (NCT01445223) on first line ART, patients started either lopinavir/r (LPV/r) (n = 34) or efavirenz (EFV) containing ART (n = 37). Lipopolysaccharide (LPS), sCD14, anti-flagellin antibodies and intestinal fatty acid binding protein (I-FABP) levels were determined in plasma at baseline (BL) and week 72 (w72). Results The levels of LPS and sCD14 were reduced from BL to w72 (157.5 pg/ml vs. 140.0 pg/ml, p = 0.0003; 3.13 ug/ml vs. 2.85 ug/ml, p = 0.005, respectively). The levels of anti-flagellin antibodies had decreased at w72 (0.35 vs 0.31 [OD]; p<0.0004), although significantly only in the LPV/r arm. I-FABP levels increased at w72 (2.26 ng/ml vs 3.13 ng/ml; p<0.0001), although significantly in EFV treated patients only. Patients given antibiotics at BL had lower sCD14 levels at w72 as revealed by ANCOVA compared to those who did not receive (Δ = −0.47 µg/ml; p = 0.015). Conclusions Markers of MT and enterocyte damage are elevated in untreated HIV-1 infected patients. Long-term ART reduces the levels, except for I-FABP which role as a marker of MT is questionable in ART-experienced patients. Why the enterocyte damage seems to persist remains to be established. Also antibiotic usage may influence the kinetics of the markers of MT. Trial Registration ClinicalTrials.gov NCT01445223

Occasional spontaneous clearance of chronic hepatitis C virus in HIV-infected individuals

The IL28B genotype has been found to have a strong influence on spontaneous clearance of acute HCV both in HCV mono- and HIV/ the HCV co-infected patients. Spontaneous clearance of chronic HCV without HCV treatment is rare. Here, we report on three chronic HCV cases co-infected with HIV with spontaneous clearance of their HCV infection, all with the IL28B CC genotype. These cases were derived from a surveillance of the total HIV/HCV co-infected cohort in Sweden (n =4 66). The estimated frequency of spontaneous clearance of chronic HCV infection in our cohort was calculated to be 0.6-4.7%. Our cases lend some support to the initiation of ART prior to HCV treatment in HIV/HCV co-infected patients. Furthermore, HCV-RNA testing should be recommended immediately before initiation of HCV treatment, to find the subset of HIV/HCV co-infected patients with IL28B CC that may have cleared their chronic infection spontaneously.

Evolution of fibrosis during HCV recurrence after liver transplantation--influence of IL-28B SNP and response to peg-IFN and ribavirin treatment.

The IL‐28 gene is associated with sustained viral response (SVR) after treatment with peg‐IFN and ribavirin in liver transplant recipients with chronic hepatitis C genotype 1 infection. We analysed the importance of recipient and donor IL‐28B genotype for response to treatment and fibrosis progression in 54 liver transplant recipients. Fibrosis stage (F) was defined as mild when F ≤ 2 and severe when F ≥ 3 in a liver biopsy or according to liver elasticity analysis. We found a significantly lower prevalence of IL‐28B SNP CC in the recipients (22%) than in the donors (67%), P < 0.0001. SVR was seen in 61% of the recipients with mild and 27% with severe fibrosis pretreatment, P = 0.01. Recipients with IL‐28 CC and non‐CC had mild fibrosis in 64% and 38% prior to treatment, P = 0.13. At follow‐up, after treatment, significantly more recipients with CC had mild fibrosis than non‐CC recipients (75% versus 32%, P = 0.0072), and all with CC and SVR had mild fibrosis. The strongest baseline factor predicting SVR was genotype. Hence, 13/19 (68%) genotype non‐1 patients reached SVR versus only 9/35 (26%) genotype 1 patients, P = 0.0022. In summary, we found that liver transplant recipients with IL‐28B CC tended to have less advanced fibrosis prior to and significantly less after SOC treatment and that all recipients with IL‐28B CC who achieved SVR had mild fibrosis at follow‐up. A significantly higher SVR rate was achieved in recipients with mild than severe fibrosis pretreatment and with genotype non‐1 than 1 infection. Our findings indicate that treatment for post‐transplant HCV recurrence should be offered before advanced fibrosis is seen in the recipient.

Low Levels of Microbial Translocation Marker LBP Are Associated with Sustained Viral Response after Anti-HCV Treatment in HIV-1/HCV Co-Infected Patients

Background Microbial translocation (MT) contributes to immune activation during HIV and HCV infections. We investigated the kinetics of MT markers during anti-HCV and anti-HIV treatments, and if baseline plasma levels of lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) could predict anti-HCV treatment outcome. Methods Plasma from 78 HIV-infected patients was evaluated for LPS, LBP and sCD14. The patients starting anti-HCV treatment (with ongoing antiretroviral (ART) treatment) were categorized into sustained viral responders (SVR; n = 21) or non-responders (NR; n = 15) based on treatment outcome. ART starting subjects—were categorized into chronically HCV-infected (CH; n = 24) and mono-infected (HIV; n = 18), based on the HCV infection status. Samples were collected before start (at baseline) of pegylated-interferon-alpha/ribavirin (peg-IFN/RBV) or antiretroviral-therapy and two years after treatment start (at follow up). χ2–test, non-parametric statistics and logistic regression were applied to determine the associations with treatment response and changes of the soluble markers. Results Plasma levels of LPS and sCD14 were elevated in all subjects before antiviral-treatment but remained unchanged at follow-up. Elevated levels of LBP were present in patients with HIV and HIV/HCV co-infection and were reduced by ART. Additionally, higher levels of LBP were present at baseline in NR vs. SVR. Higher levels of LBP at baseline were associated with non-response to peg-IFN/RBV treatment in both bivariate (OR: 0.19 95% CI: 0.06–0.31, p = 0.004) and multivariate analysis (OR: 1.43, 95% CI: 1.1–1.86, p = 0.07). Conclusion In HIV/HCV co-infected patients high baseline LBP levels are associated with non-response to peg-IFN/RBV therapy. Plasma LBP (decreased by ART) may be a more relevant MT marker than LPS and sCD14.

Virus-specific T cell immune response in children and adolescents with chronic hepatitis B virus infection.

Objectives: To study the hepatitis B–specific T cell–mediated immune response in chronically infected children and adolescents. Patients and Methods: In all, 36 HBsAg-positive patients, 2 to 19 years old, were included. There were 9 HBeAg-positive patients with normal levels of alanine aminotransferase (ALT) (group 1), 18 HBeAg-positive patients with elevated ALT (group 2), and 9 HBeAg-negative, anti-HBe–positive patients (group 3). Four patients in group 2 were treated with interferon during the study. In all patients, HBcAg-specific T cell proliferation and ALT levels were prospectively studied in repeated samples for a mean follow-up time of 1.6 years. The baseline HBV-DNA and plasma cytokine levels were determined, and genotypes were analyzed. Results: The percent of patients with at least 1 sample indicating T cell proliferation was 55% in group 1 and 89% in groups 2 and 3, respectively (P = 0.07 group 1 vs group 2, P = 0.013 group 1 vs the combined groups 2 and 3). Tendencies for positive correlations between the degree of T cell proliferation and ALT levels were noted in groups 1 and 3 and for negative correlations in HBeAg seroconverting patients of group 2. In patients with successful interferon treatment, a pattern of more vigorous T cell proliferation than in patients with spontaneous seroconversion was noted. Conclusions: A majority of patients showed signs of ongoing T cell proliferation. The continuation of the T cell–mediated immune response seems to be of importance in maintaining the HBeAg seroconversion over time.