TLR2 engagement on CD4+ T cells enhances effector functions and protective responses to Mycobacterium tuberculosis

We have previously demonstrated that mycobacterial lipoproteins engage TLR2 on human CD4⁺ T cells and upregulate TCR‐triggered IFN‐γ secretion and cell proliferation in vitro. Here we examined the role of CD4⁺ T‐cell‐expressed TLR2 in Mycobacterium tuberculosis (MTB) Ag‐specific T‐cell priming and in protection against MTB infection in vivo. Like their human counterparts, mouse CD4⁺ T cells express TLR2 and respond to TLR2 costimulation in vitro. This Th1‐like response was observed in the context of both polyclonal and Ag‐specific TCR stimulation. To evaluate the role of T‐cell TLR2 in priming of CD4⁺ T cells in vivo, naive MTB Ag85B‐specific TCR transgenic CD4⁺ T cells (P25 TCR‐Tg) were adoptively transferred into Tlr2^?/? recipient C57BL/6 mice that were then immunized with Ag85B and with or without TLR2 ligand Pam₃Cys‐SKKKK. TLR2 engagement during priming resulted in increased numbers of IFN‐γ‐secreting P25 TCR‐Tg T cells 1 week after immunization. P25 TCR‐Tg T cells stimulated in vitro via TCR and TLR2 conferred more protection than T cells stimulated via TCR alone when adoptively transferred before MTB infection. Our findings indicate that TLR2 engagement on CD4⁺ T cells increases MTB Ag‐specific responses and may contribute to protection against MTB infection.     

Iron metabolism imbalance at the time of listing increases overall and infectious mortality after liver transplantation

BACKGROUND Liver transplantation(LT) is the best treatment for patients with liver cancer or end stage cirrhosis, but it is still associated with a significant mortality. Therefore identifying factors associated with mortality could help improve patient management. The impact of iron metabolism, which could be a relevant therapeutic target, yield discrepant results in this setting. Previous studies suggest that increased serum ferritin is associated with higher mortality.Surprisingly iron deficiency which is a well described risk factor in critically ill patients has not been considered.AIM To assess the impact of pre-transplant iron metabolism parameters on posttransplant survival.METHODS From 2001 to 2011, 553 patients who underwent LT with iron metabolism parameters available at LT evaluation were included. Data were prospectively recorded at the time of evaluation and at the time of LT regarding donor and recipient. Serum ferritin(SF) and transferrin saturation(TS) were studied as continuous and categorical variable. Cox regression analysis was used to determine mortality risks factors. Follow-up data were obtained from the local and national database regarding causes of death.RESULTS At the end of a 95-mo median follow-up, 196 patients were dead, 38 of them because of infections. In multivariate analysis, overall mortality was significantly associated with TS 75% [HR: 1.73(1.14; 2.63)], SF 100 μg/L [HR: 1.62(1.12;2.35)], hepatocellular carcinoma [HR: 1.58(1.15; 2.26)], estimated glomerular filtration rate(CKD EPI Cystatin C) [HR: 0.99(0.98; 0.99)], and packed red blood cell transfusion [HR: 1.05(1.03; 1.08)]. Kaplan Meier curves show that patients with low SF( 100 μg/L) or high SF( 400 μg/L) have lower survival rates at 36 mo than patients with normal SF(P = 0.008 and P = 0.016 respectively). Patients with TS higher than 75% had higher mortality at 12 mo(91.4% ± 1.4% vs 84.6% ±3.1%, P = 0.039). TS 75% was significantly associated with infection related death [HR: 3.06(1.13; 8.23)].CONCLUSION Our results show that iron metabolism imbalance(either deficiency or overload)is associated with post-transplant overall and infectious mortality. Impact of iron supplementation or depletion should be assessed in prospective study.