The effects of tolerance on allograft damage caused by the innate immune system

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Genetic variation of IL-12B (+1188 region) is associated with its decreased circulating levels and susceptibility to Type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus is one of the most common types of endocrine disease and the immune system plays a predominant role in its pathogenesis.

AIMS

The present study aimed to examine known gene polymorphisms within IL-12B (+1188) region and its circulating serum levels in Type 2 diabetic patients from the southeastern region of Iran and compare them with unrelated controls.

MATERIALS & METHODS

In this clinical study, peripheral blood was collected from 114 Type 2 diabetic patients and 100 healthy controls. Serum levels of IL-12B were measured by ELISA. Genomic DNA was extracted from peripheral blood samples and polymorphisms at the +1188 position of the IL-12B gene were assessed using PCR restriction fragment-length polymorphism.

RESULTS

Our findings demonstrated that the AA genotype and the A allele of IL-12B were increased significantly in Type 2 diabetic patients when compared with controls. Our results also showed that the circulating levels of IL-12B were significantly decreased in Type 2 diabetic patients when compared with controls.

CONCLUSION

According to the findings of the current study, we concluded that IL-12B and its +1188 polymorphism may play a prominent role in the pathogenesis of Type 2 diabetes. Further replicative investigations using a larger sample size are essential to identify additional IL-12B genetic variants associated with a risk of Type 2 diabetes.

Donor brain death inhibits tolerance induction in miniature swine recipients of fully MHC-disparate pulmonary allografts

We have previously shown that a short course of high-dose tacrolimus induces long-term tolerance to fully mismatched lung allografts procured from healthy MHC-inbred miniature swine. Here, we investigate whether donor brain death affects tolerance induction. Four recipient swine were transplanted with fully mismatched lung grafts from donors that were rendered brain dead and mechanically ventilated for 4 h before procurement (Group 1). These recipients were compared to two control groups (Group 2: 4 h of donor ventilation without brain death [n = 5]; and Group 3: no donor brain death with <1 h of ventilation [n = 6]). All recipients were treated with a 12-day course of tacrolimus. In contrast to both groups of control animals, the swine transplanted with lung allografts from brain dead donors all rejected their grafts by postoperative day 45 and showed persistent responsiveness to donor antigen by MLR. Several additional swine underwent brain death induction and/or mechanical ventilation alone to determine the effects of these procedures on the expression of proinflammatory molecules. Significant increases in serum concentrations of IL-1, TNF-α and IL-10 were seen after brain death. Upregulation of IL-1 and IL-6 gene expression was also observed.

Mechanism and localization of CD8 regulatory T cells in a heart transplant model of tolerance

Despite accumulating evidence for the importance of allospecific CD8(+) regulatory T cells (Tregs) in tolerant rodents and free immunosuppression transplant recipients, mechanisms underlying CD8(+) Treg-mediated tolerance remain unclear. By using a model of transplantation tolerance mediated by CD8(+) Tregs following CD40Ig treatment in rats, in this study, we show that the accumulation of tolerogenic CD8(+) Tregs and plasmacytoid dendritic cells (pDCs) in allograft and spleen but not lymph nodes was associated with tolerance induction in vascularized allograft recipients. pDCs preferentially induced tolerogenic CD8(+) Tregs to suppress CD4(+) effector cells responses to first-donor Ags in vitro. When tolerogenic CD8(+) Tregs were not in contact with CD4(+) effector cells, suppression was mediated by IDO. Contact with CD4(+) effector cells resulted in alternative suppressive mechanisms implicating IFN-gamma and fibroleukin-2. In vivo, both IDO and IFN-gamma were involved in tolerance induction, suggesting that contact with CD4(+) effector cells is crucial to modulate CD8(+) Tregs function in vivo. In conclusion, CD8(+) Tregs and pDCs interactions were necessary for suppression of CD4(+) T cells and involved different mechanisms modulated by the presence of cell contact between CD8(+) Tregs, pDCs, and CD4(+) effector cells.

Immunosuppression in high-risk transplantation

PURPOSE OF REVIEW

Increasingly, transplant clinicians are faced with providing candidates with increased risks for poorer outcome with donor grafts that also carry higher risks of failure. Understanding the role of immunosuppressive management in these combinations of higher risks remains important for optimizing results.

RECENT FINDINGS

Few immunosuppressive protocols have been rigorously tested in the high-risk renal transplant setting. The two main risk categories accounted for in the trials are those ones that confer increased risks to renal function, usually carried by the donor organs, and those protocols defined by increased risk for immunological failure, mostly determined by recipient characteristics. The studied protocols generally involve reduction or avoidance of nephrotoxic drugs in the first case and use of lymphocyte-depleting agents in the case of increased immunological risk. In both scenarios, acceptable short-term results have been achieved. However, long-term results for high-risk transplants defined either by donor or recipient factors have yet to be reported.

SUMMARY

The lack of long-term data for optimizing the right immunosuppressive regimen for a given donor/recipient risk profile remains an ongoing challenge for researchers and clinicians alike.

Nephropathic complication of type-2 diabetes is following pattern of autoimmune diseases?

The impact of several environmental and genetic factors on diabetes and its complications is well documented. The present study was aimed to examine the serum levels of IL-17A and IFN-gamma as antagonistic cytokines in nephropathic and non-nephropathic type-2 diabetic patients. In this experimental study, serum samples were obtained from 180 type-2 diabetic patients, 100 nephropathic type-2 diabetic patients and 100 healthy controls. Serum levels of IL-17A and IFN-gamma was detected by ELISA. Results of this study showed that the serum level of IFN-gamma was higher in both diabetic patients (nephropathic and non-nephropathic) in comparison to the controls. In terms of IL-17A, while non-nephropathic type-2 diabetic patients showed an increased serum level of it, the other patients group had a lower serum level. Based on these findings, it can be concluded that the lower serum level of IL-17A is possibly associated with nephropathic complications of type-2 diabetes.

Evaluation of IFN-gamma serum level in nephropatic type 2 diabetic patients

The present study was aimed to examine the serum level of IFN-gamma in type 2 diabetic patients with nephropatic complications. In this experimental study, serum samples were obtained from 100 type 2 diabetic patients suffering from nephropathy and 100 healthy controls. Serum level of IFN-gamma was analyzed by ELISA. Results of this study showed that the mean serum level of IFN-gamma was 16.09 +/- 2.04 and 4.03 +/- 1.00 pg mL(-1) in nephropathic patients and healthy controls, respectively. Statistical analysis of data showed that the difference in the IFN-gamma serum level was significant between nephropathic patients and controls. Due to the elevated level of IFN-gamma in nephropathic patients, it can be possibly concluded that IFN-gamma is involved in nephropathy complication of type 2 diabetes.