Rejection and regulation: a tight balance. Curr Opin Organ Transplant. 2012;17:1-7. [PMID: 22157321 DOI: 10.1097/mot.0b013e32834ef52a]

TNF, IL-6, and IL-10 cytokines levels and their polymorphisms in renal function and time after transplantation

Cytokine polymorphisms can influence their plasma levels and thus affect the immune response in renal transplantation. A total of 146 renal transplant recipients (RTR) were classified into groups according to the estimated glomerular filtration rate (R1: < 60 and R2: ≥ 60 mL/min/1.73 m²) and time after transplantation (T1: 1 to 24, T2: 25 to 60, T3: 61 to 120, and T4: > 120 months after transplantation). The polymorphisms were genotyped by single specific primer-polymerase chain reaction. IL-10 was measured by ELISA and IL-6, and TNF levels were determined using Miliplex®. A higher frequency of the - 308G allele and the - 308G/G genotype, low-producer, was observed in the R1 group compared with R2. In addition, a higher frequency of the - 308A carriers, high-producer, was found in the R2 group. However, no significant difference was observed in cytokine levels when both groups were compared. Higher levels of IL-6 were observed in T1 compared with T2 and T4 groups. Lower IL-6 levels were found in T2 compared with T3 group. Lower levels of IL-10 were also found in T1 group in relation to T2, while higher levels of this cytokine were observed in T2 group compared with T3. The results suggest that the - 308G > A polymorphism in the TNF gene is associated with filtration function after renal transplantation, and IL-6 and IL-10 levels change according to the time after transplantation. Thus, the joint evaluation of - 308G > A polymorphism in TNF gene and IL-6 and IL-10 levels would provide a broader and effective view on the clinical monitoring of RTR.

Acute rejection after liver transplantation is less common, but predicts better prognosis in HBV-related hepatocellular carcinoma patients

BACKGROUND

With a novel finding of significantly lower incidence of acute rejection (AR) in patients with hepatocellular carcinoma (HCC) after liver transplantation, compared with those with benign end-stage liver disease (BESLD), in a large national cohort, we analyzed the correlations among the perioperative immuno-inflammation status, postoperative AR, and prognosis in HCC and BESLD patients with same etiology of hepatitis B virus (HBV), who underwent liver transplantation.

METHODS

Patients who underwent liver transplantation due to HBV-related HCC or BESLD and experienced AR between September 2008 and April 2017 were analyzed retrospectively and followed up until April 2018. HCC patients with AR were matched with those without AR according to tumor stage and immunosuppressant concentration, at a 1:3 ratio. Preoperative immuno-inflammation status and prognosis of patients in both groups were compared.

RESULTS

The overall incidences of AR in patients with HCC and BESLD were 8.60% and 10.61%, respectively. The postoperative 28-day incidence of AR was significantly lower in HCC compared with BESLD patients (3.23% vs 7.08%, p = 0.031). Compared with BESLD patients, the rejection activity index and perioperative CD₄/CD₈ ratio were significantly lower (p = 0.047 and p < 0.001, respectively), while platelet/lymphocyte ratio was significantly higher in HCC patients (p = 0.041). Later tumor stage in HCC patients was associated with higher systemic immuno-inflammation index, neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, platelet/lymphocyte ratio, aspartate aminotransferase/lymphocyte ratio, C-reactive protein/albumin ratio and fibrinogen level, and lower CD₄/CD₈ ratio before transplantation. In HCC patients with AR, the percentage of regulatory T cells (CD₄⁺/CD₂₅⁺) and the level of IL-10 significantly decreased (p = 0.0023, < 0.0001, respectively), while Th1/Th2 ratio, levels of IFN-γ and IL-2 markedly increased before transplantation (p = 0.0018, 0.0059, 0.0416, respectively). Preoperative monocyte/lymphocyte ratio was an independent risk factor for overall and recurrence-free survival after liver transplantation in HCC patients (p = 0.025, < 0.001, respectively). The 1-, 3-, and 5-year survival rates were 76%, 71% and 53% in the AR group, and 67%, 37% and 25% in the non-AR group (p = 0.042).

CONCLUSION

Preoperative tumor-related immunosuppression may persist after liver transplantation in HCC patients, and reduce the incidence of AR. AR after liver transplantation may indicate a better prognosis in HCC patients.

Sirolimus vs mycophenolate moftile in Tacrolimus based therapy following induction with Antithymocyte globulin promotes regulatory T cell expansion and inhibits RORγt and T-bet expression in kidney transplantation

BACKGROUND

Accumulating evidence suggests that regulatory T cells (Tregs) have a crucial role in immune tolerance and long-term graft survival. However, the influence of immunosuppressive drugs on the level of Tregs has not been fully understood. Therefore we prospectively compare the effect of two different calcineurin inhibitor (CNI)-based immunosuppression protocols on Tregs frequencies and expression of regulatory and effector T cell-related genes in renal transplant recipients.

METHODS

The study included 24 renal transplant recipients who received induction therapy (Antithymocyte globulin) and were on triple immunosuppressive therapy so that one group was on Tacrolimus (Tac), mycophenolate moftile (MMF) and prednisolone (P) whereas another group was on Tac, Sirolimus (SRL) and P. The frequency of circulating Treg cells was analyzed by flow cytometry before and 4 months after transplantation. Also, the mRNA expression of FOXP3, T-bet, GATA3 and RORγt was examined by quantitative RT-PCR before and 4 months after transplantation.

RESULTS

Compared to baseline, the frequency of CD4+ CD25+ FOXP3+ Treg cells was significantly increased in the all patients following transplantation. Patients who received Tac/MMF had significantly higher CD4+ CD25+ FOXP3+ Treg cells compared to patients who received Tac/SRL. There was no a significant difference in the frequency of CD3+CD8+ CD28- Tregs between two different calcineurin inhibitor (CNI)-based immunosuppression protocols. FOXP3 mRNA levels in the patients who received Tac/MMF were increased 4 months after transplantation and the expression was significantly higher than patients who received Tac/SRL. On the other hand, T-bet and RORγt expression levels were significantly lower in the Tac/SRL group in comparison to Tac/MMF group. We did not observe any significant difference in GATA3 mRNA level between the two groups.

CONCLUSIONS

Our results suggest that although Tac/MMF-containing immunosuppressive regimen could significantly increase the frequency of CD4+ CD25+ FOXP3+ Tregs, unlike to Tac/SRL-containing regimen, it could not significantly decrease the expression levels of RORγt and T-bet.

Update on the treatment of focal segmental glomerulosclerosis in renal transplantation

Focal segmental glomerulosclerosis (FSGS) represents one of the most severe glomerular diseases, with frequent progression to end-stage renal disease and a high rate of recurrence in renal allografts (30%-50%). Recurrent FSGS portends a negative outcome, with the hazard ratio of graft failure being two-fold higher then that of other glomerulonephritis. Two patterns of clinical presentations are observed: Early recurrence, which is characterized by massive proteinuria within hours to days after implantation of the renal graft, and late recurrence, which occurs several months or years after the transplantation. Many clinical conditions have been recognized as risk factors for recurrence, including younger age, rapid progression of the disease to end-stage renal disease on native kidneys, and loss of previous renal allografts due to recurrence. However, much less is known about the incidence and risk factors of the so-called “de novo” type of FSGS, for which sufferers are transplanted patients without disease on native kidneys; but, rapid development of allograft failure is frequently observed. Management of both forms is challenging, and none of the approaches proposed to date have been demonstrated as consistently beneficial or effective. In the present review we report an update on the available therapeutic strategies for FSGS in renal transplantation within the context of a critical overview of the current literature.

Tolerogenic Dendritic Cells on Transplantation: Immunotherapy Based on Second Signal Blockage

Dendritic cells (DCs), the most important professional antigen-presenting cells (APC), play crucial role in both immunity and tolerance. It is well known that DCs are able to mount immune responses against foreign antigens and simultaneously tolerate self-antigens. Since DCs can be modulated depending on the surrounding microenvironment, they can act as a bridge between innate and adaptive immunity. However, the mechanisms that support this dual role are not entirely clear. Recent studies have shown that DCs can be manipulated ex vivo in order to trigger their tolerogenic profile, what can be a tool to be used in clinical trials aiming the treatment of various diseases and the prevention of transplant rejection. In this sense, the blockage of costimulatory molecules on DC, in the attempt of inhibiting the second signal in the immunological synapse, can be considered as one of the main strategies under development. This review brings an update on current therapies using tolerogenic dendritic cells modulated with costimulatory blockers with the aim of reducing transplant rejection. However, although there are current clinical trials using tolerogenic DC to treat allograft rejection, the actual challenge is to modulate these cells in order to maintain a permanent tolerogenic profile.

Up-regulation of Galectin-9 in vivo results in immunosuppressive effects and prolongs survival of liver allograft in rats

BACKGROUND AND OBJECTIVE

Acute rejection is still a major cause of graft dysfunction and would jeopardize recipients' post-transplantation survival. Current studies demonstrate that Galectin-9 (Gal-9) is associated with down-regulation of pro-inflammatory cytokines, thus, possesses a negative immune regulatory role. However, the specific role of Gal-9 in liver transplant remains unknown.

METHODS

To establish acute rejection models of rat liver transplantation (Lewis-BN, n = 45), recipients were randomly divided into following three groups: the transfected group (n = 15); the blank plasmid group (n = 15); and the control group (n = 15). The transfected group was perfused with Ad-galectin-9 through the portal vein during the cold ischemia period. The blank plasmid group was perfused with non-target vector, and the control group was perfused with saline. The acute rejection was assayed by pathological examination; Gal-9, T-bet, RORγt, GATA3 and Foxp3 mRNA expression was detected by real-time PCR; Western blots and enzyme-linked immunosorbent assays were performed to measure IFN-γ, IL-10 and IL-17 expression.

RESULTS

The pathological change of the transfected group was ameliorated than that of the other two groups. The Gal-9 mRNA level in the transfected group was much higher than that in the other two groups (*P < 0.05); T-bet and RORγt mRNA levels were significantly lower in the transfected group than in the other two groups while GATA3 and Foxp3 were not shown statistics significances (*P < 0.05). The IFN-γ and IL-17 levels in the transfected group were significantly lower than in the other two groups (*P < 0.05 for both protein and serum levels).

CONCLUSION

Up-regulation of Gal-9 in vivo turns immune system toward immnuosuppression and prolongs rats liver allograft survival by the diminishment of Th1/Th17.

Genetic variants of innate immune receptors and infections after liver transplantation

Infection is the leading cause of complication after liver transplantation, causing morbidity and mortality in the first months after surgery. Allograft rejection is mediated through adaptive immunological responses, and thus immunosuppressive therapy is necessary after transplantation. In this setting, the presence of genetic variants of innate immunity receptors may increase the risk of post-transplant infection, in comparison with patients carrying wild-type alleles. Numerous studies have investigated the role of genetic variants of innate immune receptors and the risk of complication after liver transplantation, but their results are discordant. Toll-like receptors and mannose-binding lectin are arguably the most important studied molecules; however, many other receptors could increase the risk of infection after transplantation. In this article, we review the published studies analyzing the impact of genetic variants in the innate immune system on the development of infectious complications after liver transplantation.

Association of cytokine/costimulatory molecule polymorphism and allograft rejection: a comparative review

One reason for genetic variations among human individuals is SNP which may confer diverse disease susceptibility or resistance in a population. Genetic variations in a key immunoregulatory agent can manifest various immunological responses, such as graft rejection. In fact, the outcome of organ transplantation can be impacted by several genetic causes including polymorphisms in genes encoding cytokines and costimulatory molecules in the donor or recipient. Thus, it can be helpful to contemplate the SNPs relating to these immunological determinants in order to achieve an improved transplantation therapy.

Immunologic monitoring in kidney transplant recipients

Transplant biopsy has always been the gold standard for assessing the immune response to a kidney allograft (Chandraker A: Diagnostic techniques in the work-up of renal allograft dysfunction-an update. Curr Opin Nephrol Hypertens 8:723-728, 1999). A biopsy is not without risk and is unable to predict rejection and is only diagnostic once rejection has already occurred. However, in the past two decades, we have seen an expansion in assays that can potentially put an end to the "drug level" era, which until now has been one of the few tools available to clinicians for monitoring the immune response. A better understanding of the mechanisms of rejection and tolerance, and technological advances has led to the development of new noninvasive methods to monitor the immune response. In this article, we discuss these new methods and their potential uses in renal transplant recipients.

Different regulatory and cytotoxic CD4+ T lymphocyte profiles in renal transplants with antibody-mediated chronic rejection or long-term good graft function

Comparative analysis of the different subsets of CD4(+) T-lymphocytes may provide hints on the immunologic mechanisms operating in the long-term fate of a kidney transplant. We analyzed peripheral regulatory CD4(+) T cells (Tregs) and CD4(+) cytotoxic T lymphocytes (CTLs) in antibody-mediated chronic rejection (AMCR), in middle-term kidney transplants (2-4 years, MTKT) with good graft function and rejection-free history, in long-term kidney transplants (>15 years, LTKT) and in normal healthy subjects (NHS). Transplant groups with good prognosis (MTKT and LTKT) displayed a significant lower amount of CD4(+)CD25(high) T lymphocytes than NHS, with a trend of a higher percentage in AMCR than in MTKT and LTKT. However, CD4(+)CD25(high) Foxp3(+) cells were significantly higher in LTKT and MTKT than AMCR. Characterization of CD4(+)CD25(high) T cells showed a marked increase of intracellular CTLA-4 in the AMCR group in respect to the other transplant groups, while the expression of the surface molecule seemed to follow a reverse trend. In addition, CD27, a costimulatory receptor involved in long-term T cell survival and prevention of immune tolerance, is significantly reduced in CD4(+)CD25(high) and CD4(+)Foxp3(+) T cells in the LTKT in respect to the other transplant groups. CD4(+)CD25(high)CD45RO(+) and CD4(+)Foxp3(+)CD45RO(+) regulatory T cells with memory function were increased in LTKT compared to NHS and for the latter also in AMCR group. Finally, CD4(+)CTLs that were quantified on the basis of granzyme A expression, were more represented in AMCR patients in comparison to the other groups. Strikingly, CD27 in the CD4(+)CTLs was suppressed in LTKT and MTKT and markedly expressed in AMCR group. No significant differences in the expression of CD28 were observed among different groups. In conclusion, different profiles of Tregs and CD4(+)CTL populations correlate with different long-term conditions of kidney-transplanted patients, suggesting their role in the development of immunologic events in kidney transplantation.

Heme oxygenase, inflammation, and fibrosis: the good, the bad, and the ugly?

Upon injury, prolonged inflammation and oxidative stress may cause pathological wound healing and fibrosis, leading to formation of excessive scar tissue. Fibrogenesis can occur in most organs and tissues and may ultimately lead to organ dysfunction and failure. The underlying mechanisms of pathological wound healing still remain unclear, and are considered to be multifactorial, but so far, no efficient anti-fibrotic therapies exist. Extra- and intracellular levels of free heme may be increased in a variety of pathological conditions due to release from hemoproteins. Free heme possesses pro-inflammatory and oxidative properties, and may act as a danger signal. Effects of free heme may be counteracted by heme-binding proteins or by heme degradation. Heme is degraded by heme oxygenase (HO) that exists as two isoforms: inducible HO-1 and constitutively expressed HO-2. HO generates the effector molecules biliverdin/bilirubin, carbon monoxide, and free iron/ferritin. HO deficiency in mouse and man leads to exaggerated inflammation following mild insults, and accumulating epidemiological and preclinical studies support the widely recognized notion of the cytoprotective, anti-oxidative, and anti-inflammatory effects of the activity of the HO system and its effector molecules. In this review, we address the potential effects of targeted HO-1 induction or administration of HO-effector molecules as therapeutic targets in fibrotic conditions to counteract inflammatory and oxidative insults. This is exemplified by various clinically relevant conditions, such as hypertrophic scarring, chronic inflammatory liver disease, chronic pancreatitis, and chronic graft rejection in transplantation.