Intragraft cytokine expression in heart transplants with mild or no histological rejection

A New Concept of the Old Inhibitor NSC 74859 in Alleviating Cardiac Allograft Rejection and Extending Allograft Survival in Mice

Background

STAT1/4 has been suggested to be involved in cardiac allograft rejection. However, no direct evidence regarding STAT3 has been established in cardiac allograft rejection. Here, we hypothesized that inhibition of STAT3 attenuates cardiac allograft rejection.

Material/Methods

To test our hypothesis, homotopic mouse heart transplantation was carried out in syngeneic C57BL/6 to C57BL/6 strain mice with or without oral gavage with NSC 74859, an inhibitor of STAT3. The immune response was investigated using real-time PCR for CD4 and CD8 surface makers of T cells and CD14 of monocytes and cytokines, including IL-2, IL-15, and IL-6 of allografts at 3, 6, and 9 days after transplantation. Prognosis was also evaluated.

Results

We found that allografts with oral gavage of NSC 74859 whose CD4, CD8 T, and CD14 monocytes were significantly lower than that of allograft without oral gavage of NSC 74859, and the same was true for the expression of IL-2, IL-15, and IL-6. Immunohistochemical analysis of grafts showed reduced infiltration of monocytes/macrophages into the graft myocardium. Survival was also markedly extended in the NSC 74859 group.

Conclusions

Inhibition of IL-6/STAT3 using NSC 74859 was shown to remarkably alleviate cardiac allograft rejection in mice, indicating that the target against IL-6/STAT3 pathway might be clinically used as an alternative therapy for cardiac allograft rejection.

Cytokines of the IL-1 family: recognized targets in chronic inflammation underrated in organ transplantations

Interleukin 1 (IL-1) family is a group of cytokines with multiple local and systemic effects, which regulates both innate and adaptive immune responses. Generally, most IL-1 family cytokines express prevailing pro-inflammatory activities (IL-1α, IL-1β, IL-18, IL-33, IL-36 α, β, γ), whereas others are anti-inflammatory (IL-1Ra (IL-1 receptor antagonist), IL-36Ra, IL-38, IL-37). In addition to their immunomodulatory roles, some of them are also involved in the physiological modulation of homeostatic processes and directly affect mRNA transcription. IL-1 family cytokines bind to specific receptors composed of a ligand-binding chain and an accessory chain. The pro-inflammatory effects of IL-1 family cytokines are regulated on the level of transcription, enzymatic processing of precursors, release of soluble antagonists, and expression of decoy receptors. Members of the IL-1 family regulate the recruitment and activation of effector cells involved in innate and adaptive immunity, but they are also involved in the pathogenesis of chronic disorders, including inflammatory bowel disease, rheumatoid arthritis, and various autoimmune and autoinflammatory diseases. There are only limited data regarding the role of IL-1 cytokines in transplantation. In recent years, targeted therapeutics affecting IL-1 have been used in multiple clinical studies. In addition to the recombinant IL-1Ra, anakinra (highly effective in autoinflammatory diseases and tested for other chronic diseases), the monoclonal antibodies canakinumab, gevokizumab, and rilonacept (a long-acting IL-1 receptor fusion protein) provide further options to block IL-1 activity. Furthermore, new inhibitors of IL-18 (GSK 1070806, ABT-325, rIL-18BP (IL-18 binding protein)) and IL-33 (CNTO-7160) are presently under clinical studies and other molecules are being developed to target IL-1 family cytokines.

Identification and classification of acute cardiac rejection by intragraft transcriptional profiling

BACKGROUND

Treatment of acute rejection (AR) in heart transplantation relies on histopathological grading of endomyocardial biopsies according to International Society for Heart and Lung Transplantation guidelines. Intragraft gene expression profiling may be a way to complement histological evaluation.

METHODS AND RESULTS

Transcriptional profiling was performed on 26 endomyocardial biopsies, and expression patterns were compared with the 1990 International Society for Heart and Lung Transplantation AR grades. Importantly, transcriptional profiles from settings with an equivalent AR grade appeared the same. In addition, grade 0 profiles could not be distinguished from 1A profiles, and grade 3A profiles could not be distinguished from 3B profiles. Comparing the AR groupings (0+1A, 1B, and 3A+3B), 0+1A showed more striking differences from 1B than from 3A+3B. When these findings were extrapolated to the 2005 revised guidelines, the combination of 1A and 1B into a single category (1R) appears to have brought together endomyocardial biopsies with different underlying processes that are not evident from histological evaluation. Grade 1B was associated with upregulated immune response genes, as 1 categorical distinction from grade 1A. Although grade 1B was distinct from the clinically relevant AR grades 3A and 3B, all of these grades shared a small number of overlapping pathways consistent with common physiological underpinnings.

CONCLUSION

The gene expression similarities and differences identified here in different AR settings have the potential to revise the clinical perspective on acute graft rejection, pending the results of larger studies.

Effect of TGF-beta1 on the expression of IL-12, IL-15, IL-18, IL-4 and IL-10 in heart transplantation rejection in rats

To investigate the effect of TGF-beta1 on the expressions of IL-12, IL-15, IL-18, IL-4 and IL-10 in heart transplantation rejection in rats, a model of rat cervical heterotopic heart transplantation was set up and the model rats were randomly divided into three groups: control group, transplant group and TGF-beta1 group. The mRNA expression levels of IL-12, IL-15, IL-18, IL-4 and IL-10 were determined by RT-PCR at the 5th day after the transplantation. The mRNA expression levels of IL-12, IL-15, IL-18 were increased obviously and those of IL-4, IL-10 were significantly decreased in the transplant group as compared with the control group (P<0.01). In the TGF-beta1 group, the mRNA expression levels of IL-12, IL-15, IL-18 were significantly decreased and those of IL-4, IL-10 were significantly increased as compared with the transplant group (P<0.01). The immunosuppressive effect of TGF-beta1 on heart transplantation rejection was related to its inhibition of the expressions of Th1-type cytokines (IL-12, IL-15, IL-18 etc) and its promotion of the expressions of Th2-type cytokines (IL-4, IL-10).

TNF receptors differentially signal and are differentially expressed and regulated in the human heart

Tumor necrosis factor (TNF) utilizes two receptors, TNFR1 and 2, to initiate target cell responses. We assessed expression of TNF, TNFRs and downstream kinases in cardiac allografts, and compared TNF responses in heart organ cultures from wild-type ((WT)C57BL/6), TNFR1-knockout ((KO)), TNFR2(KO), TNFR1/2(KO) mice. In nonrejecting human heart TNFR1 was strongly expressed coincidentally with inactive apoptosis signal-regulating kinase-1 (ASK1) in cardiomyocytes (CM) and vascular endothelial cells (VEC). TNFR2 was expressed only in VEC. Low levels of TNF localized to microvessels. Rejecting cardiac allografts showed increased TNF in microvessels, diminished TNFR1, activation of ASK1, upregulated TNFR2 co-expressed with activated endothelial/epithelial tyrosine kinase (Etk), increased apoptosis and cell cycle entry in CM. Neither TNFR was expressed significantly by cardiac fibroblasts. In (WT)C57BL/6 myocardium, TNF activated both ASK1 and Etk, and increased both apoptosis and cell cycle entry. TNF-treated TNFR1(KO) myocardium showed little ASK1 activation and apoptosis but increased Etk activation and cell cycle entry, while TNFR2(KO) myocardium showed little Etk activation and cell cycle entry but increased ASK1 activation and apoptosis. These observations demonstrate independent regulation and differential functions of TNFRs in myocardium, consistent with TNFR1-mediated cell death and TNFR2-mediated repair.

Effect of the TNF-α–promoter polymorphism on cardiac allograft rejection

BACKGROUND

A polymorphism exists in the tumor necrosis factor alpha (TNF-alpha) promoter (position -308, G/A = TNFA1/TNFA2). The TNFA2 allele is associated with increased TNF-alpha production in vitro and has been reported to increase the risk of allograft rejection in pediatric recipients of cardiac transplantation. We examined the effect of the TNFA2 allele on the risk of allograft rejection in adult cardiac transplant recipients.

METHODS

We prospectively analyzed 57 subjects (aged 54 +/- 11 years, 84% men, 49% ischemic) who underwent cardiac transplantation between October 1996 and July 2001. Patients were observed after transplantation (mean, 910 +/- 605 days) and the frequency of allograft rejection (biopsy Grade > or =2) in patients with the TNFA2 allele (Group A, n = 15) was compared with TNFA1 homozygotes (Group B, n = 42). Overall survival and time to rejection episodes also were compared between groups.

RESULTS

The frequency of allograft rejection was similar between groups (Group A, 8/15 [56%]; Group B, 22/42 [52%]; p = 0.77). Time to rejection also was comparable (Group A, 17 +/- 11 days; Group B, 20 +/- 20 days, p = 0.74). Overall post-transplant survival was similar between groups (1- and 2-year percentage survival: Group A, 87% and 78%, Group B, 88% and 82%, p = 0.35).

CONCLUSION

The TNFA2 allele was not associated with increased risk of rejection in adult cardiac transplant recipients. The impact of this polymorphism on overall post-transplant outcomes will require investigation in larger multicenter studies.

Correlation between interleukin-15 and granzyme B expression and acute lung allograft rejection

The levels of interleukin (IL)-15 and granzyme B mRNA expression have been correlated with acute rejection episodes of kidney and heart allografts. Thus, the purpose of this study was to determine whether a correlation exists between the expression of IL-15 and granzyme B and acute lung allograft rejection. Toward this, the levels of IL-15 and granzyme B mRNA expression were determined in bronchoalveolar lavage-derived alveolar macrophages and total cells, respectively, from lung transplant patients with stable lung allograft function and patients undergoing acute rejection episodes. The expression levels of IL-15 mRNA was significantly higher in the patients undergoing acute rejection as compared to patients with stable lung function (P=0.02). The expression levels of granzyme B mRNA was also significantly higher in the patients undergoing acute rejection as compared to patients with stable lung function (P=0.005). The Receiver-Operating-Characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 94% and specificity of 67% with the use of a cutoff value of 3.1 fg of granzyme B mRNA per microgram of total RNA (or 71% sensitivity and 75% specificity of a cutoff value of 9.1 fg/microg). These data indicate that IL-15 secreted by activated alveolar macrophages and granzyme B secreted by activated CD8+ cytotoxic T lymphocytes play important roles in the process of acute lung allograft rejection.

Cytokine gene polymorphisms in heart transplantation: association of low IL-10 production genotype with Quilty effect

BACKGROUND

Cytokines are important modulators of post-transplant, allogeneic immune responses. In heart transplantation, endomyocardial biopsies allow monitoring of histologic and immunologic events that occur inside the graft; their correlation with risk factors condition graft outcome. Recent reports indicate that various cytokine gene allelic polymorphisms control the number of cytokines produced and may be associated with graft outcome.

METHODS

We studied 71 heart transplant recipients between December 1985 and December 2000. We used sequence-specific primers (SSP) polymerase chain reaction to study interleukin-10 (IL-10) polymorphisms at -1082 (G/A), -819 (C/T), and -592 (C/A); tumor necrosis factor alpha (TNF-alpha) at -308 (G/A) and -238 (G/A); transforming growth factor beta (TGF-beta) variants at codon 10 (C/T) and codon 25 (G/C); and interferon-gamma (IFN-gamma) polymorphisms at +874 (T/A). We determined the association of allele, genotype, and haplotype frequencies with the presence of histologically proven rejection episodes (according to International Society for Heart and Lung Transplantation criteria) and the presence of Quilty lesions in endomyocardial biopsy specimens.

RESULTS

We found no association between the polymorphisms studied and the frequency and severity of acute and chronic rejection episodes. However, the gene frequency of allele A at IL-10 -1082, associated with decreased IL-10 production, was increased in patients with Quilty lesions (p = 0.0027, odds ratio = 2.98). Similarly, we found more AA homozygous individuals, compared with AG heterozygous and GG homozygous individuals (p = 0.0017), among patients with Quilty effect. The ATA and ACC IL-10 haplotypes also were associated with Quilty effect (p = 0.0051).

CONCLUSIONS

These results suggest that genetically controlled decreased IL-10 production predisposes to the development of Quilty lesions. The decreased negative regulatory effect of IL-10 on T cells and macrophages may result in enhanced graft infiltration.

Transforming growth factor-beta expression is significantly lower in hearts preserved with blood/insulin versus crystalloid cardioplegia

The major cause of morbidity and mortality after cardiac transplantation is cardiac allograft vasculopathy (CAV). The purpose of this study was to examine the expression of markers of endothelial injury that may be affected by blood/insulin or crystalloid cardioplegia. After RNA-blot hybridization, the level of expression of tumor necrosis factor-alpha, transforming growth factor-beta (TGF-beta), intracellular adhesion molecule-1, platelet-endothelial cell adhesion molecule-1, endothelin-1, and E-selectin was increased in crystalloid cardioplegia as compared with normal and blood/insulin cardioplegia; TGF-beta was expressed at significantly lower levels in blood/insulin vs crystalloid cardioplegia (p < 0.05). Because increased expression of TGF-beta has been correlated with accelerated CAV, the use of blood/insulin cardioplegia may help to decrease the extent of endothelial damage and attenuate the progression of CAV.