Localization of C-X-C and C-C chemokines to renal tubular epithelial cells in human kidney transplants is not confined to acute cellular rejection

A candidate gene approach of the calcineurin pathway to identify variants associated with clinical outcomes in renal transplantation

AIM

To investigate the potential influence of variants in genes involved in the calcineurin pathway on the efficacy and toxicity of calcineurin inhibitors in renal transplantation.

MATERIALS & METHODS

Twenty-three polymorphisms in thirteen genes were tested in 381 renal transplant recipients receiving ciclosporin (n = 221) or tacrolimus (n = 160) and mycophenolate mofetil. Data were collected prospectively over the first year post-transplantation.

RESULTS

Multivariate survival analyses revealed no genetic associations with biopsy proven acute graft rejection and serious infections. Donor-recipient Cytomegalovirus mismatch was the only variable associated with serious infection.

CONCLUSION

This large exploratory study casts doubts on the potential interest of genetic biomarkers related to CNI pharmacodynamics but associations with other phenotypes in transplantation deserve further studies.

Parenteral iron treatment induces MCP-1 accumulation in plasma, normal kidneys, and in experimental nephropathy

INTRODUCTION

Monocyte chemoattractant protein-1 (MCP-1) promotes renal inflammation, thereby contributing to acute and chronic nephropathies. Its production is stimulated by oxidative stress. Thus, this study tested whether pro-oxidant iron/carbohydrate complexes, used to treat iron deficiency, induce MCP-1 in renal/extrarenal tissues, in plasma, and in the setting of experimental nephropathy.

METHODS

CD-1 mice received 2 mg of intravenous iron [complexed with dextran (iron dextran), sucrose (iron sucrose), or gluconate (iron gluconate)]. Renal MCP-1 and/or its mRNA were measured 3 hours to 7 days post-iron injection. Iron effects on liver, lung, spleen, and heart MCP-1 mRNA, and on peritoneal lavage fluid MCP-1 concentrations were assessed. Iron pretreatment effects on MCP-1 levels in unilaterally obstructed kidneys vs. contralateral kidneys were determined. Finally, iron gluconate's influence on proximal tubule [human kidney-2 (HK-2)] cell MCP-1 levels was assessed.

RESULTS

Iron sucrose (the primary test agent) markedly increased plasma and renal MCP-1 levels. It also induced multiorgan MCP-1 mRNA increments (liver > spleen > kidney > lung > heart). Iron gluconate was more potent than iron sucrose; conversely, iron dextran had no discernible effect. The iron dextran and iron sucrose-induced renal MCP-1 mRNA increments ( approximately 4x) were persistent, lasting for at least 3 to 7 days. Iron gluconate raised MCP-1 levels in peritoneal lavage fluid. It also doubled MCP-1 in unilaterally obstructed kidneys (ureteral ligation) without altering contralateral (control kidney) MCP-1 content. Iron gluconate raised HK-2 cell MCP-1, implying a direct proximal tubule effect.

CONCLUSION

Iron sucrose and iron gluconate (but not iron dextran) can induce MCP-1 generation in renal and extrarenal tissues, possibly via transcriptional events. This may dramatically impact renal disease-induced MCP-1 increments. Finally, iron can increase peritoneal lavage fluid MCP-1 levels. Whether the above changes have implications for renal disease progression, and/or for peritoneal inflammation/peritoneal dialysis efficiency, are issues which may need to be addressed.

Donor genomics influence graft events: the effect of donor polymorphisms on acute rejection and chronic allograft nephropathy

BACKGROUND

Organs procured from deceased donors emanate from individuals with diverse genetic backgrounds. Donor organs, therefore, may vary in their response to injury and immune stimuli in a genetically determined manner. We assessed polymorphisms from 244 renal allograft donors to better understand the impact of donor polymorphisms on selected transplant outcomes.

METHODS

Donor genomic DNA restriction fragment length polymorphisms were assayed for evidence of common cytokine [interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor (TNF)-alpha, TGF-beta, interferon (IFN)-gamma] and chemokine (CCR2, CCR5) polymorphisms. Associations between donor polymorphisms and graft events were determined using chi-square, linear regression, and Kaplan-Meier analyses.

RESULTS

Several genotypic polymorphisms demonstrated a modest association with acute rejection, including the transforming growth factor (TGF)-beta T/C codon 10 (P= 0.027) and the CCR5 G/A 59029 (P= 0.039) genes by chi-square analysis. Notably, the presence of the T allele in the IFN-gamma gene (+874) demonstrated a highly significant association with biopsy-proven chronic allograft nephropathy (P < 0.008). This association remained highly significant in a multiple linear regression model that incorporated biopsy-proven acute rejection as a covariate.

CONCLUSION

These data suggest that many of the donor polymorphisms studied in this analysis may influence a recipient's immune response to a renal allograft. However, their greatest impact may be demonstrated in long-term outcomes.

CC-chemokine RANTES is increased in serum and urine in the early post-transplantation period of human renal allograft recipients

BACKGROUND

The chemokine RANTES is a potent chemoattractant for T cells and monocytes that has been shown to enhance inflammation. The aim of our study was to investigate whether RANTES is upregulated within the early post-transplantation period that may influence short-time allograft function rate.

METHODS

Serum and urine samples from transplanted renal allograft recipients (n = 17) were obtained from specimens taken for diagnostic reasons. Four patients developed biopsy-proven rejection episodes within the first month. Time course of RANTES was studied within the first 12 days after renal transplantation using ELISA technique. Data were tested for significances between patients with rejection and without rejection, compared to healthy volunteers as controls, and correlated with clinical data.

RESULTS

In the control group RANTES concentration was 37.2 +/- 2.7 ng/ml (serum) and 8.1 +/- 1.3 pg/ml (urine), respectively. In transplanted recipients serum RANTES was significantly upregulated up to 132 +/- 28 ng/ml on day 1 after transplantation and remained elevated within the first 12 days (n = 17). Time course of urine RANTES demonstrated elevated concentrations with 754 +/- 115 pg/ml on day 1 followed by an continuous decrease to 22.3 +/- 7 pg/ml on day 12 (n = 17). No significant differences could be detected between patients with rejection and without rejection episodes.

CONCLUSIONS

In contrast to data of other urinary marker molecules (like IL-6), there are no significant differences between the rejection and non-rejection group. RANTES is therefore not suitable for early detection of rejection. Nevertheless, serum and urine RANTES concentrations were highly elevated in freshly transplanted renal allograft recipients reflecting an activated immune system.

Quantification and in situ localization of MCP-1 mRNA and its relation to the immune response of renal cell carcinoma

Malignant tumours are usually accompanied by an immune response. Chemokines such as MCP-1 have been claimed to be potent inducers of such tumour-associated reactions. In the present study MCP-1 mRNA was quantified by competitive reverse transcription polymerase reaction and localised by in situ hybridisation in renal cell carcinoma tissue in comparison to tumour-free tissue of the same nephrectomy specimen. MCP-1 mRNA levels were correlated with the immune cell infiltrate, the density of CD31(+)microvessels, and the endothelial expression of ICAM-1, VCAM-1, E-, and P-selectin. In only seven of 19 cases, MCP-1 mRNA levels in carcinoma tissue were increased in comparison to tumour-free tissue. Within tumour tissue, mRNA transcripts could be localised in tumour cells, microvessel endothelia, and in tumour-associated macrophages. A correlation between MCP-1 mRNA levels and the density of immune cells, especially macrophages, the microvessel density, and the expression of adhesion molecules could not be observed. Therefore, MCP-1 seems to be of minor importance for the induction of an immune response in renal cell carcinomas regarding at least the parameters analysed in this study.

Chemokines and their receptors in allograft rejection

Despite current recognition of over 40 chemokines and more than 18 chemokine receptors, understanding of their role in transplant immunobiology and transplant rejection is extremely limited and fragmentary. Recent literature has demonstrated the presence of chemokines and their receptors in transplants and some studies demonstrate important functional roles.