Enhanced allograft survival via simultaneous blockade of transferrin receptor and interleukin-2 receptor

miR-151-5p alleviates corneal allograft rejection by activating PI3K/AKT signaling pathway and balancing Th17/Treg after corneal transplantation via targeting IL-2Rɑ

Background

Worldwide, corneal transplantation (CT) is the most common type of tissue replacement and the increased rate of corneal graft rejection (CGR) after CT is a critical problem. Corneal endothelium cells (CECs) are often targets of the immune response mediated by graft-attacking effector T cells. However, the molecular mechanism underlying CGR remains poorly understood.

Methods

The differentially expressed microRNAs (miRNAs) and mRNA of graft-fail corneas were measured by transcriptome sequencing (RNA-Seq). real-time quantitative polymerase chain reaction was used to measure gene expression levels. Western blot and immunofluorescence staining were used to measure protein expression levels. Kaplan-Meier survival curves were constructed to assess corneal graft survival. Hematoxylin and eosin staining was used for histopathological examination. CCK-8 and ELISA staining were used to detect cell viability and inflammatory cytokines levels, respectively. Flow cytometry was used to detect cell apoptosis and the population of Treg and Th17. Transwell migration and wound-healing assays were used to measure cell migration.

Results

We identified 453 miRNAs and 4,279 mRNAs aberrant expression in the corneas showing CGR. The differentially expressed miR-151-5p and its potential target gene [interleukin 2 receptor subunit alpha (IL-2Rɑ)] were selected from the RNA-Seq microarrays. The levels of miR-151-5p and IL-2Rɑ were respectively downregulated and upregulated in the CGR. The luciferase activity assay suggested that IL-2Rɑ is a target of miR-151-5p in 293 T cells. In addition, the miR-151-5p inhibitor, si-IL-2Rɑ, and oe-IL-2Rɑ transfection tests in CECs further confirmed that miR-151-5p downregulation and IL-2Rɑ overexpression promoted apoptosis of CECs and inhibited CEC migration, tight junction-related protein ZO-1 and Claudin-5 expression, and PI3K/AKT signaling pathway activity; however, downregulation of IL-2Rɑ abolished the inhibitor effect of miR-151-5p. Similarly, upregulation of miR-151-5p alleviated CGR via activation of the PI3K/AKT signaling pathway and balancing of Th17/Treg, and upregulation of IL-2Rɑ abolished the alleviating effect of miR-151-5p.

Conclusions

Upregulation of miR-151-5p alleviated CGR by activating the PI3K/AKT signaling pathway and balancing Th17/Treg via targeting of IL-2Rɑ, which contributes to improving the results of CT.

Analysis of cytokine functions in graft rejection by gene expression profiles

BACKGROUND

The function of interferon (IFN)gamma in the regulation of the immune response after allogeneic transplantation is still poorly understood. Previous studies have suggested that IFNgamma can promote rejection and be important in tolerance induction.

METHODS

To analyze the various IFNgamma-dependent functions in terms of T helpers 1 and 2 responses during rejection, we investigated mice deficient in the transcription factors (signal transducer of activated T cells [STAT]4 and 6) and IFNgamma in fully major histocompatibility complex-mismatched vascularized cardiac transplants. Serum levels of the cytokines tumor necrosis factor-alpha, IFNgamma, and interleukin (IL)-1beta were evaluated by enzyme-linked immunosorbent assay, and the graft-infiltrating cells were examined by immunohistochemical staining. To analyze a large panel of immune parameters, we determined the expression of chemokines, chemokine receptors, and clusters of differentiation markers by RNAase protection assays. The data were analyzed with algorithms that generated hierarchic clustering dendrograms. Also, the expression profiles of individual genes were determined with self-organizing maps.

RESULTS

Our data show that both the STAT4- and STAT6-deficient groups have statistically prolonged graft survival (P<0.04 and P<0.01). Despite the absence of prolongation of graft survival in the IFNgamma-deficient group, our analysis of variance data show that more genes (18) were modulated in the IFNgamma-deficient group compared with the other two STAT4- and STAT6-deficient groups (five each).

CONCLUSIONS

Our results indicate that IFNgamma plays a distinct role in the modulation of gene expression that includes STAT4-independent mechanisms. Our study identifies eight genes (IL-1beta, IL-1RA, macrophage inflammatory protein-1beta, monocyte chemoattractant protein-1, CC-chemokine receptor (CCR)-1, CCR2, CCR5, and F4/80) that are highly expressed in all of our experimental groups. Thus, these genes become candidates for essential functions during rejection.

House keeping genes and gene expression analysis in transplant recipients: a note of caution

BACKGROUND

House keeping genes are often used as a means of standardising results obtained in gene expression investigations. This study was performed to investigate whether beta-actin, beta2-microglobulin (two genes frequently quoted as house keeping genes) and/or transferrin receptor would be suitable house keeping genes for use in gene expression analysis of renal transplant recipients.

METHODS

Sequential expression of all three genes was measured in the peripheral blood mononuclear cells of 13 living donors and 45 renal transplant recipients, pre-operatively and then daily for up to 2 weeks. Fifteen of the recipients experienced an episode of biopsy proven acute rejection. Gene expression measurement was performed using quantitative real time 'TaqMan' PCR technology.

RESULTS

Gene expression of all three genes was unchanged in the living donor cohort. However, in the transplant recipients there were significant increases in expression following transplantation in the non-rejectors, and preceding the diagnosis of acute rejection. In the latter group, levels returned to pre-transplant values after the commencement of anti-rejection therapy.

CONCLUSIONS

Beta-actin, beta2-microglobulin and transferrin receptor gene expression, although not influenced by surgery, is influenced by transplantation, acute rejection and anti-rejection therapy making these genes unsuitable as house keeping genes following renal transplantation. These findings may cast doubt on the results of some studies that used these genes for the purposes of standardisation when looking at cDNA measurement. We suggest that any group wishing to use a house keeping gene ensure that its expression is independent of study parameters prior to the start of the study.