Stella Chang

Granulysin expression is a marker for acute rejection and steroid resistance in human renal transplantation.

Differentiating etiologies of transplant dysfunction without biopsy and optimizing therapy for acute rejection by predicting steroid resistance will reduce patient morbidity. Granulysin is a cytolytic molecule released by CTL and NK cells and coexpressed with effectors of acute allograft rejection, like perforin and granzymes. Granulysin mRNA and protein expression were studied in peripheral blood lymphocytes (PBL; n = 61 total, n = 10 with intercurrent infections) and biopsy tissue from adult and children renal transplant recipients (n = 97) by competitive quantitative-reverse transcriptase-PCR (QC-RT-PCR) and immunohistochemistry. Differences in cell phenotypes were studied in steroid sensitive and resistant acute rejection biopsies. Granulysin was studied in phytohemagglutinin (PHA) stimulated cell lines (donor PBL and CD45RO(+) T cells) by FACS, Western blotting, and RT-PCR after pretreating with cyclosporine A (CSA), azathioprine, mycophenolic acid, and steroids. Granulysin mRNA was significantly increased in patient PBL and transplant biopsies during acute rejection (p < 0.0001) and infection (p < 0.001). Rejecting biopsies alone (n = 53) had mononuclear cell granulysin staining. Steroid resistant biopsies (n = 25) had denser granulysin staining (>2 cells/high power field) and CD45RO(+) lymphocytes, when compared with steroid sensitive (n = 28) rejecting tissue. Granulysin levels were unchanged after azathioprine and mycophenolic acid treatment, decreased after treating activated PBL with steroids and cyclosporine A (CSA), and paradoxically, increased (p < 0.05) after treating CD45RO(+) CTL with CSA. Elevated PBL granulysin is a peripheral marker for acute rejection and infection and dense granulysin staining a tissue marker for steroid resistance. Memory CTL abound in steroid resistant grafts and may have a markedly different response to CSA immunotherapy, suggesting a possible mechanism for steroid resistance.

Increased expression of cytotoxic effector molecules: Different interpretations for steroid‐based and steroid‐free immunosuppression

Abstract: Cytotoxic T lymphocyte (CTL) effector molecules have been studied as markers of acute rejection in renal allograft recipients on steroid‐based immunosuppression. We hypothesized that basal CTL gene expression may vary with time post‐transplantation as well as with different immunosuppression protocols (steroid‐based or steroid‐free). Variations in CTL gene expression may thus impact on the ability to predict acute allograft rejection. We used the non‐invasive method of quantitative competitive‐reverse transcription‐polymerase chain reaction (QC‐RT‐PCR) to quantify the amounts of CTL effector molecules (granulysin, GL; perforin, P; granzyme B, GB) in serial peripheral blood lymphocyte (PBL) samples from steroid‐free and steroid‐based adult and pediatric renal allograft recipients. Patients on both protocols were clinically monitored by protocol biopsies at 1, 3, 6, and 12 months post‐transplantation and for graft function at 1 yr post‐transplantation in a separate clinical study. Steroid‐free patients with stable graft function showed an increase in GL, P, and GB gene expression over time post‐transplantation with the increase being seen largely by the first post‐transplant month. A further increase in GL expression was noted at the end of the first post‐transplant year in the absence of acute rejection, whereas GB and P levels were unchanged. At comparative time‐points post‐transplantation, CTL genes were found to be higher in steroid‐free patients with stable graft function, compared to steroid‐based recipients with either clinically stable graft function or acute rejection. This study suggests that levels of CTL gene expression, although important in a steroid‐based regimen to monitor the risk of acute rejection, may not be similarly applied in patients on steroid‐free immunosuppression. The early increase in levels seen in steroid‐free patients appears to correlate with the total absence of steroids. As steroid‐free patients seem to have a lower incidence of acute rejection and better long‐term graft function at 1 yr, the early increase in CTL genes in the absence of acute rejection may suggest an early adaptive immune activation response, promoting early graft acceptance in this protocol.

Quantification of cytotoxic T-cell gene transcripts in human lung transplantation.

BACKGROUND Differentiating between acute rejection and cytomegalovirus (CMV) infection is one of the major challenges of lung transplantation. The aims of this study were to: (1) quantify the transcription of the cytotoxic T lymphocyte (CTL) effector molecules in the bronchoalveolar lavage (BAL) of lung transplant recipients and (2) evaluate the clinical usefulness of this technique. METHODS Sixty-six single-lung, double-lung, or heart-lung transplant patients were prospectively enrolled in the study. BAL was performed either for routine surveillance or for acute graft dysfunction. RNA was extracted from BAL cell pellets and underwent competitive reverse transcription-assisted polymerase chain reaction (RT-PCR) for perforin, granzyme B, granulysin, and Fas ligand. Gene transcript analysis was compared to clinical diagnosis established by conventional methods [BAL microbiological and transbronchial biopsy (TBB) analyses]. RESULTS After exclusion of several BAL according to the study criteria, 62 BAL were submitted for data analysis. Significantly higher expression of all the analyzed transcripts was found during CMV infection, compared with each of the other defined diagnostic categories, namely nonsignificant pathology, acute rejection, and nonviral pulmonary infection. CONCLUSION Quantification by competitive RT-PCR of the CTL effector molecule transcripts (perforin, granzyme B, granulysin, and Fas ligand) could represent a valuable tool for the differential diagnosis of graft dysfunction in lung transplantation.

Inducible nitric oxide synthase transcription in human lung transplantation

BACKGROUND Recent animal data suggest that inducible nitric oxide synthase (iNOS) mRNA expression in the bronchoalveolar lavage (BAL) may be useful for the diagnosis of lung rejection. The aim of this study was to evaluate iNOS mRNA transcription in the BAL fluid of human lung allografts. METHODS iNOS mRNA transcription was quantified by competitive reverse transcription-polymerase chain reaction in 51 BAL cell pellets of lung transplant patients. According to bacteriological and histological results, BAL samples were divided into three groups: normal (n=21), acute rejection (AR, n=15), and infection (INF, n=15). RESULTS Compared with the control group, iNOS transcription increased significantly with INF (P=0.0005) but only slightly with AR (P>0.05). INF values were significantly higher than AR values (P=0.0029). CONCLUSION BAL iNOS mRNA transcript determination by competitive reverse transcription-polymerase chain reaction may be useful in differentiating infected from normal and/or acutely rejecting allografts.