Antibodies against glutathione S-transferase T1 in non-solid organ transplanted patients

Pre-existing non-human leukocyte antigen antibodies are associated with allograft rejection after thoracic transplantation

BACKGROUND

There is growing evidence on the important role of non-human leukocyte antigen (HLA) antibodies in lung and heart transplant rejection. Since data on the prevalence and clinical significance of non-HLA antibodies in the Asian population are scarce, we analyzed non-HLA antibodies in heart and lung transplant patients.

METHODS

We used the Luminex method to measure non-HLA antibodies in patients who underwent heart transplantation (N = 28) or lung transplantation (N = 36) between 2016 and 2019. We evaluated the association between pre-existing non-HLA antibodies and acute rejection-free days in these recipients.

RESULTS

Of 64 patients, 27 (42.2%) patients underwent rejection, with 26 (40.6%) acute cellular rejection and one (1.6%) acute antibody-mediated rejection. Among 33 identified different non-HLA antibodies, only the anti-glutathione S-transferase theta-1 (GSTT1) antibody positive rate was significantly higher in patients with acute rejection compared to those without rejection (14.8% vs. 0%, p = 0.016). The angiotensin II type I receptor positive rate was not significantly different between the two groups (40% vs. 18.5%, p = 0.129). In the multivariate Cox regression analysis, anti-GSTT1 antibody-positive patients had a higher risk of acute allograft rejection (hazard ratio, 4.19; 95% confidence interval [CI], 1.41-12.49; p = 0.010). The Kaplan-Meier curve showed that anti-GSTT1 antibody-positive patients had fewer acute rejection-free days (χ² = 7.892; p = 0.005). Additionally, patients who underwent platelet transfusion (odds ratio, 1.49; 95% CI, 1.16-1.91; p = 0.002) before transplantation were more likely to be positive for anti-GSTT1 antibody.

CONCLUSION

Patients with antibodies against GSTT1 before heart or lung transplantation have an increased risk of acute rejection.

Rethinking de novo immune hepatitis, an old concept for liver allograft rejection: Relevance of glutathione S-transferase T1 mismatch

Antibody-mediated rejection (AMR) in liver transplantation has long been underestimated. The concept of the liver as an organ susceptible to AMR has emerged in recent years, not only in the context of the major histocompatibility complex with the presence of HLA donor-specific antibodies, but also with antigens regarded as “minor”, whose role in AMR has been demonstrated. Among them, antibodies against glutathione S-transferase T1 have been found in 100% of patients with de novo autoimmune hepatitis (dnAIH) when studied. In its latest update, the Banff Working Group for liver allograft pathology proposed replacing the term dnAIH with plasma cell (PC)-rich rejection. Antibodies to glutathione S-transferase T1 (GSTT1) in null recipients of GSTT1 positive donors have been included as a contributory but nonessential feature of the diagnosis of PC-rich rejection. Also in this update, non-organ-specific anti-nuclear or smooth muscle autoantibodies are no longer included as diagnostic criteria. Although initially found in a proportion of patients with PC-rich rejection, the presence of autoantibodies is misleading since they are not disease-specific and appear in many different contexts as bystanders. The cellular types and proportions of the inflammatory infiltrates in diagnostic biopsies have been studied in detail very recently. PC-rich rejection biopsies present a characteristic cellular profile with a predominance of T lymphocytes and a high proportion of PCs, close to 30%, of which 16.48% are IgG4⁺. New data on the relevance of GSTT1-specific T lymphocytes to PC-rich rejection will be discussed in this review.

T-cell allorecognition of donor glutathione S-transferase T1 in plasma cell-rich rejection

AIM

To investigate the role of glutathione S-transferase T1 donor-specific T lymphocytes in plasma cell-rich rejection of liver allografts.

METHODS

The study group included 22 liver transplant patients. Among them, 18 patients were mismatched for the glutathione S-transferase T1 (GSTT1) alleles (don+/rec-), and 4 were matched (don+/rec+). Seven of the mismatched patients produced anti-GSTT1 antibodies and developed plasma cell-rich rejection (former de novo immune hepatitis). For the detection of specific T lymphocytes, peripheral blood mononuclear cells were collected and stored in liquid nitrogen. The memory T cell response was studied by adding to the cell cultures to a mix of 39 custom-made, 15-mer overlapping peptides, which covered the entire GSTT1 amino acid sequence. The specific cellular response to peptides was analyzed by flow cytometry using the markers CD8, CD4, IL-4 and IFNγ.

RESULTS

Activation of CD8⁺ T cells with different peptides was observed exclusively in the group of patients with plasma-cell rich rejection (3 out of 7), with production of IL-4 and/or IFNγ at a rate of 1%-4.92% depending on the peptides. The CD4⁺ response was most common and not exclusive for patients with the disease, where 5 out of 7 showed percentages of activated cells from 1.24% to 31.34%. Additionally, two patients without the disease but with the mismatch had cells that became stimulated with some peptides (1.45%-5.18%). Highly unexpected was the finding of a double positive CD4⁺CD8^low T cell population that showed the highest degree of activation with some of the peptides in 7 patients with the mismatch, in 4 patients with plasma cell-rich rejection and in 3 patients without the disease. Unfortunately, CD4⁺CD8^low cells represent 1% of the total number of lymphocytes, and stimulation could not be analyzed in 9 patients due to the low number of gated cells. Cells from the 4 patients included as controls did not show activation with any of the peptides.

CONCLUSION

Patients with GSTT1 mismatch can develop a specific T-cell response, but the potential role of this response in the pathogenesis of plasma cell-rich rejection is unknown.

IgG subclass profile among anti-Glutathione S-transferase T1 antibodies in post-transplant de novo immune hepatitis

Although the pathogenic pathways leading to de novo immune hepatitis (IH) are not completely understood, we have shown strong evidences of an antidonor response against Glutathione S-transferase T1 (GSTT1), an antigen exclusively expressed in the donor liver. The first sign of this process is the production of GSTT1 antibodies that, in 25% of the cases, will precede de novo IH. Because the presence of the antibodies is not sufficient to trigger the disease, we aimed to study GSTT1 IgG subclasses in a group of 18 liver transplant patients, 12 that developed de novo IH and 6 that remained free of disease. Surprisingly, the predominant subclasses were IgG1-GSTT 1 and IgG4-GSTT 1. The presence of IgG4-expressing plasma cells was also investigated in 10 available liver biopsies. Six biopsies coinciding with diagnosis showed a mean value of 32.8 IgG4+ plasma cells/hpf vs. 5.55 in patients without the disease. We have not found a distinctive GSTT1-IgG profile in patients with de novo IH, but the ratio IgG1-GSTT 1 /IgG4-GSTT 1 in samples from close to the time of diagnosis seemed to be important. The novel finding of abundant IgG4-GSTT 1 in liver transplantation is intriguing, but their possible role in pathogenesis of de novo IH remains unknown.

Glutathione S-transferase T1-null seems to be associated with graft failure in hematopoietic SCT

Hematopoietic SCT (HSCT) from HLA-matched donors is sometimes complicated by GVHD or graft rejection, because of mismatched mHA. This study presents data suggesting the involvement of glutathione S-transferase theta-1 (GSTT1), a phase II detoxifying enzyme encoded by GSTT1, in Ab-mediated rejection of HSCT in children with congenital hemoglobinopathies (CHs). Mismatch of GSTT1, which often features a deletion polymorphism variant, can have major consequences in solid organ transplantation outcome. In liver transplantation, it has been shown to lead to de novo hepatitis, whereas in kidney transplantation, chronic allograft rejection has been documented. In this study on 18 children with CH who underwent HSCT, five cases of graft rejection occurred, all in GSTT1-null patients, four of which featured anti-GSTT1 antibodies. The data suggest that when GSTT1-null patients are transplanted with a GSTT1-positive graft, rejection due to an Ab-mediated immune response against GSTT1 displayed on transplanted stem cells may take place. Thus, it seems that detection of anti-GSTT1 antibodies in patients with a GSTT1-null genotype before transplantation may be predictive of graft rejection in the event of a GSTT1-positive donor.

Donor-specific antibodies against HLA, MICA, and GSTT1 in patients with allograft rejection and C4d deposition in renal biopsies

BACKGROUND

Production of antibodies against donor-specific antigens is one of the central mechanisms of allograft rejection. This antibody-mediated rejection (AMR) is evidenced by the presence of circulating donor-specific antibodies and deposition of complement component C4d on renal endothelium. Although anti-human leukocyte antigen (HLA) antibodies account for a high proportion of AMR, in many cases anti-HLA antibodies cannot be demonstrated. In liver transplant, antibodies against glutathione-S-transferase T1 (GSTT1) expressed on the graft may induce an antibody response leading to a severe graft dysfunction. In addition, presence of antibodies against major-histocompatibility-complex class I chain-related gene A (MICA) has been associated with a poor graft survival in kidney transplantation.

METHODS

Pre- and posttransplantation sera from 19 patients fulfilling the criteria for AMR including C4d deposition in renal biopsies were included. Donor-specific antibodies against HLA-I and -II and MICA were studied using Luminex. Anti-GSTT1 antibodies were analyzed by indirect immunofluorescence and by an ELISA method. A control group of 39 patients with graft dysfunction negative for C4d was also included.

RESULTS

At the time of the biopsy, 4 (21%) patients had only anti-HLA class I antibodies; 3 (15.8%) had anti-GSTT1, 2 (10.5%) had anti-HLA-class II, and 2 (10.5%) had anti-MICA; four patients had combination of antibodies: HLA-I + MICA (n=1), HLA-I + GSTT1 (n=2), and GSTT1+MICA (n=1). No antibodies were found in 4 (21%) patients. In total, 6 (31.6%) C4d+ patients had anti-GSTT1 antibodies, whereas, among the 39 C4d-negative patients, only 3 (7.7%) had anti-GSTT1 antibodies (P=0.027).

CONCLUSION

Besides anti-HLA antibodies, donor-specific antibodies against MICA and GSTT1 antigens could be responsible for the occurrence of antibody-mediated kidney graft rejection.

Autoantibodies to glutathione S-transferase theta 1 in patients with primary sclerosing cholangitis and other autoimmune diseases

Primary sclerosing cholangitis (PSC) is an enigmatic disorder with a suggested autoimmune basis. A variety of autoantigens have been suggested but no specific or highly directed epitope has been identified. To address this issue, we constructed a cDNA library from normal human choledochus and screened expressing clones with serum from a patient with PSC and inflammatory bowel disease (IBD). Based on this screening, glutathione S-transferase theta 1 (GSTT1) was identified as a potential autoantigenic target. To study the specificity of GSTT1, we determined immunoreactivity using a panel of 58 patients with PSC, with and without IBD, 57 patients with IBD, 31 patients with Hashimoto's thyroiditis, 30 patients with primary biliary cirrhosis (PBC), 20 patients with insulin dependent diabetes mellitus, 22 patients with autoimmune polyendocrine syndrome type I, 10 patients with systemic lupus erythematosus (SLE), 20 patients with Sjögren's syndrome, 12 patients with autoimmune pancreatitis, 28 patients with Addison's disease, 27 patients with Grave's disease, 17 with myasthenia gravis, and 118 healthy controls. Reactivity against GSTT1 was found with PSC and IBD as well as some patients with other autoimmune pathology, indicating that this population of antibodies is neither specific nor a sensitive serologic marker for PSC, but the frequency was clearly higher in autoimmune patients than controls. GSTT1-antibodies have been described in persons with GSTT1-null genotype and are suggested to develop as an alloimmune response to blood transfusions from GSTT1-positive donors or pregnancies with GSTT1-positive children. Therefore, two IBD patients with and 15 PSC patients without GSTT1-antibodies were genotyped for GSTT1 to investigate if the presence of GSTT1-antibodies was associated with the GSTT1-null genotype and possibly caused by an alloimmune response. Both IBD patients and three of the PSC patients were of the GSTT1-null genotype. We note that the frequency of GSTT1-antibodies in this study is more than 100-fold higher than the frequency described earlier in patients with autoimmune diseases. We also observe an increased frequency of GSTT1-antibodies in patients with autoimmune diseases compared to healthy controls. This increased frequency can be explained by an autoimmune phenotype which increases susceptibility to such autoantibodies, or by a high frequency of the GSTT1-null genotype in autoimmune disease.

Antibodies against glutathione S-transferase T1 (GSTT1) in patients with GSTT1 null genotype as prognostic marker: long-term follow-up after liver transplantation

An objective to improve the evolution of transplants is to identify risk biomarkers of morbidity and loss of allograft. In liver transplant (LTX) recipients, an association has been demonstrated between the presence of mismatch for glutathione S-transferase T1 (GSTT1) and the development of de novo immune hepatitis (IH). In 419 LTX patients we analyzed, for a period of 1 to 14 years, the development of "atypical" autoantibodies directed against GSTT1 and their relationship with the mismatch for GSTT1 genotype and with the risk for developing de novo IH. A total of 6.9% LTX recipients had "atypical" autoantibodies and 24 showed mismatch (recipient/donor) for GSTT1 genotype. From this last group, up to 70% developed de novo IH and graft dysfunction after LTX (95% confidence interval: 17.4-37.5 months). In LTX recipients with a GSTT1 null genotype, the evaluation of "atypical" autoantibodies is useful for monitoring the development of de novo IH.