Case–control study of the association between select HLA genes and anti-erythropoietin antibody-positive pure red-cell aplasia

HLA-B*46:01:01:01 and HLA-DRB1*09:01:02:01 are associated with anti-rHuEPO-induced pure red cell aplasia

Treatment of anemia in patients with chronic kidney disease (CKD) with recombinant human erythropoietin (rHuEPO) can be disrupted by a severe complication, anti-rHuEPO-induced pure red cell aplasia (PRCA). Specific HLA genotypes may have played a role in the high incidence of PRCA in Thai patients (1.7/1,000 patient years vs. 0.03/10,000 patient years in Caucasians). We conducted a case-control study in 157 CKD patients with anti-rHuEPO-induced PRCA and 56 controls. The HLA typing was determined by sequencing using a highly accurate multiplex single-molecule, real-time, long-read sequencing platform. Four analytical models were deployed: Model 1 (additive: accounts for the number of alleles), Model 2 (dominant: accounts for only the presence or absence of alleles), Model 3 (adjusted additive with rHuEPO types) and Model 4 (adjusted dominant with rHuEPO types). HLA-B*46:01:01:01 and DRB1*09:01:02:01 were found to be independent risk markers for anti-rHuEPO-induced PRCA in all models [OR (95%CI), p-values for B*46:01:01:01: 4.58 (1.55-13.51), 0.006; 4.63 (1.56-13.75), 0.006; 5.72 (1.67-19.67), 0.006; and 5.81 (1.68-20.09), 0.005; for DRB1*09:01:02:01: 3.99 (1.28-12.49), 0.017, 4.50 (1.32-15.40), 0.016, 3.42 (1.09-10.74), 0.035, and 3.75 (1.08-13.07), 0.038, in Models 1-4, respectively. HLA-B*46:01:01:01 and DRB1*09:01:02:01 are susceptible alleles for anti-rHuEPO-induced PRCA. These findings support the role of HLA genotyping in helping to monitor patients receiving rHuEPO treatment.

Investigating the Correlation Between HLA-II Gene Polymorphism and RhE Alloimmunization in Pregnant Chinese Women

The Rhesus (Rh) blood group is a significant and complicated biological system in humans. Incompatible transfusion or pregnancy with Rh antigens can lead to the production of alloantibodies, among which the anti-E antibody is prevalent. The relationship between Anti-E antibody and HLA-II gene polymorphism in Chinese pregnant women is worth exploring. Our aim in this study was to verify the correlation between HLA-II gene polymorphisms and RhE alloimmunization in pregnant Chinese women through HLA-II typing and DR-RhE structural prediction. In total, 94 anti-E-negative pregnant women and 103 anti-E-positive pregnant women were enrolled from Southwest China Second Hospital, and HLA-II genotyping was performed using next-generation sequencing. NetMHCpan software was used to predict the binding of E -derived anchoring peptides to HLA-DRB1 molecules. AlphaFold was used to analyze the differences in antigen presentation based on the structure of major histocompatibility complex peptides. The HLA-DRB1*09:01-DQA1*03:02-DQB1*03:03 haplotype showed a significant positive association with anti-E. One E-derived anchoring peptide (219FWPSVNSPL227) was predicted to bind to the HLA-DRB1*09:01 molecule. The interaction between the 60Ser of DR9 and 226pro of RhE comprised one hydrogen bond. This study demonstrated that HLA-II haplotypes are associated with allo-anti-E antibodies in pregnant women from Sichuan Province, China. The HLA-DRB1*09:01-DQA1*03:02-DQB1*03:03 phenotype may enhance the formation of anti-E alloantibodies, and the HLA-DRB1*09:01 molecule may play a key role in alloimmunity.

Comprehensive RNA-Sequencing Analysis in Peripheral Blood Cells Reveals Differential Expression Signatures with Biomarker Potential for Idiopathic Membranous Nephropathy

To date, the clinical course of idiopathic membranous nephropathy (iMN) remains unclear and lacks direct and effective diagnostic methods. To better understand the host gene expression changes involved in the iMN process and identify the potential signatures for clinical diagnosis, we performed a whole genome-wide transcriptome profile of peripheral blood cells (PBC) from patients with iMN and healthy controls (HCs). A total of 188 differentially expressed genes (DEGs) were detected in patients with iMN versus HCs. Gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that these DEGs were mainly correlated with protein targeting, ion homeostasis GO terms, and ribosome and phagosome pathways. The top 10 differentially expressed protein-coding genes with >2-fold changes and high expression levels were validated using quantitative real-time PCR, and showed high consistency with the high-throughput sequencing results. HLA-C, S100A8, and FTH1 genes were selected for further validation and showed the most significant difference between the iMN and HC group, indicating that they could be used as potential clinical diagnostic biomarkers. Our results provide novel potential diagnostic signatures for iMN and have important implications for better understanding the pathogenesis of iMN.

T-cell assays confirm immunogenicity of tungsten-induced erythropoietin aggregates associated with pure red cell aplasia

Immunogenicity of biotherapeutics and the elicitation of anti-drug antibodies are a key concern for their efficacy, pharmacokinetics, and safety. A particularly severe consequence of immunogenicity of a biotherapeutic is the rare development of antibody-mediated pure red cell aplasia (PRCA) in anemic patients treated with aggregated forms of recombinant human erythropoietin (rhEPO). Here, we investigated in vitro T-cell responses to experimentally heat-induced rhEPO aggregates, and to tungsten-induced rhEPO aggregates in clinical lots associated with rhEPO-neutralizing antibodies and PRCA. Heat-stressed rhEPO elicited T-cell responses only in blood obtained from healthy individuals identified as responders, whereas nonstressed rhEPO overall did not induce reactions neither in responders nor nonresponders. Tungsten-induced rhEPO aggregates in clinical lots associated with rhEPO-neutralizing antibodies and PRCA could induce in vitro T-cell responses in blood obtained from healthy donors, in contrast to rhEPO from low tungsten syringes. Importantly, ex vivo T-cell recall responses of patients treated with rhEPO without PRCA showed no T-cell responses, whereas T cells of a patient who developed PRCA after treatment with a clinical batch with elevated levels of tungsten and rhEPO aggregates showed a clear response to rhEPO from that clinical batch. To our knowledge, this is the first time that T-cell assays confirm the root cause of increased rhEPO immunogenicity associated with PRCA.

A cluster of Epoetin-associated pure red cell aplasia: clinical features and the possible association of HLA-DRB1*12:02

Antibody-mediated pure red cell aplasia is a rare but serious complication in chronic kidney disease patients receiving recombinant human erythropoietin (r-HuEpo). Between April 2012 and May 2013, eight such cases were reported in our institution. Their clinical features were reviewed and their HLA alleles were compared with those of healthy controls. All patients were exposed to epoetin alfa (Eprex^®) with polysorbate-80 as stabilizer via subcutaneous route with a mean age of 61.9 years and mean exposure of 11.2 months of r-HuEpo before loss of efficacy. 87.5% of the cases were male and Chinese and received immunosuppression as treatment for pure red cell aplasia. All three of the successfully treated patients are alive compared with only 40% of the transfusion-dependent patients. DRB1*12:02 was more frequently expressed among the cases than healthy controls suggesting a plausible molecular link.

Biosimilar recombinant human erythropoietin induces the production of neutralizing antibodies

Recombinant human erythropoietin (r-HuEpo) has been used for the treatment of renal anemia. With the loss of its patent protection, there has been an upsurge of more affordable biosimilar agents, increasing patient access to treatment for these conditions. The complexity of the manufacturing process for these recombinant proteins, however, can result in altered properties that may significantly affect patient safety. As it is not known whether various r-HuEpo products can be safely interchanged, we studied 30 patients with chronic kidney disease treated by subcutaneous injection with biosimilar r-HuEpo and who developed a sudden loss of efficacy. Sera from 23 of these patients were positive for r-HuEpo-neutralizing antibodies, and their bone marrow biopsies indicated pure red-cell aplasia, indicating the loss of erythroblasts. Sera and bone marrow biopsies from the remaining seven patients were negative for anti-r-HuEpo antibodies and red-cell aplasia, respectively. The cause for r-HuEpo hyporesponsiveness was occult gastrointestinal bleeding. Thus, subcutaneous injection of biosimilar r-HuEpo can cause adverse immunological effects. A large, long-term, pharmacovigilance study is necessary to monitor and ensure patient safety for these agents.