Roles of immune responses in the pathogenesis of immunorelated pancytopenia

Anti-PGK1 antibodies in immuno-related pancytopenia

OBJECTIVE

Phosphoglycerate kinase 1 (PGK1) was previously screened as a possible autoantigen for IRP, this study further investigates the value of PGK1 autoantibodies in the diagnosis of IRP and their correlation with other clinical indicators.

METHOD

Anti-PGK1 antibodies were screened in untreated IRP patients and SAA patients by ELISA.CD5 + B cells and BMMNC-Ab were detected in untreated and recovered IRP patients by FCM. Clinical findings were compared between different groups.

RESULT

The serum level of anti-PGK1 antibodies of untreated IRP patients was significantly higher than that of SAA patients; the percentage of PGK1-Ab positive patients was lower in PLT > 50*109/L group in recovered IRP patients and PGK1-Ab levels in the recovered IRP patients were positively correlated with WBC and CIC levels and negatively correlated with PLT levels. PLT was positively correlated with CIC levels in the untreated IRP group. After treatment, the levels of C3 and C4, the percentage of CD34+ IgM positivity, and CD5+ B cells of IRP patients decreased significantly.

CONCLUSION

Detecting anti-PGK1 antibodies might have some clinical value in differentiating IRP from SAA. The tests of CD34+ IgM positivity, CD5+ B cells, and C3 and C4 levels are of clinical value in assessing the curative effect of IRP patients.

Identification of TRAPPC4 as a Key Autoantigen in Immune-Related Pancytopenia: Epitope Characterization and Immune Activation Mechanisms

Objective

Immune-related pancytopenia (IRP) is characterized by autoantibody-mediated destruction or suppression of bone marrow cells, leading to pancytopenia. This study aimed to explore the role of trafficking protein particle complex subunit 4 (TRAPPC4) as a key autoantigen in IRP, including epitope identification and immune activation mechanisms.

Materials and Methods

A total of 90 participants were included in the study, divided into four groups: 30 newly diagnosed IRP patients, 25 patients with IRP in remission, 20 patients with other hematological conditions (severe aplastic anemia [SAA] and myelodysplastic syndrome [MDS]) as a patient control group, and 15 healthy individuals as a healthy control group. TRAPPC4 was identified using affinity screening with a phage-display random peptide library and confirmed with ELISPOT and epitope prediction software. TRAPPC4 expression in bone marrow cells and serum antibody titers was assessed via flow cytometry, ELISA assay, and real-time polymerase chain reaction. Immune cell profiling of peripheral blood mononuclear cells was conducted using flow cytometry.

Results

TRAPPC4 was overexpressed in the CD34+ bone marrow hematopoietic progenitor cells of newly diagnosed IRP patients compared to patients in remission, the patient control group (SAA and MDS), and the healthy control group, with no significant differences observed for CD15+ granulocytes or CD235a+ nucleated red blood cells. The epitope peptide YTADGKEVLEYLG activated Th2 cells, as confirmed by ELISPOT. Newly diagnosed IRP patients exhibited elevated TRAPPC4 mRNA and protein levels in bone marrow mononuclear cells and higher serum antibody titers compared to controls. Immune profiling revealed increased CD19+ and CD5+CD19+ B lymphocytes in IRP patients.

Conclusion

TRAPPC4 was found to be a key autoantigen in IRP along with CD34+ cells as primary targets of autoantibody attacks. The identification of TRAPPC4 and its epitope provides insights into IRP pathogenesis and suggests potential diagnostic and therapeutic strategies.

Immunostimulatory Effect of Ovomucin Hydrolysates by Pancreatin in RAW 264.7 Macrophages via Mitogen-Activated Protein Kinase (MAPK) Signaling Pathway

Ovomucin (OM), which has insoluble fractions is a viscous glycoprotein, found in egg albumin. Enzymatic hydrolysates of OM have water solubility and bioactive properties. This study investigated that the immunostimulatory effects of OM hydrolysates (OMHs) obtained by using various proteolytic enzymes (Alcalase®, bromelain, α-chymotrypsin, Neutrase®, pancreatin, papain, Protamax®, and trypsin) in RAW 264.7 cells. The results showed that OMH prepared with pancreatin (OMPA) produced the highest levels of nitrite oxide in RAW 264.7 cells, through upregulation of inducible nitric oxide synthase mRNA expression. The production of pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin-6 were increased with the cytokines mRNA expression. The effect of OMPA on mitogen-activated protein kinase signaling pathway was increased the phosphorylation of p38, c-Jun NH2-terminal kinase, and extracellular signal-regulated kinase in a concentration-dependent manner. Therefore, OMPA could be used as a potential immune-stimulating agent in the functional food industry.

A case report of AQP4-IgG-seropositive refractory neuromyelitis optica spectrum disorder patient with Sjögren's syndrome and pancytopenia treated with inebilizumab

Patients with neuromyelitis optica spectrum disorder (NMOSD) coexisting with both Sjögren's syndrome (SS) and pancytopenia are exceptionally rare. There is no study on the treatment of such patients. We presented a case of AQP4-IgG seropositive refractory NMOSD patient combined with SS and pancytopenia with significant response to inebilizumab. In 2017 the 49-year-old female patient was diagnosed with SS and pancytopenia without any treatment. In August 2022, she had a sudden onset of lower limbs weakness, manifested as inability to walk, accompanied by urinary incontinence. After receiving methylprednisolone and cyclophosphamide, she regained the ability to walk. In February 2023, she suffered from weakness of both lower limbs again and paralyzed in bed, accompanied by retention of urine and stool, and loss of vision in both eyes. After receiving methylprednisolone and three plasmapheresis, the condition did not further worsen, but there was no remission. In March 2023, the patient was admitted to our hospital and was formally diagnosed with AQP4-IgG seropositive NMOSD combined with SS and pancytopenia. After receiving two 300 mg injections of inebilizumab, not only the symptoms of NMOSD improved significantly, but also the symptoms of concurrent SS and pancytopenia. In the cases of AQP4-IgG seropositive NMOSD who have recurrent episodes and are comorbid with other autoimmune disorders, inebilizumab may be a good choice.

Swiss Survey on current practices and opinions on clinical constellations triggering the search for PNH clones

This national survey investigated the current practice in Switzerland by collecting participants' opinions on paroxysmal nocturnal hemoglobinuria (PNH) clone assessment and clinical practice.

Aim

This study aimed to investigate clinical indications prompting PNH clones' assessment and physician's accessibility of a flow cytometry facility, and also to understand clinical attitudes on the follow-up (FU) of patients with PNH clones.

Methods

The survey includes 16 multiple-choice questions related to PNH and targets physicians with a definite level of experience in the topic using two screener questions. Opinion on clinical management was collected using hypothetical clinical situations. Each participant had the option of being contacted to further discuss the survey results. This was an online survey, and 264 physicians were contacted through email once a week for 5 weeks from September 2020.

Results

In total, 64 physicians (24.2%) from 23 institutions participated (81.3% hematologists and 67.2% from university hospitals). All had access to flow cytometry for PNH clone testing, with 76.6% having access within their own institution. The main reasons to assess for PNH clones were unexplained thrombosis and/or hemolysis, and/or aplastic anemia (AA). Patients in FU for PNH clones were more likely to be aplastic anemia (AA) and symptomatic PNH. In total, 61% of the participants investigated PNH clones repetitively during FU in AA/myelodysplastic syndromes patients, even when there was no PNH clone found at diagnosis, and 75% of the participants tested at least once a year during FU. Opinions related to clinical management were scattered.

Conclusion

The need to adhere to guidelines for the assessment, interpretation, and reporting of PNH clones emerges as the most important finding, as well as consensus for the management of less well-defined clinical situations. Even though there are several international guidelines, clear information addressing specific topics such as the type of anticoagulant to use and its duration, as well as the indication for treatment with complement inhibitors in some borderline situations are needed. The analysis and the discussion of this survey provide the basis for understanding the unmet needs of PNH clone assessment and clinical practice in Switzerland.

Ferritin Light Chain: A Candidate Autoantigen in Immuno-Related Pancytopenia

The characteristic feature of immune-related pancytopenia (IRP) is autoantibody-mediated bone marrow (BM) damage and peripheral blood cytopenia. We found that the potential antigen of IRP was Ferritin light chain (FTL) by SEREX (serological analysis of recombinant cDNA expression libraries) in the previous study. In this study, we tried to explore the antigenic epitopes of FTL and verify its antigenicity in IRP. We found the possible FTL epitope: VNLYLQASYTYLSLG by phage random peptide library. Through ELISPOT, it was found that peptide VNLYLQASYTYLSLG can significantly stimulate the production of interleukin-4 and cannot stimulate the production of interferon-γ, which suggested that the peptide can obviously activate Th2 cells. Peptide-major histocompatibility complex tetramer elicited antigen-specific T cell responses. The expression levels of FTL were significantly increased in the patients with untreated IRP (P < 0.05). In conclusion, we found that FTL is the target antigen for some patients with IRP. The peptide of VNLYLQASYTYLSLG is an epitope of the target antigen. The target antigen is abnormally overexpressed on the membrane of BM cells, especially on the surface of CD34+ BM cells of patients with IRP. In addition, it is related to the severity of disease. These results provide a possible new target for the treatment of IRP in the future.