Introduction of direct-acting antiviral agents alters frequencies of anti-GPIIb/IIIa antibody-producing B cells in chronic hepatitis C patients with thrombocytopenia.

The pathogenesis of thrombocytopenia in chronic hepatitis C (CHC) conceivably involves autoimmunity; however, the dynamics of autoantibodies and other autoimmune mechanisms remain unclear. In this study, we examined the changes in the frequency of anti-glycoprotein (GP) IIb/IIIa antibody-producing B cells and the levels of plasma B-cell-activating factor (BAFF), a proliferation-inducing ligand (APRIL), and interleukin (IL)-21 following treatment of CHC with direct-acting antiviral agents (DAA). We recruited 28 patients with CHC who underwent treatment with DAA for 8-12 weeks and subsequently tested negative for serum hepatitis C virus RNA. Thirty healthy controls were recruited for comparison. Platelet counts increased significantly (p = .016), and the frequency of anti-GPIIb/IIIa antibody-producing B cells decreased significantly (p = .002) in CHC patients with thrombocytopenia at the end of treatment (EOT) than before DAA treatment (baseline). However, these changes were not observed in CHC patients without thrombocytopenia. Plasma BAFF levels in CHC patients with thrombocytopenia significantly decreased from baseline to EOT (p = .002). Anti-GPIIb/IIIa antibody-producing B cells were positively correlated with plasma BAFF levels in these patients (r = 0.669, p = .039). These results suggest that DAA treatment suppresses the autoimmune response against platelets and improves thrombocytopenia.

What is the context? Production of antiplatelet antibodies is one of the mechanisms underlying thrombocytopenia in patients with chronic hepatitis C.Antiplatelet antibodies against platelet membrane glycoprotein (GP) IIb/IIIa are commonly detected in hepatitis C virus-associated immune thrombocytopenia.Hepatitis C virus elimination by direct-acting antiviral agents (DAA) improves thrombocytopenia in patients with hepatitis C; however, the dynamics of autoantibodies and other autoimmune mechanisms remain unclear.What is new? In this study, we determined whether DAA treatment can alter the autoimmune response against platelets and improve platelet count.The frequency of anti-GPIIb/IIIa antibody-producing B cells decreased significantly from the baseline following DAA treatment in chronic hepatitis C patients with thrombocytopenia.DAA treatment reduced the levels of B-cell-activating factor, a cytokine associated with autoantibody production.What is the impact? The study provides evidence that DAA treatment diminishes the autoimmune response to GPIIb/IIIa and, therefore, improves platelet counts in chronic hepatitis C patients with thrombocytopenia.

B cell-activating factor is involved in thrombocytopenia in patients with liver cirrhosis.

Liver cirrhosis (LC) involves B cells that produce anti-glycoprotein (GP) IIb/IIIa antibodies, found in primary immune thrombocytopenia (ITP). The role of autoimmunity in the pathology of thrombocytopenia in LC was investigated using 25 LC patients with thrombocytopenia, 18 ITP patients, and 30 healthy controls. Anti-GPIIb/IIIa antibody-producing B cells were quantified using enzyme-linked immunospot assay. Platelet-associated and plasma anti-GPIIb/IIIa antibody, plasma B cell-activating factor (BAFF), and a proliferation-inducing ligand (APRIL) levels were measured using enzyme-linked immunosorbent assay. B cell subset fractions and regulatory T cells (Tregs) were quantified using flow cytometry.The number of anti-GPIIb/IIIa antibody-producing B cells was significantly higher in LC patients than in ITP patients and healthy controls (both p < 0.001). Platelet-associated anti-GPIIb/IIIa antibodies were significantly higher in LC patients than in ITP patients and healthy controls (p = 0.002, p < 0.001, respectively). BAFF levels were significantly higher in LC patients than in ITP patients and healthy controls (p = 0.001 and p < 0.001, respectively), and APRIL levels were significantly higher in LC patients than in healthy controls (p < 0.001). Anti-GPIIb/IIIa antibody-producing B cells and platelet-associated anti-GPIIb/IIIa antibodies were positively correlated with BAFF levels in LC patients. LC patients had more naïve B cells and plasmablasts than healthy controls (p = 0.005, p = 0.03, respectively); plasmablasts were positively correlated with BAFF levels. LC patients had similar Tregs levels as ITP patients and healthy controls. Therefore, excessive BAFF production in LC patients with thrombocytopenia is likely associated with autoimmune B cell response, inducing anti-GPIIb/IIIa antibody production.

Impact of Anti-GPIIb/IIIa Antibody-Producing B Cells as a Predictor of the Response to Lusutrombopag in Thrombocytopenic Patients with Liver Disease.

BACKGROUND: To make an accurate estimate of the response to thrombopoietin (TPO) receptor agonists for thrombocytopenia associated with chronic liver disease, we evaluated the influence of antiplatelet autoantibodies on the response to lusutrombopag in thrombocytopenic patients with liver disease. METHODS: A prospective study was conducted at 2 hospitals. Thrombocytopenic patients with liver disease received oral lusutrombopag 3.0 mg once daily for up to 7 days. We analyzed changes in platelet counts from baseline to the maximum platelet count on days 9-14. The definition of clinical response was a platelet count of ≥5 × 104/µL with an increased platelet count of ≥2 × 104/µL from baseline. We assessed the correlation between the response to treatment drug and antiplatelet autoantibodies measured by anti-GPIIb/IIIa antibody-producing B cells. RESULTS: Thirty patients received the trial drug. There were 25 responders and 5 nonresponders. The median change in platelet counts was 3.9 × 104/µL (95% CI 2.8-4.6, p < 0.0001). The correlation between change in platelet counts and the frequency of the anti-glycoprotein IIb/IIIa antibody-producing B cells was moderate (r = 0.414, 95% CI 0.064-0.674, p = 0.023). In multivariate analysis of factors affecting the change in platelet counts, the anti-GPIIb/IIIa antibody-producing B cells were identified as an independent factor (regression coefficient [B] = 0.089; CI 0.021-0.157, p = 0.013). CONCLUSION: Anti-GPIIb/IIIa antibody-producing B cells may be a predictor for TPO receptor agonists in patients with chronic liver disease.