Defective cytokine production from monocytes/macrophages of E-beta thalassemia patients in response to Pythium insidiosum infection

Background Pythium insidiosum has been mainly reported to cause morbidity and mortality in thalassemia patients. P. insidiosum zoospores can germinate to be hyphae within a few hours; therefore, it is difficult to study the initial immune response that P. insidiosum zoospores induce. The present study aims to compare immune responses against P. insidiosum zoospore infection by comparing monocytes/macrophages from thalassemia patients with those from non-thalassemia controls. Methods: In order to keep P. insidiosum in the zoospore stage in vitro for inoculation, the P. insidiosum zoospores were preserved without germination by treatment with inorganic hypochlorite solution. CD14+ cells were isolated from peripheral blood mononuclear cells of thalassemia and non-thalassemia donors and then left to transition to macrophages. Monocytes/macrophage culture was infected with P. insidiosum zoospores and culture supernatants were subjected to Th1/Th2 multiplex cytokine detection. Results: Our study of cytokine production revealed that the basal level of GM-CSF produced by thalassemia monocytes/macrophages was lower than that observed in monocytes/macrophages of non-thalassemia individuals. Higher GM-CSF and IFN-gamma response was also found when cells from non-thalassemia people were stimulated with P. insidiosum zoospores compared to thalassemia cells. It was also found that TNF-alpha, GM-CSF and IFN-gamma productions from monocytes/macrophages of thalassemia patients who received iron chelator treatment were significantly higher than those produced from thalassemia patients without iron chelator treatment. Conclusion: For the first time, the present study demonstrates defective immune responses in monocytes/macrophages derived from thalassemia patients in response to P. insidiosum zoospore infection. The results also show an inverse correlation between iron overload and cytokine production in monocytes/macrophages of thalassemia patients. This finding could explain why thalassemia patients are susceptible to P. insidiosum infection.