Elevated plasma interleukin 34 levels correlate with disease severity-reflecting parameters of patients with haemorrhagic fever with renal syndrome

Abstract

<b>Background:</b> Haemorrhagic fever with renal syndrome (HFRS) is characterized by an uncontrolled cytokine storm that causes vascular leakage and kidney injury. The cytokine interleukin 34 (IL-34) enhances proliferation and differentiation of myeloid cells and secretion of pro-inflammatory cytokines, which is involved in the pathogenesis of some inflammatory and infectious diseases, including acute kidney injury. To date, however, the role of IL-34 in patients with HFRS is unclear. This study aims to determine the plasma IL-34 levels of HFRS patients and discuss the possible effects of IL-34 in the pathogenesis of HFRS. <b>Methods:</b> Plasma levels of IL-34 in 52 HFRS patients and 20 healthy controls were quantified using enzyme-linked immunosorbent assay. <b>Results:</b> Compared with healthy controls, the plasma IL-34 levels in HFRS patients were significantly elevated in acute phase [37.92 (0-215.45) pg/ml vs. 7.13 (0-19.44) pg/ml, <i>p</i> < .0001], and then decreased to the normal levels in convalescent phase. Importantly, IL-34 levels correlated positively with white blood cell counts and mononuclear cell counts (<i>r</i> = 0.592, <i>p</i> < .0001 and <i>r</i> = 0.458, <i>p</i> < .0001, respectively), and correlated negatively with platelet counts and serum albumin levels (<i>r</i> = -0.430, <i>p</i> < .0001 and <i>r</i> = -0.479, <i>p</i> = .0001, respectively). <b>Conclusions:</b> Plasma levels of IL-34 in HFRS patients were significantly elevated in acute phase and correlated with disease severity-reflecting parameters, which suggests a potential role of IL-34 in HFRS and should be future explored.