Elevated Plasma Interleukin 34 Levels Correlate with Disease Severity-Reflecting Parameters of Patients with Haemorrhagic Fever with Renal Syndrome

Abstract Background: Haemorrhagic fever with renal syndrome (HFRS) is characterised 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. However, to date, the role of IL-34 in patients with HFRS is unclear. This study aims to detect the plasma IL-34 levels of HFRS patients and discuss the possible effects of IL-34 in the pathogenesis of HFRS. Methods: IL-34 levels in the plasmas from 52 HFRS patients and 20 healthy controls were quantified using enzyme-linked immunosorbent assay. Results: Compared with healthy controls, the plasma IL-34 levels in HFRS patients were significantly elevated at acute phase [37.92 (10.58-73.86) pg/ml vs. 7.13 (3.99-11.31) pg/ml, p < 0.0001], and then decreased to the normal levels at convalescent phase. Importantly, IL-34 levels positively correlated with white blood cell count and monocyte count (r = 0.503, p < 0.0001 and r = 0.367, p = 0.0003, respectively), and negatively correlated with platelet count and serum albumin levels (r = -0.614, p < 0.0001 and r = -0.598, p = 0.0003, respectively). Conclusions: IL-34 levels in plasma of HFRS patients were significantly elevated at acute phase and correlated with disease severity-reflecting parameters, which suggests a potential role of IL-34 in the pathogenesis of HFRS and should be future explore.