Lale Saka Baraz, Evrim Ataca, Nur Düzen Oflas, Seyma Canavar Kosali, Büşra Usta, Alihan Oral, Mustafa Cihangiroglu, Metin Ozgen, Demet Yalcin Kehribar
Neurotrophins such as nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF) are crucial for neuronal maintenance and immune regulation. However, their dynamics during coronavirus disease 2019 (COVID-19) remain unclear. In this prospective study, 30 hospitalized patients with PCR-confirmed COVID-19 were evaluated longitudinally. Serum NGF, GDNF, and conventional inflammatory markers (CRP, ESR, fibrinogen, ferritin, D-dimer, LDH, hematological counts) were measured on Day 1, Day 4, and at discharge. A control group of 37 healthy individuals was included for cross-sectional comparison. Both NGF and GDNF levels were significantly lower in COVID-19 patients at admission compared with healthy individuals. NGF showed a modest early decline from Day 1 to Day 4, followed by partial recovery at discharge, whereas GDNF remained stable throughout hospitalization. Inflammatory markers demonstrated expected clinical trajectories: CRP, ESR, LDH, and fibrinogen decreased during recovery, while WBC, neutrophils, and platelets increased. Ferritin and D-dimer showed no meaningful temporal changes. NGF appears to reflect acute neuroimmune activation in COVID-19 and may serve as a dynamic biomarker of early inflammatory resolution. Conversely, GDNF remained persistently suppressed, suggesting a distinct role in chronic neuroimmune regulation. These findings highlight NGF and GDNF as potential targets for monitoring and modulating neuroimmune responses in COVID-19 and other inflammation-driven conditions.