The role of neuropeptides in the diagnosis of childhood community-acquired pneumonia

The role of neuropeptides in the diagnosis of childhood community-acquired pneumonia, Bolu Abant Izzet Baysal University Faculty of Medicine, Department of Pediatrics, Thesis of Graduation, Bolu, 2023 Background: Pneumonia is one of the most significant causes of morbidity in children under the age of 5 worldwide. Despite improvements in diagnosis, treatment, and prophylaxis, pneumonia remains the leading cause of death in non-neonatal children. Neuropeptides are molecules that play a role in synaptic activity. Our aim is to investigate the potential role of neuropeptides in the diagnosis and differentiation between viral and bacterial childhood pneumonias. Materials and Methods: The study included 124 patients with moderate or severe pneumonia who presented to our hospital between February 2022 and January 2023, as well as 56 healthy individuals. Chest radiographs were taken for the patients. Procalcitonin(PCT), calcitonin gene-related peptide(CGRP), substance P, vasoactive intestinal peptide(VIP) and neuropeptide Y were measured in the serum of all patients at admission. Results: Of the patients, 71 were male and 53 were female. The mean age of the patients ranged from two months to 17 years, with an average of 67.5±50.5 months. PCT levels were significantly higher in pneumonia patients compared to controls (67±54.8 vs. 54.8±16 pg/mL, p<0.001). CGRP and VIP levels were also significantly higher in patients with pneumonia compared to controls (respectively, 50.8±17.8 vs. 34.8±13 ng/L, p<0.001 and 85.9±30.7 vs. 66.3±16 ng/L, p=0.011), while neuropeptide Y levels were significantly lower (53.6±27 vs. 60.4±22.8 ng/L, p=0.002). Among the pneumonia cases, 25 were diagnosed as bacterial/mixed, while 99 were diagnosed as viral pneumonia. PCT (respectively, 54.8±16 vs. 95.2±10.9 pg/mL, p<0.001 and 54.8±16 vs. 59.6±9.3 pg/mL, p=0.035) and CGRP values (respectively, 34.8±13 vs. 79±13.8 ng/L, p<0.001 and 34.8±13 vs. 43.7±10 ng/L, p<0.001) were significantly higher in patients with bacterial/mixed and viral pneumonia compared to controls. On the other hand, neuropeptide Y were significantly higher in patients with bacterial/mixed pneumonia and significantly lower in patients with viral pneumonia compared to controls (respectively, 60.4±22.8 vs. 81.7±27 ng/L, p=0.001 and 60.4±22.8 vs. 46.5±22 ng/L, p=0.001). In contrast, substance P and VIP values were significantly higher in patients with only bacterial/mixed pneumonia compared to controls (respectively, 129.4±49.5 vs. 227.8±59.8 ng/L, p<0.001 and 66.3±16 vs. 99.6±21.8 ng/L, p=0.002). There was also a significant difference in PCT (95.2±10.9 vs. 59.6±9.3 pg/mL, p<0.001), CGRP (79±13.8 vs. 43.7±10 ng/L, p<0.001), neuropeptide Y (81. 7±27 vs. 46.5±22 ng/dL, p<0.001) and substance P values (227.8±59.8 vs. 120.4±39.5 ng/L, p<0.001) between patients with bacterial/mixed and viral pneumonia. ROC analysis indicated that 58.3 cut-off value of CGRP had a sensitivity of 88% and a specificity of 88% (AUC: 0.96; 95% CI (0.93-1), p<0.001), 85.3 cut-off value of VIP had a sensitivity of 70% and a specificity of 70% (AUC: 0.73; 95% CI (0.60-0.85), p=0. 005), 62 cut-off values of neuropeptide Y showed a sensitivity of 76% and specificity of 76% (AUC: 0.78; 95% CI (0.64-0.92), p<0.001), and 159.4 cut-off values of substance P showed a sensitivity of 88% and specificity of 84% (AUC: 0.92; 95% CI (0.85-0.98), p<0.001) in differentiating between bacterial/mixed and viral pneumonia. Conclusion: These findings suggest that neuropeptides may be utilized in the diagnosis of pneumonia and the differentiation between bacterial/mixed and viral pneumonias. Key words: Childhood Community-Acquired Pneumonia, Substance P, Calcitonin Gene-Related Peptide, Neuropeptide Y, Vasoactive Intestinal Peptide, Procalcitonin