Fig 2: The levels of serum IL-17 in CAP patients with different severity scores. A–F The levels of serum IL-17 in CAP patients with different severity scores. A CRB-65 score. B SMART-COP score. C APACHE II score. D CURB-65 score. E CURXO score. F PSI score. All data were expressed as mean ± SEM. *P < 0.05, **P < 0.01

Fig 3: The levels of serum IL-17 in CAP patients with different prognostic outcomes. A–E The levels of serum IL-17 in CAP patients with different prognostic outcomes during hospitalizations. A Mechanical ventilation. B Vasoactive agent. C ICU admission. D Lengths of hospital stay. E Death. All data were expressed as mean ± SEM. *P < 0.05, **P < 0.01

Fig 4: Melatonin suppresses Th17 and enhances Treg differentiation via SIRT1 activation. Sorted naïve CD4+ T cells (CD3+ CD4+ CD45RA+ CD45RO-) from umbilical cord blood of healthy newborns were transduced with lentivirus-containing control-shRNA (CTRL shRNA) and SIRT1-shRNA (SIRT1 shRNA) (A-I), or control lentivirus (CTRL LV), and SIRT1-expressing lentivirus (SIRT1 LV) (J-R). At 24 h after transduction, CD4+ T cells were differentiated under Th17 or Treg conditions for 4 days in the presence of melatonin (20 ng/mL). (A) Representative flow cytometric plots of IL-17 and Foxp3 expression in gated CD4+ T cells under Th17 (top) and Treg (bottom) conditions following transduction with CTRL or SIRT1 shRNA. (B, C) Quantification of the frequency of Th17 (B) and Treg (C) cells in (A). (D-I) Real-time qRT-PCR analysis of relative mRNA expression of ROR?t (D), IL-17 (E), IL-22 (F), Foxp3 (G), TGF-ß (H), and IL-10 (I) in Th17 (D-F) and Treg (G-I) conditions. (J) Representative flow cytometric plots of IL-17 and Foxp3 expression in gated CD4+ T cells under Th17 (top) and Treg (bottom) conditions following transduction with CTRL LV or SIRT1 LV. (K, L) Quantification the frequency of Th17 (K) and Treg (L) cells in (J). (M-R) Real-time qRT-PCR analysis relative mRNA expression of ROR?t (M), IL-17 (N), IL-22 (O), Foxp3 (P), TGF-ß (Q), and IL-10 (R) in Th17 (M-O) and Treg (P-R) conditions (as described in the Methods). Each symbol (B-I, K-R) represents an individual experiment (n = 5); column graphs represent the mean with error bars indicating standard deviation (SD), *P < 0.05; **P < 0.01; ***P < 0.001; ns: not significant. P values were derived from one-way ANOVA followed by the Bonferroni multiple comparison test (B-I, K-R).

Fig 5: SIRT1 pathway inhibition attenuates maintenance of the Th17/Treg balance. (A) Representative flow cytometric plots of IL-17 and Foxp3 expression in gated lamina propria CD4+ T cells from ileum sections of pups following necrotizing enterocolitis (NEC) induction upon treatment with vehicle (VEH) alone or with melatonin (MEL) or melatonin combined with Ex-527 (MEL + Ex-527). (B, C) Quantification of the percentages of Th17 (B) and Treg (C) cells in (A), n = 5 per group. (D) Immunoblot analysis of ROR?t, Foxp3, p-STAT3, STAT3, p-STAT5, and STAT5 in ilea of VEH, MEL, and MEL + Ex-527 pups, ß-actin was used as an internal control. (E-H) Quantification of ROR?t (E), Foxp3 (F), p-STAT3/STAT3 (G), and p-STAT5/STAT5 (H). n = 6 per group. Each symbol (B, C, E-H) represents an individual mouse; column graphs represent the mean with error bars indicating standard deviation (SD), *P < 0.05; ***P < 0.001; ns: not significant. P values were derived from one-way ANOVA followed by a Bonferroni multiple comparison test (B, C, E-H). Data are representative of three independent experiments (B, C, E-H).