All authors contributed to the article and approved the submitted version. Conflict of Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Acknowledgments This study was supported from 2020 Shanxi Province Emerging Industry Leadership Project and Youth Fund of the Second Hospital of Shanxi Medical University, (no.?201902-6).. 5.56 vs 26.56 5.37 ng/ml, p 0.001). The levels of serum liver enzyme ALT and AST Eletriptan hydrobromide and muscle mass enzyme CK, CKMB, LDH and HBDH were elevated as deficiency of vitamin D. In addition, the serum 25-(OH)-D levels were negatively correlated to ALT (r = -0.408, p = 0.001) and AST (r = -0.338, p = 0.007). The 25-(OH)-D levels in IIM patients in presence of anti-Jo-1 were significantly lower than those in patients without anti-Jo-1 (5.24 3.17 vs 9.32 5.60 ng/ml; p = 0.037). Comparable results were found in patients with or without anti-Mi-2 antibody. The serum 25-(OH)-D levels were positively associated with total T (r = 0.203, p = 0.012) and Treg cells (r = 0.331, p = 0.013). The patients with deficient levels of vitamin D were more likely to have heliotrope, gastrointestinal and liver involvement. Conclusions Vitamin D deficiency existed in IIM patients, which was significantly correlated with muscle mass enzyme, presence of anti-Jo-1 and anti-Mi-2 antibody, and the complete numbers of total T and Eletriptan hydrobromide Treg cells Eletriptan hydrobromide in IIM. It is suggested that vitamin D may play an important role in the immunological pathogenesis of IIM. (value of less than Klf4 0.05 was considered statistically significant. Statistical analyses were performed by SPSS version 23.0 (IBM Corp, Armonk, NY, USA) and GraphPad Prism version 8.01. Results The imply serum 25-(OH)-D levels of IIM patients were significantly lower than those of HCs (9.13 5.29 vs 22.86 5.38; p 0.001; Physique 1A ) and those in male or female patients was also significantly lower than those in healthy males or females, respectively ( Physique 1B ). Furthermore, the serum vitamin D levels in all IIM subgroups were significantly lower than those of HCs ( Physique 1A ). The patients were categorized into four groups based on the serum 25-(OH)-D levels ( Table 2 ). Of 63 IIM individuals and all IIM subgroups, the mind-boggling majority were extremely deficient in 25-(OH)-D levels 10 ng/ml, while almost all HCs experienced vitamin D with 25-(OH)-D levels over 20 ng/ml. Open in a separate window Physique 1 The levels of 25-(OH)-D (ng/ml) in IIM patients and HCs. (A) The levels of 25-(OH)-D in IIM and its subgroups were significantly lower than those of HCs. (B) Eletriptan hydrobromide The levels of 25-(OH)-D in IIM were significantly lower than those of HCs in male and female. HCs, Healthy controls; IIM, idiopathic inflammatory myopathy; PM, polymyositis; DM, dermatomyositis; CTM, connective tissue myositis. **p 0.01, ***p 0.001 by indie samples t-test. Table 2 Number (%) of IIM patients and controls with extremely deficient, deficient, insufficient and Sufficient serum levels of 25-(OH)-D. thead th valign=”top” align=”left” rowspan=”1″ colspan=”1″ /th th valign=”top” align=”center” rowspan=”1″ colspan=”1″ Extremely deficient ( 10 ng/ml) /th th valign=”top” align=”center” rowspan=”1″ colspan=”1″ Deficient (10.1-20 ng/ml) /th th valign=”top” align=”center” rowspan=”1″ colspan=”1″ Insufficient (20.1-30 ng/ml) /th th valign=”top” align=”center” rowspan=”1″ colspan=”1″ Sufficient ( 30 ng/ml) /th th valign=”top” align=”center” rowspan=”1″ colspan=”1″ Total /th /thead Controls1 (1.8%)8 (14.6%)22 (40%)24 (43.6%)55 (100%)IIM42 (66.7%)17 (27.0%)4 (6.3%)0 (0%)63 (100%)PM5 (71.4%)2 (28.6%)0 (0%)0 (0%)7 (11.1%)DM32 (65.3%)14 (28.6%)3 (6.1%)0 (0%)49 (77.8%)CTM5 (71.4%)1 (14.3%)1 (14.3%)0 (0%)7 (11.1%) Open in a separate windows In IIM patients with different levels of vitamin D, the ESR had not significantly difference ( Physique 2A ), but the CRP in IIM with deficient vitamin D was significantly higher than those in IIM with insufficient vitamin D ( Physique 2B ). Interesting, the levels of serum liver enzyme ALT and AST and muscle mass enzyme CK, CKMB, LDH and HBDH were elevated as deficiency of vitamin D became severer ( Figures 2CCH ). In addition, the serum 25-(OH)-D levels were unfavorable correlated with ALT (r = -0.408, p?=?0.001; Figures 2I, J ) and AST (r = -0.338, p = 0.007; Figures 2I, K ). Open in a separate window Physique 2 The associations of vitamin D levels with inflammatory biomarkers in IIM patients. (A) ESR has no significant correlation with vitamin D. (B) The level of CRP in patients with deficient vitamin D were significantly higher than those of patients with insufficient vitamin D. (CCH) As the degree of vitamin D deficiency increased, the levels of serum muscle mass enzymes elevated. (I) The associations of 25-(OH)-D levels with inflammatory biomarkers in.