Elevated Serum Cathelicidin and Inverse Correlation with Vitamin D in Patients with Intestinal Tuberculosis

Nuri Dyah Indrasari (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Astuti Giantini (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Ninik Sukartini (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Dewi Wulandari (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Dean Handimulya Djumaryo (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Nindy Auliana (Division of Clinical Pathology, Department of Medical Laboratory, Dr. Cipto Mangunkusumo Central General Hospital, Jl. Diponegoro No.71, Jakarta 10430)
Pande Made Satrya Dharma Pathni (Department of Clinical Pathology, Faculty of Medicine, Universitas Indonesia, Jl. Salemba Raya No.6, Jakarta 10430)
Fathoni Afif (Department of Clinical Pathology, Faculty of Medicine, Universitas Indonesia, Jl. Salemba Raya No.6, Jakarta 10430)

The Indonesian Biomedical Journal
Vol 18, No 3 (2026)

BACKGROUND: Intestinal tuberculosis (ITB) is a type of tuberculosis (TB) that affects the gastrointestinal tract. Cathelicidin, an antimicrobial peptide, contributes to defense against Mycobacterium tuberculosis, which causes TB. Its expression is tightly regulated by vitamin D through vitamin D receptor signaling and autophagy pathways. Despite the increasing evidence on TB, studies exploring the correlation between cathelicidin and vitamin D in the ITB remain poorly characterized and almost exclusively derived from pulmonary TB. Therefore, the present study was conducted to compare serum cathelicidin and vitamin D levels between subjects with ITB and without ITB, and to determine the correlation between these two biomarkers.METHODS: This comparative cross-sectional study utilized stored serum samples obtained from participants enrolled in a previous ITB project. Twenty-two ITB and 22 non-ITB subjects aged >18 years who had undergone colonoscopy, histopathological examinations, and fulfilled predefined clinical and diagnostic criteria were included. Serum cathelicidin and vitamin D levels were measured using sandwich enzyme-linked immunosorbent assay (ELISA) and chemiluminescent microparticle immunoassay (CMIA), respectively.RESULTS: Significantly higher levels of serum cathelicidin were identified in ITB subjects, with a median level of 3.67 (2.27‒5.95) ng/mL, compared with non-ITB subjects with a median level of 2.04 (1.66‒2.46) ng/mL (p<0.0001). Although the difference was not statistically significant (p=0.091), vitamin D level tended to be lower in subjects with ITB, with a median level of 11.05 (6.80‒25.25) ng/mL, compared to non-ITB subjects with a median level of 17.95 (12.13‒23.63) ng/mL. A significant moderate negative correlation was found between cathelicidin and vitamin D (r=-0.485, p=0.001).CONCLUSION: The ITB is associated with elevated cathelicidin levels and a tendency toward lower vitamin D levels. The inverse correlation suggests a complex relationship between vitamin D status and cathelicidin expression, highlighting immunological mechanisms involved in ITB pathogenesis.KEYWORDS: antimicrobial peptide, cathelicidin, innate immunity, intestinal tuberculosis, vitamin D