{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T16:48:52Z","timestamp":1786121332240,"version":"build-2736575974"},"reference-count":17,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T00:00:00Z","timestamp":1786060800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>\n                      Coinfection with\n                      <jats:italic>Mycobacterium tuberculosis<\/jats:italic>\n                      (TB) and SARS-CoV-2 poses unique challenges in pediatric population due to overlapping immune pathways and potential immune dysregulation. The complement system, a key arm of innate immunity, plays a dual role in pathogen clearance and inflammation.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This study aimed to investigate complement activation in TB in children with or without serological evidence of prior SARS-CoV-2 exposure. Children aged 2\u201317 years with pulmonary or extrapulmonary TB were recruited from two tertiary hospitals in South India. Participants were grouped based on SARS-CoV-2 IgG serostatus: CoV2\u207a (n = 30) and CoV2\u207b (n = 30). Blood samples were collected at baseline, and at months 3, and 6 for complement profiling. Levels of classical, lectin, and alternative pathway proteins, as well as regulatory factors, were quantified using multiplex bead-based assays. Canonical discriminant analysis (CDA) and Spearman correlation were used to analyse temporal and relational patterns in complement activation.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      CoV2\n                      <jats:sup>+<\/jats:sup>\n                      children had significantly elevated levels of classical pathway proteins (C1q, C3, C4, C5a) and regulatory factors (Factor B, H, and I) at baseline, month 3 and month 6 in comparison to CoV2\n                      <jats:sup>-<\/jats:sup>\n                      children. However C2 and C5 diminished in CoV2\n                      <jats:sup>+<\/jats:sup>\n                      children in comparison to CoV2-CDA revealed distinct, time-resolved complement activity in CoV2\u207b children, whereas CoV2\u207a profiles showed overlap, suggesting prolonged immune alteration. Correlation analysis identified significant associations between SARS-CoV-2 IgG and complement proteins, with differing patterns in CoV2\n                      <jats:sup>+<\/jats:sup>\n                      and CoV2\n                      <jats:sup>-<\/jats:sup>\n                      groups over time.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>SARS-CoV-2 seropositivity may contribute to changes in the complement activation trajectory in TB-diseased children, potentially contributing to persistent inflammation. Complement profiling may inform therapeutic strategies and serve as a biomarker of immune recovery in TB\u2013 SARS-CoV-2 co-infection.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1761877","type":"journal-article","created":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T04:22:33Z","timestamp":1786076553000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Profiling complement proteins in pediatric tuberculosis children with or without serological evidence of prior SARS-CoV-2 exposure"],"prefix":"10.3389","volume":"17","author":[{"given":"Nathella Pavan","family":"Kumar","sequence":"first","affiliation":[{"name":"ICMR - National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guruprashath","family":"Mohan","sequence":"additional","affiliation":[{"name":"ICMR - National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sarath","family":"Balaji","sequence":"additional","affiliation":[{"name":"Institute of Child Health and Hospital for Children","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Agalya","family":"Vanamudhu","sequence":"additional","affiliation":[{"name":"ICMR - 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National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gopika","family":"S","sequence":"additional","affiliation":[{"name":"ICMR - National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sravan Kumar","family":"Adavath","sequence":"additional","affiliation":[{"name":"ICMR - National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hema Giranab","family":"C","sequence":"additional","affiliation":[{"name":"ICMR - National Institute for Research in Tuberculosis","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Poovazhagi","family":"Varadarajan","sequence":"additional","affiliation":[{"name":"Institute of Child Health and Hospital for Children","place":["Chennai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Subash","family":"Babu","sequence":"additional","affiliation":[{"name":"National Institutes of Health - 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