A recent study published in Odontology has identified salivary immune markers that could improve the diagnosis of Rheumatoid Arthritis (RA) and shed new light on its connection with Periodontitis. The researchers found that levels of CD11b and CD38 are significantly elevated in patients with RA, with CD11b emerging as a particularly promising diagnostic biomarker and a potential mechanistic link between joint and periodontal inflammation.
RA is a chronic autoimmune condition driven by persistent inflammation, in which immune cells such as B cells and macrophages play a central role. These cells show increased expression of CD11b and CD38, contributing to sustained immune activation and tissue damage. CD11b, a leukocyte integrin encoded by ITGAM, forms part of the Mac-1 complex involved in immune cell adhesion and migration. Although traditionally considered a myeloid marker, its genetic associations with autoimmune diseases suggest a broader immunological role. CD38 is a multifunctional ectoenzyme involved in NAD metabolism and calcium signaling and is widely expressed across immune cells, including lymphocytes and macrophages. It is also being explored as a therapeutic target in conditions such as Multiple Myeloma due to its role in cellular metabolism and immune regulation.
The observational case-control study included 33 patients with RA and 22 controls comprising healthy individuals and those with degenerative joint pain. Salivary levels of CD11b, CD38, and HLA-DR were measured using flow cytometry, representing a novel application of this technique in saliva-based immunological assessment. Periodontal evaluation included probing pocket depth, clinical attachment level, plaque index, and bleeding on probing, while systemic markers such as anti-citrullinated peptide antibodies, rheumatoid factor, and C-reactive protein were obtained from clinical records.
The study demonstrated that CD11b (p = 0.043) and CD38 (p = 0.002) were significantly elevated in RA patients. CD11b showed positive correlations with key periodontal parameters, including bleeding on probing, plaque index, and lesion severity, indicating its association with active periodontal inflammation. Anti-citrullinated peptide antibody levels were also associated with bleeding on probing, further supporting the immunological link between RA and periodontal disease. Patients with RA and periodontitis exhibited more severe periodontal lesions compared to non-RA individuals with periodontitis.
The findings support a bidirectional relationship between RA and periodontal disease, in which systemic inflammation may exacerbate oral disease, while periodontal inflammation may contribute to RA progression. CD11b is proposed as a key regulator of osteoclastogenesis, potentially driving bone resorption in both joints and periodontal tissues. The use of saliva as a diagnostic medium highlights the potential for non-invasive, accessible biomarkers in clinical practice.
Further large-scale studies are needed to validate these findings and establish the clinical utility of salivary CD11b and CD38 as diagnostic and prognostic markers. Overall, the study adds to growing evidence of the oral-systemic health connection and suggests that integrated approaches to managing autoimmune and periodontal diseases may improve patient outcomes.
References
- Bonilla M, Bravo M, Moradi M, Martín-Morales N, Raya-Álvarez E, Mesa F. CD11b as a diagnostic biomarker of rheumatoid arthritis and as a risk factor of periodontitis: a pilot study. Odontology. 2026 Apr;114(2):510-519.
- Zhou M, Dascani P, Ding C, Kos JT, Tieri D, Lin X, Caster D, Powell D, Wen C, Watson CT, Yan J. Integrin CD11b Negatively Regulates B Cell Receptor Signaling to Shape Humoral Response during Immunization and Autoimmunity. J Immunol. 2021 Oct 1;207(7):1785-1797.
- Wang H, Fang K, Yan W, Chang X. T-Cell Immune Imbalance in Rheumatoid Arthritis Is Associated with Alterations in NK Cells and NK-Like T Cells Expressing CD38. J Innate Immun. 2022;14(2):148-166.