Salivary and Serum Inflammatory Profiles Reflect Different Aspects of Inflammatory Bowel Disease Activity.

BACKGROUND: Inflammatory bowel disease (IBD) can manifest both macroscopically and microscopically in the oral cavity; however, little is known about salivary changes in IBD. Therefore, this study aimed to assess salivary and circulatory inflammatory profiles in IBD and to compare their potential to reflect the presence and activity of IBD. METHODS: We measured 92 known inflammatory proteins in serum and in unstimulated and stimulated whole saliva samples from patients with IBD with active intestinal inflammation (n = 21) and matched control patients (n = 22) by proximity extension assay. Fifteen of the patients with IBD returned 10 to 12 weeks after treatment escalation for resampling. RESULTS: Sixty-seven of the proteins were detected in all 3 sample fluids but formed distinct clusters in serum and saliva. Twenty-one inflammatory proteins were significantly increased and 4 were significantly decreased in the serum of patients with IBD compared with that of the control patients. Two of the increased serum proteins, IL-6 and MMP-10, were also significantly increased in stimulated saliva of patients with IBD and correlated positively to their expressions in serum. None of the investigated proteins in serum or saliva were significantly altered by IBD treatment at follow-up. Overall, inflammatory proteins in serum correlated to biochemical status, and salivary proteins correlated positively to clinical parameters reflecting disease activity. CONCLUSIONS: Saliva and serum inflammatory profiles in IBD share a similar composition but reflect different aspects of disease activity. The oral cavity reflects IBD through elevated IL-6 and MMP-10 in stimulated saliva.

S100A12 Expression Is Modulated During Monocyte Differentiation and Reflects Periodontitis Severity.

S100A12 is a calcium-binding protein of the S100 subfamily of myeloid-related proteins that acts as an alarmin to induce a pro-inflammatory innate immune response. It has been linked to several chronic inflammatory diseases, however its role in the common oral immunopathology periodontitis is largely unknown. Previous in vitro monoculture experiments indicate that S100A12 production decreases during monocyte differentiation stages, while the regulation within tissue is poorly defined. This study evaluated S100A12 expression in monocyte subsets, during monocyte-to-macrophage differentiation and following polarization, both in monoculture and in a tissue context, utilizing a three-dimensional co-culture oral tissue model. Further, we explored the involvement of S100A12 in periodontitis by analyzing its expression in peripheral circulation and gingival tissue, as well as in saliva. We found that S100A12 expression was higher in classical than in non-classical monocytes. S100A12 expression and protein secretion declined significantly during monocyte-to-macrophage differentiation, while polarization of monocyte-derived macrophages had no effect on either. Peripheral monocytes from periodontitis patients had higher S100A12 expression than monocytes from controls, a difference particularly observed in the intermediate and non-classical monocyte subsets. Further, monocytes from periodontitis patients displayed an increased secretion of S100A12 compared with monocytes from controls. In oral tissue cultures, monocyte differentiation resulted in increased S100A12 secretion over time, which further increased after inflammatory stimuli. Likewise, S100A12 expression was higher in gingival tissue from periodontitis patients where monocyte-derived cells exhibited higher expression of S100A12 in comparison to non-periodontitis tissue. In line with our findings, patients with severe periodontitis had significantly higher levels of S100A12 in saliva compared to non-periodontitis patients, and the levels correlated to clinical periodontal parameters. Taken together, S100A12 is predominantly secreted by monocytes rather than by monocyte-derived cells. Moreover, S100A12 is increased in inflamed tissue cultures, potentially as a result of enhanced production by monocyte-derived cells. This study implicates the involvement of S100A12 in periodontitis pathogenesis, as evidenced by increased S100A12 expression in inflamed gingival tissue, which may be due to altered circulatory monocytes in periodontitis.

Salivary calprotectin is elevated in patients with active inflammatory bowel disease.

OBJECTIVES: To assess the concentration of calprotectin, a heterodimer of S100A8 and S100A9 implicated in inflammatory bowel disease (IBD), in saliva of IBD patients compared to controls. METHODS: Unstimulated and stimulated saliva, and serum was collected from 23 IBD patients with active intestinal inflammation, verified by endoscopy. Fifteen patients were re-sampled after treatment. Saliva was collected from 15 controls for protocol validation and group comparisons. Calprotectin concentrations were measured by enzyme-linked immunosorbent assay, correlated to clinical data/indexes and routine laboratory parameters. RESULTS: Calprotectin was 4.0-fold (median) elevated in stimulated saliva of IBD patients compared to controls and tended to be elevated in unstimulated saliva (P = 0.001, P = 0.090). Crohn's (CD) patients had significantly elevated calprotectin in both unstimulated and stimulated saliva compared to controls (P = 0.011, P = 0.002). Newly diagnosed, treatment naïve CD patients had 8.2-fold (median) higher calprotectin concentrations in unstimulated saliva and 1.5-fold in stimulated saliva, compared to CD patients with established disease (P = 0.059, P = 0.019). Calprotectin decreased in serum of IBD patients after treatment (P = 0.011), and in unstimulated saliva of newly diagnosed, treatment naïve CD patients (P = 0.046, P = 0.028). CONCLUSION: Salivary calprotectin is elevated in IBD, which suggests subclinical inflammatory responses in the oral cavity as a manifestation of IBD.

MMP-12 and S100s in saliva reflect different aspects of periodontal inflammation.

Matrix metalloproteinase (MMP)-12, S100A8/A9, and S100A12 are involved in innate immune responses. We addressed whether different aspects of oral health and non-disease-related covariates influence their levels in saliva. 436 participants were clinically examined, completed a health questionnaire, and provided stimulated saliva. Salivary levels of MMP-12, S100A8/A9, and S100A12 were determined by enzyme-linked immunosorbent assays. Lower MMP-12 levels were observed in individuals 40-64 years old (yo) compared to < 40 yo, and higher S100A8/A9 levels were found in individuals > 64 yo compared to 40-64 yo. Smokers exhibited lower MMP-12 and S100A12 levels compared to non-smokers. All three proteins were elevated in individuals with bleeding on probing (BOP) > 20% compared to those with BOP ≤ 20%, and the S100A8/A9 levels were higher in individuals having ≥ 10% gingival pocket depths (PPD) ≥ 4 mm compared to the ones with shallow pockets < 4 mm. The extent of alveolar bone loss or presence of manifest caries did not alter any of the markers. MMP-12, S100A8/A9, and S100A12 levels were higher in participants with high periodontal inflammatory burden. All three proteins correlated positively to BOP, PPD, and to several inflammatory mediators. The explanatory variables for MMP-12 in saliva were age, smoking, presence of any tumor, and percentage of PPD ≥ 4 mm. The determinant of salivary S100A8/A9 was percentage of BOP, while S100A12 levels were associated with percentage of BOP and presence of any tumor. Taken together, MMP-12 and the S100/calgranulin levels in saliva reflect different aspects of periodontal inflammation. Smoking and age should be taken into account in further investigation of these proteins as biomarker candidates of periodontal disease.

Increased Eotaxin and MCP-1 Levels in Serum from Individuals with Periodontitis and in Human Gingival Fibroblasts Exposed to Pro-Inflammatory Cytokines.

Periodontitis is a chronic inflammatory disease of tooth supporting tissues resulting in periodontal tissue destruction, which may ultimately lead to tooth loss. The disease is characterized by continuous leukocyte infiltration, likely mediated by local chemokine production but the pathogenic mechanisms are not fully elucidated. There are no reliable serologic biomarkers for the diagnosis of periodontitis, which is today based solely on the degree of local tissue destruction, and there is no available biological treatment tool. Prompted by the increasing interest in periodontitis and systemic inflammatory mediators we mapped serum cytokine and chemokine levels from periodontitis subjects and healthy controls. We used multivariate partial least squares (PLS) modeling and identified monocyte chemoattractant protein-1 (MCP-1) and eotaxin as clearly associated with periodontitis along with C-reactive protein (CRP), years of smoking and age, whereas the number of remaining teeth was associated with being healthy. Moreover, body mass index correlated significantly with serum MCP-1 and CRP, but not with eotaxin. We detected higher MCP-1 protein levels in inflamed gingival connective tissue compared to healthy but the eotaxin levels were undetectable. Primary human gingival fibroblasts displayed strongly increased expression of MCP-1 and eotaxin mRNA and protein when challenged with tumor necrosis factor-α (TNF-α and interleukin-1ß (IL-1ß), key mediators of periodontal inflammation. We also demonstrated that the upregulated chemokine expression was dependent on the NF-κΒ pathway. In summary, we identify higher levels of CRP, eotaxin and MCP-1 in serum of periodontitis patients. This, together with our finding that both CRP and MCP-1 correlates with BMI points towards an increased systemic inflammatory load in patients with periodontitis and high BMI. Targeting eotaxin and MCP-1 in periodontitis may result in reduced leukocyte infiltration and inflammation in periodontitis and maybe prevent tooth loss.

Interleukin 34: a new modulator of human and experimental inflammatory bowel disease.

IBD (inflammatory bowel disease), where CD (Crohn's disease) and UC (ulcerative colitis) represent the two main forms, are chronic inflammatory conditions of the intestine. Macrophages play a central role in IBD pathogenesis and are regulated by major differentiation factors such as CSF-1 (colony-stimulating factor 1) in homoeostasis and inflammation. IL (interleukin)-34 has recently been discovered as a second ligand for CSF-1R (CSF-1 receptor). However, expression and involvement of IL-34 in IBD remain unknown. In the present paper, we investigated the expression of IL34, CSF1 and their shared receptor CSF1R in normal human ileum and colon, in inflamed and non-inflamed tissues of CD and UC patients, and in a mouse model of experimental colitis. We found distinct expression patterns of IL34 and CSF1 in ileum and colon, with higher IL34 in ileum and, in contrast, higher CSF1 in colon. Furthermore, IL34 and CSF1 expression was increased with inflammation in IBD patients and in experimental colitis. In humans, infiltrating cells of the lamina propria and intestinal epithelial cells expressed IL-34, and TNF-α (tumour necrosis factor α) regulated IL-34 expression in intestinal epithelial cells through the NF-κB (nuclear factor κB) pathway. These data demonstrate the expression pattern of IL-34 in ileum and colon and suggest IL-34 as a new modulator of inflammation in IBD.