Association between plasma leptin level and systemic inflammatory markers in patients with aggressive periodontitis

Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles

BACKGROUND

Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.

HIGHLIGHTS

The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.

CONCLUSION

Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.

Adipocyte inflammation and pathogenesis of viral pneumonias: an overlooked contribution

Epidemiological evidence establishes obesity as an independent risk factor for increased susceptibility and severity to viral respiratory pneumonias associated with H1N1 influenza and SARS-CoV-2 pandemics. Given the global obesity prevalence, a better understanding of the mechanisms behind obese susceptibility to infection is imperative. Altered immune cell metabolism and function are often perceived as a key causative factor of dysregulated inflammation. However, the contribution of adipocytes, the dominantly altered cell type in obesity with broad inflammatory properties, to infectious disease pathogenesis remains largely ignored. Thus, skewing of adipocyte-intrinsic cellular metabolism may lead to the development of pathogenic inflammatory adipocytes, which shape the overall immune responses by contributing to either premature immunosenescence, delayed hyperinflammation, or cytokine storm in infections. In this review, we discuss the underappreciated contribution of adipocyte cellular metabolism and adipocyte-produced mediators on immune system modulation and how such interplay may modify disease susceptibility and pathogenesis of influenza and SARS-CoV-2 infections in obese individuals.

Plaque control alleviated renal damage that was aggravated by experimental periodontitis in obese rats

OBJECTIVE

This study aimed to evaluate the influence of experimental periodontitis on renal damage in obese rats.

MATERIALS AND METHODS

Thirty-two male Sprague Dawley rats were randomly allocated into 4 groups with 8 animals each: obese rats (obese group), obese rats with periodontitis (periodontitis obese group), obese rats with periodontitis that underwent plaque control (plaque-control obese group), and healthy rats (healthy group). Rats were fed a high-fat diet to establish an obesity model. Experimental periodontitis was induced by local ligation with silk around the bilateral maxillary second molars. The plaque control was accomplished by removing ligations and local wiping with an antiseptic rinse. Histology was used to observe the gingival inflammation and clinical attachment level (CAL) to further assess bone loss and to also observe renal structure. Serum creatinine, urea nitrogen, and kidney injury molecule-1 (KIM-1) levels were measured to evaluate renal function. Renal Toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), serum C-reactive protein (CRP), lipopolysaccharides (LPS), and interleukin-1β (IL-1β) were measured to evaluate renal and systemic inflammation.

RESULTS

Periodontal histology showed that in the periodontitis obese group, the epithelial barrier was considerably eroded by inflammatory cells, which infiltrated into the subepithelial connective tissue and lamina propria. A periodontal pocket was forming accompanied by the loss of attachment. The extent of infiltration of inflammatory cells and the CAL were significantly higher than those of the obese group (p < .001). In the plaque-control obese group, although the inflammatory condition was significantly improved than in the periodontitis obese group, the clinical attachment level with the presence of fiber hyperplasia could not be restored. Renal histology showed that renal tubular structural damage was aggravated in the periodontitis obese group, including vacuolar degeneration, exfoliation of the proximal tubular epithelial cell lining, multifocal loss of the brush border, and movement of several nuclei from the basement membrane to the lumen. These alterations were improved in the plaque-control obese group. Kidney TLR4 and NF-κB mRNA levels increased significantly in the periodontitis obese group compared to the obese group (p = .015 and p = .015, respectively) and decreased significantly in the plaque-control obese group (p = .028 and p = .021, respectively). Kidney TLR4 and NF-κB protein expression in the plaque-control obese group were significantly lower than those in the periodontitis obese group (p < .001 and p = .043, respectively). Serum creatinine and KIM-1 levels significantly decreased in the plaque-control obese group compared to the periodontitis obese group (p = .001 and p = .002, respectively). At 21 weeks (1 week after periodontal ligation), serum CRP levels in the periodontitis obese group were significantly higher than that in the healthy group (p = .017). Other serum inflammatory markers (LPS and IL-1β) did not change significantly.

CONCLUSION

Experimental periodontitis induced dysfunction and structural destruction of the kidney in obese rats. Plaque control relieved renal damage.

Adipokines and periodontal markers as risk indicators of early rheumatoid arthritis: a cross-sectional study

OBJECTIVE

To establish the association between adipokine levels and markers of periodontal involvement as risk indicators of early stages of RA (eRA) and the interaction between the presence of markers of periodontal disease with adipokine in eRA individuals.

MATERIALS AND METHODS

Fifty-one patients with a diagnosis of eRA and 51 healthy controls matched for age and sex were studied. Clinical joint condition, clinical and serological markers of disease activity, serum adipokine levels (leptin, adiponectin, resistin, adipsin, vaspin, and IL-6), periodontal diagnosis, presence of Porphyromonas gingivalis, and related IgG1 and IgG2 antibodies were evaluated. Comparisons were made between eRA and healthy controls for periodontal indicators and adipokines. A subgroup analysis was realized with a non-conditional logistic regression to establish the association between the levels of leptin in individuals with eRA and controls according to the periodontal condition, presence of P. gingivalis, or high titers of IgG antibodies against P. gingivalis.

RESULTS

The condition of overweight or obesity is associated with the diagnosis of eRA (p = 0.05), and these individuals also have higher levels of leptin (p = 0.001) and vaspin (p = 0.007). Higher frequency of P. gingivalis (p = 0.001) was found in the eRa group. Individuals with eRA with higher IgG2 titers against P. gingivalis had higher levels of leptin (OR: 1.66 (CI 95% 1.01-2.73)); however, individuals with periodontitis or P. gingivalis with eRA were associated with highest levels of leptin (OR: 1.86, CI 95% 1.19-24.3; and OR: 2.04, CI 95% 1.37-3 respectively).

CONCLUSIONS

eRA individuals have high levels of leptin and vaspin. However, the presence of periodontitis and related-periodontal disease markers showed an effect only in leptin levels in eRA individuals.

CLINICAL RELEVANCE

Emphasizing in personalized medicine, monitoring serum leptin levels and periodontitis markers can improve the early diagnosis of RA.

Adipokine gene variability and plasma levels in patients with chronic periodontitis -a case-control study

Specific variants in genes that encode adipokines and their mRNA and protein expression were previously studied in type 2 diabetes mellitus (T2DM) and obesity, and similar studies have been performed for chronic periodontitis (CP). The aim of this case-control study was to investigate the possible impacts of adiponectin (ADIPOQ), leptin (LEP) and its receptor (LEPR), and resistin (RETN) on the etiopathogenesis of CP. Examinations were performed on 118 non-periodontitis healthy subjects (healthy controls, HC), 205 healthy individuals with CP (H + CP) and 86 type 2 diabetes patients with CP (T2DM + CP). Variants within the ADIPOQ (rs2241766, rs1501299), LEP (rs13228377, rs2167270), LEP receptor (rs1805096), and RETN (rs1862513) genes were determined by qPCR. In addition, the plasma levels of ADIPOQ, LEP, and RETN were analysed by ELISA for 80 individuals. The genotype frequencies of the SNP ADIPOQ +45G/T (rs2241766) differed between the HC and H + CP groups (p=0.03, pcorr>0.05), and carriers of the TT genotype had a lower risk of developing CP compared to carriers of the GG or TG genotypes (p<0.01, pcorr>0.05). However, there were no significant differences in the plasma levels of ADIPOQ, LEP or RETN between the study groups (p > 0.05). Plasma levels of the adipokines were also independent of the gene profiles (p > 0.05). Adipokine plasma levels did not change in patients with H + CP/T2DM + CP compared to HC, but we did identify a specific polymorphism in the ADIPOQ gene that was associated with CP. Although the ADIPOQ +45G/T (rs2241766) gene variant may be a candidate biomarker for CP, further research is required in larger populations with different ethnic backgrounds before any final conclusions can be drawn about the role of this gene in CP.

C-reactive protein in patients with aggressive periodontitis

BACKGROUND/PURPOSE

The aim of this study was to evaluate and compare the systemic levels of C-reactive protein (CRP) in peripheral blood samples of patients with aggressive periodontitis during the first twelve months of periodontal treatment, at exactly six month interval measurements, and compare them with clinical periodontal parameters.

MATERIALS AND METHODS

All patients (N = 45) were examined prior to the initiation of periodontal treatment. Patients were divided into two groups GAgP (Generalised form of aggressive periodontitis, N = 23) and group LAgP (Localised form of aggressive periodontitis, N = 22). Control group (CON) included 60 individuals with healthy periodontium. The levels of CRP were determined in both groups GAgP and LAgP three times in 6 month intervals during the periodontal treatment.

RESULTS

CRP is a plasma protein that reflects the extent of the acute phase response to inflammation and is one of the markers of choice for monitoring this response. In our study, CRP levels decreased in course of periodontal treatment in both groups (GAgP and LAgP) in a similar way as bleeding on probing (BOP) and probing pocket depth (PPD) indices.

CONCLUSION

Our study results showed that CRP levels, as well as bleeding on probing (BOP) and probing pocket depth (PPD), indices decreased in course of periodontal treatment in patients with generalised and localised aggressive periodontitis. Therefore this marker might be exploitable as a means to evaluate periodontal health in patients with aggressive periodontitis.

Periodontitis and Alzheimer's Disease: A Possible Comorbidity between Oral Chronic Inflammatory Condition and Neuroinflammation

Periodontitis is an oral chronic infection/inflammatory condition, identified as a source of mediators of inflammation into the blood circulation, which may contribute to exacerbate several diseases. There is increasing evidence that inflammation plays a key role in the pathophysiology of Alzheimer’s disease (AD). Although inflammation is present in both diseases, the exact mechanisms and crosslinks between periodontitis and AD are poorly understood. Therefore, this article aims to review possible comorbidity between periodontitis and AD. Here, the authors discuss the inflammatory aspects of periodontitis, how this oral condition produces a systemic inflammation and, finally, the contribution of this systemic inflammation for worsening neuroinflammation in the progression of AD.

Association of circulating leptin and adiponectin with periodontitis: a systematic review and meta-analysis

BACKGROUND

This study aimed to assess the difference in serum levels of leptin and adiponectin in patients with periodontitis and in periodontally healthy individuals and evaluate the changes in circulating leptin and adiponectin after periodontal therapy. Leptin and adiponectin are the most generally studied adipokines that function as inflammatory cytokines. Although the association between periodontitis and serum levels of leptin and adiponectin has been studied extensively, the results were not consistent.

METHODS

A systematic search of the Pubmed, Embase, Web of Science, and Cochrane Library up to September 2016 was conducted. The studies were screened and selected by two writers according to the specific eligibility criteria. The quality of included cross-sectional studies was assessed using the quality assessment form recommended by the Agency for Healthcare Research and Quality and Methodological Index for Nonrandomized Studies. The meta-analyses were conducted using the STATA 12.0 software.

RESULTS

A total of 399 manuscripts were yielded and 25 studies were included in the present meta-analysis. Significantly elevated serum levels of leptin and decreased serum levels of adiponectin in patients with periodontitis were observed in the subgroup analysis of body mass index (BMI) <30. The overall and subgroup analyses showed no significant change in the serum levels of leptin in patients with periodontitis after periodontal treatment. The subgroup analysis of systemically healthy patients showed no significant change in serum levels of adiponectin in patients with periodontitis after periodontal treatment.

CONCLUSIONS

The present meta-analysis supported elevated serum levels of leptin and decreased serum levels of adiponectin in patients with periodontitis compared with controls in the BMI <30 population. In systemically healthy patients with periodontitis, serum levels of leptin and adiponectin do not significantly change after periodontal treatment.

Upregulated Leptin in Periodontitis Promotes Inflammatory Cytokine Expression in Periodontal Ligament Cells

BACKGROUND

Imbalance or disruption in the expression of inflammatory mediators contributes greatly to the breakdown of the periodontal supporting tissues. Leptin, through binding to its receptor (obesity-related leptin and leptin receptor [OBR]), has potent effects on immunity and inflammation. However, to date, researchers only indicated a role of leptin in periodontitis. No direct or valid evidence exists about how leptin and its receptor are regulated by local inflammation, what effects they have, and the underlying mechanisms.

METHODS

Experimental periodontitis was induced by ligation of mandibular second molars in beagle dogs. The expression of leptin, OBR, and interleukin (IL)-1β was examined by immunohistochemistry. Meanwhile, recombinant human IL-1β was used to stimulate human periodontal ligament cells (hPDLCs) in vitro, and mRNA and protein levels of leptin were measured using real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Then, mRNA and protein levels of IL-6 and IL-8 were measured using real-time PCR and ELISA, after stimulation with various concentrations of leptin, knocking down all or only the long form of OBR (OBRb) by small interfering RNA and incubation with multiple intracellular signaling pathway inhibitors, respectively.

RESULTS

Leptin and OBR increased substantially in inflammatory periodontal tissues, which correlated well with the extent of inflammatory infiltration, and was a result of the upregulation in resident cells themselves. A high dose of leptin could induce the expression of mRNA and protein of IL-6 and IL-8 in hPDLCs through binding with OBRb and activating different intracellular signaling pathways.

CONCLUSION

Upregulated leptin and OBR in periodontitis stimulated proinflammatory cytokine expression in PDL cells to additionally promote local inflammation.