Neutrophil elastase aggravates periodontitis by disrupting gingival epithelial barrier via cleaving cell adhesion molecules

Cleavage of cell junction proteins as a host invasion strategy in leptospirosis

Infection and invasion are the prerequisites for developing the disease symptoms in a host. While the probable mechanism of host invasion and pathogenesis is known in many pathogens, very little information is available on Leptospira invasion/pathogenesis. For causing systemic infection Leptospira must transmigrate across epithelial barriers, which is the most critical and challenging step. Extracellular and membrane-bound proteases play a crucial role in the invasion process. An extensive search for the proteins experimentally proven to be involved in the invasion process through cell junction cleavage in other pathogens has resulted in identifying 26 proteins. The similarity searches on the Leptospira genome for counterparts of these 26 pathogenesis-related proteins identified at least 12 probable coding sequences. The proteins were either extracellular or membrane-bound with a proteolytic domain to cleave the cell junction proteins. This review will emphasize our current understanding of the pathogenic aspects of host cell junction-pathogenic protein interactions involved in the invasion process. Further, potential candidate proteins with cell junction cleavage properties that may be exploited in the diagnostic/therapeutic aspects of leptospirosis will also be discussed. KEY POINTS: • The review focussed on the cell junction cleavage proteins in bacterial pathogenesis • Cell junction disruptors from Leptospira genome are identified using bioinformatics • The review provides insights into the therapeutic/diagnostic interventions possible.

Elevated neutrophil extracellular trap levels in periodontitis: Implications for keratinization and barrier function in gingival epithelium

AIM

To explore the levels of neutrophil extracellular traps (NETs) in patients with periodontitis and examine their effects on keratinization, barrier function of human gingival keratinocytes (HGKs) and the associated mechanisms.

MATERIALS AND METHODS

Saliva, gingival crevicular fluid (GCF), clinical periodontal parameters and gingival specimens were collected from 10 healthy control subjects and 10 patients with stage II-IV periodontitis to measure the NET levels. Subsequently, mRNA and protein levels of keratinization and barrier indicators, as well as intracellular calcium and epithelial barrier permeability, were analysed in HGKs after NET stimulation.

RESULTS

The study showed that NET levels significantly elevated in patients with periodontitis, across multiple specimens including saliva, GCF and gingival tissues. Stimulation of HGKs with NETs resulted in a decrease in the expressions of involucrin, cytokeratin 10, zonula occludens 1 and E-cadherin, along with decreased intracellular calcium levels and increased epithelial barrier permeability. Furthermore, the inhibition of keratinization by NETs is ERK-KLF4-dependent.

CONCLUSIONS

This study indicates that NETs impair the barrier function of HGKs and suppress keratinization through ERK/KLF4 axis. These findings provide potential targets for therapeutic approaches in periodontitis to address impaired gingival keratinization.

Matrix Metalloproteinases in the Periodontium-Vital in Tissue Turnover and Unfortunate in Periodontitis

The extracellular matrix (ECM) is a complex non-cellular three-dimensional macromolecular network present within all tissues and organs, forming the foundation on which cells sit, and composed of proteins (such as collagen), glycosaminoglycans, proteoglycans, minerals, and water. The ECM provides a fundamental framework for the cellular constituents of tissue and biochemical support to surrounding cells. The ECM is a highly dynamic structure that is constantly being remodeled. Matrix metalloproteinases (MMPs) are among the most important proteolytic enzymes of the ECM and are capable of degrading all ECM molecules. MMPs play a relevant role in physiological as well as pathological processes; MMPs participate in embryogenesis, morphogenesis, wound healing, and tissue remodeling, and therefore, their impaired activity may result in several problems. MMP activity is also associated with chronic inflammation, tissue breakdown, fibrosis, and cancer invasion and metastasis. The periodontium is a unique anatomical site, composed of a variety of connective tissues, created by the ECM. During periodontitis, a chronic inflammation affecting the periodontium, increased presence and activity of MMPs is observed, resulting in irreversible losses of periodontal tissues. MMP expression and activity may be controlled in various ways, one of which is the inhibition of their activity by an endogenous group of tissue inhibitors of metalloproteinases (TIMPs), as well as reversion-inducing cysteine-rich protein with Kazal motifs (RECK).

Proteomics of appetite-regulating system influenced by menstrual cycle and intensive exercise in female athletes: a pilot study

Female athletes who endure intense training are at risk of developing the 'female athlete triad,' making energy intake management crucial. However, the fluctuations in estradiol and progesterone levels throughout the menstrual cycle present a challenge in maintaining consistent energy intake. This study aimed to uncover the underlying factors associated with appetite regulation linked to menstrual phases and exercise using proteomic approach. Five female athletes engaged in 60 min of bicycle exercise, followed by 90 min of rest, during both the follicular and luteal phases. Serum samples were collected before, during, and after exercise, and the serum proteome was analyzed using 2D-gel electrophoresis. A total of 511 spots were detected in the subjects' serum profiles, with significant decreases observed in haptoglobin during the luteal phase and complement component 3 during bicycle training. Unsupervised learning with a generalized estimating equation analysis showed that serum peptide YY (PYY), an appetite suppressor, significantly influenced the fluctuations of serum proteins induced by exercise (p < 0.05). Regression analysis demonstrated a positive correlation between PYY and serum IgM (R = 0.87), implying that the intestinal environment and the immune response in female athletes may contribute to appetite regulation.

Research on the Association Between Periodontitis and COPD

Periodontitis is a common chronic bacteria-initiated inflammatory disease that is closely associated with various systemic diseases, including chronic obstructive pulmonary disease (COPD). Periodontitis and COPD share similar risk factors, pathology and microorganisms. Epidemiological and clinical research have shown positive correlation between the two diseases. Individuals with severe periodontitis had a higher risk of developing COPD. Moreover, the relative risk of COPD in severe periodontitis was much higher compared to people without periodontal disease and patients with mild to moderate periodontitis. COPD patients with periodontitis had a higher frequency of COPD exacerbation and periodontal treatment demonstrated some control of COPD. However, the nature of periodontitis affecting COPD still needs further exploration. Periodontitis caused microbial and immune imbalances of the lung through several aspects: (I) under periodontitis status, periodontal pathogens directly caused the lung inflammatory reaction after inhalation and colonization on the lung, (II) periodontitis status promoted the oral colonization of pneumonia-associated pathogens, (III) periodontitis status affected the respiratory epithelium structure and (IV) periodontitis status caused imbalances in neutrophils, macrophages and inflammatory cytokines. In this review, we conclude the association between periodontitis and COPD through several aspects and further discuss the potential mechanism by which periodontitis affects COPD.

Induction of Periodontitis Using Bacterial Strains Isolated from the Human Oral Microbiome in an Experimental Rat Model

Periodontal disease is that condition resulting in the destruction of periodontal tissues, bone resorption, and tooth loss, the etiology of which is linked to immunological and microbiological factors. The aim of this study was to evaluate the potential trigger of periodontal disease in a rat model using bacterial species incriminated in the pathology of human periodontitis and to establish their optimal concentrations capable of reproducing the disease, with the idea of subsequently developing innovative treatments for the condition. In this study, we included 15 male Wistar rats, aged 20 weeks, which we divided into three groups. In each group, we applied ligatures with gingival retraction wire on the maxillary incisors. The ligature and the gingival sac were contaminated by oral gavage with a mixture of fresh cultures of Aggregatibacter actinomycetemcomitans (A.a), Fusobacterium nucleatum (F.n) and Streptococcus oralis (S.o) in concentrations of 108, 109, and 1010 CFU/mL each for 5 days a week for 4 weeks. During the clinical monitoring period of 28 days, overlapped with the period of oral contamination, we followed the expression of clinical signs specific to periodontitis. We also monitored the evolution of body weight and took weekly samples from the oral cavity for the microbiological identification of the tested bacteria and blood samples for hematological examination. At the end of the study, the animals were euthanized, and the ligated incisors were taken for histopathological analysis. The characteristic symptomatology of periodontal disease was expressed from the first week of the study and was maintained until the end, and we were able to identify the bacteria during each examination. Hematologically, the number of neutrophils decreased dramatically (p < 0.0001) in the case of the 109 group, unlike the other groups, as did the number of lymphocytes. Histopathologically, we identified neutrophilic infiltrate in all groups, as well as the presence of coccobacilli, periodontal tissue hyperplasia, and periodontal lysis. In the 109 group, we also observed pulpal tissue with necrotic bone fragments and pyogranulomatous inflammatory reaction. By corroborating the data, we can conclude that for the development of periodontal disease using A.a, F.n, and S.o, a concentration of 109 or 1010 CFU/mL is required, which must necessarily contaminate a ligature thread applied to the level of the rat's dental pack.

Choline and geranic acid (CAGE) ionic liquids inhibit both elastase activity and growth of oral bacteria

Choline and geranic acid (CAGE) ionic liquids have recently been shown to have applications in the delivery of macromolecules and poorly soluble drugs across epithelial barriers and in bacterial growth inhibition. Ionic liquids are known to denature proteins by the disruption of forces that guide natural protein folding, and the inflammatory enzyme elastase was recently shown to be inhibited by a variety of ionic liquids other than CAGE. Inhibition of collagenolytic enzymes, including elastase, has been shown to improve outcomes in cases of periodontitis via amelioration of periodontal inflammation and alveolar bone resorption. In this study, we investigated whether CAGE prepared with varying stoichiometries was able to inhibit elastase at varying concentrations and whether these CAGE formulations could inhibit the growth of key pathogenic bacterial species associated with oral health conditions. We found that CAGE was capable of inhibiting both porcine elastase and human neutrophil elastase at concentrations as low as 5 mM, and that CAGE formulations were effective at inhibiting the growth of all tested pathogenic oral bacteria. The inhibition of elastase by CAGE may be a mechanism by which CAGE can improve outcomes in periodontitis independent from CAGE's known antibacterial properties.

Salivary E-cadherin as a biomarker for diagnosis and predicting grade of periodontitis

OBJECTIVES

To determine the abilities of salivary E-cadherin to differentiate between periodontal health and periodontitis and to discriminate grades of periodontitis.

BACKGROUND

E-cadherin is the main protein responsible for maintaining the integrity of epithelial-barrier function. Disintegration of this protein is one of the events associated with the destructive forms of periodontal disease leading to increase concentration of E-cadherin in the oral biofluids.

MATERIALS AND METHODS

A total of 63 patients with periodontitis (case) and 35 periodontally healthy subjects (control) were included. For each patient, periodontal parameters including bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded. Concentration of salivary E-cadherin was determined by ELISA. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to determine the diagnostic potentials of E-cadherin.

RESULTS

Level of salivary E-cadherin was significantly higher in periodontitis cases than controls. The ROC analysis showed that salivary E-cadherin exhibits excellent sensitivity and specificity (AUC 1.000) to differentiate periodontal health from periodontitis with a cutoff concentration equal to 1.325 ng/mL. The AUCs of E-cadherin to differentiate grade A from grade B and C periodontitis were 0.731 (cutoff point = 1.754 ng/mL) and 0.746 (cutoff point = 1.722 ng/mL), respectively. However, the AUC of salivary E-cadherin to differentiate grade B from grade C periodontitis was lower (0.541). Additionally, BOP and PPD were significantly and positively correlated with the concentration of salivary E-cadherin.

CONCLUSION

Salivary E-cadherin exhibited excellent sensitivity and specificity to differentiate periodontitis from a healthy periodontium. The level of accuracy of E-cadherin was also sufficient to recognize grade A periodontitis from grade B and C periodontitis.

Breaking the Gingival Barrier in Periodontitis

The break of the epithelial barrier of gingiva has been a subject of minor interest, albeit playing a key role in periodontal pathology, transitory bacteraemia, and subsequent systemic low-grade inflammation (LGI). The significance of mechanically induced bacterial translocation in gingiva (e.g., via mastication and teeth brushing) has been disregarded despite the accumulated knowledge of mechanical force effects on tight junctions (TJs) and subsequent pathology in other epithelial tissues. Transitory bacteraemia is observed as a rule in gingival inflammation, but is rarely observed in clinically healthy gingiva. This implies that TJs of inflamed gingiva deteriorate, e.g., via a surplus of lipopolysaccharide (LPS), bacterial proteases, toxins, Oncostatin M (OSM), and neutrophil proteases. The inflammation-deteriorated gingival TJs rupture when exposed to physiological mechanical forces. This rupture is characterised by bacteraemia during and briefly after mastication and teeth brushing, i.e., it appears to be a dynamic process of short duration, endowed with quick repair mechanisms. In this review, we consider the bacterial, immune, and mechanical factors responsible for the increased permeability and break of the epithelial barrier of inflamed gingiva and the subsequent translocation of both viable bacteria and bacterial LPS during physiological mechanical forces, such as mastication and teeth brushing.

[The Relationship Between Oral Microbiota and Chronic Obstructive Pulmonary Disease]

Oral microbiota have a complex impact on the host's health and disease states. It has been found that the composition of lung flora bears a striking resemblance to the composition of oral flora. Moreover, oral pathogenic bacteria have been detected in the sputum and bronchoalveolar lavage fluid of patients with chronic obstructive pulmonary disease (COPD), suggesting that oral microbiota play an important role in the pathogenesis and development of COPD. Findings from lots of studies have shown that oral microbiota may participate in the pathogenesis and development of COPD through non-specific immune response, specific immune response, and the activities of protein hydrolase. Herein, we mainly summarized the available evidence on the relationship between oral microbiota and COPD. By examining the relationship between the two, we elaborated on the application of oral microbiota in the diagnosis and prevention of COPD, discussed possible directions for future research, and provided references for developing new therapeutic approaches.