Gingipains of Porphyromonas gingivalis Affect the Stability and Function of Serine Protease Inhibitor of Kazal-type 6 (SPINK6), a Tissue Inhibitor of Human Kallikreins

Rapid detection of Lys-gingipain using fluorogenic peptide substrate for diagnosis of periodontitis

Background/purpose

Early detection of periodontitis and its associated pathogens has become imperative in oral health. Porphyromonas gingivalis (P. gingivalis), a leading oral pathogen, is known to secrete Lys-gingipain (Kgp) enzyme. The aim of this study was to validate the detection of P. gingivalis in human saliva samples by measuring the fluorescence intensity generated by a Lys-specific peptide substrate after it is cleaved in the presence of Kgp.

Materials and methods

To confirm the biological activity of the fluorogenic His-Glu-Lys containing peptide substrate which is specific to the Kgp, we compared the fluorescence intensity of the fluorogenic peptide substrate with saliva samples obtained from both healthy individuals (n = 31) and periodontitis patients (n = 30).

Results

The results from the fluorogenic substrate were statistically compared with polymerase chain reaction (PCR) results of P. gingivalis quantification. Whereas the PCR test had an area under curve (AUC) value of 0.729, the normalized relative fluorescence unit (RFU) obtained from fluorogenic peptide samples had an AUC value of 0.756.

Conclusion

We anticipate that the fluorogenic peptide substrate will assist in detecting early stages of periodontitis and ultimately prevent further complications. This fluorogenic peptide substrate can be used as a basic material for various types of biosensors.

A Narrative Review of Periodontal Vaccines: Hope or Hype?

Globally, periodontal diseases, mainly driven by polymicrobial biofilms, are a widespread concern of social medicine due to their considerable incidence and tie-up to systemic disorders like diabetes, cardiovascular diseases, and complications during pregnancy. Traditional treatments focus on mechanical debridement and antimicrobial therapies, but these approaches have limitations, including recurrence and antibiotic resistance. Periodontal vaccines offer a promising alternative by targeting the immunological mechanisms underlying periodontal disease. This review explores the current state of periodontal vaccine development, highlighting key antigens, vaccine delivery systems, and preclinical and clinical advancements. Special emphasis is placed on antigen selection, host variability, immune tolerance, and future directions to overcome these barriers. This article highlights the advancements and challenges in periodontal vaccine research, offering insights into the capability of immunoprophylaxis as a groundbreaking way to manage periodontal diseases.

BAP31-ELAVL1-SPINK6 axis induces loss of cell polarity and promotes metastasis in hepatocellular carcinoma

Tumor metastasis is the main cause of hepatocellular carcinoma (HCC) related death. Loss of cell polarity may lead to weakened cell adhesion, epithelial-mesenchymal transition (EMT), and metastasis of HCC. However, the mechanism involved in HCC cells polarity loss is still less studied. Here, we found that BAP31 expression increased with tumor grade and metastasis. Moreover, BAP31 silencing inhibited invasion and migration and recovered the polarity of HCC cells. RNA-seq identified SPINK6 was a downstream gene of BAP31, and was associated with tumor stage and metastasis in HCC. IP-MS and IF assays showed that BAP31 bound to the RNA binding protein ELAVL1, and promoted its maturation. In addition, RIP, RNA-FISH, RNA stability and luciferase reporter assays confirmed that ELAVL1 could bind to the 3 'UTR region of SPINK6 mRNA to stabilize its expression. Depletion of SPINK6 inhibited the invasion and migration, re-established the cell polarity and suppressed EMT in HCC cells, while overexpression of SPINK6 partially counteracted BAP31/ELAVL1 knockdown caused attenuation of metastasis and recovery of polarity. Finally, in vivo experiments verified that BAP31-ELAVL1-SPINK6 axis induced cell polarity loss and promoted metastasis in HCC. Our study shed new light on the mechanism of cell polarity loss and metastasis in HCC.

Exploring heme and iron acquisition strategies of Porphyromonas gingivalis-current facts and hypotheses

Iron and heme are crucial for pathogenic bacteria living in the human host but are not available in free form due to their binding by iron- and heme-sequestering proteins. Porphyromonas gingivalis causes dysbiosis in the oral microbiome and is considered a keystone pathogen in the onset and progression of periodontal diseases. Its ability to infect and multiply in host cells and its presence in distant tissues and fluids highlights its pathogenic versatility and explains the relationship between periodontal diseases and systemic or neurodegenerative diseases. Porphyromonas gingivalis has evolved specialized mechanisms that allow it to thrive in the host under adverse nutrient-limited conditions. This review presents the updated summary of the mechanisms of iron and heme acquisition by P. gingivalis, with a central role played by gingipains and the unique Hmu system. The potential role of other iron and heme acquisition systems, such as Hus and Iht, indicates the importance of the partially conserved heme biosynthesis pathway, involving homologs of the HemN, HemG, and HemH proteins. In light of increasing antibiotic resistance, difficulties with diagnosis, and drug administration, targeting the mechanisms of heme and iron acquisition of P. gingivalis represents a promising target for developing diagnostic tests, preventive or therapeutic strategies.

Exploring Periodontal Conditions, Salivary Markers, and Systemic Inflammation in Patients with Cardiovascular Diseases

(1) Background: This cross-sectional investigation appreciated the role of serum C-reactive protein (CRP), several hematologic-cell markers, and salivary inflammation-related molecules [calprotectin (S100A8/A9), interleukin-1β (IL-1β), kallikrein] to predict periodontitis in patients with atherosclerotic cardiovascular disease (ACVD), arrhythmia, or both. Also, we appreciated the relationship between the inflammatory burden and periodontal destruction with the type of cardiac pathology. (2) Methods: Demographic, behavioral characteristics, periodontal indicators, blood parameters, and saliva samples were collected. (3) Results: All 148 patients exhibited stage II or III/IV periodontitis. Stage III/IV cases exhibited significantly increased S100A8/A9 levels (p = 0.004). A positive correlation between S100A8/A9 and IL-1β [0.35 (<0.001)], kallikrein [0.55 (<0.001)], and CRP [0.28 (<0.001)] was observed. Patients with complex cardiac involvement had a significantly higher number of sites with attachment loss ≥ 5 mm [19 (3-30)] compared to individuals with only arrhythmia [9 (3.25-18)] or ACVD [5 (1-12)] [0.048♦ {0.162/0.496/0.14}]. (4) Conclusions: Severe, extensive attachment loss may be indicative of patients with complex cardiac conditions, which underscores the essential role of periodontal status in relation to systemic diseases. The correlations between the rising trends of the inflammatory parameters suggest a potential interconnection between oral and systemic inflammation.

SPINKs in Tumors: Potential Therapeutic Targets

The serine protease inhibitor Kazal type (SPINK) family includes SPINK1-14 and is the largest branch in the serine protease inhibitor family. SPINKs play an important role in pancreatic physiology and disease, sperm maturation and capacitation, Nager syndrome, inflammation and the skin barrier. Evidence shows that the unregulated expression of SPINK1, 2, 4, 5, 6, 7, and 13 is closely related to human tumors. Different SPINKs exhibit various regulatory modes in different tumors and can be used as tumor prognostic markers. This article reviews the role of SPINK1, 2, 4, 5, 6, 7, and 13 in different human cancer processes and helps to identify new cancer treatment targets.

Kinins and Their Receptors in Infectious Diseases

Kinins and their receptors have been implicated in a series of pathological alterations, representing attractive pharmacological targets for several diseases. The present review article aims to discuss the role of the kinin system in infectious diseases. Literature data provides compelling evidence about the participation of kinins in infections caused by diverse agents, including viral, bacterial, fungal, protozoan, and helminth-related ills. It is tempting to propose that modulation of kinin actions and production might be an adjuvant strategy for management of infection-related complications.

Kallikrein-Related Peptidase 14 Activates Zymogens of Membrane Type Matrix Metalloproteinases (MT-MMPs)-A CleavEx Based Analysis

Kallikrein-related peptidases (KLKs) and matrix metalloproteinases (MMPs) are secretory proteinases known to proteolytically process components of the extracellular matrix, modulating the pericellular environment in physiology and in pathologies. The interconnection between these families remains elusive. To assess the cross-activation of these families, we developed a peptide, fusion protein-based exposition system (Cleavage of exposed amino acid sequences, CleavEx) aiming at investigating the potential of KLK14 to recognize and hydrolyze proMMP sequences. Initial assessment identified ten MMP activation domain sequences which were validated by Edman degradation. The analysis revealed that membrane-type MMPs (MT-MMPs) are targeted by KLK14 for activation. Correspondingly, proMMP14-17 were investigated in vitro and found to be effectively processed by KLK14. Again, the expected neo-N-termini of the activated MT-MMPs was confirmed by Edman degradation. The effectiveness of proMMP activation was analyzed by gelatin zymography, confirming the release of fully active, mature MT-MMPs upon KLK14 treatment. Lastly, MMP14 was shown to be processed on the cell surface by KLK14 using murine fibroblasts overexpressing human MMP14. Herein, we propose KLK14-mediated selective activation of cell-membrane located MT-MMPs as an additional layer of their regulation. As both, KLKs and MT-MMPs, are implicated in cancer, their cross-activation may constitute an important factor in tumor progression and metastasis.

The potential role of P.gingivalis in gastrointestinal cancer: a mini review

Bacterial infection may be involved in the entire process of tissue carcinogenesis by directly or indirectly affecting the occurrence and development of tumors. Porphyromonas gingivalis (P.gingivalis) is an important pathogen causing periodontitis. Periodontitis may promote the occurrence of various tumors. Gastrointestinal tumors are common malignant tumors with high morbidity, high mortality, and low early diagnosis rate. With the rapid development of molecularbiotechnology, the role of P.gingivalis in digestive tract tumors has been increasingly explored. This article reviews the correlation between P.gingivalis and gastrointestinal cancer and the pathogenesis of the latter. The relationship among P.gingivalis, periodontal disease, and digestive tract tumors must be clarifiedthrough a multi-center, prospective, large-scale study.

A2ML1 and otitis media: novel variants, differential expression, and relevant pathways

A genetic basis for otitis media is established, however, the role of rare variants in disease etiology is largely unknown. Previously a duplication variant within A2ML1 was identified as a significant risk factor for otitis media in an indigenous Filipino population and in US children. In this report exome and Sanger sequencing was performed using DNA samples from the indigenous Filipino population, Filipino cochlear implantees, US probands, Finnish, and Pakistani families with otitis media. Sixteen novel, damaging A2ML1 variants identified in otitis media patients were rare or low-frequency in population-matched controls. In the indigenous population, both gingivitis and A2ML1 variants including the known duplication variant and the novel splice variant c.4061 + 1 G>C were independently associated with otitis media. Sequencing of salivary RNA samples from indigenous Filipinos demonstrated lower A2ML1 expression according to the carriage of A2ML1 variants. Sequencing of additional salivary RNA samples from US patients with otitis media revealed differentially expressed genes that are highly correlated with A2ML1 expression levels. In particular, RND3 is upregulated in both A2ML1 variant carriers and high-A2ML1 expressors. These findings support a role for A2ML1 in keratinocyte differentiation within the middle ear as part of otitis media pathology and the potential application of ROCK inhibition in otitis media.

Proteases: Pivot Points in Functional Proteomics

Proteases drive the life cycle of all proteins, ensuring the transportation and activation of newly minted, would-be proteins into their functional form while recycling spent or unneeded proteins. Far from their image as engines of protein digestion, proteases play fundamental roles in basic physiology and regulation at multiple levels of systems biology. Proteases are intimately associated with disease and modulation of proteolytic activity is the presumed target for successful therapeutics. "Proteases: Pivot Points in Functional Proteomics" examines the crucial roles of proteolysis across a wide range of physiological processes and diseases. The existing and potential impacts of proteolysis-related activity on drug and biomarker development are presented in detail. All told the decisive roles of proteases in four major categories comprising 23 separate subcategories are addressed. Within this construct, 15 sets of subject-specific, tabulated data are presented that include identification of proteases, protease inhibitors, substrates, and their actions. Said data are derived from and confirmed by over 300 references. Cross comparison of datasets indicates that proteases, their inhibitors/promoters and substrates intersect over a range of physiological processes and diseases, both chronic and pathogenic. Indeed, "Proteases: Pivot Points …" closes by dramatizing this very point through association of (pro)Thrombin and Fibrin(ogen) with: hemostasis, innate immunity, cardiovascular and metabolic disease, cancer, neurodegeneration, and bacterial self-defense.

Conditioned medium from relapsing-remitting multiple sclerosis patients reduces the expression and release of inflammatory cytokines induced by LPS-gingivalis in THP-1 and MO3.13 cell lines

The present research was aimed at evaluating the effect of the conditioned medium (CM) from human periodontal ligament stem cells (hPDLSCs) obtained from healthy donors (hPDLSCs-CM) and from Relapsing-Remitting Multiple Sclerosis patients (RR-MS-CM) on inflammatory response induced by Porphyromonas gingivalis lipopolysaccharide (LPS-G) in a monocytoid human cell line (THP-1) and human oligodendrocyte cell line (MO3.13). Human periodontal ligament biopsies were carried out from control donor patients and selected RR-MS donors. Sample tissues were obtained from premolar teeth during root scaling and subsequently cultured. The effect of hPDLSCs-CM and RR-MS-CM on cell viability in PMA differentiated THP-1 (as a model of microglia) was measured using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. The same experiments were performed in undifferentiated and differentiated MO3.13 cells used as models of progenitor cells and oligodendrocytes, respectively. The expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1β and IL-6 was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA). The expression level of the Toll-like receptor 4 (TLR-4), for which LPS-G is a ligand, was evaluated by Western blot analysis. The results were analyzed by ANOVA using Graph Pad Prism software. LPS-G significantly increased TNFα, IL-1β and IL-6 mRNA expression and protein levels in the differentiated THP-1 cells and oligodendrocyte MO3.13 progenitor cells. Treatment with hPDLSCs-CM or with RR-MS-CM significantly attenuated the LPS-induced expression and production of these pro-inflammatory cytokines. The CM from both healthy donors and RR-MS patients also reduced the LPS-G stimulated protein levels of TLR-4 in differentiated THP-1 cells. On the whole our data add new evidence on the anti-inflammatory effects of these peculiar stem cells even when derived from RR-MS patients and open novel perspectives in the therapeutic use of autologous periodontal stem cells in neuroinflammatory/neurodegenerative diseases including MS.