The pathogenesis of periodontitis depends on a sustained feedback loop where bacterial virulence factors and immune responses both contribute to inflammation and tissue degradation. Periodontitis is a multifactorial disease that is associated with a pathogenic shift in the oral microbiome. Within this shift, low-abundance Gram-negative anaerobic pathobionts transition from harmless colonisers of the subgingival environment to a virulent state that drives evasion and subversion of innate and adaptive immune responses. This, in turn, drives the progression of inflammatory disease and the destruction of tooth-supporting structures. From an evolutionary perspective, bacteria have developed this phenotypic plasticity in order to respond and adapt to environmental stimuli or external stressors. This review summarises the available knowledge of genetic, transcriptional, and post-translational mechanisms which mediate the commensal-pathogen transition of periodontal bacteria. The review will focus primarily on Porphyromonas gingivalis.

Background Liver biopsy is the reference standard for assessing liver fibrosis. Moreover, it is an invasive procedure. Transient elastography (TE) is an accurate, noninvasive method for evaluating liver stiffness as a surrogate of liver fibrosis. The aspartate aminotransferase to platelet ratio index (APRI) and Hyaluronic acid (HA) are noninvasive alternatives to liver biopsy for detecting hepatic fibrosis. This study aimed to identify the accuracy of APRI, HA, and TE concerning liver biopsy in children with chronic viral hepatitis. Methods This cross-sectional study included 50 children, 5–18 years with chronic viral hepatitis B (HBV) or hepatitis C (HCV) who underwent liver biopsy within nine months of laboratory tests, determining APRI & performing TE. Twenty healthy children of age and sex-matching patients were included as a control group for the serum HA levels. Results The histopathological findings of the studied cases showed seven cases with (F0) fibrosis, 36 cases with mild (F1,2), two children with moderate (F3,4), and five children with severe (F5,6). The median (IQR) of steatosis was 4 (three had HCV). When correlating TE, APRI, and HA values in all cases with their laboratory data, there was a positive correlation between ALT and APRI values (P-value = 0.000), a positive correlation between AST and HA values (P-value = 0.02), and a negative correlation between stiffness and APRI. The sensitivity of HA, APRI, and TE compared to fibrosis detected by histopathology was 60.5, 65.1, and 60.5%, and their specificity was 71.4, 57.1, and 85.7%, respectively. TE was significantly higher in a group with (moderate to severe) fibrosis. Conclusion APRI, HA, and TE are good indicators of the presence of fibrosis almost with the same accuracy. TE is the only method to differentiate mild cases from those with significant fibrosis.

Background Single-cell sequencing studies on the lung microenvironment have revealed that the outcome of COVID-19 depends largely on the immune system response rather than the viral load. A robust innate immune response and a regulated adaptive immunity can prevent the worst outcomes such as hospitalization and the need for mechanical ventilation. Main body Intriguingly, several vaccines pertaining to the routine vaccination schedule, not only BCG, can skew the immune response towards the aforementioned beneficial effects. Short conclusion This means that routine immunization not only can help in the current pandemic but can also offer a rapid rescue in the subsequent epidemics or pandemics until a vaccine is developed.