Cellular Senescence and Periodontitis: Mechanisms and Therapeutics

Low-level laser therapy alleviates periodontal age-related inflammation in diabetic mice via the GLUT1/mTOR pathway

Diabetes mellitus (DM) is a chronic age-related disease that was recently found as a secondary aging pattern regulated by the senescence associated secretory phenotype (SASP). The purpose of this study is to detect the potential efficacy and the specific mechanisms of low-level laser therapy (LLLT) healing of age-related inflammation (known as inflammaging) in diabetic periodontitis. Diabetic periodontitis (DP) mice were established by intraperitoneal streptozotocin (STZ) injection and oral P. gingivalis inoculation. Low-level laser irradiation (810 nm, 0.1 W, 398 mW/cm2, 4 J/cm2, 10 s) was applied locally around the periodontal lesions every 3 days for 2 consecutive weeks. Micro-CT and hematoxylin-eosin (HE) stain was analyzed for periodontal soft tissue and alveolar bone. Western blots, immunohistochemistry, and immunofluorescence staining were used to evaluate the protein expression changes on SASP and GLUT1/mTOR pathway. The expression of aging-related factors and SASP including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 were reduced in periodontal tissue of diabetic mice. The inhibitory effect of LLLT on GLUT1/mTOR pathway was observed by detecting the related factors mTOR, p-mTOR, GLUT1, and PKM2. COX, an intracytoplasmic photoreceptor, is a key component of the anti-inflammatory effects of LLLT. After LLLT treatment a significant increase in COX was observed in macrophages in the periodontal lesion. Our findings suggest that LLLT may regulate chronic low-grade inflammation by modulating the GLUT1/mTOR senescence-related pathway, thereby offering a potential treatment for diabetic periodontal diseases.

Sex-based influential factors for dental caries in patients with schizophrenia

BACKGROUND

Schizophrenia is a common mental disorder that seriously affects patients' daily lives and brings heavy psychological and economic burdens to their families and society. The oral problems of patients with schizophrenia are gradually gaining attention, among which dental caries are among the most common oral diseases. Sex differences may be related not only to the various clinical symptoms of schizophrenia but also to different oral hygiene statuses; therefore, the main purpose of this paper is to investigate sex differences related to influencing factors for dental caries in patients with schizophrenia.

METHOD

Inpatients with schizophrenia over 18 years old were included in this study, and multidimensional indicators such as demographics, symptom and cognitive impairment assessments, medications, and the caries index of decayed, missing, and filled teeth (DMFT) were collected. An analysis of sex-based influential factors for dental caries in schizophrenia patients was performed.

RESULTS

Four-hundred and ninety-six patients with schizophrenia were included, with a mean age of 46.73 ± 12.23 years, of which 142 were females and 354 were males. The mean DMFT was significantly higher in males (8.81 ± 8.50) than in females (5.63 ± 6.61, p < 0.001), and the odd ratio of caries in males to females was significantly higher as well (OR = 2.305, p < 0.001). The influential factors of caries in male patients were independently associated with age and smoking status, in which current smokers were at the highest risk for developing caries, and different smoking statuses had various influencing factors for caries. The influencing factors for caries in female patients were independently associated with age, antipsychotic dose, PANSS-positive symptoms, and MMSE levels.

CONCLUSION

Our findings suggest sex differences exist among influential factors for caries in patients with schizophrenia. These risk factors may even be associated with and affect the treatment and prognosis of psychiatric symptoms in patients. Therefore, oral hygiene management of patients with schizophrenia should be enhanced. These differential factors provide new visions and ideas for formulating individual interventions, treatments, and care priorities.

Rejuvenation of Mesenchymal Stem Cells to Ameliorate Skeletal Aging

Advanced age is a shared risk factor for many chronic and debilitating skeletal diseases including osteoporosis and periodontitis. Mesenchymal stem cells develop various aging phenotypes including the onset of senescence, intrinsic loss of regenerative potential and exacerbation of inflammatory microenvironment via secretory factors. This review elaborates on the emerging concepts on the molecular and epigenetic mechanisms of MSC senescence, such as the accumulation of oxidative stress, DNA damage and mitochondrial dysfunction. Senescent MSCs aggravate local inflammation, disrupt bone remodeling and bone-fat balance, thereby contributing to the progression of age-related bone diseases. Various rejuvenation strategies to target senescent MSCs could present a promising paradigm to restore skeletal aging.