Periodontitis aggravates kidney injury by upregulating STAT1 expression in a mouse model of hypertension

Role of Inflammatory Processes in the Brain-Body Relationship Underlying Hypertension

PURPOSE OF REVIEW

Essential hypertension is a huge health problem that significantly impacts worldwide population in terms of morbidity and mortality. Idiopathic in its nature, elevated blood pressure results from a complex interaction between polygenic components and environmental and lifestyle factors. The constant growth in the burden of hypertension is at odds with expectations, considering the availability of therapeutic strategies. Hence, there is an endless need to further investigate the complexity of factors contributing to blood pressure elevation.

RECENT FINDINGS

Recent data indicate that bidirectional interactions between the nervous system and the immune system alter inflammation in the brain and periphery, contributing to chronic hypertension. These findings indicate that the nervous system is both a direct driver of hypertension and also a target of feedback that often elevates blood pressure further. Similarly, the immune system is both target and driver of the blood pressure increases. The contributions of the feedback loops among these systems appear to play an important role in hypertension. Together, recent mechanistic studies strongly suggest that the interactions among the brain, immune system, and inflammation affect the participation of each system in the pathogenesis of hypertension, and thus, all of these systems must be considered in concert to gain a full appreciation of the development and potential treatments of hypertension.

Dentoalveolar Alterations in an Adenine-Induced Chronic Kidney Disease Mouse Model

Chronic kidney disease (CKD) is characterized by kidney damage and loss of renal function. CKD mineral and bone disorder (CKD-MBD) describes the dysregulation of mineral homeostasis, including hyperphosphatemia and elevated parathyroid hormone (PTH) secretion, skeletal abnormalities, and vascular calcification. CKD-MBD impacts the oral cavity, with effects including salivary gland dysfunction, enamel hypoplasia and damage, increased dentin formation, decreased pulp volume, pulp calcifications, and altered jaw bones, contributing to clinical manifestations of periodontal disease and tooth loss. Underlying mechanisms are not fully understood, and CKD mouse models commonly require invasive procedures with high rates of infection and mortality. We aimed to characterize the dentoalveolar effects of an adenine diet (AD)-induced CKD (AD-CKD) mouse model. Eight-week-old C57BL/6J mice were provided either a normal phosphorus diet control (CTR) or adenine and high-phosphorus diet CKD to induce kidney failure. Mice were euthanized at 15 weeks old, and mandibles were collected for micro-computed tomography and histology. CKD mice exhibited kidney failure, hyperphosphatemia, and hyperparathyroidism in association with porous cortical bone in femurs. CKD mice showed a 30% decrease in molar enamel volume compared to CTR mice. Enamel wear was associated with reduced ductal components, ectopic calcifications, and altered osteopontin (OPN) deposition in submandibular salivary glands of CKD mice. Molar cusps in CKD mice were flattened, exposing dentin. Molar dentin/cementum volume increased 7% in CKD mice and pulp volume decreased. Histology revealed excessive reactionary dentin and altered pulp-dentin extracellular matrix proteins, including increased OPN. Mandibular bone volume fraction decreased 12% and bone mineral density decreased 9% in CKD versus CTR mice. Alveolar bone in CKD mice exhibited increased tissue-nonspecific alkaline phosphatase localization, OPN deposition, and greater osteoclast numbers. AD-CKD recapitulated key aspects reported in CKD patients and revealed new insights into CKD-associated oral defects. This model has potential for studying mechanisms of dentoalveolar defects or therapeutic interventions. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Study on the effect of periodontitis on renal tissue in atherosclerotic mice

BACKGROUND AND OBJECTIVE

Periodontitis is immune inflammatory disease, atherosclerosis (AS) and chronic kidney disease (CKD) are two common systemic diseases. Periodontitis promotes AS and CKD, and CKD interacts with AS. The objective of this animal study was to evaluate the changes of kidney when periodontitis and atherosclerosis exist separately and the degenerative effects of periodontitis on the kidney in atherosclerotic mice.

MATERIALS AND METHODS

A total of 40 male Apoe-/- mice were randomly divided into four groups: control (NC), periodontitis (PD), AS and AS with PD (AS + PD). AS was induced by high-fat diet feeding, and PD was induced by injection of Porphyromonas gingivalis-Lipopolysaccharide (P.g-LPS) (endotoxin suspension) into the buccal side of mouse maxillary molars. The right maxilla of mice was scanned with micro-CT to evaluate alveolar bone loss; aortic tissue was stained with HE and Oil-Red O to evaluate arterial plaque formation; serum was collected to detect the changes of blood lipids and serum renal function parameters (blood urea nitrogen [BUN], serum creatinine [Scr]); renal histopathological changes were evaluated by HE staining (glomerular and tubular damage scores), PAS staining (glomerular Mesangial matrix index) and Masson staining (percentage of renal fibrosis area); qRT-PCR and ELISA were used to evaluate the expression of renal inflammatory cytokines (tumor necrosis factor-α, Interleukin-1β, neutrophil surface marker Ly6G).

RESULTS

The amount of alveolar bone loss: PD group was significantly higher than NC group (p < .05); AS + PD group was higher than PD group, the difference was not statistically significant. Atherosclerotic plaque formation and serum lipid changes: AS group were significantly worse than NC group (p < .05), and AS + PD group were worse than AS group. The results of the corresponding qualitative and quantitative analyses of kidney tissue in experimental animals gradually deteriorated in the NC group, PD group, AS group and AS + PD group and worsened sequentially. Renal function parameters: the content of BUN in AS group was higher than that in PD group, the difference was not statistically significant; Scr in AS group was significantly higher than that in PD group (p < .05); the contents of BUN and Scr in AS + PD group were higher than those in AS group, the difference was not statistically significant. Glomerular and tubular damage scores: AS group were higher than PD group, the difference was not statistically significant; AS + PD group were significantly higher than AS group (p < .001). The ratio of glomerular mesangial matrix to glomerular area and the percentage of renal fibrosis area: AS group were significantly higher than PD group (p < .001), and AS + PD group were significantly higher than AS group (p < .001). Expression of inflammatory cytokines: AS group was higher than PD group, the difference was not statistically significant; AS + PD group was significantly higher than AS group (p < .05).

CONCLUSION

Both PD and AS can aggravate the inflammatory stress of kidney tissue and cause the damage of kidney tissue, and the inflammatory increase and damage effect of AS is stronger; PD can promote kidney damage of atherosclerotic mice by aggravating the renal inflammation in atherosclerotic mice; renal function parameters were not completely synchronized with the changes of renal inflammation and histopathology in each group of mice; PD can promote AS, periodontal inflammation in mice with AS is more severe, and the special changes of blood lipids in mice with AS are closely related to the above results.

Cold Storage Followed by Transplantation Induces Interferon-Gamma and STAT-1 in Kidney Grafts

Cold storage (CS)-mediated inflammation, a reality of donor kidney processing and transplantation, can contribute to organ graft failure. However, the mechanisms by which this inflammation is perpetuated during and after CS remain unclear. Here, we examined the immunoregulatory roles of signal transducer and activator of transcription (STAT) family proteins, most notably STAT1 and STAT3, with our in vivo model of renal CS and transplant. Donor rat kidneys were exposed to 4 h or 18 h of CS, which was then followed by transplantation (CS + transplant). STAT total protein level and activity (phosphorylation) were evaluated via Western blot analysis and mRNA expression was tabulated using quantitative RT-PCR after organ harvest on day 1 or day 9 post-surgery. In vivo assays were further corroborated via similar analyses featuring in vitro models, specifically proximal tubular cells (human and rat) as well as macrophage cells (Raw 264.7). Strikingly, gene expression of IFN-γ (a pro-inflammatory cytokine inducer of STAT) and STAT1 were markedly increased after CS + transplant. STAT3 dephosphorylation was additionally observed after CS, a result suggestive of dysregulation of anti-inflammatory signaling as phosphorylated STAT3 acts as a transcription factor in the nucleus to increase the expression of anti-inflammatory signaling molecules. In vitro, IFN-γ gene expression as well as amplification of downstream STAT1 and inducible nitric oxide synthase (iNOS; a hallmark of ischemia reperfusion injury) was remarkably increased after CS + rewarming. Collectively, these results demonstrate that aberrant induction of STAT1 is sustained in vivo post-CS exposure and post-transplant. Thus, Jak/STAT signaling may be a viable therapeutic target during CS to mitigate poor graft outcomes when transplanting kidneys from deceased donors.

Pre and Probiotics Involved in the Modulation of Oral Bacterial Species: New Therapeutic Leads in Mental Disorders?

This systematic review aims to identify probiotics and prebiotics for modulating oral bacterial species associated with mental disorders. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guideline, we search the electronic MEDLINE database published till January 2021 to identify the studies on probiotics and/or prebiotics for preventing and treating major oral dysbiosis that provokes mental disorders. The outcome of the search produces 374 records. After excluding non-relevant studies, 38 papers were included in the present review. While many studies suggest the potential effects of the oral microbiota on the biochemical signalling events between the oral microbiota and central nervous system, our review highlights the limited development concerning the use of prebiotics and/or probiotics in modulating oral dysbiosis potentially involved in the development of mental disorders. However, the collected studies confirm prebiotics and/or probiotics interest for a global or targeted modulation of the oral microbiome in preventing or treating mental disorders. These outcomes also offer exciting prospects for improving the oral health of people with mental disorders in the future.