Mechanisms for inducing nasal mucosal tolerance in experimental autoimmune uveoretinitis

Association between Porphyromonas Gingivalis and systemic diseases: Focus on T cells-mediated adaptive immunity

The association between periodontal disease and systemic disease has become a research hotspot. Porphyromonas gingivalis (P. gingivalis), a crucial periodontal pathogen, affects the development of systemic diseases. The pathogenicity of P. gingivalis is largely linked to interference with the host's immunity. This review aims to discover the role of P. gingivalis in the modulation of the host's adaptive immune system through a large number of virulence factors and the manipulation of cellular immunological responses (mainly mediated by T cells). These factors may affect the cause of large numbers of systemic diseases, such as atherosclerosis, hypertension, adverse pregnancy outcomes, inflammatory bowel disease, diabetes mellitus, non-alcoholic fatty liver disease, rheumatoid arthritis, and Alzheimer's disease. The point of view of adaptive immunity may provide a new idea for treating periodontitis and related systemic diseases.

The Role of the Microbiota in the Diabetic Peripheral Artery Disease

Vascular complications of diabetes mellitus represent a major public health problem. Although many steps forward have been made to define the causes and to find the best possible therapies, the problem remains crucial. In recent years, more and more evidences have defined a link between microbiota and the initiation, promotion, and evolution of atherosclerotic disease, even in the diabetic scenario. There is an urgency to develop the knowledge of modern medicine about the link between gut microbiota and its host's metabolic pathways, and it would be useful to understand and justify the interindividual diversity of clinical disease presentation of diabetic vascular complication even if an optimization of pharmacological treatment has been made or in the case of young patients where hypertension, dyslipidemia, and diabetes are not able to justify a very quick progress of atherosclerotic process. The aim of the present review is to gather all the best available evidence in this regard and to define a new role of the microbiota in this field, from biomarker to possible therapeutic target.

Periodontal pathogens and atherosclerosis: implications of inflammation and oxidative modification of LDL

Inflammation is well accepted to play a crucial role in the development of atherosclerotic lesions, and recent studies have demonstrated an association between periodontal disease and cardiovascular disease. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, causative agents of destructive chronic inflammation in the periodontium, can accelerate atheroma deposition in animal models. Emerging evidence suggests that vaccination against virulence factors of these pathogens and anti-inflammatory therapy may confer disease resistance. In this review, we focus on the role of inflammatory mechanisms and oxidative modification in the formation and activation of atherosclerotic plaques accelerated by P. gingivalis or A. actinomycetemcomitans in an ApoE-deficient mouse model and high-fat-diet-fed mice. Furthermore, we examine whether mucosal vaccination with a periodontal pathogen or the anti-inflammatory activity of catechins can reduce periodontal pathogen-accelerated atherosclerosis.

Sublingual Vaccine with GroEL Attenuates Atherosclerosis

Autoimmune responses to heat-shock protein 60 (HSP60) contribute to the progression of atherosclerosis, whereas immunization with HSP60 may induce atheroprotective responses. We assessed the capacity of an atheroprotective vaccine that targeted a recombinant HSP60 from Porphyromonas gingivalis (rGroEL) to induce a protective mucosal immune response. Female apolipoprotein E-deficient spontaneously hyperlipidemic (Apoeshl) mice received sublingual delivery of rGroEL prior to P. gingivalis 381 injection. The animals were euthanized 16 weeks later. Sublingual immunization with rGroEL induced significant rGroEL-specific serum IgG responses. Antigen-specific cells isolated from spleen produced significantly high levels of IL-10 and IFN-γ after antigen re-stimulation in vitro. Flow cytometric analysis indicated that the frequencies of both IL-10+ and IFN-γ+ CD4+ Foxp3+ cells increased significantly in submandibular glands (SMG). Furthermore, sublingual immunization with rGroEL significantly reduced atherosclerosis lesion formation in the aortic sinus and decreased serum CRP, MCP-1, and ox-LDL levels. These findings suggest that sublingual immunization with rGroEL is associated with the increase of IFNγ+ or IL-10+ Foxp3+ cells in SMG and a systemic humoral response, which could be an effective strategy for the prevention of naturally occurring or P. gingivalis-accelerated atherosclerosis.

CX3CR1-deficiency is associated with increased severity of disease in experimental autoimmune uveitis

The role of CX3CR1 in regulating the function of monocytes and microglia was examined in mice in which CX3CR1 had been replaced by green fluorescent protein (GFP). Induction of experimental autoimmune uveitis (EAU) in these mice resulted in increased disease severity at day 23 postimmunization with uveitogenic peptide when compared with CX3CR1-positive mice and increased apoptosis of neuronal cells in the inner nuclear layer. Resident microglia within the retina were activated equally as EAU developed in mice with or without CX3CR1, as determined by changes in morphology, suggesting that the microglial cell response did not account for the differences. Although the inflammatory infiltrate had increased in mice without CX3CR1 at day 23 postimmunization, the percentage of natural killer cells in the infiltrate was not changed in these mice. Similarly, increased disease severity at this stage was not associated with an overall increased percentage of macrophages in the retinal inflammatory infiltrate or in increased activation of these cells. The increased recruitment of monocytes to the retina in response to EAU induction in CX3CR1(GFP/GFP) mice compared with CX3CR1(GFP/+) mice was not reflected in increased migration away from vessels, leading to marked clustering of GFP(+) cells around veins and venules in these mice. It is possible that this monocyte/macrophage clustering leads to the increased severity of disease seen in the mice by focusing and so intensifying the inflammatory response.

Nasal immunization with heat shock protein 65 attenuates atherosclerosis and reduces serum lipids in cholesterol-fed wild-type rabbits probably through different mechanisms

In recent years atherosclerosis has proved to be associated with microbial infection, inflammation and autoimmunity. Conservative heat shock protein (HSP) 65/60 is a major autoantigen of atherosclerosis. In the current study, experiments were specifically designed to investigate whether a nasal immunization with HSP65 could attenuate atherosclerosis in a cholesterol-fed wild-type animal model and explore its influence on serum lipids. Wild-type rabbits were nasally treated with HSP65 10 times on alternate days. At the end of the experiment, the rabbits showed remarkably lightened lesions in aortas. The suppression of T cell proliferation, increase of IL-10 production and absence of related antibodies implied that a tolerance to HSP65 was successfully established. Simultaneously, the serum lipid levels were down-regulated significantly in this group. Further results of another group immunized with conjugated protein HSP65+CTB-P277 showed that the lipid reduction could also be achieved by an immunization without inducing tolerance. But this simple reduction of lipids could not eventually alleviate atherosclerosis. In conclusion, nasal administration of HSP65 can effectively attenuate atherosclerosis in cholesterol-fed wild-type rabbits primarily by inducing an unresponsive state of tolerance. The accompanying reduction of lipids, which probably results from a different immune mechanism other than tolerance, cannot ultimately prevent the development of atherosclerotic lesions alone.