Alveolar bone resorption and Th1/Th17-associated immune response triggered during Aggregatibacter actinomycetemcomitans-induced experimental periodontitis are serotype-dependent.
Monasterio Gustavo,Castillo Francisca,Ibarra Juan Pablo,Guevara José,Rojas Leticia,Alvarez Carla,Fernández Baltasar,Agüero Amaru,Betancur Daniel,Vernal Rolando
Journal of periodontology
BACKGROUND:Aggregatibacter actinomycetemcomitans expresses several virulence factors that may contribute to the pathogenesis of periodontitis. Based on the antigenicity of the O-polysaccharide component of the lipopolysaccharide (LPS), different A. actinomycetemcomitans serotypes have been described. Among them, serotype b has demonstrated a stronger capacity to trigger Th1 and Th17-associated cytokine, CC-chemokine, and CC-chemokine receptor production on immune cells in vitro. With a murine model of experimental periodontitis, this investigation aimed to analyze the alveolar bone resorption and the pattern of immune response triggered by the different A. actinomycetemcomitans serotypes within periodontal lesions. METHODS:For periodontal lesion induction, mice were orally infected with the different A. actinomycetemcomitans serotypes or their purified LPS. Alveolar bone resorption was analyzed using microcomputed tomography and scanning electron microscopy. Bacterial infection, receptor activator of nuclear factor-kappa B ligand (RANKL) and Th1 and Th17-associated cytokine, CC-chemokine, and CC-chemokine receptor levels were quantified by quantitative polymerase chain reaction (qPCR). T lymphocytes isolated from periodontal lesions were analyzed by flow cytometry. RESULTS:In periodontal lesions, serotype b of A. actinomycetemcomitans induced higher alveolar bone resorption and expression of RANKL compared with the other serotypes. In addition, serotype b induced greater levels of Th1- and Th17-related cytokines, CC-chemokines, and CC-chemokine receptors than the others. Similarly, higher numbers of infiltrating Th1 and Th17 lymphocytes were detected in serotype b-induced periodontal lesions. CONCLUSIONS:These results demonstrate that periodontal lesions induced with different A. actinomycetemcomitans serotypes elicited distinct alveolar bone resorption and immune response. In particular, serotype b was more pathogenic than the others and induced stronger Th1 and Th17 patterns of immune responses during experimental periodontitis.
Capsular-defective Porphyromonas gingivalis mutant strains induce less alveolar bone resorption than W50 wild-type strain due to a decreased Th1/Th17 immune response and less osteoclast activity.
Monasterio Gustavo,Fernández Baltasar,Castillo Francisca,Rojas Carolina,Cafferata Emilio A,Rojas Leticia,Alvarez Carla,Fernández Alejandra,Hernández Marcela,Bravo Denisse,Vernal Rolando
Journal of periodontology
BACKGROUND:Encapsulation of Porphyromonas gingivalis has been demonstrated as responsible of several host immunological changes, which have been associated with the pathogenesis of periodontitis. Using a murine model of periodontitis and two isogenic non-capsulated mutants of P. gingivalis, this study aimed to analyze whether P. gingivalis encapsulation induces more severe alveolar bone resorption, and whether this bone loss is associated with a T-helper (Th)1 and Th17-pattern of immune response. METHODS:Experimental periodontal infections were generated by oral inoculation with the encapsulated W50 wild-type strain or isogenic non-encapsulated ΔPG0116-PG0120 (GPA) and ΔPG0109-PG0118 (GPC) mutants of P. gingivalis. Periodontal infections induced with the encapsulated HG184 or non-encapsulated ATCC 33277 strains of P. gingivalis were used as controls. Alveolar bone resorption was analyzed using microcomputed tomography and scanning electron microscopy. The expression levels of Th1, Th2, Th17, or T regulatory-associated cytokines and RANKL, as well as the periodontal bacterial load, were quantified by quantitative polymerase chain reaction. The detection of Th1 and Th17 lymphocytes was analyzed by flow cytometry. RESULTS:In the periodontal lesions, both capsular-defective knockout mutant strains of P. gingivalis induced less alveolar bone resorption than the encapsulated W50 wild-type strain. This decreased bone loss was associated with a dismissed RANKL expression, decreased Th1- and Th17-type of cytokine expression, reduced Th1 and Th17 lymphocyte detection, and low osteoclast finding. CONCLUSION:These data demonstrate that encapsulation of P. gingivalis plays a key role in the alveolar bone resorption induced during periodontitis, and this bone loss is associated with a Th1- and Th17-pattern of immune response triggered in the periodontal lesions.
The Role of Immunity in Alzheimer's Disease.
With the increase in the aging population, age-related conditions such as dementia and Alzheimer's disease will become ever more prevalent in society. As there is no cure for dementia and extremely limited therapeutic options, researchers are examining the mechanisms that contribute to the progression of cognitive decline in hopes of developing better therapies and even an effective, long-lasting treatment for this devastating condition. This review will provide an updated perspective on the role of immunity in triggering the changes that lead to the development of dementia. It will detail the latest findings on Aβ- and tau-induced microglial activation, including the role of the inflammasome. The contribution of the adaptive immune system, specifically T cells, will be discussed. Finally, whether the innate and adaptive immune system can be modulated to protect against dementia will be examined, along with an assessment of the prospective candidates for these that are currently in clinical trials.
Insights into T-cell dysfunction in Alzheimer's disease.
Dai Linbin,Shen Yong
T cells, the critical immune cells of the adaptive immune system, are often dysfunctional in Alzheimer's disease (AD) and are involved in AD pathology. Reports highlight neuroinflammation as a crucial modulator of AD pathogenesis, and aberrant T cells indirectly contribute to neuroinflammation by secreting proinflammatory mediators via direct crosstalk with glial cells infiltrating the brain. However, the mechanisms underlying T-cell abnormalities in AD appear multifactorial. Risk factors for AD and pathological hallmarks of AD have been tightly linked with immune responses, implying the potential regulatory effects of these factors on T cells. In this review, we discuss how the risk factors for AD, particularly Apolipoprotein E (ApoE), Aβ, α-secretase, β-secretase, γ-secretase, Tau, and neuroinflammation, modulate T-cell activation and the association between T cells and pathological AD hallmarks. Understanding these associations is critical to provide a comprehensive view of appropriate therapeutic strategies for AD.
CD4+ T cell effector activities accelerate Alzheimer's disease pathologies.
Machhi Jatin,Yeapuri Pravin,Lu Yaman,Lee Mosley R,Gendelman Howard E
Alzheimer's & dementia : the journal of the Alzheimer's Association
BACKGROUND:Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive impairments linked to pathological deposition of misfolded self-protein amyloid beta (Aβ) which in kind facilitates tau aggregation and neurodegeneration. Neuroinflammation is accepted as key disease driver caused by innate microglia activation. Recently, adaptive immune alterations have been uncovered beginning early and extending throughout the disease. How these occurs and whether they can be harnessed to affect disease progress is unclear. We propose that self-antigens would induct autoreactive effector T cells (Teff) serving to drive pro-inflammatory and neurodestructive immunity. Here, we investigated the role of effector immunity could affect cellular level disease pathobiology in an AD animal model. METHOD:Aβ-specific Th1 and Th17 Teff were induced by Aβ-immunization of donors, CD4+ T cells isolated, expanded by selective culture in the presence of Aβ, and cloned as monoclonal Teff lines. Aβ-specific Th1 and Th17 Teff were adoptively transferred into the APP/PS1 double transgenic mice. Three weeks after transfer, radial arm water maze (RAWM), biochemical, immunohistochemical and transcriptomic tests assessed memory functions, pathologies, and mechanism. RESULT:Development of stable monoclonal Aβ-Th1 and Aβ-Th17 cells was verified by specific cytokine signatures, nuclear transcription factors and haplotype matched major histocompatibility-II (MHCII)-Aβ tetramer staining. Accelerated memory impairments were observed in APP/PS1 mice that received Aβ-specific Teffs. Both Aβ-Th1 and Aβ-Th17 cells significantly induced pro-inflammatory cytokines TNF-α, IFN-γ and IL-17 and transcription factors Tbet and RORγ compared to controls in the periphery. Aβ load significantly increased while synaptic plasticity decreased in the brain of AD mice received Aβ-Th1 cells. Aβ-Teff driven systemic inflammatory responses were attributed to the decreased numbers and functions of regulatory T cells (Treg) in both the CNS and periphery. Additionally, transferred Aβ-Teff increased microglia reactivity and neuroinflammatory activities in the affected brain regions. CONCLUSION:Autoreactive Aβ-Teff transform a pro-inflammatory microenvironment accelerating AD pathology. This is sped by limiting Treg activities. Control of this neurodestructive environment represents a potential therapeutic strategy and can be sped by augmenting peripheral Treg numbers and function. Similar therapeutic ends have been shown to be efficacious in both pre-clinical and clinical trials in related neurodegenerative disorders.
CD4+ effector T cells accelerate Alzheimer's disease in mice.
Journal of neuroinflammation
BACKGROUND:Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by pathological deposition of misfolded self-protein amyloid beta (Aβ) which in kind facilitates tau aggregation and neurodegeneration. Neuroinflammation is accepted as a key disease driver caused by innate microglia activation. Recently, adaptive immune alterations have been uncovered that begin early and persist throughout the disease. How these occur and whether they can be harnessed to halt disease progress is unclear. We propose that self-antigens would induct autoreactive effector T cells (Teffs) that drive pro-inflammatory and neurodestructive immunity leading to cognitive impairments. Here, we investigated the role of effector immunity and how it could affect cellular-level disease pathobiology in an AD animal model. METHODS:In this report, we developed and characterized cloned lines of amyloid beta (Aβ) reactive type 1 T helper (Th1) and type 17 Th (Th17) cells to study their role in AD pathogenesis. The cellular phenotype and antigen-specificity of Aβ-specific Th1 and Th17 clones were confirmed using flow cytometry, immunoblot staining and Aβ T cell epitope loaded haplotype-matched major histocompatibility complex II IA (MHCII-IA-KLVFFAEDVGSNKGA) tetramer binding. Aβ-Th1 and Aβ-Th17 clones were adoptively transferred into APP/PS1 double-transgenic mice expressing chimeric mouse/human amyloid precursor protein and mutant human presenilin 1, and the mice were assessed for memory impairments. Finally, blood, spleen, lymph nodes and brain were harvested for immunological, biochemical, and histological analyses. RESULTS:The propagated Aβ-Th1 and Aβ-Th17 clones were confirmed stable and long-lived. Treatment of APP/PS1 mice with Aβ reactive Teffs accelerated memory impairment and systemic inflammation, increased amyloid burden, elevated microglia activation, and exacerbated neuroinflammation. Both Th1 and Th17 Aβ-reactive Teffs progressed AD pathology by downregulating anti-inflammatory and immunosuppressive regulatory T cells (Tregs) as recorded in the periphery and within the central nervous system. CONCLUSIONS:These results underscore an important pathological role for CD4+ Teffs in AD progression. We posit that aberrant disease-associated effector T cell immune responses can be controlled. One solution is by Aβ reactive Tregs.