Polyfunctional Type-1, -2, and -17 CD8+ T Cell Responses to Apoptotic Self-Antigens Correlate with the Chronic Evolution of Hepatitis C Virus Infection

Caspase-dependent cleavage of antigens associated with apoptotic cells plays a prominent role in the generation of CD8+ T cell responses in various infectious diseases. We found that the emergence of a large population of autoreactive CD8+ T effector cells specific for apoptotic T cell-associated self-epitopes exceeds the antiviral responses in patients with acute hepatitis C virus infection. Importantly, they endow mixed polyfunctional type-1, type-2 and type-17 responses and correlate with the chronic progression of infection. This evolution is related to the selection of autoreactive CD8+ T cells with higher T cell receptor avidity, whereas those with lower avidity undergo prompt contraction in patients who clear infection. These findings demonstrate a previously undescribed strict link between the emergence of high frequencies of mixed autoreactive CD8+ T cells producing a broad array of cytokines (IFN-γ, IL-17, IL-4, IL-2…) and the progression toward chronic disease in a human model of acute infection

Phylogeography and Genetic Variation of Triatoma dimidiata, the Main Chagas Disease Vector in Central America, and Its Position within the Genus Triatoma

Chagas disease is a serious parasitic disease of Latin America. Human contamination in poor rural or periurban areas is mainly attributed to haematophagous triatomine insects. Triatoma includes important vector species, as T. dimidiata in Central and Meso-America. DNA sequences, phylogenetic methods and genetic variation analyses are combined in a large interpopulational approach to investigate T. dimidiata and its closest relatives within Triatoma. The phylogeography of Triatoma indicates two colonization lineages northward and southward of the Panama isthmus during ancient periods, with T. dimidiata presenting a large genetic variability related to evolutionary divergences from a Mexican-Guatemalan origin. One clade remained confined to Yucatan, Chiapas, Guatemala and Honduras, with extant descendants deserving species status: T. sp. aff. dimidiata. The second clade gave rise to four subspecies: T. d. dimidiata in Guatemala and Mexico (Chiapas) up to Honduras, Nicaragua, Providencia island, and introduced into Ecuador; T. d. capitata in Panama and Colombia; T. d. maculipennis in Mexico and Guatemala; and T. d. hegneri in Cozumel island. This taxa distinction may facilitate the understanding of the diversity of vectors formerly included under T. dimidiata, their different transmission capacities and the disease epidemiology. Triatoma dimidiata will offer more problems for control than T. infestans in Uruguay, Chile and Brazil, although populations in Ecuador are appropriate targets for insecticide-spraying

Potential Role of Venular Amyloid in Alzheimer’s Disease Pathogenesis

Insurmountable evidence has demonstrated a strong association between Alzheimer’s disease (AD) and cerebral amyloid angiopathy (CAA), along with various other cerebrovascular diseases. One form of CAA, which is the accumulation of amyloid-beta peptides (Aβ) along cerebral vessel walls, impairs perivascular drainage pathways and contributes to cerebrovascular dysfunction in AD. To date, CAA research has been primarily focused on arterial Aβ, while the accumulation of Aβ in veins and venules were to a lesser extent. In this review, we describe preclinical models and clinical studies supporting the presence of venular amyloid and potential downstream pathological mechanisms that affect the cerebrovasculature in AD. Venous collagenosis, impaired cerebrovascular pulsatility, and enlarged perivascular spaces are exacerbated by venular amyloid and increase Aβ deposition, potentially through impaired perivascular clearance. Gaining a comprehensive understanding of the mechanisms involved in venular Aβ deposition and associated pathologies will give insight to how CAA contributes to AD and its association with AD-related cerebrovascular disease. Lastly, we suggest that special consideration should be made to develop Aβ-targeted therapeutics that remove vascular amyloid and address cerebrovascular dysfunction in AD

Interaction between therapeutic interventions for Alzheimer’s disease and physiological Aβ clearance mechanisms

Most therapeutic agents are designed to target a molecule or pathway without consideration of the mechanisms involved in the physiological turnover or removal of that target. In light of this and in particular for Alzheimer’s disease, a number of therapeutic interventions are presently being developed/investigated which target the amyloid-β peptide (Aβ). However, the literature has not adequately considered which Aβ physiological clearance pathways are necessary and sufficient for the effective action of these therapeutics. In this review, we evaluate the therapeutic strategies targeting Aβ presently in clinical development, discuss the possible interaction of these treatments with pathways that under normal physiological conditions are responsible for the turnover of Aβ and highlight possible caveats. We consider immunization strategies primarily reliant on a peripheral sink mechanism of action, small molecules that are reliant on entry into the CNS and thus degradation pathways within the brain as well as lifestyle interventions that affect vascular, parenchymal and peripheral degradation pathways. We propose that effective development of Alzheimer’s disease therapeutic strategies targeting Aβ peptide will require consideration of the age- and disease-specific changes to endogenous Aβ clearance mechanisms in order to elicit maximal efficacy

Effects of Neurotrophic Support and Amyloid-Targeted Combined Therapy on Adult Hippocampal Neurogenesis in a Transgenic Model of Alzheimer's Disease

<div><p>Although it is recognized that multi-drug therapies may be necessary to combat AD, there is a paucity of preclinical proof of concept studies. We present a combination treatment paradigm, which temporally affects different aspects of Alzheimer’s disease (AD)-like pathology, specifically Aβ-toxicity and neurogenesis. At early stages of AD-like pathology, in TgCRND8 mice, we found that combating Aβ pathology with <i>scyllo</i>-inositol ameliorated deficits in neurogenesis. Older TgCRND8 mice with established amyloid load had decreased progenitor cell proliferation and survival compared to non-transgenic mice, regardless of <i>scyllo</i>-inositol treatment. The prolonged exposure to Aβ-pathology leads to deficits in the neurogenic niche, thus targeting Aβ alone is insufficient to rescue neurogenesis. To support the neurogenic niche, we combined <i>scyllo</i>-inositol treatment with leteprinim potassium (neotrofin), the latter of which stimulates neurotrophin expression. We show that the combination treatment of <i>scyllo</i>-inositol and neotrofin enhances neuronal survival and differentiation. We propose this proof of concept combination therapy of targeting Aβ-pathology and neurotrophin deficits as a potential treatment for AD.</p></div

Hippocampal cell differentiation and survival in <i>scyllo</i>-inositol, neotrofin, and <i>scyllo</i>-inositol/neotrofin treated 200 day old Tg mice.

<p>(A) The number of DCX+ cells in Tg-SI (n = 6), Tg-NEO (n = 6) and Tg-SI/NEO (n = 7) mice were not significantly different between cohorts. (B) The percentage of DCX+ cells that were DCX+/CR+ immature neurons were assessed and showed no difference between treatment groups. (C) The percentage of DCX+/CR+ cells that were NeuN+ represents immature neurons approaching maturity. Tg-SI/NEO mice had a significantly greater percentage of DCX+/CR+/NeuN+ cells than Tg-SI and Tg-NEO mice. Tg-SI mice had a greater percentage than Tg-NEO mice. (D/E) Representative images of DCX (green) and CR (red) positive cells in the hippocampus, showing DCX+/CR- and DCX+/CR+ cells in Tg-SI mice and in Tg-SI/NEO mice. (E) Arrows indicate DCX+/CR+ cells. Scale bar indicates 20 μm. Data are mean ± SEM. One-way ANOVA with Fisher’s Post-hoc test, *** represents p<0.001.</p

Hippocampal cell proliferation in Tg mice with late AD-like pathology and age-matched NTg littermates.

<p>Cell proliferation was assessed at 200 days of age (A,B). (A) The number of proliferating BrdU+ cells in NTg (n = 6), NTg-SI (n = 6), Tg (n = 6) and Tg-SI (n = 5) mice was compared, demonstrating less proliferation in Tg and Tg-SI vs. NTg-SI. (B) The percentage of BrdU+/DCX+ cells in the dentate gyrus was not different between cohorts. (C) Dentate gyrus stained with BrdU (red) and DCX (green) demonstrating the distribution of proliferating cells, as well as neuroblasts and immature neurons, respectively. (D) Representative orthogonal projection of a BrdU+/DCX+ cell. Scale bar indicates 100 μm (C) or 25 μm (D). Data are mean ± SEM. One-way ANOVA with Fisher’s Post-hoc test, ** represents p< 0.01.</p

Timeline of therapeutic interventions.

<p>(A) TgCRND8 (Tg) mice with early AD-like pathology and age-matched non-transgenic (NTg) mice were treated or untreated from 72 days of age until sacrifice at either 100 or 121 days, for proliferation and differentiation/survival, respectively. BrdU was intraperitoneally injected in these cohorts of mice for 5 days from day 96–100. (B) Tg mice with late AD-like pathology and age-matched NTg mice were treated or untreated from day 172 days of age until sacrifice at either 200 or 221 days. Tg mice were treated with <i>scyllo</i>-inositol (Tg-SI), neotrofin (Tg-NEO) or a combination of both (Tg-SI/NEO) for 28 days. BrdU was injected in these cohorts of mice for 5 days from day 196–200.</p

Hippocampal Aβ plaques in 121 and 221 day old <i>scyllo</i>-inositol treated and untreated Tg mice.

<p>(A) Percent hippocampal area covered in plaques in 121 day old Tg (n = 5) and Tg-SI (n = 6) mice showed decreased plaques after treatment. (B) Representative images of Aβ plaques in the hippocampus of 121 day old mice demonstrate the reduction in plaques after <i>scyllo</i>-inositol treatment. (C) Percent hippocampal area covered in plaques in 221 day old Tg (n = 5) and Tg-SI (n = 6) mice also showed less plaques after treatment. (D) Representative images of Aβ plaques in the hippocampus of 221 day old mice demonstrate the reduction in plaques after <i>scyllo</i>-inositol treatment. Scale bar indicates 200 μm. Data are mean ± SEM. Unpaired t-test, * represents p< 0.05.</p

Hippocampal cell differentiation and survival in Tg mice with late AD-like pathology and age-matched NTg littermates.

<p>Differentiation and survival was examined at 221 days of age (A,B) as a function of <i>scyllo</i>-inositol treatment. (A) The number of BrdU+ cells surviving in NTg (n = 7), NTg-SI (n = 7), Tg (n = 6) and Tg-SI (n = 6) mice showed no difference between treatment or genotype. (B) The percentage of BrdU+/NeuN+ cells in the dentate gyrus showed Tg and Tg-SI mice had a lower percentage of BrdU+/NeuN+ cells compared to NTg-SI mice. (C) Dentate gyrus stained with BrdU (red) and NeuN (blue) demonstrating the distribution of surviving newborn cells (red) within the population of mature granular neurons (blue). (D) Representative orthogonal projection of BrdU+/NeuN+ cell. Scale bar indicates 100 μm (C) or 25 μm (D). Data are mean ± SEM. One-way ANOVA with Fisher’s Post-hoc test, * represents p< 0.05 and ** represents p< 0.01.</p