Coexistance of different damage-associated myeloid populations in the hippocampus of Alzheimer's patients

Parenchymal microglia are the brain-resident immune cells capable of responding to damage. Though the role of microglial cells in the development/progression of AD is still unknown, a dysfunctional response has recently gained support since the identification of genetic risk factors related to microglial. In this sense, we reported an attenuated microglial activation in the hippocampus of AD patients, including a degenerative process of the microglial population in the dentate gyrus. On the other hand, it is also known that others myeloid components could also be involved in the neurodegenerative process. However, the implication of the diverse immune cells in the human pathology have not been determined yet. In this work, we analyzed the phenotypic profile displayed by damage-associated myeloid cells in the hippocampus of AD brains. For this purpose, immunohistochemistry and image analysis approaches have been carried out in non-demented controls and AD cases. Damage-associated myeloid cells from Braak II and Braak VI individuals were clustered around amyloid plaques and expressed Iba1, TMEM119, CD68, Trem2 and CD45high. A subset of these cells also expressed ferritin. However, and even though some Braak II individuals accumulated CD45-positive plaques, only AD patients exhibited parenchymal infiltration of CD163-positive cells, along with a decrease of the resident microglial marker TMEM119. Moreover, a negative correlation was observed between CD163 and TMEM119 intensities in Braak VI patients, showing a functional cooperation among these different myeloid populations. Taken together, these findings suggest the existence of different populations of amyloid-associated myeloid cells in the hippocampus during disease progression. The differential contribution of these myeloid populations to the pathogenesis remains to be elucidated. The dynamic of the myeloid molecular phenotypes associated to AD pathology needs to be considered for guarantee clinical success.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Microglial responses in the human Alzheimer’s disease frontal cortex

The continuing failure to develop an effective treatment for Alzheimer’s disease (AD) reveals the complexity for this pathology. Increasing evidence indicates that neuroinflammation involving particularly microglial cells contributes to AD pathogenesis. The actual view, based on the findings in APP based models, gives a cytotoxic/proinflammatory role to activated microglia. However, we have previously reported a limited activation and microglial degeneration in the hippocampus of AD patients in contrast with that observed in amyloidogenic models. Here, we evaluated the microglial response in a different region of AD brains, the frontal cortex. Post mortem tissue from controls (Braak 0-II) and AD patients (Braak V-VI) including familial cases, were obtained from Spain Neurological Tissue Banks. Cellular (immunohistochemistry and image analysis) and molecular (qPCR and western blots) approaches were performed. Frontal cortex of AD patients (Braak V-VI) showed strong microglial activation similar to that observed in amyloidogenic mice. These strongly activated microglial cells, predominantly located surrounding amyloid plaques, could drive the AD pathology and, in consequence, could be implicated in the pathology progression. Furthermore, different microglial responses were observed between sporadic and familial AD cases. These findings in the frontal cortex were highly in contrast to the attenuated activation and degenerative morphology displayed by microglial cells in the hippocampus of AD patients. Regional differences in the microglial response suggest different functional states of microglial cells in a region-specific manner. All together, these data provide a better understanding of the immunological mechanisms underlying AD progression and uncover new potential therapeutic targets to fight this devastating neurodegenerative disease.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Supported by PI18/01557 (AG) and PI18/01556 (JV) grants from ISCiii of Spain co-financed by FEDER funds from European Unio

Decoding damage-associated microglia in post mortem hippocampus of Alzheimer’s disease patients

The relationship between Alzheimer’s disease (AD) and neuroinflammation has become stronger since the identification of several genetic risk factors related to microglial function. Though the role of microglial cells in the development/progression of AD is still unknown, a dysfunctional response has recently gained support. In this sense, we have reported an attenuated microglial activation associated to amyloid plaques in the hippocampus of AD patients, including a prominent degenerative process of the microglial population in the dentate gyrus, which was in contrast to the exacerbated microglial response in amyloidogenic models. This microglial degeneration could compromise their normal role of surveying the brain environment and respond to the damage. Here, we have further analyzed the phenotypic profile displayed by the damage-associated microglial cells by immunostaining and qPCR in the hippocampus of postmortem samples of AD patients (Braak V-VI) and control cases (Braak 0-II). Damage-associated microglial cells of Braak V-VI individuals were clustered around amyloid plaques and expressed Iba1, CD68, Trem2, TMEM119 and CD45high. A subset of these cells also expressed ferritin. On the contrary, these microglia down-regulated homeostatic markers, such as Cx3cr1 and P2ry12. The homeostatic and ramified microglial cells of non-demented Braak II cases were characterized by Iba1, CX3CR1, P2ry12, TMEM119 and CD45low expression. The dynamic of the microglial molecular phenotypes associated to AD pathology needs to be considered for better understand the disease complexity and, therefore, guarantee clinical success. Correcting dysregulated brain inflammatory responses might be a promising avenue to prevent/slow cognitive decline.Universidad de Málaga. Campus de excelencia Internacional-Andalucía Tech. Supported by PI18/01557 (AG) and PI18/01556 (JV) grants from ISCiii of Spain co-financed by FEDER funds from European Union

Diversity of plaque-associated myeloid cells subtypes in human alzheimer’s disease brain

Aims: Parenchymal microglia, as well other myeloid cells, have been postulated as a critical factor in Alzheimer´s disease (AD) pathogenesis since the identification of genetic risk factors related to their functions. However, the different phenotypes and the implication of the diverse immune cells in the human pathology have not been determined yet. In this work, we have further analyzed the phenotypic profile of the damage-associated myeloid cells in two AD vulnerable brain regions, the frontal cortex and hippocampus. Methods: Immunohistochemistry and image analysis approaches have been carried out in postmortem brain samples from patients with AD (Braak V-VI) and aged controls without neurological symptoms (Braak II). Results: Damage-associated microglial cells were clustered around amyloid plaques and expressed Iba1, TMEM119, CD68, Trem2 and CD45high. Moreover, AD brains exhibited parenchymal infiltration of CD163-positive monocyte-derived cells that invaded plaque near blood vessels. While the frontal cortex showed strong microglial activation similarly to that reported in amyloidogenic mice, the hippocampus of the same patients showed an attenuated microglial activation with a degenerative phenotype. Conclusions: These findings suggest the existence of different myeloid populations associated with Aβ plaques that correlates with disease severity. These results open the opportunity to design targeted therapies, not only to microglia, but also to the population of macrophages to modulate amyloid pathology and provide a better understanding of the immunological mechanisms underlying AD progression.Supported by ISCiii of Spain grants PI18/01557 (AG), PI18/01556 (JV) co-financed by FEDER funds from EU, by Junta de Andalucia grants UMA18-FEDERJA-211(AG), P18-RT-2233(AG) and US-1262734(JV) co-financed by Programa Operativo FEDER 2014-2020, and by B1-2019_07 Universidad de Malaga. Campus de Excelencia Internacional Andalucia Tech (ESM)

Understanding microglial responses in the frontal cortex of alzheimer´s disease patients

Microglial cells, the immune cells of the brain, and the neuroinflammatory process associated, have been postulated as a critical factor in AD pathogenesis, since the identification of genetic risk factors related to microglial function. However, the microglial role in the development/progression of AD has not been determined yet. In this sense, we have previously reported a limited activation and microglial degeneration in the hippocampus of AD patients in contrast to the proinflammatory view based on findings in amyloidogenic models. Here, we have further analyzed the functional/phenotypic profile displayed by microglial cells in other vulnerable brain region of AD patients, the frontal cortex. Immunohistochemistry and image analysis approaches were performed in the frontal cortex of post mortem samples from controls (Braak 0-II) and AD patients (Braak V-VI) including familial cases. Microglia of Braak V-VI individuals were observed forming clusters and showed, both plaque (Iba1+/TMEM119+/P2ry12-/CD45high/Trem2+) and inter-plaque (Iba1+/ TMEM119+/P2ry12-/CD45high/Trem2-) microglial activation, similar that observed in amyloidogenic mice. By contrast, homeostatic and ramified microglial cells of non-demented Braak II cases presented Iba1+/P2ry12+/TMEM119+/CD45low/Trem2- profile. Furthermore, different microglial responses were observed between sporadic and familial AD cases. These different microglial phenotypes associated with AD pathology show the heterogeneity and complexity of the microglial phenotypes and suggest different functional states of these glial cells in a region-specific manner. These data need to be considered for better understand the immunological mechanisms underlying AD progression. Modulating brain inflammatory responses might be a promising avenue to prevent cognitive dysfunction in AD patients. ISCiii:PI18/01557(AG)-PI18/01556(JV);Junta Andalucia:UMA18-FEDERJA211(AG). All cofinanced by FEDER funds (European-Union).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Tau pathology and astroglial reactivity: a comparative study of two mouse models of tauopathy

Objectives: Astrocytes are becoming crucial players in the context of neurodegenerative proteinopathies, such as Alzheimer’s disease (AD). Astroglial response has been mainly analyzed in amyloidogenic scenarios, but less is known about their involvement in tauopathies. Here, we aimed to analyze astroglial reactivity to hyperphosphorylated-tau (ptau) in the hippocampus of two transgenic mouse models of tauopathy, ThyTau22 and P301S (2- to 12/18-months). Methods: Proteinopathy was assessed by western-blotting and immunohistochemistry (AT8). Neuroinflammation was analyzed by qPCR and bright-field immunohistochemistry, glial-ptau relationship by confocal and transmission electron microscopy. Results: P301S mice exhibited an intense reactive astrogliosis, increasing progressively with aging accordingly to a strong ptau accumulation, whereas ThyTau22 model showed slighter astrocytosis related to lesser proteinopathy. P301S astrogliosis correlated with an acute DAM-like microglial activation, not observed in ThyTau22 hippocampus. In both models, reactive astrocytes contained ptau, especially around vessels. Conclusions: Our results support that astrocytes respond to ptau in the absence of Abeta. This reactivity correlates with tau pathology and depends on microglial DAM-like activation. In addition, reactive astrocytes may play a role in the elimination/spreading of ptau species through the brain. Deciphering the mechanisms underlying these processes might allow the development of strategies to slow down the progression of AD and other tauopathies.Supported by Instituto de Salud Carlos III of Spain, co-financed by FEDER funds from European Union, through grants PI18/01557 (to AG),PI18/01556 (to JV), and Junta de Andalucia through Consejería de Economía y Conocimiento grants UMA18-FEDERJA-211 (AG), P18-RT-2233 (AG) and US-1262734 (JV) co-financed by Programa Operativo FEDER 2014-2020. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Involvement of different aβ-associated myeloid populations in the human alzheimer’s brain

Parenchymal microglia, the brain-resident immune cells, have been postulated as a critical factor in Alzheimer´s disease (AD) since the identification of genetic risk factors related to their functions. Though the role of microglia in the AD progression/development is still unknown, a dysfunctional response has recently gained support. However, the different phenotypes and the implication of others myeloid cells in the human pathology have not been determined yet. In this work, we analyzed the phenotypic profile displayed by damage-associated myeloid cells in two AD vulnerable brain regions, the frontal cortex and hippocampus. For this purpose, immunohistochemistry and image analysis approaches have been carried out in postmortem brain samples from patients with AD (Braak VVI stage) and aged controls without neurological symptoms (Braak 0-II stage). Damage-associated microglial cells were clustered around amyloid plaques and expressed Iba1, CD32,TMEM119, CD68,Trem2 and CD45high. A subset of these cells also expressed ferritin and Gal-3. However, and even though some Braak II individuals accumulated reactive CD45 and CD68-positive plaques, only AD patients exhibited parenchymal infiltration of CD163-positive monocyte-derived cells that invaded plaque near blood vessels. While the frontal cortex showed strong microglial activation similar to that reported in amyloidogenic mice, the hippocampus of the same patients showed an attenuated microglial activation with a degenerative phenotype. These results reveal the co-existence of distinct myeloid populations associated with amyloid plaques during disease progression, as well their region-specific contribution to neuroimmune protection. These findings open the opportunity to design targeted therapies, not only to microglia, but also to the population of macrophages to modulate amyloid pathology and provide a better understanding of the immunological mechanisms underlying AD progression.Supported by ISCiii grants (PI21-0915 (AG), PI21-00914 (JV)); FEDER funds from European Union, by Junta de Andalucia grants (P18-RT-2233 (AG), US-1262734 (JV)); Programa Operativo FEDER 2014-2020, and by grant PPIT.UMA.B1-2019-07 (ESM). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Comparing astroglial reactivity in two transgenic mouse models of tauopathy

Astrocytes are becoming crucial players in the pathology of neurodegenerative disorders, such as Alzheimer’s disease (AD). Astrocyte responses have been mainly analyzed in the context of amyloid-beta (Abeta) pathology, highlighting their role in the development/progression of amyloidosis and their relationship with the microglial response. Regarding tau pathology, some studies have reported that astrocytes respond to hyperphosphorylated tau (phospho-tau) and suggested their implication on tau transmission/elimination. Here, we aimed to analyze the astroglial reactivity to tau pathology in the hippocampus of two transgenic mouse models of tauopathy, ThyTau22 and P301S. Proteinopathy was assessed by western-blotting and immunohistochemistry using phospho-tau antibodies (AT8). Inflammatory markers (GFAP, Iba-1, CD45, TREM2) were analyzed by qPCR and immunohistochemistry for bright-field microscopy; glial-phospho-tau relationship was analyzed under confocal and transmission electron microscopy. P301S mice exhibited an intense reactive astrogliosis, increasing with aging in parallel to a strong phospho-tau pathology. ThyTau22 model showed a slighter astrocyte reactivity accompanied by a lesser accumulation of phospho-tau. Astrogliosis in P301S mice closely correlated with an acute DAM-like microglial activation, not observed in ThyTau22 hippocampus. Confocal and ultrastructural studies revealed that, in both models, astrocytic processes contained phospho-tau, especially those surrounding blood vessels. Our results support that astrocytes respond to tau pathology in the absence of Abeta. This reactivity highly correlates with phospho-tau pathology and markedly depends on microglial activation. Moreover, astrocytes may play a role in the elimination/spreading of phospho-tau species through the brain. Deciphering the mechanisms underlying these processes might help to develop therapies to slow down the progression of AD.Supported by Instituto de Salud Carlos III (ISCiii) of Spain, co-financed by FEDER funds from European Union through grants PI18/01557 (to AG), PI18/01556 (to JV), and by Junta de Andalucia through Consejería de Economía y Conocimiento grants UMA18-FEDERJA-211 (AG), P18-RT-2233 (AG) and US-1262734 (JV) co-financed by Programa Operativo FEDER2014-2020. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Plaque-Associated Oligomeric Amyloid-Beta Drives Early Synaptotoxicity in APP/PS1 Mice Hippocampus: Ultrastructural Pathology Analysis

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by initial memory impairments that progress to dementia. In this sense, synaptic dysfunction and loss have been established as the pathological features that best correlate with the typical early cognitive decline in this disease. At the histopathological level, post mortem AD brains typically exhibit intraneuronal neurofibrillary tangles (NFTs) along with the accumulation of amyloid-beta (Abeta) peptides in the form of extracellular deposits. Specifically, the oligomeric soluble forms of Abeta are considered the most synaptotoxic species. In addition, neuritic plaques are Abeta deposits surrounded by activated microglia and astroglia cells together with abnormal swellings of neuronal processes named dystrophic neurites. These periplaque aberrant neurites are mostly presynaptic elements and represent the first pathological indicator of synaptic dysfunction. In terms of losing synaptic proteins, the hippocampus is one of the brain regions most affected in AD patients. In this work, we report an early decline in spatial memory, along with hippocampal synaptic changes, in an amyloidogenic APP/PS1 transgenic model. Quantitative electron microscopy revealed a spatial synaptotoxic pattern around neuritic plaques with significant loss of periplaque synaptic terminals, showing rising synapse loss close to the border, especially in larger plaques. Moreover, dystrophic presynapses were filled with autophagic vesicles in detriment of the presynaptic vesicular density, probably interfering with synaptic function at very early synaptopathological disease stages. Electron immunogold labeling showed that the periphery of amyloid plaques, and the associated dystrophic neurites, was enriched in Abeta oligomers supporting an extracellular location of the synaptotoxins. Finally, the incubation of primary neurons with soluble fractions derived from 6-month-old APP/PS1 hippocampus induced significant loss of synaptic proteins, but not neuronal death. Indeed, this preclinical transgenic model could serve to investigate therapies targeted at initial stages of synaptic dysfunction relevant to the prodromal and early AD.This study was supported by the Instituto de Salud Carlos III (ISCiii) of Spain, co-financed by the FEDER funds from European Union, through grants PI18/01557 (to AG) and PI18/01556 (to JV); by the Junta de Andalucia Consejería de Economía y Conocimiento through grants UMA18-FEDERJA-211 (to AG), P18-RT-2233 (to AG), and US-1262734 (to JV) co-financed by Programa Operativo FEDER 2014–2020; by the Spanish Minister of Science and Innovation grant PID2019-108911RA-100 (to DB-V), Beatriz Galindo program BAGAL18/00052 (to DB-V) grant PID2019-107090RA-I00 (to IM-G), and Ramon y Cajal Program RYC-2017-21879 (to IM-G); and by the Malaga University grants B1-2019_07 (to ES-M) and B1-2019_06 (to IM-G). MM-O held a predoctoral contract from Malaga University and ES-M a postdoctoral contract (DOC_00251) from Junta de Andalucia

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass