Role of Striatal-Enriched Protein Tyrosine Phosphatase (STEP) in the control of microglial

Protein tyrosine phosphatases (PTPs) are key regulatory factors in inflammatory signaling pathways. The central nervous system has as resident immune cells the microglial cells, which participate in the initiation and propagation of the inflammatory response. STriatal-Enriched Protein Tyrosine Phosphatase (STEP) is a central nervous system specific phosphatase encoded by the PTPN5 gene. STEP mRNA is alternatively spliced into the membrane-associated STEP61 and the cytosolic STEP46. Accumulating evidence implicates STEP dysregulation in the molecular basis of several neuropsychiatric disorders. Published data about STEP, focus on expression and role at the neuronal level. To our knowledge, there are no published data on the expression of STEP by microglial cells or on the regulation of microglial reactivity by this phosphatase. Our results from PCR analysis show the expression of STEP mRNA in primary cultures of microglia obtained from rat brain. STEP expression was further confirmed by the immunocytochemical analysis and Western blot. On the other hand, STEP expression levels appear to be regulated by exposure to inflammatory stimuli. Microglia cultures exposed to the pro-inflammatory agent lipopolysaccharide (LPS) showed increased levels of STEP61 and STEP46. To examine the role of STEP in the control of microglia reactivity induced by LPS, we used a specific pharmacological inhibitor of STEP (TC-2153). STEP inhibition significantly reduced the number of microglial cells expressing inducible nitric oxide synthase (iNOS) and the number of phagocytic cells quantified after LPS stimulation. On the other hand, inhibition of STEP did not significantly affect the nitric oxide (NO) release and the expression of Interleukin 1 beta (IL-1ß) or tumor necrosis factor alpha (TNFa). Taken together, our results show that STEP is expressed by cells that do not belong to the neuronal lineage and suggest that STEP participates in some of the pathways involved in microglia reactivity.As proteínas tirosina fosfatases (PTPs) são fatores reguladores nas vias de sinalização inflamatórias. O sistema nervoso central tem como células imunes residentes as células microgliais, as quais participam no início e na propagação da resposta inflamatória. A proteína fosfatase de resíduos de tirosina enriquecida no estriado (STEP), é uma fosfatase específica do sistema nervoso central codificada pelo gene PTPN5. O mRNA STEP origina por splicing alternativo a STEP61, isoforma associada à membrana e a STEP46, isoforma citosólica. A desregulação da STEP está implícita na base molecular de vários distúrbios neuropsiquiátricos. Os estudos publicados sobre a STEP centram-se na expressão e papel a nível neuronal. Tanto quanto é do nosso conhecimento não existem dados publicados sobre a expressão da STEP pela microglia ou sobre a regulação da reatividade microglial por esta fosfatase. Os nossos dados da análise de PCR mostraram a expressão do RNAm da STEP em culturas primárias da microglia obtidas a partir de cérebro de rato. A presença da proteína STEP foi também verificada por análise imunocitoquímica e Western blot. Por outro lado, os níveis de expressão da STEP parecem ser regulados por exposição a estímulos inflamatórios. Culturas de microglia expostas ao agente pró-inflamatório lipopolissacarídeo (LPS) apresentaram níveis aumentados de STEP61 e STEP46. Como forma de avaliar o papel da STEP no controlo da reatividade da microglia induzida por LPS, recorremos ao inibidor específico da STEP (TC-2153). O tratamento com este inibidor reduziu significativamente o número de células microgliais que expressam a sintase do óxido nítrico induzida (iNOS) e também o número de células fagocitícas quantificadas após a exposição ao LPS. Contudo, a inibição da STEP não afetou significativamente a libertação de óxido nitríco nem a expressão da interleucina-1beta (Il-1ß) ou do fator de necrose tumoral alfa (TNFa). Em suma, nossos resultados mostram que a STEP é expressa por células que não pertencem à linhagem neuronal, e sugerem que a STEP participa em algumas das vias envolvidas na reatividade da microglial

Different risk profiles for progression of nonproliferative diabetic retinopathy: a 2-year study

Characterization of 2-year progression of different risk phenotypes in eyes with mild and moderate nonproliferative diabetic retinopathy (NPDR) in type 2 diabetes (T2D). A 2-year prospective longitudinal cohort study (CORDIS, NCT03696810) was conducted. Ophthalmological examinations were performed including best corrected visual acuity, color fundus photography and optical coherence tomography (OCT and OCTA). OCT metrics, central retinal thickness and ganglion cell layer + inner plexiform layer (GCL + IPL) thickness were analyzed. OCTA metrics, vessel density (VD), perfusion density (PD) and area of intercapillary spaces (AIS) were obtained from superficial and deep capillary plexus (SCP, DCP). Only phenotype C identified by decreased VD ≥ 2 SD of healthy controls and phenotype B identified by subclinical macular edema with decreased VD < 2 SD of healthy controls were included. One hundred twenty-two eyes from T2D individuals were included in study; 65 eyes (53%) were classified as phenotype B and 57 eyes (47%) as phenotype C. For phenotype B, progression was associated with thinning of the GCL + IPL (ETDRS 35, 1 year p = 0.013, 2 year p < 0.001; ETDRS 43–47, 2 year p = 0.003) and vessel closure involving mainly the DCP for both ETDRS grades (ETDRS 35, 1 year p = 0.025, 2 year p = 0.034; ETDRS 43–47, 1 year p = 0.011). For phenotype C there was also progressive thinning of the GCL + IPL (ETDRS 35, in both years p ≤ 0.001; ETDRS 43–47, 1 year p = 0.002, 2 year p = 0.001), with vessel closure involving mainly SCP (ETDRS 35, 1 year p = 0.012, 2 year p = 0.023 in full-retina), which appeared to stabilize at maximal values in ETDRS grade 43–47 at the end of 2 years. ETDRS severity changes at the end of the 2-year period showed that worsening was associated with phenotype C with changes involving predominantly the SCP (VD, p = 0.005; PD, p = 0.008; AIS, p = 0.005). Association between ETDRS classification of NPDR severity and identification of different risk phenotypes offers new perspective to predict disease progression in T2D individuals with NPDR.info:eu-repo/semantics/publishedVersio

CD45RA, CD8β, and IFNγ Are Potential Immune Biomarkers of Human Cognitive Function

There is increasing evidence that in humans the adaptive immunological system can influence cognitive functions of the brain. We have undertaken a comprehensive immunological analysis of lymphocyte and monocyte populations as well as of HLA molecules expression in a cohort of elderly volunteers (age range, 64-101) differing in their cognitive status. Hereby, we report on the identification of a novel signature in cognitively impaired elderly characterized by: (1) elevated percentages of CD8+ T effector-memory cells expressing high levels of the CD45RA phosphate receptor (Temra hi); (2) high percentages of CD8+ T cells expressing high levels of the CD8β chain (CD8βhi); (3) augmented production of IFNγ by in vitro activated CD4+ T cells. Noteworthy, CD3+CD8+ Temra hi and CD3+CD8βhi cells were associated with impaired cognition. Cytomegalovirus seroprevalence showed that all volunteers studied but one were CMV positive. Finally, we show that some of these phenotypic and functional features are associated with an increased frequency of the HLA-B8 serotype, which belongs to the ancestral haplotype HLA-A1, Cw7, B8, DR3, DQ2, among cognitively impaired volunteers. To our knowledge, this is the first proof in humans linking the amount of cell surface CD45RA and CD8β chain expressed by CD8+ Temra cells, and the amount of IFNγ produced by in vitro activated CD4+ T cells, with impaired cognitive function in the elderly.info:eu-repo/semantics/publishedVersio

In vitro IL-15-activated human naïve CD8+ T cells down-modulate the CD8β chain and become CD8αα T cells

Antigen-driven human effector-memory CD8+ T cells expressing low levels of the CD8β chain have been previously described. However, little is known on a possible antigen-independent trigger. We have examined the impact that IL-15 has on the expression of CD8β on purified human naïve CD8+ T cells after CFSE labeling and culture with IL-15. As expected, IL-15 induced naïve CD8+ T cells to proliferate and differentiate. Remarkably, the process was associated with a cell-cycle dependent down-modulation of CD8β from the cell surface, leading to the generation of CD8αβlow and CD8αβ− (i.e., CD8αα) T cells. In contrast, expression of the CD8α chain remained steady or even increased. Neither IL-2 nor IL-7 reproduced the effect of IL-15. Determination of mRNA levels for CD8α and CD8β isoforms by qPCR revealed that IL-15 promoted a significant decrease in mRNA levels of the CD8β M-4 isoform, while levels of the M-1/M-2 isoforms and of CD8α increased. Noteworthy, CD8+ T cell blasts obtained after culture of CD8+ T cells with IL-15 showed a cell-cycle dependent increase in the level of the tyrosine kinase Lck, when compared to CD8+ T cells at day 0. This study has shown for the first time that IL-15 generates CD8αα+αβlow and CD8αα+αβ− T cells containing high levels of Lck, suggesting that they may be endowed with unique functional features

HLA‐A23/HLA‐A24 serotypes and dementia interaction in the elderly: Association with increased soluble HLA class I molecules in plasma

MHC class I molecules regulate brain development and plasticity in mice and HLA class I molecules are associated with brain disorders in humans. We investigated the relationship between plasma-derived soluble human HLA class I molecules (sHLA class I), HLA class I serotypes and dementia. A cohort of HLA class I serotyped elderly subjects with no dementia/predementia (NpD, n = 28), or with dementia (D, n = 28) was studied. Multivariate analysis was used to examine the influence of dementia and HLA class I serotype on sHLA class I levels, and to compare sHLA class I within four groups according to the presence or absence of HLA-A23/A24 and dementia. HLA-A23/A24 and dementia, but not age, significantly influenced the level of sHLA class I. Importantly, the concurrent presence of HLA-A23/A24 and dementia was associated with higher levels of sHLA class I (p < 0.001). This study has shown that the simultaneous presence of HLA-A23/HLA-A24 and dementia is associated with high levels of serum sHLA class I molecules. Thus, sHLA class I could be considered a biomarker of neurodegeneration in certain HLA class I carriers.info:eu-repo/semantics/publishedVersio