Hipertensão pulmonar na cardiopatia reumática

Orientador: Paulo Franco de OliveiraDissertaçao (mestrado) - Universidade Federal do Paraná. Curso de Pós-Graduação em Cardiologi

Endoplasmic reticulum-mitochondria crosstalk and beta-cell destruction in type 1 diabetes

Beta-cell destruction in type 1 diabetes (T1D) results from the combined effect of inflammation and recurrent autoimmunity. In response to inflammatory signals, beta-cells engage adaptive mechanisms where the endoplasmic reticulum (ER) and mitochondria act in concert to restore cellular homeostasis. In the recent years it has become clear that this adaptive phase may trigger the development of autoimmunity by the generation of autoantigens recognized by autoreactive CD8 T cells. The participation of the ER stress and the unfolded protein response to the increased visibility of beta-cells to the immune system has been largely described. However, the role of the other cellular organelles, and in particular the mitochondria that are central mediator for beta-cell survival and function, remains poorly investigated. In this review we will dissect the crosstalk between the ER and mitochondria in the context of T1D, highlighting the key role played by this interaction in beta-cell dysfunctions and immune activation, especially through regulation of calcium homeostasis, oxidative stress and generation of mitochondrial-derived factors.Therapeutic cell differentiatio

Conversion of Mature Human β-Cells Into Glucagon-Producing α-Cells

Conversion of one terminally differentiated cell type into another (or transdifferentiation) usually requires the forced expression of key transcription factors. We examined the plasticity of human insulin-producing β-cells in a model of islet cell aggregate formation. Here, we show that primary human β-cells can undergo a conversion into glucagon-producing α-cells without introduction of any genetic modification. The process occurs within days as revealed by lentivirus-mediated β-cell lineage tracing. Converted cells are indistinguishable from native α-cells based on ultrastructural morphology and maintain their α-cell phenotype after transplantation in vivo. Transition of β-cells into α-cells occurs after β-cell degranulation and is characterized by the presence of β-cell–specific transcription factors Pdx1 and Nkx6.1 in glucagon+ cells. Finally, we show that lentivirus-mediated knockdown of Arx, a determinant of the α-cell lineage, inhibits the conversion. Our findings reveal an unknown plasticity of human adult endocrine cells that can be modulated. This endocrine cell plasticity could have implications for islet development, (patho)physiology, and regeneration

IFN(sic) but not IFNa increases recognition of insulin defective ribosomal product-derived antigen to amplify islet autoimmunity

Aims/hypothesisThe inflammatory milieu characteristic of insulitis affects translation fidelity and generates defective ribosomal products (DRiPs) that participate in autoimmune beta cell destruction in type 1 diabetes. Here, we studied the role of early innate cytokines (IFNα) and late immune adaptive events (IFNɣ) in insulin DRiP-derived peptide presentation to diabetogenic CD8+ T cells.MethodsSingle-cell transcriptomics of human pancreatic islets was used to study the composition of the (immuno)proteasome. Specific inhibition of the immunoproteasome catalytic subunits was achieved using siRNA, and antigenic peptide presentation at the cell surface of the human beta cell line EndoC-βH1 was monitored using peptide-specific CD8 T cells.ResultsWe found that IFNγ induces the expression of the PSMB10 transcript encoding the β2i catalytic subunit of the immunoproteasome in endocrine beta cells, revealing a critical role in insulin DRiP-derived peptide presentation to T cells. Moreover, we showed that PSMB10 is upregulated in a beta cell subset that is preferentially destroyed in the pancreases of individuals with type 1 diabetes.Conclusions/interpretationOur data highlight the role of the degradation machinery in beta cell immunogenicity and emphasise the need for evaluation of targeted immunoproteasome inhibitors to limit beta cell destruction in type 1 diabetes.Nephrolog

Single-cell transcriptomics links loss of human pancreatic beta-cell identity to ER stress

The maintenance of pancreatic islet architecture is crucial for proper beta-cell function. We previously reported that disruption of human islet integrity could result in altered beta-cell identity. Here we combine beta-cell lineage tracing and single-cell transcriptomics to investigate the mechanisms underlying this process in primary human islet cells. Using drug-induced ER stress and cytoskeleton modification models, we demonstrate that altering the islet structure triggers an unfolding protein response that causes the downregulation of beta-cell maturity genes. Collectively, our findings illustrate the close relationship between endoplasmic reticulum homeostasis and beta-cell phenotype, and strengthen the concept of altered beta-cell identity as a mechanism underlying the loss of functional beta-cell mass.Diabetes mellitus: pathophysiological changes and therap

Long RNA sequencing and ribosome profiling of inflamed beta-cells reveal an extensive translatome landscape

Type 1 diabetes (T1D) is an autoimmune disease characterized by autoreactive T cell-mediated destruction of the insulin-producing pancreatic beta -cells. Increasing evidence suggest that the beta -cells themselves contribute to their own destruction by generating neoantigens through the production of aberrant or modified proteins that escape central tolerance. We recently demonstrated that ribosomal infidelity amplified by stress could lead to the generation of neoantigens in human beta -cells, emphasizing the participation of nonconventional translation events in autoimmunity, as occurring in cancer or virus-infected tissues. Using a transcriptome-wide profiling approach to map translation initiation start sites in human beta -cells under standard and inflammatory conditions, we identify a completely new set of polypeptides derived from noncanonical start sites and translation initiation within long noncoding RNA. Our data underline the extreme diversity of the beta -cell translatome and may reveal new functional biomarkers for beta -cell distress, disease prediction and progression, and therapeutic intervention in T1D.Molecular Epidemiolog

Apolipoprotein L genes are novel mediators of inflammation in beta cells

Aims/hypothesisInflammation induces beta cell dysfunction and demise but underlying molecular mechanisms remain unclear. The apolipoprotein L (APOL) family of genes has been associated with innate immunity and apoptosis in non-pancreatic cell types, but also with metabolic syndrome and type 2 diabetes mellitus. Here, we hypothesised that APOL genes play a role in inflammation-induced beta cell damage.MethodsWe used single-cell transcriptomics datasets of primary human pancreatic islet cells to study the expression of APOL genes upon specific stress conditions. Validation of the findings was carried out in EndoC-βH1 cells and primary human islets. Finally, we performed loss- and gain-of-function experiments to investigate the role of APOL genes in beta cells.ResultsAPOL genes are expressed in primary human beta cells and APOL1, 2 and 6 are strongly upregulated upon inflammation via the Janus kinase (JAK)−signal transducer and activator of transcription (STAT) pathway. APOL1 overexpression increases endoplasmic reticulum stress while APOL1 knockdown prevents cytokine-induced beta cell death and interferon-associated response. Furthermore, we found that APOL genes are upregulated in beta cells from donors with type 2 diabetes compared with donors without diabetes mellitus.Conclusions/interpretationAPOLs are novel regulators of islet inflammation and may contribute to beta cell damage during the development of diabetes.Therapeutic cell differentiatio

Proteasomal Degradation of Proinsulin Requires Derlin-2, HRD1 and p97

Nephrolog

Update on HHV-8-Associated Malignancies

The human herpesvirus 8 (HHV-8) is the oncogenic virus associated with Kaposi’s sarcoma (KS) and lymphoproliferative disorders, namely, primary effusion lymphoma and multicentric Castleman’s disease. KS is among the most common malignancies seen in HIV-infected patients despite the decreased incidence of KS in the era of highly active antiretroviral therapy. Advances in molecular pathology reveal HHV-8 tumorigenesis is mediated through molecular mimicry wherein viral-encoded proteins can activate several cellular signaling cascades while evading immune surveillance. This knowledge has led to the evolution of multiple therapeutic strategies against specific molecular targets. Many such therapeutic modalities have shown activity, but none have proven to be curative. Identifying possible prognostic factors is another active area of research. This review summarizes the recent developments in the fields of virus transmission, molecular biology, and treatment of HHV-8-related neoplasms

Identification of germline cancer predisposition variants in pediatric sarcoma patients from somatic tumor testing

Genetic predisposition is an important risk factor for cancer in children and adolescents but detailed associations of individual genetic mutations to childhood cancer are still under intense investigation. Among pediatric cancers, sarcomas can arise in the setting of cancer predisposition syndromes. The association of sarcomas with these syndromes is often missed, due to the rarity and heterogeneity of sarcomas and the limited search of cancer genetic syndromes. This study included 43 pediatric and young adult patients with different sarcoma subtypes. Tumor profiling was undertaken using the Oncomine Childhood Cancer Research Assay (Thermo Fisher Scientific). Sequencing results were reviewed for potential germline alterations in clinically relevant genes associated with cancer predisposition syndromes. Jongmans¿ criteria were taken into consideration for the patient selection. Fifteen patients were selected as having potential pathogenic germline variants due to tumor sequencing that identified variants in the following genes: CDKN2A, NF1, NF2, RB1, SMARCA4, SMARCB1 and TP53. The variants found in NF1 and CDKN2A in two different patients were detected in the germline, confirming the diagnosis of a cancer predisposition syndrome. We have shown that the results of somatic testing can be used to identify those at risk of an underlying cancer predisposition syndrome