Pro-inflammatory monocyte phenotype during acute progression of cerebral small vessel disease
Ontology highlight
ABSTRACT: The aetiology of cerebral small vessel disease (SVD) remains elusive, though currently evidence is accumulating that inflammation contributes to its pathophysiology. In this prospective high-frequency imaging study, we showed that the incidence of acute SVD progression coincides with a functional and transcriptional pro-inflammatory monocyte phenotype. To detect SVD progression, individuals with SVD underwent monthly magnetic resonance imaging (MRI) for 10 consecutive months. RNA sequencing revealed a pro-inflammatory monocyte signature with upregulation of the EGR2 gene. Collectively, we showed that individuals with progressive SVD have pro-inflammatory circulating monocytes characterized by an augmented cytokine production capacity and a pro-inflammatory transcriptional signature.
Project description:The intricate aetiology of type 1 diabetes mellitus (T1DM) implicating a detrimental cross talk between immune cells and insulin producing b-cells leading to their destruction has stumped the development of effective disease modifying therapies. The discovery that the pharmacological activation of LRH-1/NR5A2 can revert hyperglycemia in pre-clinical mouse models of T1DM by attenuating the autoimmune attack coupled to b-cell survival/regeneration, prompt us to investigate whether LRH-1/NR5A2-mediated immune tolerization could be achieved in individuals with T1DM and improve islet survival and function subsequent to xenotransplantation. We found that LRH-1/NR5A2 activation using the agonist BL001 blunted the pro-inflammatory genetic signature and cytokine secretome of both monocyte-derived macrophages (MDM1) and mature dendritic cells (mDCs) from individuals with T1DM. Mechanistically, mitohormesis was induced in MDM1 restricting pro-inflammation propagation while mitochondria turnover was increased in mDCs assisting transit towards a tolerogenic phenotype. BL001 treatment also increased T-regulatory cells within the T-cell subpopulation. BL001-treated MDM1, mDCs or T-cells impeded T-effector cell expansion. Engraftment and function of human islets transplanted into hyperglycemic immunocompetent mice was enhanced by BL001 treatment leading to improved glycemia. Collectively, LRH-1/NR5A2 agonism fosters a coordinated re-programming of T1DM immune cells from a pro- to an anti-inflammatory/tolerizing phenotype empowering them to repress cytotoxic T-cell proliferation and facilitates islet engraftment and function after transplantation. Our finding demonstrate the feasibility of re-establishing human immune tolerance within a pro-inflammatory environment, rather than suppression, opening an unprecedent pharmacological therapeutic venue for T1DM
Project description:The intricate aetiology of type 1 diabetes mellitus (T1DM) implicating a detrimental cross talk between immune cells and insulin producing -cells leading to their destruction has stumped the development of effective disease modifying therapies. The discovery that the pharmacological activation of LRH-1/NR5A2 can revert hyperglycemia in pre-clinical mouse models of T1DM by attenuating the autoimmune attack coupled to -cell survival/regeneration, prompt us to investigate whether LRH-1/NR5A2-mediated immune tolerization could be achieved in individuals with T1DM and improve islet survival and function subsequent to xenotransplantation. We found that LRH-1/NR5A2 activation using the agonist BL001 blunted the pro-inflammatory genetic signature and cytokine secretome of both monocyte-derived macrophages (MDM1) and mature dendritic cells (mDCs) from individuals with T1DM. Mechanistically, mitohormesis was induced in MDM1 restricting pro-inflammation propagation while mitochondria turnover was increased in mDCs assisting transit towards a tolerogenic phenotype. BL001 treatment also increased T-regulatory cells within the T-cell subpopulation. BL001-treated MDM1, mDCs or T-cells impeded T-effector cell expansion. Engraftment and function of human islets transplanted into hyperglycemic immunocompetent mice was enhanced by BL001 treatment leading to improved glycemia. Collectively, LRH-1/NR5A2 agonism fosters a coordinated re-programming of T1DM immune cells from a pro- to an anti-inflammatory/tolerizing phenotype empowering them to repress cytotoxic T-cell proliferation and facilitates islet engraftment and function after transplantation. Our finding demonstrate the feasibility of re-establishing human immune tolerance within a pro-inflammatory environment, rather than suppression, opening an unprecedent pharmacological therapeutic venue for T1DM.
Project description:In this study, we performed the first genome-wide expression profiling of post-mortem brains of a cohort of patients deceased from SVD and compared them to age-matched normal controls. Normal-appearing frontal temporal and occipital cortical and subcortical brain samples were dissected at autopsy from 5 patients diagnosed with pure SVD and 5 control patients without neurological disease and immediately frozen.
Project description:CD14+ monocytes, the predominant population in human blood, are primarily engaged in host defense and pro-inflammatory cytokine responses. Aberrant monocyte activity causes life-threatening cytokine storms, while dysfunctional monocytes lead to 'immunoparalysis.' Understanding the mechanisms controlling monocyte functions is therefore paramount. Here, we reveal platelets' vital role in human monocytes' pro-inflammatory responses. Natural low platelet counts in patients with immune thrombocytopenia (ITP) , platelet depletion in healthy human monocytes, or in vivo platelet depletion in mice, result in monocyte immunoparalysis, characterized by reduced pro-inflammatory gene expression and weakened cytokine responses to immune challenge. Remarkably, supplementation with fresh platelets reverses monocyte immunoparalysis. In mice, thrombocytopenia results in down-regulation of myeloid innate immune genes, and compromised host defense transcriptional programs in monocytes despite normal responses to LPS. Platelets control monocyte cytokines independently of traditional cross-talk pathways, acting as reservoirs of transcription factors like NF?B and MAPK p38. We pinpointed a vesicle-derived NF?B2 transfer to human monocytes by mass spectrometry-based proteomics. Functionally, platelets proportionally restored impaired cytokine secretion in human monocytes lacking MAPK p38a and NF?B p65 and NF?B2. We unveil the intercellular transfer of inflammatory regulators, positioning platelets as central checkpoints in monocyte-mediated inflammation.
Project description:Chronic myelomonocytic leukemia (CMML) is an aggressive myeloid neoplasm of older individuals characterized by persistent monocytosis. Somatic mutations in CMML are heterogeneous and only partially explain the variability in clinical outcomes. Recent data suggest that cardiovascular morbidity is increased in CMML and contributes to reduced survival. Clonal hematopoiesis of indeterminate potential (CHIP), the presence of mutated blood cells in hematologically normal individuals, is a precursor of age-related myeloid neoplasms and associated with increased cardiovascular risk. To isolate CMML-specific alterations from those related to aging, we performed RNA sequencing and DNA methylation profiling on purified monocytes from CMML patients and from age-matched (old) and young healthy controls. We found that the transcriptional signature of CMML monocytes is highly pro-inflammatory, with upregulation of multiple inflammatory pathways, including tumor necrosis factor, IL-6 and IL-17 signaling, while age per se does not significantly contribute to this pattern. We observed no consistent correlations between aberrant gene expression and CpG island methylation, suggesting that pro-inflammatory signaling in CMML monocytes is governed by multiple and complex regulatory mechanisms. We propose that pro-inflammatory monocytes may contribute to cardiovascular morbidity in CMML patients, and promote progression by selection of mutated cell clones. Our data raise questions whether asymptomatic CMML patients may benefit from monocyte-depleting or anti-inflammatory therapies.