The Onset of Intussusceptive Angiogenesis in COVID-19 Patients Might Come from the Mobilization of Stem Cell Sub-Populations Expressing the Hemangioblast Marker CD143.

COVID-19 and infectious diseases have been included in strategic development goals (SDG) of United Nations (UN). The SARS-CoV-2 pandemic has unveiled complex pathophysiological mechanisms underpinning COVID-19, notably inducing a systemic acquired vascular hemopathy characterized by endothelial dysfunction and intussusceptive angiogenesis, a rapid vascular remodeling process identified as a hallmark in severe COVID-19 cases affecting pulmonary and cardiac tissues. Stem cell migration have been proposed as significant regulators of this neoangiogenic process. In a monocentric cross-sectional study, through spectral flow cytometry analysis of peripheral blood mononuclear cells, we identified a distinct stem cell subpopulation mobilized in critical COVID-19. Indeed, by an unsupervised analysis generating a UMAP representation we highlighted eleven different clusters in critical and non-critical COVID-19 patients. Only one cluster was significantly associated to critical COVID-19 compared to non-critical patients. This cluster expressed the markers: CD45dim, CD34+, CD117+, CD147+, and CD143+, and were negative for CD133. Higher level of expression of hemangioblast markers CD143 were found in critical COVID-19 patients. This population, indicative of hemangioblast-like cells, suggests a key role in COVID-19-related neoangiogenesis, potentially driving the severe vascular complications observed. Our findings underscore the need for further investigation into the contributions of adult stem cells in COVID-19 pathology, offering new insights into therapeutic targets and interventions.

Residual ANTXR1+ myofibroblasts after chemotherapy inhibit anti-tumor immunity via YAP1 signaling pathway.

Although cancer-associated fibroblast (CAF) heterogeneity is well-established, the impact of chemotherapy on CAF populations remains poorly understood. Here we address this question in high-grade serous ovarian cancer (HGSOC), in which we previously identified 4 CAF populations. While the global content in stroma increases in HGSOC after chemotherapy, the proportion of FAP+ CAF (also called CAF-S1) decreases. Still, maintenance of high residual CAF-S1 content after chemotherapy is associated with reduced CD8+ T lymphocyte density and poor patient prognosis, emphasizing the importance of CAF-S1 reduction upon treatment. Single cell analysis, spatial transcriptomics and immunohistochemistry reveal that the content in the ECM-producing ANTXR1+ CAF-S1 cluster (ECM-myCAF) is the most affected by chemotherapy. Moreover, functional assays demonstrate that ECM-myCAF isolated from HGSOC reduce CD8+ T-cell cytotoxicity through a Yes Associated Protein 1 (YAP1)-dependent mechanism. Thus, efficient inhibition after treatment of YAP1-signaling pathway in the ECM-myCAF cluster could enhance CD8+ T-cell cytotoxicity. Altogether, these data pave the way for therapy targeting YAP1 in ECM-myCAF in HGSOC.

Repeated peripheral infusions of anti-EGFRvIII CAR T cells in combination with pembrolizumab show no efficacy in glioblastoma: a phase 1 trial.

We previously showed that chimeric antigen receptor (CAR) T-cell therapy targeting epidermal growth factor receptor variant III (EGFRvIII) produces upregulation of programmed death-ligand 1 (PD-L1) in the tumor microenvironment (TME). Here we conducted a phase 1 trial (NCT03726515) of CAR T-EGFRvIII cells administered concomitantly with the anti-PD1 (aPD1) monoclonal antibody pembrolizumab in patients with newly diagnosed, EGFRvIII+ glioblastoma (GBM) (n = 7). The primary outcome was safety, and no dose-limiting toxicity was observed. Secondary outcomes included median progression-free survival (5.2 months; 90% confidence interval (CI), 2.9-6.0 months) and median overall survival (11.8 months; 90% CI, 9.2-14.2 months). In exploratory analyses, comparison of the TME in tumors harvested before versus after CAR + aPD1 administration demonstrated substantial evolution of the infiltrating myeloid and T cells, with more exhausted, regulatory, and interferon (IFN)-stimulated T cells at relapse. Our study suggests that the combination of CAR T cells and PD-1 inhibition in GBM is safe and biologically active but, given the lack of efficacy, also indicates a need to consider alternative strategies.

Detection of the interactions of tumour derived extracellular vesicles with immune cells is dependent on EV-labelling methods.

Cell-cell communication within the complex tumour microenvironment is critical to cancer progression. Tumor-derived extracellular vesicles (TD-EVs) are key players in this process. They can interact with immune cells and modulate their activity, either suppressing or activating the immune system. Deciphering the interactions between TD-EVs and immune cells is essential to understand immune modulation by cancer cells. Fluorescent labelling of TD-EVs is a method of choice to study such interaction. This work aims to determine the impact of EV labelling methods on the detection by imaging flow cytometry and multicolour spectral flow cytometry of EV interaction and capture by the different immune cell types within human Peripheral Blood Mononuclear Cells (PBMCs). EVs released by the triple-negative breast carcinoma cell line MDA-MB-231 were labelled either with the lipophilic dye MemGlow-488 (MG-488), Carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE) or through ectopic expression of a MyrPalm-superFolderGFP reporter (mp-sfGFP), which incorporates into EVs during their biogenesis. Our results show that these labelling strategies, although analysed with the same techniques, led to diverging results. While MG-488-labelled EVs incorporate in all cell types, CFSE-labelled EVs are restricted to a minor subset of cells and mp-sfGFP-labelled EVs are mainly detected in CD14+ monocytes which are the main uptakers of EVs and other particles, regardless of the labelling method. Furthermore, our results show that the method used for EV labelling influences the detection of the different types of EV interactions with the recipient cells. Specifically, MG-488, CFSE and mp-sfGFP result in observation suggesting, respectively, transient EV-PM interaction that results in dye transfer, EV content delivery, and capture of intact EVs. Consequently, the type of EV labelling method has to be considered as they can provide complementary information on various types of EV-cell interaction and EV fate.

DRAG in situ barcoding reveals an increased number of HSPCs contributing to myelopoiesis with age.

Ageing is associated with changes in the cellular composition of the immune system. During ageing, hematopoietic stem and progenitor cells (HSPCs) that produce immune cells are thought to decline in their regenerative capacity. However, HSPC function has been mostly assessed using transplantation assays, and it remains unclear how HSPCs age in the native bone marrow niche. To address this issue, we present an in situ single cell lineage tracing technology to quantify the clonal composition and cell production of single cells in their native niche. Our results demonstrate that a pool of HSPCs with unequal output maintains myelopoiesis through overlapping waves of cell production throughout adult life. During ageing, the increased frequency of myeloid cells is explained by greater numbers of HSPCs contributing to myelopoiesis rather than the increased myeloid output of individual HSPCs. Strikingly, the myeloid output of HSPCs remains constant over time despite accumulating significant transcriptomic changes throughout adulthood. Together, these results show that, unlike emergency myelopoiesis post-transplantation, aged HSPCs in their native microenvironment do not functionally decline in their regenerative capacity.

Low-Intensity Pulsed Ultrasound-Mediated Blood-Brain Barrier Opening Increases Anti-Programmed Death-Ligand 1 Delivery and Efficacy in Gl261 Mouse Model.

Therapeutic antibodies targeting immune checkpoints have shown limited efficacy in clinical trials in glioblastoma (GBM) patients. Ultrasound-mediated blood-brain barrier opening (UMBO) using low-intensity pulsed ultrasound improved drug delivery to the brain. We explored the safety and the efficacy of UMBO plus immune checkpoint inhibitors in preclinical models of GBM. A blood-brain barrier (BBB) opening was performed using a 1 MHz preclinical ultrasound system in combination with 10 µL/g microbubbles. Brain penetration of immune checkpoint inhibitors was determined, and immune cell populations were evaluated using flow cytometry. The impact of repeated treatments on survival was determined. In syngeneic GL261-bearing immunocompetent mice, we showed that UMBO safely and repeatedly opened the BBB. BBB opening was confirmed visually and microscopically using Evans blue dye and magnetic resonance imaging. UMBO plus anti-PDL-1 was associated with a significant improvement of overall survival compared to anti-PD-L1 alone. Using mass spectroscopy, we showed that the penetration of therapeutic antibodies can be increased when delivered intravenously compared to non-sonicated brains. Furthermore, we observed an enhancement of activated microglia percentage when combined with anti-PD-L1. Here, we report that the combination of UMBO and anti-PD-L1 dramatically increases GL261-bearing mice's survival compared to their counterparts treated with anti-PD-L1 alone. Our study highlights the BBB as a limitation to overcome in order to increase the efficacy of anti-PD-L1 in GBM and supports clinical trials combining UMBO and in GBM patients.

Bioprosthetic Total Artificial Heart Implantation Does Not Induce Chronic Inflammation.

The Aeson total artificial heart (A-TAH) has been developed for patients at risk of death from biventricular failure. We aimed to assess the inflammatory status in nine subjects implanted with the A-TAH in kinetics over one year. Laboratory assessment of leukocyte counts, inflammatory cytokines assay, and peripheral blood mononuclear cell collection before and after A-TAH implantation. Leukocyte counts were not significantly modulated according to time after A-TAH implantation (coefficient of the linear mixed effect model with 95% CI, -0.05 (-0.71 to -0.61); p = 0.44). We explored inflammatory cytokine after A-TAH and did not observe, at any time, a modified profile compared to pre-implantation values (all p -values > 0.05). Finally, we compared the distribution of circulating immune cell subpopulations identified based on sequential expression patterns for multiple clusters of differentiation. None of the population explored had significant modulation during the 12-month follow-up (all p -values > 0.05). In conclusion, using a cytokine multiplex assay combined with a flow cytometry approach, we demonstrated the absence of inflammatory signals in peripheral blood over a period of 12 months following A-TAH implantation.

Glycolysis Dependency as a Hallmark of SF3B1-Mutated Cells.

SF3B1 mutations are recurrent in cancer and result in aberrant splicing of a previously defined set of genes. Here, we investigated the fate of aberrant transcripts induced by mutant SF3B1 and the related functional consequences. We first demonstrate that mutant SF3B1 does not alter global nascent protein synthesis, suggesting target-dependent consequences. Polysome profiling revealed that 35% of aberrantly spliced transcripts are more translated than their corresponding canonically spliced transcripts. This mostly occurs in genes with enriched metabolic functions. Furthermore, LC-MS/MS analysis showed that mutant SF3B1 impacts the abundance of proteins involved in metabolism. Functional metabolic characterization revealed that mutant SF3B1 decreases mitochondrial respiration and promotes glycolysis to compensate for defective mitochondrial metabolism. Hence, mutant SF3B1 induces glycolysis dependency, which sensitizes cells to glycolysis inhibition. Overall, we provide evidence of the oncogenic involvement of mutant SF3B1 in uveal melanoma through a metabolic switch to glycolysis, revealing vulnerability to glycolysis inhibitors as a promising therapeutic strategy.

TLR or NOD receptor signaling skews monocyte fate decision via distinct mechanisms driven by mTOR and miR-155.

Monocytes are rapidly recruited to inflamed tissues where they differentiate into monocyte-derived macrophages (mo-mac) or dendritic cells (mo-DC). At infection sites, monocytes encounter a broad range of microbial motifs. How pathogen recognition impacts monocyte fate decision is unclear. Here, we show, using an in vitro model allowing the simultaneous differentiation of human mo-mac and mo-DC, that viruses promote mo-mac while Mycobacteria favor mo-DC differentiation. Mechanistically, we found that pathogen sensing through toll-like receptor (TLR) ligands increases mo-mac differentiation via mTORC1. By contrast, nucleotide-binding oligomerization domain (NOD) ligands favor mo-DC through the induction of TNF-α secretion and miR-155 expression. We confirmed these results in vivo, in mouse skin and by analyzing transcriptomic data from human individuals. Overall, our findings allow a better understanding of the molecular control of monocyte differentiation and of monocyte plasticity upon pathogen sensing.

Elevated Circulating Stem Cells Level is Observed One Month After Implantation of Carmat Bioprosthetic Total Artificial Heart.

The Aeson® total artificial heart (A-TAH) has been developed as a total heart replacement for patients at risk of death from biventricular failure. We previously described endothelialization of the hybrid membrane inside A-TAH probably at the origin of acquired hemocompatibility. We aimed to quantify vasculogenic stem cells in peripheral blood of patients with long-term A-TAH implantation. Four male adult patients were included in this study. Peripheral blood mononuclear cells were collected before A-TAH implantation (T0) and after implantation at one month (T1), between two and five months (T2), and then between six and twelve months (T3). Supervised analysis of flow cytometry data confirmed the presence of the previously identified Lin-CD133+CD45- and Lin-CD34+ with different CD45 level intensities. Lin-CD133+CD45-, Lin-CD34+CD45- and Lin-CD34+CD45+ were not modulated after A-TAH implantation. However, we demonstrated a significant mobilization of Lin-CD34+CD45dim (p = 0.01) one month after A-TAH implantation regardless of the expression of CD133 or c-Kit. We then visualized data for the resulting clusters on a uniform manifold approximation and projection (UMAP) plot showing all single cells of the live Lin- and CD34+ events selected from down sampled files concatenated at T0 and T1. The three clusters upregulated at T1 are CD45dim clusters, confirming our results. In conclusion, using a flow cytometry approach, we demonstrated in A-TAH-transplanted patients a significant mobilization of Lin-CD34+CD45dim in peripheral blood one month after A-TAH implantation. Using a flow cytometry approach, we demonstrated in A-TAH transplanted patients a significant mobilization of Lin-CD34+CD45dim in peripheral blood one month after A-TAH implantation. This cell population could be at the origin of newly formed endothelial cells on top of hybrid membrane in Carmat bioprosthetic total artificial heart.

Calpastatin prevents Angiotensin II-mediated podocyte injury through maintenance of autophagy.

The strong predictive value of proteinuria in chronic glomerulopathies is firmly established as well as the pathogenic role of angiotensin II promoting progression of glomerular disease with an altered glomerular filtration barrier, podocyte injury and scarring of glomeruli. Here we found that chronic angiotensin II-induced hypertension inhibited autophagy flux in mouse glomeruli. Deletion of Atg5 (a gene encoding a protein involved autophagy) specifically in the podocyte resulted in accelerated angiotensin II-induced podocytopathy, accentuated albuminuria and glomerulosclerosis. This indicates that autophagy is a key protective mechanism in the podocyte in this condition. Angiotensin-II induced calpain activity in podocytes inhibits autophagy flux. Podocytes from mice with transgenic expression of the endogenous calpain inhibitor calpastatin displayed higher podocyte autophagy at baseline that was resistant to angiotensin II-dependent inhibition. Also, sustained autophagy with calpastatin limited podocyte damage and albuminuria. These findings suggest that hypertension has pathogenic effects on the glomerular structure and function, in part through activation of calpains leading to blockade of podocyte autophagy. These findings uncover an original mechanism whereby angiotensin II-mediated hypertension inhibits autophagy via calcium-induced recruitment of calpain with pathogenic consequences in case of imbalance by calpastatin activity. Thus, preventing a calpain-mediated decrease in autophagy may be a promising new therapeutic strategy for nephropathies associated with high renin-angiotensin system activity.

TREM-1 orchestrates angiotensin II-induced monocyte trafficking and promotes experimental abdominal aortic aneurysm.

The triggering receptor expressed on myeloid cells 1 (TREM-1) drives inflammatory responses in several cardiovascular diseases but its role in abdominal aortic aneurysm (AAA) remains unknown. Our objective was to explore the role of TREM-1 in a mouse model of angiotensin II-induced (AngII-induced) AAA. TREM-1 expression was detected in mouse aortic aneurysm and colocalized with macrophages. Trem1 gene deletion (Apoe-/-Trem1-/-), as well as TREM-1 pharmacological blockade with LR-12 peptide, limited both AAA development and severity. Trem1 gene deletion attenuated the inflammatory response in the aorta, with a reduction of Il1b, Tnfa, Mmp2, and Mmp9 mRNA expression, and led to a decreased macrophage content due to a reduction of Ly6Chi classical monocyte trafficking. Conversely, antibody-mediated TREM-1 stimulation exacerbated Ly6Chi monocyte aorta infiltration after AngII infusion through CD62L upregulation and promoted proinflammatory signature in the aorta, resulting in worsening AAA severity. AngII infusion stimulated TREM-1 expression and activation on Ly6Chi monocytes through AngII receptor type I (AT1R). In human AAA, TREM-1 was detected and TREM1 mRNA expression correlated with SELL mRNA expression. Finally, circulating levels of sTREM-1 were increased in patients with AAA when compared with patients without AAA. In conclusion, TREM-1 is involved in AAA pathophysiology and may represent a promising therapeutic target in humans.

Multidimensional Proteomic Approach of Endothelial Progenitors Demonstrate Expression of KDR Restricted to CD19 Cells.

Endothelial progenitor cells (EPCs) are involved in vasculogenesis and cardiovascular diseases. However, the phenotype of circulating EPCs remains elusive but they are more often described as CD34+KDR+. The aim of the study was to extensively characterize circulating potential vasculogenic stem cell candidates in two populations of patients with cardiovascular disease by powerful multidimensional single cell complementary cytometric approaches (mass, imaging and flow). We identified cellular candidates in one patient before and after bioprosthetic total artificial heart implantation and results were confirmed in healthy peripheral and cord blood by mass cytometry. We also quantified cellular candidates in 10 patients with different COVID-19 severity. Both C-TAH implantation and COVID-19 at critical stage induce a redistribution of circulating CD34+ and CD19+ sub-populations in peripheral blood. After C-TAH implantation, circulating CD34+ progenitor cells expressed c-Kit stem marker while specific subsets CD34+CD133-/+CD45-/dimc-Kit+KDR- were mobilized. KDR was only expressed by CD19+ B-lymphocytes and CD14+ monocytes subpopulations in circulation. We confirmed by mass cytometry this KDR expression on CD19+ in healthy peripheral and cord blood, also with a VE-cadherin expression, confirming absence of endothelial lineage marker on CD34+ subtypes. In COVID-19, a significant mobilization of CD34+c-Kit+KDR- cells was observed between moderate and critical COVID-19 patients regardless CD133 or CD45 expression. In order to better evaluate EPC phenotype, we performed imaging flow cytometry measurements of immature CD34+KDR+ cells in cord blood and showed that, after elimination of non-circular events, those cells were all CD19+. During COVID-19, a significant mobilization of CD19+KDR+ per million of CD45+ cells was observed between moderate and critical COVID-19 patients regardless of CD34 expression. CD34+c-Kit+ cells are mobilized in both cardiovascular disease described here. KDR cells in peripheral blood are CD19 positive cells and are not classic vasculogenic stem and/or progenitor cells. A better evaluation of c-Kit and KDR expressing cells will lead to the redefinition of circulating endothelial progenitors.Graphical abstract Central illustration figure. Multidimensional proteomic approach of endothelial progenitors demonstrate expression of KDR restricted to CD19 cells. Endothelial progenitor cells (EPCs) are involved in cardiovascular diseases, however their phenotype remains elusive. We elucidated here EPCs phenotype by a deep characterization by multidimensional single cell complementary cytometric approaches after Bioprosthetic total artificial heart implantation and during COVID-19. We showed a redistribution of circulating CD34+ and CD19+ sub-populations in both situations. None of the immature cell population expresses KDR. Mobilized CD34+ expressed c-Kit. Imaging flow cytometry demonstrated that CD34+KDR+ cells, after elimination of non-circular events, are all CD19+. Our results suggest a new definition of circulating EPCs and emphasize involvement of CD19 cells in cardiovascular disease.

Deletion of the myeloid endothelin-B receptor confers long-term protection from angiotensin II-mediated kidney, eye and vessel injury.

The endothelin system may be an important player in hypertensive end-organ injury as endothelin-1 increases blood pressure and is pro-inflammatory. The immune system is emerging as an important regulator of blood pressure and we have shown that the early hypertensive response to angiotensin-II infusion was amplified in mice deficient of myeloid endothelin-B (ETB) receptors (LysM-CreEdnrblox/lox). Hypothesizing that these mice would display enhanced organ injury, we gave angiotensin-II to LysM-CreEdnrblox/lox and littermate controls (Ednrblox/lox) for six weeks. Unexpectedly, LysM-CreEdnrblox/lox mice were significantly protected from organ injury, with less proteinuria, glomerulosclerosis and inflammation of the kidney compared to controls. In the eye, LysM-CreEdnrblox/lox mice had fewer retinal hemorrhages, less microglial activation and less vessel rarefaction. Cardiac remodeling and dysfunction were similar in both groups at week six but LysM-CreEdnrblox/lox mice had better endothelial function. Although blood pressure was initially higher in LysM-CreEdnrblox/lox mice, this was not sustained. A natriuretic switch at about two weeks, due to enhanced ETB signaling in the kidney, induced a hypertensive reversal. By week six, blood pressure was lower in LysM-CreEdnrblox/lox mice than in controls. At six weeks, macrophages from LysM-CreEdnrblox/lox mice were more anti-inflammatory and had greater phagocytic ability compared to the macrophages of Ednrblox/lox mice. Thus, myeloid cell ETB receptor signaling drives this injury both through amplifying hypertension and by inflammatory polarization of macrophages.

The tetraspanin CD9 controls migration and proliferation of parietal epithelial cells and glomerular disease progression.

The mechanisms driving the development of extracapillary lesions in focal segmental glomerulosclerosis (FSGS) and crescentic glomerulonephritis (CGN) remain poorly understood. A key question is how parietal epithelial cells (PECs) invade glomerular capillaries, thereby promoting injury and kidney failure. Here we show that expression of the tetraspanin CD9 increases markedly in PECs in mouse models of CGN and FSGS, and in kidneys from individuals diagnosed with these diseases. Cd9 gene targeting in PECs prevents glomerular damage in CGN and FSGS mouse models. Mechanistically, CD9 deficiency prevents the oriented migration of PECs into the glomerular tuft and their acquisition of CD44 and ß1 integrin expression. These findings highlight a critical role for de novo expression of CD9 as a common pathogenic switch driving the PEC phenotype in CGN and FSGS, while offering a potential therapeutic avenue to treat these conditions.

A novel role for myeloid endothelin-B receptors in hypertension.

AIMS: Hypertension is common. Recent data suggest that macrophages (Mφ) contribute to, and protect from, hypertension. Endothelin-1 (ET-1) is the most potent endogenous vasoconstrictor with additional pro-inflammatory properties. We investigated the role of the ET system in experimental and clinical hypertension by modifying Mφ number and phenotype. METHODS AND RESULTS: In vitro, Mφ ET receptor function was explored using pharmacological, gene silencing, and knockout approaches. Using the CD11b-DTR mouse and novel mice with myeloid cell-specific endothelin-B (ETB) receptor deficiency (LysMETB-/-), we explored the effects of modifying Mφ number and phenotype on the hypertensive effects of ET-1, angiotensin II (ANG II), a model that is ET-1 dependent, and salt. In patients with small vessel vasculitis, the impacts of Mφ depleting and non-depleting therapies on blood pressure (BP) and endothelial function were examined. Mouse and human Mφ expressed both endothelin-A and ETB receptors and displayed chemokinesis to ET-1. However, stimulation of Mφ with exogenous ET-1 did not polarize Mφ phenotype. Interestingly, both mouse and human Mφ cleared ET-1 through ETB receptor mediated, and dynamin-dependent, endocytosis. Mφ depletion resulted in an augmented chronic hypertensive response to both ET-1 and salt. LysMETB-/- mice displayed an exaggerated hypertensive response to both ET-1 and ANG II. Finally, in patients who received Mφ depleting immunotherapy BP was higher and endothelial function worse than in those receiving non-depleting therapies. CONCLUSION: Mφ and ET-1 may play an important role in BP control and potentially have a critical role as a therapeutic target in hypertension.

Selective EGF-Receptor Inhibition in CD4+ T Cells Induces Anergy and Limits Atherosclerosis.

BACKGROUND: Several epidermal growth factor receptor (EGFR) inhibitors have been successfully developed for the treatment of cancer, limiting tumor growth and metastasis. EGFR is also expressed by leukocytes, but little is known about its role in the modulation of the immune response. OBJECTIVES: The aim of this study was to determine whether EGFR expressed on CD4+ T cells is functional and to address the consequences of EGFR inhibition in atherosclerosis, a T cell-mediated vascular chronic inflammatory disease. METHODS: The authors used EGFR tyrosine kinase inhibitors (AG-1478, erlotinib) and chimeric Ldlr-/-Cd4-Cre/Egfrlox/lox mouse with a specific deletion of EGFR in CD4+ T cells. RESULTS: Mouse CD4+ T cells expressed EGFR, and the EGFR tyrosine kinase inhibitor AG-1478 blocked in vitro T cell proliferation and Th1/Th2 cytokine production. In vivo, treatment of Ldlr-/- mice with the EGFR inhibitor erlotinib induced T cell anergy, reduced T cell infiltration within atherosclerotic lesions, and protected against atherosclerosis development and progression. Selective deletion of EGFR in CD4+ T cells resulted in decreased T cell proliferation and activation both in vitro and in vivo, as well as reduced interferon-γ, interleukin-4, and interleukin-2 production. Atherosclerotic lesion size was reduced by 2-fold in irradiated Ldlr-/- mice reconstituted with bone marrow from Cd4-Cre/Egfrlox/lox mice, compared to Cd4-Cre/Egfr+/+ chimeric mice, after 4, 6, and 12 weeks of high-fat diet, associated with marked reduction in T cell infiltration in atherosclerotic plaques. Human blood T cells expressed EGFR and EGFR inhibition reduced T cell proliferation both in vitro and in vivo. CONCLUSIONS: EGFR blockade induced T cell anergy in vitro and in vivo and reduced atherosclerosis development. Targeting EGFR may be a novel strategy to combat atherosclerosis.

Selective EGFR (Epidermal Growth Factor Receptor) Deletion in Myeloid Cells Limits Atherosclerosis-Brief Report.

OBJECTIVE: To determine the consequences of specific inhibition of EGFR (epidermal growth factor receptor) in myeloid cells in atherosclerosis development. APPROACH AND RESULTS: Atherosclerotic lesion size was significantly reduced in irradiated Ldlr-/- mice reconstituted with LysMCre+Egfrlox/lox bone marrow, compared with chimeric Ldlr-/- mice reconstituted with LysMCre-Egfrlox/lox bone marrow, after 4 (-43%; P<0.05), 7 (-34%; P<0.05), and 12 weeks (-54%; P<0.001) of high-fat diet. Reduction of lesion size was associated with marked reduction in macrophage accumulation and necrotic core size. Specific deletion of Egfr in myeloid cells reduced TNF-α (tumor necrosis factor-α) and IL (interleukin)-6 production by stimulated macrophages but had no effect on IL-10 and IL-12p70 secretion. Finally, we found that myeloid deletion of Egfr limited cytoskeletal rearrangements and also lipid uptake by macrophages through a downregulation of the scavenger receptor CD36 (cluster of differentiation 36). CONCLUSIONS: Gene deletion of Egfr in myeloid cells limits IL-6 and TNF-α production, lipid uptake, and consecutively reduces atherosclerosis development.

Genetic and pharmacological inhibition of microRNA-92a maintains podocyte cell cycle quiescence and limits crescentic glomerulonephritis.

Crescentic rapidly progressive glomerulonephritis (RPGN) represents the most aggressive form of acquired glomerular disease. While most therapeutic approaches involve potentially toxic immunosuppressive strategies, the pathophysiology remains incompletely understood. Podocytes are glomerular epithelial cells that are normally growth-arrested because of the expression of cyclin-dependent kinase (CDK) inhibitors. An exception is in RPGN where podocytes undergo a deregulation of their differentiated phenotype and proliferate. Here we demonstrate that microRNA-92a (miR-92a) is enriched in podocytes of patients and mice with RPGN. The CDK inhibitor p57Kip2 is a major target of miR-92a that constitutively safeguards podocyte cell cycle quiescence. Podocyte-specific deletion of miR-92a in mice de-repressed the expression of p57Kip2 and prevented glomerular injury in RPGN. Administration of an anti-miR-92a after disease initiation prevented albuminuria and kidney failure, indicating miR-92a inhibition as a potential therapeutic strategy for RPGN. We demonstrate that miRNA induction in epithelial cells can break glomerular tolerance to immune injury.