Significance of Soluble CD93 in Type 2 Diabetes as a Biomarker for Diabetic Nephropathy: Integrated Results from Human and Rodent Studies

Ultrasound Imaging of Tumor Vascular CD93 with MMRN2 Modified Microbubbles for Immune Microenvironment Prediction

Vascular microenvironment is found to be closely related to immunotherapy efficacy. Identification and ultrasound imaging of the unique vascular characteristics, able to predict immune microenvironment, is important for immunotherapy decision-making. Herein, it is proved that high CD93 expression in the tumor vessels is closely related to the poor immune response of prostate cancer. For ultrasound molecular imaging of CD93, CD93-targeted microbubbles (MBs) consist a gaseous core and the MMRN2 (Multimerin-2) containing cell membrane (CM) /lipid hybrid membrane is then synthesized. In vitro and in vivo assays demonstrate that these MBs can recognize CD93 efficiently and then accumulate within tumor regions highly expressing CD93. Contrast-enhanced ultrasound (CEUS) imaging with CD93-targeted MBs demonstrates that targeted ultrasound intensity is negatively related to inflammatory tumor immune microenvironment (TIME) and cytotoxic T cell infiltration. Together, endothelial expression of CD93 in tumor is a unique predictor of immunosuppressive microenvironment and CD93-targeted MBs have a great potential to evaluate tumor immune status.

The C-Type Lectin Receptor CD93 Regulates Platelet Activation and Surface Expression of the Protease Activated Receptor 4

BACKGROUND

 The C-type lectin receptor CD93 is a single pass type I transmembrane glycoprotein involved in inflammation, immunity, and angiogenesis. This study investigates the role of CD93 in platelet function. CD93 knockout (KO) mice and wild-type (WT) controls were compared in this study.

METHODS

 Platelet activation and aggregation were investigated by flow cytometry and light transmission aggregometry, respectively. Protein expression and phosphorylation were analyzed by immunoblotting. Subcellular localization of membrane receptors was investigated by wide-field and confocal microscopy.

RESULTS

 The lack of CD93 in mice was not associated to any evident bleeding defect and no alterations of platelet activation were observed upon stimulation with thromboxane A2 analogue and convulxin. Conversely, platelet aggregation induced by stimulation of the thrombin receptor PAR4 was significantly reduced in the absence of CD93. This defect was associated with a significant reduction of α-granule secretion, integrin αIIbβ3 activation, and protein kinase C (PKC) stimulation. Resting WT and CD93-deficient platelets expressed comparable amounts of PAR4. However, upon stimulation with a PAR4 activating peptide, a more pronounced clearance of PAR4 from the platelet surface was observed in CD93-deficient platelets compared with WT controls. Confocal microscopy analysis revealed a massive movement of PAR4 in cytosolic compartments of activated platelets lacking CD93. Accordingly, platelet desensitization following PAR4 stimulation was more pronounced in CD93 KO platelets compared with WT controls.

CONCLUSION

 These results demonstrate that CD93 supports platelet activation triggered by PAR4 stimulation and is required to stabilize the expression of the thrombin receptor on the cell surface.

Targeted Proteomics Reveals Functional Targets for Early Diabetes Susceptibility in Young Adults

BACKGROUND

The circulating proteome may encode early pathways of diabetes susceptibility in young adults for surveillance and intervention. Here, we define proteomic correlates of tissue phenotypes and diabetes in young adults.

METHODS

We used penalized models and principal components analysis to generate parsimonious proteomic signatures of diabetes susceptibility based on phenotypes and on diabetes diagnosis across 184 proteins in >2000 young adults in the CARDIA (Coronary Artery Risk Development in Young Adults study; mean age, 32 years; 44% women; 43% Black; mean body mass index, 25.6±4.9 kg/m2), with validation against diabetes in >1800 individuals in the FHS (Framingham Heart Study) and WHI (Women's Health Initiative).

RESULTS

In 184 proteins in >2000 young adults in CARDIA, we identified 2 proteotypes of diabetes susceptibility-a proinflammatory fat proteotype (visceral fat, liver fat, inflammatory biomarkers) and a muscularity proteotype (muscle mass), linked to diabetes in CARDIA and WHI/FHS. These proteotypes specified broad mechanisms of early diabetes pathogenesis, including transorgan communication, hepatic and skeletal muscle stress responses, vascular inflammation and hemostasis, fibrosis, and renal injury. Using human adipose tissue single cell/nuclear RNA-seq, we demonstrate expression at transcriptional level for implicated proteins across adipocytes and nonadipocyte cell types (eg, fibroadipogenic precursors, immune and vascular cells). Using functional assays in human adipose tissue, we demonstrate the association of expression of genes encoding these implicated proteins with adipose tissue metabolism, inflammation, and insulin resistance.

CONCLUSIONS

A multifaceted discovery effort uniting proteomics, underlying clinical susceptibility phenotypes, and tissue expression patterns may uncover potentially novel functional biomarkers of early diabetes susceptibility in young adults for future mechanistic evaluation.

Role of CD93 in Health and Disease

CD93 (also known as complement protein 1 q subcomponent receptor C1qR1 or C1qRp), is a transmembrane glycoprotein encoded by a gene located on 20p11.21 and composed of 652 amino acids. CD93 can be present in two forms: soluble (sCD93) and membrane-bound (CD93). CD93 is mainly expressed on endothelial cells, where it plays a key role in promoting angiogenesis both in physiology and disease, such as age-related macular degeneration and tumor angiogenesis. In fact, CD93 is highly expressed in tumor-associated vessels and its presence correlates with a poor prognosis, poor immunotherapy response, immune cell infiltration and high tumor, node and metastasis (TNM) stage in many cancer types. CD93 is also expressed in hematopoietic stem cells, cytotrophoblast cells, platelets and many immune cells, i.e., monocytes, neutrophils, B cells and natural killer (NK) cells. Accordingly, CD93 is involved in modulating important inflammatory-associated diseases including systemic sclerosis and neuroinflammation. Finally, CD93 plays a role in cardiovascular disease development and progression. In this article, we reviewed the current literature regarding the role of CD93 in modulating angiogenesis, inflammation and tumor growth in order to understand where this glycoprotein could be a potential therapeutic target and could modify the outcome of the abovementioned pathologies.

Diagnostic and Prognostic Role of CD93 in Cardiovascular Disease: A Systematic Review

INTRODUCTION

Cluster of Differentiation (CD) 93 (also known as complement protein 1 q subcomponent receptor C1qR1 or C1qRp) is a transmembrane glycoprotein that can also be present in a soluble (sCD93) form. Recent studies have investigated the role of this protein in cardiovascular disease (CVD). The present systematic review aims to assess the associations between CD93 and cardiovascular (CV) risk factors and disease at both the proteomic and genomic levels.

METHODS

We conducted systematic searches in the PubMed, EMBASE, and Web of Science databases to identify all human studies since inception to February 2023 that investigated the role of CD93 in CV risk factors, CVD, and CV-associated outcomes. The data collection and analysis have been independently conducted by two reviewers. The search terms included: cardiovascular, heart failure, acute stroke, myocardial infarction, stroke, peripheral artery disease, cardiovascular death, MACE, hypertension, metabolic syndrome, hyperuricemia, diabetes, cd93, c1qr, C1qR1, complement protein 1 q subcomponent receptor.

RESULTS

A total of 182 references were identified, and 15 studies investigating the associations between CD93 protein levels or CD93 genetic polymorphisms and the development or prevalence of CV risk factors (i.e., hypertension, dyslipidemia, and obesity) and CVD (i.e., heart failure, coronary artery disease, and ischemic stroke) were included. Although promising, the quality and dimension of the analyzed studies do not allow for a definitive answer to the question of whether CD93 may hold diagnostic and prognostic value in CVD.

Glomerular endothelial cell-podocyte stresses and crosstalk in structurally normal kidney transplants

Increased podocyte detachment begins immediately after kidney transplantation and is associated with long-term allograft failure. We hypothesized that cell-specific transcriptional changes in podocytes and glomerular endothelial cells after transplantation would offer mechanistic insights into the podocyte detachment process. To test this, we evaluated cell-specific transcriptional profiles of glomerular endothelial cells and podocytes from 14 patients of their first-year surveillance biopsies with normal histology from low immune risk recipients with no post-transplant complications and compared these to biopsies of 20 healthy living donor controls. Glomerular endothelial cells from these surveillance biopsies were enriched for genes related to fluid shear stress, angiogenesis, and interferon signaling. In podocytes, pathways were enriched for genes in response to growth factor signaling and actin cytoskeletal reorganization but also showed evidence of podocyte stress as indicated by reduced nephrin (adhesion protein) gene expression. In parallel, transcripts coding for proteins required to maintain podocyte adherence to the underlying glomerular basement membrane were downregulated, including the major glomerular podocyte integrin α3 and the actin cytoskeleton-related gene synaptopodin. The reduction in integrin α3 protein expression in surveillance biopsies was confirmed by immunoperoxidase staining. The combined growth and stress response of patient allografts post-transplantation paralleled similar changes in a rodent model of nephrectomy-induced glomerular hypertrophic stress that progress to develop proteinuria and glomerulosclerosis with shortened kidney life span. Thus, even among patients with apparently healthy allografts with no detectable histologic abnormality including alloimmune injury, transcriptomic changes reflecting cell stresses are already set in motion that could drive hypertrophy-associated glomerular disease progression.

Soluble Complement Component 1q Receptor 1 (sCD93) Is Associated with Graft Function in Kidney Transplant Recipients

Cluster of differentiation 93 (CD93), also known as complement component 1q receptor 1 is a transmembrane glycoprotein expressed in endothelial and hematopoietic cells and associated with phagocytosis, cell adhesion, angiogenesis and inflammation. The extracellular part, soluble CD93 (sCD93), is released to body fluids in inflammation. Data on sCD93 in kidney diseases are limited. Our aim was to evaluate serum sCD93 in long-term kidney transplant recipients as a marker of inflammation and endothelial dysfunction that may be potentially useful in early recognition of graft dysfunction. Seventy-eight adult patients with functioning kidney graft and stable clinical state were examined at least one year after kidney transplantation. Serum sCD93 was measured by enzyme immunosorbent assay. Estimated glomerular filtration rate (eGFR) and albuminuria or proteinuria were assessed at baseline and over one-year follow-up. Increased sCD93 was associated with lower baseline eGFR independently of the confounders. Moreover, sCD93 was negatively associated with eGFR during one-year follow-up in simple analysis; however, this was not confirmed after adjustment for confounders. Baseline sCD93 was positively associated with baseline albuminuria and with increased proteinuria during the follow-up. Serum sCD93 was not correlated with other studied inflammatory markers (interleukin 6, C-reactive protein, procalcitonin and C3 and C4 complement components). To the best of our knowledge, this is the first report regarding the concentrations of sCD93 in kidney transplant recipients and one of the first reports showing the inverse association between sCD93 and renal function. Serum sCD93 should be further evaluated as a diagnostic and prognostic marker in renal transplantation.