Siglec-5 is a novel marker of critical limb ischemia in patients with diabetes

Co-Delivery of Bioengineered Exosomes and Oxygen for Treating Critical Limb Ischemia in Diabetic Mice

Diabetic patients with critical limb ischemia face a high rate of limb amputation. Regeneration of the vasculature and skeletal muscles can salvage diseased limbs. Therapy using stem cell-derived exosomes that contain multiple proangiogenic and promyogenic factors represents a promising strategy. Yet the therapeutic efficacy is not optimal because exosomes alone cannot efficiently rescue and recruit endothelial and skeletal muscle cells and restore their functions under hyperglycemic and ischemic conditions. To address these limitations, we fabricated ischemic-limb-targeting stem cell-derived exosomes and oxygen-releasing nanoparticles and codelivered them in order to recruit endothelial and skeletal muscle cells, improve cell survival under ischemia before vasculature is established, and restore cell morphogenic function under high glucose and ischemic conditions. The exosomes and oxygen-releasing nanoparticles, delivered by intravenous injection, specifically accumulated in the ischemic limbs. Following 4 weeks of delivery, the exosomes and released oxygen synergistically stimulated angiogenesis and muscle regeneration without inducing substantial inflammation and reactive oxygen species overproduction. Our work demonstrates that codelivery of exosomes and oxygen is a promising treatment solution for saving diabetic ischemic limbs.

Plasma Siglec-5 and CD163 as Novel Biomarkers for Fulminant Myocarditis

Fulminant myocarditis (FM) is the severest type of myocarditis and requires timely diagnosis and treatment. However, effective biomarkers for early diagnosis of FM are limited. First, 12 common inflammatory cytokines levels in the plasma of patients with FM were measured using human cytokine 12-Plex assay. Then, enzyme-linked immunosorbent assay (ELISA) was used to detect the plasma levels of another eight cytokines that we previously reported on. Moreover, a Spearman correlation test was employed to investigate the correlations between the plasma cytokine levels and the clinical parameters of patients with FM. Finally, receiver operating characteristic (ROC) curve analyses were performed to assess the diagnostic performance of plasma cytokine levels for the detection of FM. Five of the twelve common inflammation cytokines were significantly altered in patients with FM, but none of them was correlated with the severity of FM. Six of the eight significantly changed cytokines that we previously reported on were validated by ELISA. Among these, sST2, Siglec-5, and CD163 were negatively correlated with ejection fraction values. Furthermore, plasma Siglec-5 and CD163 levels were found to be associated with the severity of FM. Finally, both plasma Siglec-5 and CD163 showed outstanding diagnostic performance for FM. The current study identified plasma Siglec-5 and CD163 as valuable novel biomarkers for the early diagnosis of FM.

Thrombospondin-4 (TSP4) gene-modified bone marrow stromal cells (BMSCs) promote the effect of therapeutic angiogenesis in critical limb ischemia (CLI) of diabetic rats

Critical limb ischemia (CLI) is the leading cause of lower limb amputation. Traditional treatments for CLI have limitations. Studies have shown that thrombospondin-4 (TSP4) can promote the growth of neovascularization. In this study, we observed the angiogenesis efficiency of TSP4-overexpressing BMSC transplantation in CLI treatment. The recombinant FT106-tsp4-gfp lentiviral vector plasmid was constructed and transfected into 293FT cells. Primary BMSCs were successfully infected with the tsp4 virus, and TSP4 overexpression was confirmed before TSP4-BMSCs infusion. A rat CLI model was established, and 60 CLI rats were randomly divided into the CLI, BMSC + CLI and TSP4-BMSC + CLI groups. The effect of TSP4-BMSC on angiogenesis was detected by the motor function, immunohistochemistry and immunofluorescence staining assays. Neovascular density was detected by digital subtraction angiography (DSA). Our results demonstrated that TSP4-BMSCs improved the motor function score of the CLI rats and increased MMP2, MMP9, Ang-1, VEGF and vWF protein expression in tissue of the ischaemic area. Meanwhile, new blood vessels can be observed around the ischemic area after TSP4-BMSCs treatment. Our data illustrate that TSP4-BMSCs can promote the recovery of motor function in diabetic hind limb ischaemic rats. TSP4-BMSCs have better therapeutic effects than BMSCs.

Common determinants of severe Covid-19 infection are explicable by SARS-CoV-2 secreted glycoprotein interaction with the CD33-related Siglecs, Siglec-3 and Siglec-5/14

SARS-CoV-2 interaction with the ACE-2 receptor cannot alone explain the demography and remarkable variation in clinical progression of Covid-19 infection.

Unlike SARS-CoV, the cause of SARS, several SARS-CoV-2 spike glycans contain sialic acid residues. In contrast to the SARS secreted glycoprotein (SGP), SARS-CoV-2 SGP are thus potential ligands for Sialic acid-binding Siglecs on host immune cells, known to regulate immune function. Such SARS-CoV-2 glycoproteins would contribute to immune deviation.

CD33-related Siglecs are important immune regulators. Siglec-5 and −14 are paired receptors with opposed actions on the NLRP3 inflammasome, which is critical in early viral clearance. SGP binding in persons of Siglec-14 null genotype (30–70% in Black, Asian and Minority Ethnic (BAME) persons, 10% in North Europeans) would induce unopposed inhibitory signalling, causing viral persistence through inflammasome inhibition.

Siglec-3 (CD33) and Siglec-5 are expressed on CD33 myeloid derived suppressor cells (CD33 MDSC). Immunosuppressive CD33 MDSC populations are increased in all groups at risk of severe Covid-19 infection. CD33 expression is increased in persons with the CD33 rs3865444 CC allele, associated with Alzheimer’s disease, who would thus show enhanced susceptibility. Viral SGP ligation of CD33, potentially in conjunction with Siglec-5, would promote expansion of CD33 MDSC cells, as occurs in cancers but at much greater scale.

CD33 is expressed on CNS microglia, potentially activated by SGP penetration through the porous cribriform plate to cause anosmia.

Genotyping of severe or fatal Covid-19 cases can confirm or refute this pathophysiological mechanism. Early data have confirmed extremely high-level increase of CD33 MDSC numbers in severe Covid-19 infection, consistent with the proposed mechanism.

Proteomic Technology "Lens" for Epithelial-Mesenchymal Transition Process Identification in Oncology

The epithelial-mesenchymal transition (EMT) is a complex transformation process that induces local and distant progression of many malignant tumours. Due to its complex array of proteins that are dynamically over-/underexpressed during this process, proteomic technologies gained their place in the EMT research in the last years. Proteomics has identified new molecular pathways of this process and brought important insights to develop new therapy targets. Various proteomic tools and multiple combinations were developed in this area. Out of the proteomic technology armentarium, mass spectrometry and array technologies are the most used approaches. The main characteristics of the proteomic technology used in this domain are high throughput and detection of minute concentration in small samples. We present herein, using various proteomic technologies, the identification in cancer cell lines and in tumour tissue EMT-related proteins, proteins that are involved in the activation of different cellular pathways. Proteomics has brought besides standard EMT markers (e.g., cell-cell adhesion proteins and transcription factors) other future potential markers for improving diagnosis, monitoring evolution, and developing new therapy targets. Future will increase the proteomic role in clinical investigation and validation of EMT-related biomarkers.

Plasma NAP-2 levels are associated with critical limb ischemia in peripheral arterial disease patients

IMPACT STATEMENT

Critical limb ischemia (CLI) is a serious arterial obstruction, resulting in serious reduction of blood flow to the extremities. CLI is a symptomatic disorder and is frequently not diagnosed in time. This results in a high mortality and elevated risk of limb amputation. Serum or plasma biomarkers play important roles in disease prevention, diagnosis, and prognosis. Elevated plasma neutrophil-activating peptide-2 (NAP-2) was found independently associated with CLI, but not with T2DM. Plasma NAP-2 levels might be an early CLI diagnostic biomarker and might provide a novel target for CLI treatment.

Wound exudate CXCL6: a potential biomarker for wound healing of diabetic foot ulcers

AIM

The aim of this study was to investigate the relationship between CXCL-6 levels in wound exudates and healing of diabetic foot ulcers (DFU).

MATERIALS & METHODS

One hundred patients with neuropathic DFU were recruited. Wound exudate CXCL-6 levels were measured by enzyme-linked immunosorbent assay. Patients were followed for 24 weeks and divided into rapidly healing and nonhealing groups.

RESULTS

Compared with the NH group, the mean CXCL-6 levels in the wound exudates of the rapidly healing group were significantly higher. After adjusting for traditional risk factors, wound exudate CXCL-6 levels were still significantly associated with wound healing.

CONCLUSION

CXCL6 is an independent predictor of wound healing in DFU patients and may be a potentially novel therapeutic target for the treatment of DFU.

ENA-78 Is a Novel Predictor of Wound Healing in Patients with Diabetic Foot Ulcers

OBJECTIVES

Chronic foot ulceration is a severe complication of diabetes, driving morbidity and mortality. The aim of our study was to identify novel biomarkers of impaired wound healing in diabetic foot ulcers.

METHODS

109 patients with neuropathic diabetic foot ulcers and 30 burn victims otherwise healthy participated. Antibody-coated glass slide arrays were used to determine the levels of 80 human cytokines in pooled plasma or pooled wound exudate of diabetic foot ulcers with rapidly healing (RH, n = 12) and matched nonhealing (NH, n = 12) patients. Potential biomarkers were confirmed in an independent cohort by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Protein array profiling identified 27 proteins or 15 proteins significantly altered in protein profiling of pooled plasma or pooled wound exudate of 12 RH patients compared with 12 matched NH patients, respectively. In an independent cohort, quantitative ELISA validation confirmed a decrease in MCP-2 and ENA-78 levels in NH patients versus RH patients or burn victims. After adjusting for the traditional risk factors (sex, age, body mass index, fasting plasma glucose, ulcer area, HbA1C, diabetes duration, hyperlipidemia, and antibiotic therapy), only wound exudate level of ENA-78 remained having a significant association with an increased odds ratio (OR) for wound healing by binary logistic regression analysis (P < 0.05).

CONCLUSION

Decreased wound exudate ENA-78 was independently associated with wound healing of patients with diabetic foot. Exudate ENA-78 level is implicated as a novel predictor of wound healing in patients with diabetic foot ulcers.

Circulating MicroRNA-4739 May Be a Potential Biomarker of Critical Limb Ischemia in Patients with Diabetes

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease, which is common but rarely diagnosed. Noninvasive biomarkers are urgently required to assist in the diagnosis of CLI. Accumulating evidence indicates that miRNAs play an important role in the development of various diseases. In this study, microarray profiling revealed 11 miRNAs with significantly altered expression in four T2DM patients with CLI compared with that in four sex- and age-matched T2DM patients without CLI. In independent cohorts, qRT-PCR validation confirmed the increased miRNA-4739 level in patients with CLI versus patients without CLI. miRNA-4739 levels increased with FPG and HbA1c (all P < 0.05). After adjusting for the risk factors, miRNA-4739 levels were found to be associated with an increased odds ratio (OR) of T2DM with CLI (OR =12.818, 95% confidence intervals (CI) 1.148 to 143.143, P = 0.038). ROC curve analysis revealed that the area under the curve (AUC) of miR-4739+confounding risk factors was 0.94 (95% CI 0.891 to 0.998, P < 0.001), which was higher than that of confounding risk factors (AUC 0.94 vs. 0.91, 95% CI -0.122 to 0.060, P > 0.05) and of miR-4739 (AUC 0.94 vs. 0.69, 95% CI -0.399 to -0.101, P < 0.001), respectively. We conclude that elevated plasma miRNA-4739 levels are independently associated with CLI in T2DM patients. miRNA-4739 is implicated as a novel diagnostic marker and a potential therapeutic target for CLI in diabetes.

MiR-323b-5p acts as a novel diagnostic biomarker for critical limb ischemia in type 2 diabetic patients

Type 2 diabetes mellitus (T2DM) is a major contributor to peripheral artery disease (PAD), especially in cases that advance to critical limb ischemia (CLI). Accumulating evidence indicates that miRNAs play an important role in the development of PAD and T2DM. Due to the limited value of current diagnostic methods for CLI in T2DM patients, we compared the miRNA expression profiles of Chinese T2DM patients with or without CLI to find out whether distinctive miRNAs could serve as potential diagnostic biomarkers. We statistically identified 7 miRNAs (hsa-miR-200b-3p, hsa-miR-2115-3p, hsa-miR-431-5p, hsa-miR-486-5p, hsa-miR-210-3p, hsa-miR-1264, hsa-miR-323b-5p) which were up-regulated in the CLI group, whereas other 4 miRNAs (hsa-miR-5579-3p, hsa-miR-665, hsa-miR-4285, hsa-miR-500a-3p) were down-regulated. Our validation test suggested a relatively high diagnostic accuracy of serum hsa-miR-323b-5p levels for the detection of CLI in T2DM patients, with a sensitivity of 62.67% and a specificity of 80.65%. The area under the curve (AUC) for miR-323b-5p + confounding risk factors was 0.94 (95% CI: 0.884-0.994, P < 0.001), which was higher than that for miR-323b-5p. Taken together, our results indicate that circulating hsa-miR-323b-5p could be a promising serum biomarker for the diagnosis of critical limb ischemia in type 2 diabetic patients.