Secreted Protein Acidic and Rich in Cysteine Mediates the Development and Progression of Diabetic Retinopathy

Pipecolic acid mitigates ferroptosis in diabetic retinopathy by regulating GPX4-YAP signaling

Diabetic retinopathy (DR) is currently recognized as the leading cause of end-stage eye disease. Pipecolic acid, a metabolite, has a significant regulatory effect on several pathological processes. However, the exact mechanism by which it causes damage in diabetic retinopathy is unknown. Between September 2021 and December 2022, 40 patients were retrospectively examined and divided into two groups: the healthy group (n = 20) and the DR group (n = 20). Metabolomic analysis found that pipecolic acid plays an important role in this process. Streptozotocin-induced diabetic mice and high-glucose cultured human retinal capillary endothelial cells (HRCECs) were then treated with pipecolic acid. Several oxidative stress measurements and RNA sequencing of retinal cells were tested. A gene interaction study was conducted using bioinformatics. Comparison of serological metabolites between healthy volunteers and DR patients showed that pipecolic acid was significantly lower in DR patients, and there was a negative correlation between the level of pipecolic acid with blood glucose and glycated hemoglobin. Yes-associated protein (YAP) mRNA, Malondialdehyde (MDA), and reactive oxygen species (ROS) levels were significantly higher in diabetic mice, but glutathione peroxidase (GSH-Px) levels were significantly lower. Pipecolic acid significantly alleviated oxidative stress and YAP expression. The number of vascular tubes was significantly higher in the DR group, and pipecolic acid treatment significantly reduced tube formation. RNA-Sequencing analysis revealed that YAP and glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) expression was reduced, and functional enrichment analysis revealed that ferroptosis and Hippo signaling pathways play an important role in this process. Additionally, pipecolic acid's ability to improve DR is diminished after YAP and GPX4 ablation. This study found that pipecolic acid, as a metabolite, may impede the progression of DR by inhibiting the YAP-GPX4 signaling pathway.

The Notch signaling-regulated angiogenesis in rheumatoid arthritis: pathogenic mechanisms and therapeutic potentials

Angiogenesis plays a key role in the pathological process of inflammation and invasion of the synovium, and primarily drives the progression of rheumatoid arthritis (RA). Recent studies have demonstrated that the Notch signaling may represent a new therapeutic target of RA. Although the Notch signaling has been implicated in the M1 polarization of macrophages and the differentiation of lymphocytes, little is known about its role in angiogenesis in RA. In this review, we discourse the unique roles of stromal cells and adipokines in the angiogenic progression of RA, and investigate how epigenetic regulation of the Notch signaling influences angiogenesis in RA. We also discuss the interaction of the Notch-HIF signaling in RA's angiogenesis and the potential strategies targeting the Notch signaling to improve the treatment outcomes of RA. Taken together, we further suggest new insights into future research regarding the challenges in the therapeutic strategies of RA.

Extracellular matrix-related and serine protease proteins in the amniotic fluid of women with early preterm labor: Association with spontaneous preterm birth, intra-amniotic inflammation, and microbial invasion of the amniotic cavity

PROBLEM

We aimed to determine whether altered levels of various extracellular matrix (ECM)-related and serine protease proteins in the amniotic fluid (AF) are associated with imminent spontaneous preterm birth (SPTB; ≤7 days) and intra-amniotic inflammation and/or microbial invasion of the amniotic cavity (IAI/MIAC) in women with early preterm labor (PTL).

METHOD OF STUDY

This retrospective cohort study included 252 women with singleton pregnancies undergoing transabdominal amniocentesis who demonstrated PTL (24-31 weeks). The AF was cultured for microorganism detection to characterize MIAC. IL-6 concentrations were determined in the AF samples to identify IAI (≥2.6 ng/mL). The following mediators were measured in the AF samples using ELISA: kallistatin, lumican, MMP-2, SPARC, TGFBI, and uPA.

RESULTS

Kallistatin, MMP-2, TGFBI, and uPA levels were significantly higher and SPARC and lumican levels were significantly lower in the AF of women who spontaneously delivered within 7 days than in the AF of those who delivered after 7 days; the levels of the first five mediators were independent of baseline clinical variables. In the multivariate analysis, elevated levels of kallistatin, MMP-2, TGFBI, and uPA and low levels of lumican and SPARC in the AF were significantly associated with IAI/MIAC and MIAC, even after adjusting for the gestational age at sampling. The areas under the curves of the aforementioned biomarkers ranged from 0.58 to 0.87 for the diagnoses of each of the corresponding endpoints.

CONCLUSION

ECM-related (SPARC, TGFBI, lumican, and MMP-2) and serine protease (kallistatin and uPA) proteins in the AF are involved in preterm parturition and regulation of intra-amniotic inflammatory/infectious responses in PTL.

CD44 Drives M1 Macrophage Polarization in Diabetic Retinopathy

PURPOSE

Diabetic retinopathy is a typical complication of diabetes, which can facilitate the risk of blindness in severe cases. We sought to determine the function of CD44 in inflammatory responses of human retinal microvascular endothelial cells (HRMECs) and macrophage polarization during diabetic retinopathy (DR).

METHODS

The hub genes were tested based on two datasets from the Gene Expression Omnibus database. Gene Ontology and pathway enrichment analysis was conducted on the base of differentially expressed genes (DEGs). The infiltration score and infiltration of the immune cells were assessed, and the link between key genes and macrophages was analyzed. The role of CD44 in HRMECs and macrophage polarization was determined by quantitative reverse transcription polymerase chain reaction, western blot, cell counting kit-8, Enzyme-linked immunosorbent assay, flow cytometry, and immunofluorescence.

RESULTS

DEGs were enriched in several pathways linked to DR, such as cellular response to retinoic acid, retinol metabolic process, retina homeostasis, PI3K-AKT signaling pathway, and leukocyte transendothelial migration. A total of 144 DEGs were identified by up-regulation both in GSE102485 and GSE160306. Moreover, the infiltration of macrophages was greater in the DR group than that in the control group. We highlighted an obvious increase in the expression of CD44 and CD86 in patients with DR, and distinct positive associations were found between levels of macrophages and levels of CD44 and CD86. Furthermore, CD44 expression was substantially increased in HRMECs under high glucose (HG) conditions and CD44 knockdown markedly inhibited HG-induced inflammatory responses of HRMECs. HG-induced HRMECs remarkably influenced M1 polarization of macrophages, but CD44 knockdown significantly nullified this effect.

CONCLUSIONS

CD44 influenced the advancement of DR via meditating M1 polarization of macrophages. Our findings could enhance the understanding of the mechanism of DR, which might offer a therapeutic target for DR patients.

Adipose Tissue Paracrine-, Autocrine-, and Matrix-Dependent Signaling during the Development and Progression of Obesity

Obesity is an ever-increasing phenomenon, with 42% of Americans being considered obese (BMI ≥ 30) and 9.2% being considered morbidly obese (BMI ≥ 40) as of 2016. With obesity being characterized by an abundance of adipose tissue expansion, abnormal tissue remodeling is a typical consequence. Importantly, this pathological tissue expansion is associated with many alterations in the cellular populations and phenotypes within the tissue, lending to cellular, paracrine, mechanical, and metabolic alterations that have local and systemic effects, including diabetes and cardiovascular disease. In particular, vascular dynamics shift during the progression of obesity, providing signaling cues that drive metabolic dysfunction. In this review, paracrine-, autocrine-, and matrix-dependent signaling between adipocytes and endothelial cells is discussed in the context of the development and progression of obesity and its consequential diseases, including adipose fibrosis, diabetes, and cardiovascular disease.

Exosomes from adipose-derived stem cells inhibit inflammation and oxidative stress in LPS-acute kidney injury

Acute renal damage presents a significant danger to kidney health. Previous research has found that acute kidney injury shows high levels of oxidative stress and inflammation caused by sepsis. Although mesenchymal stem cells (MSCs) can repair acute kidney injury. However, involvement of MSCs exosomes generated from adipose tissue and bone marrow in lipopolysaccharide-induced acute kidney damage is not clear. LPS (7.5 mg/kg) intraperitoneal injection was used to produce AKI, and 30 min before the LPS administration, adipose-derived MSCs (ADSCs) exosomes (1 × 10⁵ and 5 × 10⁵) and bone marrow-derived MSCs(BMSCs) exosomes (1 × 10⁵ and 5 × 10⁵) were delivered individually. The function of the rat kidney was explored. Inflammation, oxidative stress, and autophagy levels were further investigated. Both adipose-derived and bone marrow-derived MSCs can enhance renal function and structural damage, such as BUN, Creatinine, and cystatin C levels, as well as tubular damage scores. These findings indicate that both adipose-derived MSCs exosomes and bone marrow-derived MSCs exosomes decrease oxidative stress and inflammation, as well as make a substantial influence on kidney tissue in autophagy levels. Furthermore, compared to bone marrow-derived MSCs exosomes, adipose-derived MSCs exosomes improved kidney function and structure more significantly. We discovered that adipose-derived MSCs exosomes protect against LPS-induced AKI by inhibiting oxidative stress and inflammation.