TGF-β1 serum concentrations and receptor expressions in the lens capsular of dogs with diabetes mellitus

Status of higher TGF-β1 and TGF-β2 levels in the aqueous humour of patients with diabetes and cataracts

BACKGROUND

Transforming growth factor (TGF) is a cytokine that acts on the proliferation, migration, differentiation, and apoptosis of cells and the accumulation of extracellular matrix components. Very few studies have precisely evaluated the concentration of TGF-β in the aqueous humour (AH) of diabetic and cataract (DMC) eyes due to the low expression of proteins in the AH or other reasons. The concentrations of TGF-β1, -β2, and -β3 in the AH of the DMC group were compared with those of the age-related cataract (ARC) group.

METHODS

We collected AH and lens epithelium samples from 33 DMC patients and 36 ARC patients. Luminex liquid suspension chip detection was applied to detect the concentration of TGF-β1, -β2, and -β3 in the AH samples. The expression of TGFB1/2/3 in lens epithelium samples was determined by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The concentrations of TGF-β1 and TGF-β2 in AH samples of DMC eyes were higher than those of ARC eyes. The differences in TGF-β1 and TGF-β2 between the two groups were statistically significant (P value = 0.001 for TGF-β1, P value = 0.023 for TGF-β2). The difference of the correlation between TGF-β1 and glycosylated haemoglobin was significant (P value = 0.011, and Pearson correlation coefficient = 0.306). The difference of the correlation between TGF-β2 and glycosylated haemoglobin was significant (P value = 0.026, and Pearson correlation coefficient = 0.269). The mRNA expression levels of TGFB1 and TGFB2 were upregulated in DMC epithelium samples compared with ARC epithelium samples. The differences in TGFB1 and TGFB2 between the two groups were statistically significant (P value for TGFB1 = 0.041, P value for TGFB2 = 0.021).

CONCLUSIONS

The concentrations of TGF-β1 and TGF-β2 in AH samples were significantly higher in DMC eyes than in ARC eyes. The higher the glycosylated haemoglobin was, the higher the concentrations of TGF-β1 and -β2 were. The mRNA expression of TGFB1 and TGFB2 was significantly upregulated in DMC epithelial samples compared with ARC epithelial samples, suggesting the proinflammatory status of the anterior chamber of DMC eyes.

Exosomal miR-29b found in aqueous humour mediates calcium signaling in diabetic patients with cataract

AIM

To investigate the role of exosomal miR-29b and Ca²⁺ in regulating the function of human lens epithelial cells (HLECs).

METHODS

Exosomes were isolated from human aqueous humour (AH) by ultracentrifugation, and visualized by nanoparticle tracking and transmission electron microscopy. Exosomal miRNA sequencing was performed to identify differentially expressed miRNAs between diabetes with cataracts (DMC) group and age-related cataracts (ARC) group. TargetScan was used to predict potential target of certain miRNA. The expression of CACNA1C mRNA was determined by quantitative real-time polymerase chain reaction and CACNA1C protein was determined by Western blotting. Concentration of Ca²⁺ in human AH and the culture supernatant of cells were detected by the calcium assay kit. Cell counting kit-8 was used to determine cell viability.

RESULTS

Exosomes were isolated from human AH, which had a typical cup-shaped phenotype and a particle size distribution in accordance with micro extracellular vesicles. Exosomal miRNA sequencing revealed that miR-29b was significantly downregulated in DMC group compared with ARC. Ca²⁺ concentration of human AH in DMC was higher than that in ARC. The culture supernatant of cells transfected with miR-29b inhibitors had a higher concentration of Ca²⁺ than that transfected with miR-29b mimics. miR-29b reduced the viability of HLECs by upregulating CACNA1C expression.

CONCLUSION

Exosomes isolated from human AH contains abundant miRNAs. A significantly expressed miRNA, miR-29b, can affect the concentration of Ca²⁺ and regulate HLEC processes by upregulating CACNA1C.

Exosomal miRNA Analysis of Aqueous Humour of Diabetes and Cataract Patients

BACKGROUND

The mechanism of diabetes and cataracts is complicated. Considering our increasing acknowledge of exosomes, exosomal miRNAs isolated from aqueous humour (AH) may play an important role in the mechanism of diabetes and cataracts. Our study aimed to isolate exosomes from human aqueous humour and study the functions of exosomal miRNAs on human lens epithelial cells (HLECs).

RESULTS

MiRNA sequencing revealed that 295 miRNAs were upregulated and 138 miRNAs were downregulated in exosomes of the diabetes and cataracts group (DMC) compared with the age-related cataracts group (ARC), among which miR-551b was highly expressed with a log2 fold change of 5.99. GO and KEGG analyses indicated that the predicted genes were mainly involved in cadherin binding, proteoglycans in cancer and AGE-RAGE signalling pathway in diabetic complications. We then examined the function of miR-551b and found that miR-551b reduced the viability and increased the apoptosis of HLECs by downregulating CRYAA expression.

CONCLUSIONS

Exosomes isolated from human aqueous humour contained abundant miRNAs. A highly expressed miRNA, miR-551b, could regulate the functions of HLEC by targeting CRYAA.

METHODS

We pooled all the aqueous humour of each group into one sample and isolated exosomes from human aqueous humour by ultracentrifugation, measured the size and concentration of exosomes by nanoparticle tracking analysis (NTA), observed the morphology of exosomes by transmission electron microscopy (TEM), and sequenced exosomal miRNAs. We performed bioinformatic analysis of the sequencing results, including GO analysis and KEGG pathway enrichment. We then examined CRYAA mRNA expression levels and protein levels by quantitative real-time PCR and Western blot. Cell Counting Kit-8 and flow cytometry were applied to examine cell viability, proliferation and apoptosis.

Salvia miltiorrhiza in diabetes: A review of its pharmacology, phytochemistry, and safety

BACKGROUND

Salvia miltiorrhiza (SM), one of the frequently used herbs in traditional Chinese medicine (TCM), has now attracted rising interests for a possible alternative in the management of diabetes. This review is aimed to providing a comprehensive perspective of SM in phytochemical constituents, pharmacological activities against diabetes and its complications, and safety.

METHODS

A comprehensive search of published literatures was conducted to locate original publications pertaining to SM and diabetes till the end of 2017 using PubMed, China National Knowledge Infrastructure, National Science and Technology Library, China Science and Technology Journal Database, and Web of Science database. The main inquiry was used for the presence of the following keywords in various combinations in the titles and abstracts: Salvia miltiorrhiza, diabetes, obesity, phytochemistry, pharmacology, and safety. About 200 research papers and reviews were consulted.

RESULTS

SM exhibited anti-diabetic activities by treating macro- and micro-vascular diseases in preclinical experiments and clinical trials through an improvement of redox homeostasis and inhibition of apoptosis and inflammation via the regulation of Wnt/β-catenin, TSP-1/TGF-β1/STAT3, JNK/PI3K/Akt, kinin B2 receptor-Akt-GSK-3β, AMPKβ/PGC-1α/Sirt3, Akt/AMPK, TXNIP/NLRP3, TGF-β1/NF-κB, mineralocorticoid receptor/Na⁺/K⁺-ATPase, AGEs/RAGE, Nrf2/Keap1, CaMKKβ/AMPK, AMPK/ACC, IRS-1/PI3K signaling pathways, and modulation of K⁺-Ca²⁺ channels, as well as influence of VEGF, NOS, AGEs, PPAR expression and hIAPP aggregation. The antidiabetic effects of this herb may be related to its TCM characters of improving blood circulation and reliving blood stasis. The main ingredients of SM included salvianolic acids and diterpenoid tanshinones, which have been well studied in the diabetic animals. Acute and subacute toxicity studies supported the notion that SM is well tolerated.

CONCLUSION

SM may offer a new strategy for prevention and treatment of diabetes and its complications that stimulates extensive research into identifying potential anti-diabetic compounds and fractions as well as exploring the underlying mechanisms of this herb. Further scientific evidences are still required from well-designed preclinical experiments and clinical trials on its anti-diabetic effects and safety.