[HIF-1α activation induces cholesterol homeostasis dysfunction to accelerate progression of diabetic nephropathy in rats]

OBJECTIVE

To investigate the effect of hypoxia inducible factor-1α (HIF-1α) activation on cholesterol homeostasis dysfunction in diabetic nephropathy (DN).

METHODS

Rat models of type 1 diabetes established by intraperitoneal STZ injection were treated with intraperitoneal injection of Lificiguat (YC-1, a HIF-1α inhibitor). Human proximal tubular cell line HK-2 was incubated with cobalt chloride (CoCl2, 100 μmol/L) in the presence or absence of 30 mmol/L glucose for 24 h. Renal injury of the rats was assessed by measuring 24-h urinary total protein level and PAS staining of the renal tubules. Cholesterol deposition in rat kidneys and HK-2 cells were observed using a quantitative assay of total cholesterol and Filipin staining, and HIF-1α protein expression was detected using Western blotting, immunohistochemistry or immunofluorescence assay; the expressions of cholesterol metabolism-related proteins HMGCR, LDLr, CXCL16 and profibrogenic factors including TGF-β1 and CTGF were also analyzed.

RESULTS

The diabetic rats showed significantly increased 24-h urinary protein level (P<0.001), obvious renal tubular injury, and increased renal cholesterol content (P<0.05) with significantly increased HIF-1α expression in the renal tubular (P<0.01). YC-1 treatment significantly ameliorated tubulointerstitial injury in the diabetic rats as shown by decreased 24-h urinary total protein (P<0.05) and reduced damage area of the tubules, and effectively decreased renal cholesterol levels and renal expression of HIF-1α (P<0.05). In HK-2 cells, CoCl2 stimulation in the presence of high glucose effectively activated HIF-1α expression (P<0.0001), aggravated cholesterol accumulation (P<0.05), and increased the expressions of HMGCR, LDLr, CXCL16, TGF-β1, and CTGF (P<0.05 or 0.01). Consistent with the in vitro study, YC-1 treatment also significantly decreased the expressions of cholesterol metabolism-related proteins and the profibrogenic factors in the renal tubules of the diabetic rats.

CONCLUSION

HIF-1α activation induces cholesterol homeostasis dysregulation possibly by upregulating the de novo synthesis and uptake of cholesterol, thereby aggravating tubulointerstitial injury in DN.

[The value of quantitative measurement of key structures of inner ear by HRCT in hearing evaluation of patients with congenital severe sensorineural deafness]

Objective:Study on the value of quantitative measurement of key structures of inner ear by high resolution computer tomography（HRCT） in hearing evaluation of patients with congenital severe sensorineural hearing loss（SNHL）. Methods:A total of 90 children with extremely severe SNHL diagnosed and treated in Beilun District People's Hospital from January 2018 to February 2021 were collected as the experimental group. In the same period, 90 children（180 ears） with normal inner ear structure and hearing were scanned because of head trauma and suspected temporal bone fracture. Logistic univariate and multivariate regression analysis were used to analyze the factors affecting the occurrence of extremely severe SNHL. Based on the results of multivariate analysis, a Nomogram prediction model was established. The model before and after internal correction was evaluated by the receiver working characteristic curve. Results:Inner ear malformation, SSCC bone island width, LSCC bone island width and cochlear height were independent risk factors for extremely severe SNHL. The results of Nomogram predictive model showed that cochlear height 34 points, LSCC bone island width 19 points, SSCC bone island width 22 points, inner ear malformation 37 points, the total score（112 points） corresponding to the incidence of extremely severe SNHL（0.3%）. The actual C-index value of Nomogram prediction model is 0.858, the C-index of internal verification is 0.851, and the C-index of external verification is 0.847. The coincidence of the model is good. It is suggested that the model can effectively predict the risk factors of congenital extremely severe SNHL and has high prediction accuracy. Conclusion:The standardized measurement of SSCC bone island width, LSCC bone island width and cochlear height by HRCT is of great value in the diagnosis of microinner ear malformation in children with extremely severe SNHL.