Biopsie rénale : les différentes techniques

TRPM7 promotes lipopolysaccharide-induced inflammatory dysfunction in renal tubular epithelial cells

BACKGROUND

Sepsis-associated acute kidney injury (S-AKI) has been reported to affect 30%-50% of all sepsis patients; this condition is associated with a notable fatality rate. Following lipopolysaccharide (LPS) stimulation, the expression of transient receptor potential cation channel subfamily M member 7 (TRPM7), a nonselective cation channel expressed by the renal tubular epithelial cells (RTECs) was found to be upregulated. We aimed to determine how TRPM7 functions in S-AKI.

METHODS

To establish an in vitro model of S-AKI, RTECs were treated with LPS. The effect of TRPM7 knockdown on cell viability, lactate dehydrogenase (LDH) release, apoptosis, inflammation, and oxidative stress was studied. The binding site between Kruppel-like factor 2 (KLF2) and TRPM7 was predicted using JASPAR. The influence of KLF2 on the regulatory roles of TRPM7 in cells, as well as the effect of their knockdown on the MAPK signaling pathway, was investigated.

RESULTS

TRPM7 was upregulated in LPS-treated cells, and knocking improved cell viability, reduced LDH levels, and minimized apoptosis, inflammation, and oxidative stress. KLF2 was shown to be associated with TRPM7 and its level decreased in LPS-treated cells. KLF2 knockdown increased TRPM7 expression and reversed the effects of TRPM7 knockdown in LPS-treated cells, including suppression of p38 MAPK, ERK1/2, and JNK activation.

CONCLUSION

Taken together, our results show that TRPM7 is negatively regulated by KLF2 and promotes LPS-induced inflammatory dysfunction by activating the MAPK pathway in RTECs. The theoretical foundation for the prevention and management of S-AKI is laid out in this article.

[Hemorrhagic shock following a renal biopsy: report of a case]

La ponction biopsie rénale (PBR) est un examen indispensable en néphrologie mais à risque de complications graves surtout hémorragique. Nous rapportons l'observation d'un patient âgé de 27 ans ayant bénéficié d'une PBR pour un diagnostic étiologique d'une insuffisance rénale aigue, l’évolution après la biopsie a été marquée par l'installation d'un choc hémorragique d'où la prise en charge en réanimation avec une néphrectomie d'hémostase.

Advantages and controversies in the era of intrarenal volumetry

BACKGROUND/AIMS

Ultrasound is the preferred imaging modality in nephrology. In many kidney diseases, however, more accurate methods are needed to distinguish between relevant intrarenal structures. MRI could be a solution, although the use of MRI contrast has caused severe complications in some cases, and invasive kidney biopsies may follow, even though such small specimens traditionally provide inaccurate quantitative data. We evaluated the usefulness of MRI volumetry and quantitative kidney biopsies to assess glomerular number and volume as well as cortical volume.

METHODS

We specifically highlight an experimental study in which different MRI scans were performed in healthy pigs as well as pigs with unilateral ureteral obstruction to assess intrarenal volume. Single-kidney glomerular filtration rate (GFR) was measured using ureteral cannulation and (51)Cr-EDTA. Kidney biopsies were taken and evaluated employing stereological techniques to measure number and volume of glomeruli. Pigs were sacrificed and kidneys were removed for stereological analysis. Non-contrast-based MRI intrarenal volumes were - without significant difference to intrarenal volumes - obtained using contrast-enhanced MRI and ex vivo techniques.

RESULTS

Kidney biopsies gave valid estimates regarding quantitative parameters, such as mean number and volume of glomeruli in the cortex. Different structural parameters correlated with kidney GFR with high, although varying, correlation coefficients.

CONCLUSION

Non-contrast MRI is suitable for estimating intrarenal volumes in healthy and diseased kidneys. We advocate further research in diagnostic modalities combining MRI and biopsies. Major challenges are the cortical architecture and heterogeneous distribution of glomeruli within the kidney.