Apparent treatment-resistant hypertension and chronic kidney disease: another cardiovascular-renal syndrome?

Signaling Integration of Hydrogen Sulfide and Iron on Cellular Functions

Significance: Hydrogen sulfide (H₂S) is an endogenous signaling molecule, regulating numerous physiological functions from vasorelaxation to neuromodulation. Iron is a well-known bioactive metal ion, being the central component of hemoglobin for oxygen transportation and participating in biomolecule degradation, redox balance, and enzymatic actions. The interplay between H₂S and iron metabolisms and functions impacts significantly on the fate and wellness of different types of cells. Recent Advances: Iron level in vivo affects the production of H₂S via nonenzymatic reactions. On the contrary, H₂S quenches excessive iron inside the cells and regulates the redox status of iron. Critical Issues: Abnormal metabolisms of both iron and H₂S are associated with various conditions and diseases such as iron overload, anemia, oxidative stress, and cardiovascular and neurodegenerative diseases. The molecular mechanisms for the interactions between H₂S and iron are unsettled yet. Here we review signaling links of the production, metabolism, and their respective and integrative functions of H₂S and iron in normalcy and diseases. Future Directions: Physiological and pathophysiological importance of H₂S and iron as well as their therapeutic applications should be evaluated jointly, not separately. Future investigation should expand from iron-rich cells and tissues to the others, in which H₂S and iron interaction has not received due attention. Antioxid. Redox Signal. 36, 275-293.

Swimming Exercise Ameliorates Hypertension-Induced Kidney Dysfunction via Alleviating Renal Interstitial Fibrosis and Apoptosis

BACKGROUND

Hypertensive nephropathy is one of the major causes of ESRD. Exercise has been considered a nonpathological therapy for hypertension and its complications, yet mechanisms remain unclear. We sought to investigate whether periodic swimming could ameliorate hypertension-induced kidney dysfunction and its underlying mechanisms.

METHODS

Four-week male spontaneously hypertensive rats (SHRs) were randomly divided into the hypertension group (SHR, n = 8) and exercise group (SE, n = 8, 60 min swimming/day, 6 days per week, for 8 weeks). Wistar-Kyoto rats (WKY, n = 8) were served as a sedentary normotensive group. Bodyweight and blood pressure (BP) were recorded weekly. After 8-week sedentary or swimming exercise, lipids profile, BUN, and Cr were measured. The renal interstitial fibrosis was examined by the histopathological analysis using Masson's trichrome staining and hematoxylin and eosin staining. The kidney cell apoptosis was tested by TUNEL staining. The expressions of critical proteins responsible for the TGF-β1/Smad signaling of fibrosis, that is, TGF-β1, Smad2/3, and Smad7, as well as apoptosis related proteins, Bax and Bcl-2 in kidney cortex tissues were measured.

RESULTS

The 8-week swimming exercise reduced BP and bodyweight, lowered concentrations of BUN, and serum Cr, compared with SHR. Exercise remarkably inhibited hypertension-induced tubular degeneration, cellular cluster, and tubular cell swelling as well as glomerular degeneration in the kidney cortical tissues, attenuated renal interstitial fibrosis, and renal cell apoptosis. Moreover, expressions of TGF-β1, Smad2/3, and Bax were higher in the SHR than the WKY, which were significantly suppressed by the exercise. In contrast, hypertension-reduced expressions of Smad7 and Bcl-2 were enhanced by the swimming exercise. Strong correlations were found between kidney function indices, blood lipids, and key protein expressions.

CONCLUSION

Our results demonstrate beneficial effects of the periodic swimming on ameliorating hypertension-induced kidney dysfunction highlighting the potential of swimming exercise as a nonpathological therapy for early prevention of hypertension-caused kidney diseases.

A clinical evaluation of renal amyloidosis in the Japan renal biopsy registry: a cross-sectional study

BACKGROUND AND AIM

The available clinical data are limited in a rare glomerular disease, renal amyloidosis. We aimed to clarify the clinical features of renal amyloidosis from database of the Japan Renal Biopsy Registry (J-RBR).

METHODS

We performed a cross-sectional study with database of the J-RBR of the Japanese Society of Nephrology. We identified 281 cases of renal amyloidosis from 20,997 cases enrolled into the J-RBR from 2007 to 2014. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were compared among the levels of ages, amount of urine protein excretion (AUPE) or CKD G stages.

RESULTS

The prevalence of renal amyloidosis was 1.3 % (281/20,997). DBP significantly decreased in higher age quartiles (P = 0.034). SBP and DBP did not increase in the progression of AUPE levels and CKD G stages. In multiple regression analysis, eGFR was a significant independent factor for SBP in all cases and a subgroup without hypertensive agents. There was a reverse significant relationship between SBP and eGFR.

CONCLUSION

Blood pressure did not significantly increase in elderly and much proteinuric condition in renal amyloidosis. The progression of CKD and decrease of eGFR did not produce the higher SBP. The mechanism underlying these results remains unclear; however, they are unique features of renal amyloidosis. The couple of hypotensive and hypertensive conditions might produce no relationship between blood pressure and CKD stages.