The attributable burden of hypertension: focus on CKD

Hypoxia and chronic kidney disease: Possible mechanisms, therapeutic targets, and relevance to cats

There is mounting evidence that kidney ischaemia/hypoxia plays an important role in feline chronic kidney disease (CKD) development and progression, as well as in human disease and laboratory animal models. Ischaemic acute kidney injury is widely accepted as a cause of CKD in people and data from laboratory species has identified some of the pathways underlying this continuum. Experimental kidney ischaemia in cats results in morphological changes, namely chronic tubulointerstitial inflammation, tubulointerstitial fibrosis, and tubular atrophy, akin to those observed in naturally-occurring CKD. Multiple situations are envisaged that could result in acute or chronic episodes of kidney hypoxia in cats, while risk factors identified in epidemiological studies provide further support that kidney hypoxia contributes to spontaneously occurring feline CKD. This review evaluates the evidence for the role of kidney ischaemia/hypoxia in feline CKD and the proposed mechanisms and consequences of kidney hypoxia. As no effective treatments exist that substantially slow or prevent feline CKD progression, there is a need for novel therapeutic strategies. Targeting kidney hypoxia is one such promising approach, with therapies including those that attenuate the hypoxia-inducible factor (HIF) pathway already being utilised in human CKD.

Adherence to antihypertensive therapy and its determinants among patients attending primary care hospitals of Kashmir, India

Background:

Adherence to antihypertensive therapy is an important factor in determining the clinical course of hypertension. This study was planned to estimate adherence to antihypertensive therapy and its determinants among OPD patients attending two primary care hospitals in Kashmir valley.

Methods:

This study employed a cross-sectional study design. All subjects who reported to OPD between October and December 2020 and had been prescribed antihypertensive medications for at least 1 year were included. Sociodemographic information was collected on a pretested schedule and adherence to medications was assessed by using the-14 item Hill-Bone HBP Compliance to High Blood Pressure Therapy Scale (HB-HBP). Mann–Whitney test and Spearman’s rank correlation coefficient were used.

Results:

A total of 406 subjects were included in the final analysis with a mean age of 58 years for women and 56 years for men. The sample comprised 54% women. More than 60% of subjects were currently married, urban area residents, and belonged to middle strata of social class. The mean score obtained in the HB-MAS (maximum score 56) was 19.26 (SD ± 4.3). Subjects aged 60 years and above, those belonging to lower socioeconomic class, and subjects prescribed three or more drugs with more than once-daily dosing regimen had higher odds of having poor adherence.

Conclusion:

There is suboptimal adherence among OPD patients at primary care level. There is a need for enhanced counselling regarding medication adherence particularly for elderly, poor, illiterate persons and those prescribed multiple medicines with more than once-daily dosing.

Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease

There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone-induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia-induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.

Risk factors to predict the development of chronic kidney disease in patients with lupus nephritis

Objectives

We analyzed the clinical follow-up results of 88 lupus nephritis patients to find prognostic factors for the development of chronic kidney disease in ethnically homogeneous Korean patients with biopsy-proven lupus nephritis.

Methods

Sociodemographic, clinical, laboratory, and treatment-related data at the time of kidney biopsy and during follow-up were obtained. Renal biopsy specimens were reclassified according to the International Society of Pathology/Renal Pathology Society classification, separately, by two renal pathologists blinded to the previous classification. Univariate and multivariate analyses were performed using the Cox proportional hazard regression model to identify independent risk factors for chronic kidney disease in lupus nephritis patients.

Results

Eighteen of 88 patients (20.5%) developed chronic kidney disease during a mean follow-up of 47.6 months (range: 12–96 months). Patients who developed chronic kidney disease were older at onset of lupus nephritis, had less education, and were more likely to have hypertension; they had lower serum albumin levels, lower platelet levels, higher serum creatinine levels, lower estimated glomerular filtration rate, higher chronicity index, and lower frequency of anti-ribosomal P antibodies, and they were less likely to be in complete remission in the first year. In stepwise multivariable analyses, hypertension, lower glomerular filtration rate, and failure to achieve complete remission in the first year of treatment were significant predictors of the development of chronic kidney disease in lupus nephritis patients.

Conclusions

These findings suggest that patients with hypertension and decreased kidney function at the onset of lupus nephritis and showing a poor response to immunosuppressive drugs in the first year should be monitored carefully and managed aggressively to avoid deterioration of kidney function.

Current Understanding of the Pathogenesis of Progressive Chronic Kidney Disease in Cats

In cats with chronic kidney disease (CKD), the most common histopathologic finding is tubulointerstitial inflammation and fibrosis. However, these changes reflect a nonspecific response of the kidney to any inciting injury. The risk of developing CKD is likely to reflect the composite effects of genetic predisposition, aging, and environmental and individual factors that affect renal function over the course of a cat's life. However, there is still little information available to determine exactly which individual risk factors predispose a cat to develop CKD. Although many cats diagnosed with CKD have stable disease for years, some cats show overtly progressive disease.

Association Between Interleukin-6 -572 C>G and -174 G>C Polymorphisms and Hypertension: A Meta-analysis of Case-control Studies

Whether hypertension is associated with -572 C>G or -174 G>C polymorphism in interleukin (IL)-6 genes still remains hazy and ambiguous.We conducted a meta-analysis to offer a more reliable and clearer evaluation about the association.Electronic literature databases including PubMed, Web of Science, EMBASE, Google Scholar, Chinese National Knowledge Infrastructure and Wanfang database were searched.The study included the following: evaluating associations between -572 C>G or -174 G>C polymorphism in IL-6 gene and hypertension; case-control design; essential information must be offered; precise diagnostic criteria of hypertension; and no language restriction.Patients who met the diagnostic criteria and controls without a history of hypertension were included. Interventions were not available.A quality assessment was conducted using Newcastle-Ottawa scale. Combined odds ratios with 95% confidence intervals were calculated in 5 genetic models. Sources of heterogeneity were explored by subgroup analysis, meta-regression, and Galbraith plots. Finally, test for publication bias was performed to prove the stabilization.Fifteen studies were finally included. Eleven articles were judged high-quality reports. Overall, the -572 C>G polymorphism was proved to be significantly associated with hypertension in 4 genetic models. Subgroup analysis based on ethnicity revealed significant associations in Asian population in recessive model and homozygote comparison. The association in Europeans and Mid-East required further confirmation. No significant association was observed between the -174 G>C polymorphism and hypertension under all of the genetic models.The limitations of the study were the following: restrictive number of eligible studies limited the extrapolation range in subgroup analysis; gene-environment factors could not be described due to lack of data; some relevant studies could not be included because of various reasons.Current researches supported the association between the development of hypertension and the -572 C>G rather than -174 G>C polymorphism. Future well designed epidemiological studies may evaluate the possible gene-environment interactions.

Rethinking hypertensive kidney disease: arterionephrosclerosis as a genetic, metabolic, and inflammatory disorder

PURPOSE OF REVIEW

Hypertension is the attributed cause of approximately 30% of end-stage kidney disease cases in the United States, but there has been controversy as to whether benign hypertension is a cause of chronic kidney disease.

RECENT FINDINGS

The histology of chronic kidney disease attributed to nonmalignant hypertension is arterionephrosclerosis, with pathology in the terminal branches of the interlobular arteries, together with global glomerulosclerosis. The identification of coding region variants in APOL1, encoding apolipoprotein L1, has opened a new perspective on this debate. These variants are restricted to populations of recent African descent and are strongly associated with clinically diagnosed arterionephrosclerosis, particularly when there is moderate-grade or high-grade proteinuria or progression to more advanced levels of kidney dysfunction. Nevertheless, not all African Americans with hypertension who progress to end-stage kidney disease have two APOL1 risk variants, and individuals of European and Asian descent also manifest arterionephrosclerosis. Further, we do not understand the mechanisms by which APOL1 initiates pathology in the renal microcirculation.

SUMMARY

APOL1 nephropathy comprises a disease spectrum (perhaps with distinct endophenotypes), including focal segmental glomerulosclerosis, collapsing glomerulopathy, and arterionephrosclerosis. The terms hypertensive kidney disease and hypertensive nephrosclerosis have outlived their usefulness. It may be time to use the established, etiologically neutral term, arterionephrosclerosis, to consider whether this is a disease rather than a pathologic description, and to determine the causal role of various clinical correlates including aging, obesity, hyperlipidemia, smoking, chronic inflammation, and oxidative stress.

Renal tissue oxygenation in essential hypertension and chronic kidney disease

Animal studies suggest that renal tissue hypoxia plays an important role in the development of renal damage in hypertension and renal diseases, yet human data were scarce due to the lack of noninvasive methods. Over the last decade, blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI), detecting deoxyhemoglobin in hypoxic renal tissue, has become a powerful tool to assess kidney oxygenation noninvasively in humans. This paper provides an overview of BOLD-MRI studies performed in patients suffering from essential hypertension or chronic kidney disease (CKD). In line with animal studies, acute changes in cortical and medullary oxygenation have been observed after the administration of medication (furosemide, blockers of the renin-angiotensin system) or alterations in sodium intake in these patient groups, underlining the important role of renal sodium handling in kidney oxygenation. In contrast, no BOLD-MRI studies have convincingly demonstrated that renal oxygenation is chronically reduced in essential hypertension or in CKD or chronically altered after long-term medication intake. More studies are required to clarify this discrepancy and to further unravel the role of renal oxygenation in the development and progression of essential hypertension and CKD in humans.

Is nocturnal blood pressure reduction the secret to reducing the rate of progression of hypertensive chronic kidney disease?

Hypertension is a significant risk factor for cardiovascular and renal disease. Lowering blood pressure (BP) has been shown to reduce the incidence of cardiovascular disease, but randomized trials have not demonstrated a benefit of lowering BP for the progression of renal disease except in secondary analyses in patients with significant proteinuria. Recently, there has been increasing interest in measuring BP outside of the clinic, using both home and ambulatory blood pressure monitoring (ABPM). ABPM has the advantage of measuring BP throughout both the day and night. Elevated nighttime BP and a lack of decline in BP from day to night (nondipping) are more potent risk factors for cardiovascular and renal outcomes than elevated daytime or clinic BP. Studies have shown that it is possible to lower nighttime BP and restore normal dipping with the administration of antihypertensive medications in the evening, known as chronotherapy. Evening administration of antihypertensives not only lowers nighttime BP but also is associated with decreased urinary protein excretion, decreased cardiovascular events, and decreased all-cause mortality. Reducing nighttime BP may slow the progression of chronic kidney disease and may be the key to linking the treatment of hypertension with improved renal outcomes.