Pentoxifylline: Evidence strong enough for renoprotection?

Diabetik Nefropati Progresyonuna Pentoksifilin Tedavisinin Etkisi

Amaç: Diabetik nefropati (DN) son dönem böbrek yetersizliğinin önemli bir nedenidir. Vasküler hastalıklarda kullanılan ve anti-inflamatuar özellikleri olan pentoksifilinin diyabetik nefropatide olumlu etkileri olabileceği öne sürülmüştür. Bu çalışmada DN nedeni ile takipte olan ve pentoksifilin kullanan hastaların tedavi öncesi ve sonrası dönemdeki böbrek fonksiyonları ve proteinürileri değerlendirilmiştir. Gereç ve Yöntemler: Kliniğimizde takipte olup pentoksifilin (1200 mg/gün) tedavisi alan 36 diabetik nefropati hastası retrospektif olarak tarandı. Tedavi başlanmadan önceki 3. ve 6. ay; pentoksifilin tedavisinin 3., 6., 9. ve 12. aylardaki günlük proteinüri miktarı ve eGFR (estimated glomerular filtration rate, tahmini glomerüler filtrasyon hızı) değerleri kayıt edildi. Bulgular: Çalışmaya alınan 36 hastanın ortalama yaşı 51,9±12,3 yıl, 12’si erkek ve 16’sı Anjiotensin dönüştürücü enzim (Angiotensin converting enzyme inhibitor, ACEİ) ya da Anjiotensin reseptör blokeri (Angiotensin receptor blocker, ARB) kullanıyordu. Pentoksifilini 23 hasta ≤6 ay (A grubu) 13 hasta >6 ay (B grubu) süre kullanmıştı. Proteinüri miktarı ve eGFR kaybı yönünden her iki grupta anlamlı farklılık saptanmadı. Sonuç: Çalışmamızda diabetik nefropatili hastalarda 1 yıllık takip sırasında pentoksifilin tedavisinin proteinüri miktarı ve eGFR kaybına etkisi saptanamamıştır. Anahtar kelimeler: Diabetik nefropati, pentoksifilin, proteinüri

Old age is a positive modifier of renal outcome in Taiwanese patients with stages 3-5 chronic kidney disease

BACKGROUND

The incidence of end-stage renal disease (ESRD) is increasing in elderly patients with chronic kidney disease (CKD). This contradicts the general notion that elderly people are more likely to die than to ever reach ESRD. And racial disparity in relation to age on kidney disease outcomes has always been a subject of research interest.

AIMS

We investigated the effect of age on outcome in a cohort with stages 3-5 CKD patients by age category.

METHODS

A total of 430 patients with a mean age of 65.6 years were enrolled and followed till death, ESRD, or end of 2015. Multivariable Cox regression was used to identify predictors of all-cause mortality. Competing risk-adjusted Cox regression was used to identify determinants of ESRD. The median follow-up was 7.3 (interquartile range 8.8) years.

RESULTS

Cox regression showed old age and low mean arterial pressure were predictors of mortality before and after onset of ESRD. Competing risk analysis revealed patients aged 20-39 years and 40-64 years exhibited greater risks of ESRD, compared to those aged over 75 years. These effects of age on outcomes occurred independently of traditional risk factors such as low estimated glomerular filtration rate and high proteinuria.

CONCLUSIONS

Age over 75 years is associated with decreased risk for ESRD even after adjustment for competing mortality. Given the global trends in population aging, there is a need to develop age-specific strategies, on top of the existing stage-based measures, to optimize the management of CKD in the elderly.

Role of renin-angiotensin system in acute kidney injury-chronic kidney disease transition

Acute kidney injury (AKI) can increase the risk of developing incident chronic kidney disease (CKD). The severity, frequency and duration of AKI are crucial predictors of poor renal outcome. A repair process after AKI can be adaptive and kidney recovers completely after a mild injury. However, severe injury will lead to a maladaptive repair, which frequently progresses to nephron loss, vascular rarefaction, chronic inflammation and fibrosis. Although different mechanisms underlying AKI-CKD transition have been extensively discussed, no definite intervention has been proved effective to block or to retard the transition until recently. In CKD, renin-angiotensin system (RAS) inhibitor has been proved effective to slow down disease progression. Furthermore, RAS needs to be highlighted again in AKI-CKD transition because recent animal studies have shown the activation of intra-renal RAS after AKI, and RAS blockade can reduce the ensuing CKD and mortality. In patients with the complete renal recovery after AKI, administration of RAS inhibitor is associated with reduced risk of subsequent CKD as well. In this article, we will demonstrate the role of RAS in AKI-CKD transition comprehensively. We will then emphasize the promising effect of RAS inhibitor on CKD prevention in patients recovering from AKI based on evidence from the bench to clinical research. All of these discussions will contribute to the establishment of reliable monitoring and therapeutic strategies for patients with functional recovery from AKI who can be most easily ignored.

Targeting inflammation in diabetic nephropathy: a tale of hope

INTRODUCTION

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Beyond the new anti-diabetic drugs that possess markedly cardiovascular and renal protective effects, no novel direct therapies for DN have become available on the market in the last twenty years. Recently well-designed clinical trials for the treatment of DN, with attractive pathogenetic rationale, e.g. bardoxolone and atrasentan, were canceled or stopped because of safety concerns or lack of reaching the end points, respectively.

AREAS COVERED

In this review, we focus on the involvement of inflammation in the pathogenesis of DN. We update information from recent experimental and clinical studies that reported beneficial effects of several agents targeting chemokines, cytokines, transcription factors and kinases as well as several compounds with anti-inflammatory properties on DN.

EXPERT OPINION

Inflammation plays a key role in the DN progression. Preclinical studies have identified several anti-inflammatory molecules that effective decrease albuminuria and/or proteinuria. However, limited clinical trials in humans have been performed to confirm these results. Inhibitors of CCL2/CCR2, IL-1β and JAK/STAT pathways, and Nrf2 inducers are promising therapeutic options to improve the renal outcome of patients with DN, but appropriate clinical trials are necessary.

Protective effect of pentoxifylline on oxidative renal cell injury associated with renal crystal formation in a hyperoxaluric rat model

The aim of the study is to investigate the effects of pentoxifylline (PTX) on the renal tubular cell injury and stone formation in a hyperoxaluric rat model induced by ethylene glycol and its possible underlying mechanisms. The study was performed with 30 male Wistar rats and randomized into three groups of teen. The sham-control (group 1) received only drinking water orally. The EG/untreated (group 2) received drinking water containing 0.75% EG for 4 weeks orally. The EG/PTX treated (group 3) received drinking water containing 0.75% EG for 4 weeks orally and PTX. Urine and blood were collected to determine some parameters. The kidneys were also removed for histological examination. Serum and urinary parameters were significantly improved in the EG/PTX treated. In the EG/PTX-treated group, the MDA, TOS and MPO activity reduced and the TAS, SOD, CAT and GSH-Px activities were increased markedly compared with the group 2. In urine of the group 2 rats, a large number of CaOx crystals were displayed and most tubules that contained crystals were dilated and showed degeneration, necrosis, and desquamation of the lining epithelium. Only few CaOx crystals were r in EG/PTX-treated animal's urine. Mild tissue damage was observed in PTX-treated rats. iNOS expression was significantly elevated in the group 2. In contrast, in the EG/PTX-treated group, eNOS expression in renal tubular epithelial cells was increased. Current study indicates that PTX may partially reduce renal tubular injury resulting from hyperoxaluria-induced oxidative and nitrosative stress.

Update of pathophysiology and management of diabetic kidney disease

Diabetic kidney disease (DKD) is a major cause of morbidity and mortality in patients with diabetes mellitus and the leading cause of end-stage renal disease in the world. The most characteristic marker of DKD is albuminuria, which is associated with renal disease progression and cardiovascular events. Renal hemodynamics changes, oxidative stress, inflammation, hypoxia and overactive renin-angiotensin-aldosterone system (RAAS) are involved in the pathogenesis of DKD, and renal fibrosis plays the key role. Intensified multifactorial interventions, including RAAS blockades, blood pressure and glucose control, and quitting smoking, help to prevent DKD development and progression. In recent years, novel agents are applied for preventing DKD development and progression, including new types of glucose-lowering agents, pentoxifylline, vitamin D analog paricalcitol, pyridoxamine, ruboxistaurin, soludexide, Janus kinase inhibitors and nonsteroidal minerocorticoid receptor antagonists. In this review, recent large studies about DKD are also summarized.

Therapeutic efficacy of pentoxifylline on proteinuria and renal progression: an update

Blood pressure control with renin-angiotensin system (RAS) blockade has remained the gold standard for treating patients with proteinuric chronic kidney disease (CKD) up to date. Nevertheless, RAS blockade slows but does not halt the progression of kidney disease, thus highlighting the need to search for additional therapeutic approaches. The nonselective phosphodiesterase (PDE) inhibitor pentoxifylline (PTX) is an old drug that exhibits prominent anti-inflammatory, anti-proliferative and anti-fibrotic activities both in vitro and in vivo. Studies in human subjects have shown that PTX monotherapy decreases urinary protein excretion, and add-on therapy of PTX to background RAS blockade additively reduces proteinuria in patients with CKD of various etiology. More recent studies find that PTX combined with RAS blockade delays the decline of glomerular filtration rate in diabetic patients with mild to moderate CKD, and reduces the risk of end-stage renal disease in diabetic and non-diabetic patients in late stage of CKD with high proteinuria levels. In this review, we update the clinical trial results of PTX as monotherapy, or in conjunction or in comparison with RAS blockade on patients with proteinuria and CKD, and propose a mechanistic scheme explaining the renoprotective activities of this drug.

Novel insights into acute kidney injury-chronic kidney disease continuum and the role of renin-angiotensin system

Acute kidney injury (AKI) is an independent risk factor for chronic kidney disease (CKD). If injury is mild, a repair process can be adaptive and lead to complete renal recovery. However, severe injury will be accompanied by a maladaptive repair which usually leads to nephron loss, fibrosis, vascular rarefaction, and chronic inflammation. Although various mechanisms underlying AKI-CKD transition have been explored, no intervention has been proved effective to block the transition until very recently. A lack of consensus for monitoring renal function and defining renal recovery after AKI should be the reasons for the slow advance in the discovery of a timely pharmacologic treatment to block AKI-CKD transition. Recently, animal studies have shown the activation of renin-angiotensin system (RAS) after AKI. In patients with complete renal recovery after AKI defined as the decrease of serum creatinine level to within 0.3 mg/dL above the baseline, administration of RAS inhibitor can prevent the ensuing CKD. In this review, we will discuss the renal recovery after AKI and the mechanisms underlying AKI-CKD transition. We will then highlight the promising effect of RAS inhibitor on CKD prevention in patients with complete renal recovery from AKI based on the recent clinical evidence.

Pentoxifylline Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats: Possibly via Inhibiting TLR 4/NF-κB Signaling Pathway

Early brain injury (EBI) after subarachnoid hemorrhage (SAH) generally causes significant and lasting damage. Pentoxifylline (PTX), a nonselective phosphodiesterase inhibitor, has shown anti-inflammatory and neuroprotective properties in several brain injury models, but the role of PTX with respect to EBI following SAH remains uncertain. The purpose of this study was to investigate the effects of PTX on EBI after SAH in rats. Adult male Sprauge-Dawley rats were randomly assigned to the sham and SAH groups. PTX (30 or 60 mg/kg) or an equal volume of the administration vehicle (normal saline) was administrated at 30 min intervals following SAH. Neurological scores, brain edema, and neural cell apoptosis were evaluated. In order to explore other mechanisms, changes in the toll-like receptor 4 (TLR4) and the nuclear factor-κB (NF-κB) signaling pathway, in terms of the levels of apoptosis-associated proteins, were also investigated. We found that administration of PTX (60 mg/kg) notably improved neurological function and decreased brain edema at both 24 and 72 h following SAH. Treatment with PTX (60 mg/kg) significantly inhibited the protein expressions of TLR4, NF-κB, MyD88 and the downstream pro-inflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). PTX also significantly reduced neural cell death and BBB permeability. Our observations may be the first time that PTX has been shown to play a neuroprotective role in EBI after SAH, potentially by suppressing the TLR4/NF-κB inflammation-related pathway in the rat brain.