Pathophysiology of Physical Exercise in Kidney Patients: Unveiling New Players- The Role of Myokines.

Background Chronic kidney disease (CKD) is a progressive systemic condition characterized by numerous complications. Among these, alterations in skeletal muscle physiology, such as sarcopenia, are particularly significant, as they are associated with poor outcomes and reduced quality of life. Summary Various interventions, including pharmacological approaches and lifestyle modifications have been investigated to slow CKD progression and prevent or treat its complications. Physical exercise, in particular, has emerged as a promising intervention with multiple beneficial effects. These include improvements in physical functioning, increased muscle mass, modulation of metabolic abnormalities, and reduced cardiovascular risk. However, the pathophysiology of physical exercise in patients with kidney disease is complex and remains only partially understood. A crucial advancement in understanding this phenomenon has been the identification of myokines-molecules expressed and released by skeletal muscle in response to physical activity. These myokines can exert both paracrine and systemic effects, influencing not only skeletal muscle physiology but also other processes such as energy metabolism and lipid regulation. Key Messages The interplay among skeletal muscle, physical activity, and myokines may act as a pivotal regulator in various physiological processes, including aging, as well as in pathological conditions like cachexia and sarcopenia, frequently observed in CKD patients at different stages, including patients on dialysis. Despite the potential importance of this relationship, only a limited number of studies have explored the relationship between exercise and myokine, and the effect of this interaction on experimental models or individuals with kidney disease. In the following sections, we review and discuss this topic.

Prognostic Value and Relative Cutoffs of Triglycerides Predicting Cardiovascular Outcome in a Large Regional-Based Italian Database.

BACKGROUND: Despite longstanding epidemiologic data on the association between increased serum triglycerides and cardiovascular events, the exact level at which risk begins to rise is unclear. The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension has conceived a protocol aimed at searching for the prognostic cutoff value of triglycerides in predicting cardiovascular events in a large regional-based Italian cohort. METHODS AND RESULTS: Among 14 189 subjects aged 18 to 95 years followed-up for 11.2 (5.3-13.2) years, the prognostic cutoff value of triglycerides, able to discriminate combined cardiovascular events, was identified by means of receiver operating characteristic curve. The conventional (150 mg/dL) and the prognostic cutoff values of triglycerides were used as independent predictors in separate multivariable Cox regression models adjusted for age, sex, body mass index, total and high-density lipoprotein cholesterol, serum uric acid, arterial hypertension, diabetes, chronic renal disease, smoking habit, and use of antihypertensive and lipid-lowering drugs. During 139 375 person-years of follow-up, 1601 participants experienced cardiovascular events. Receiver operating characteristic curve showed that 89 mg/dL (95% CI, 75.8-103.3, sensitivity 76.6, specificity 34.1, P<0.0001) was the prognostic cutoff value for cardiovascular events. Both cutoff values of triglycerides, the conventional and the newly identified, were accepted as multivariate predictors in separate Cox analyses, the hazard ratios being 1.211 (95% CI, 1.063-1.378, P=0.004) and 1.150 (95% CI, 1.021-1.295, P=0.02), respectively. CONCLUSIONS: Lower (89 mg/dL) than conventional (150 mg/dL) prognostic cutoff value of triglycerides for cardiovascular events does exist and is associated with increased cardiovascular risk in an Italian cohort.

SA-ß-Gal in Kidney Tubules as a Predictor of Renal Outcome in Patients with Chronic Kidney Disease.

Cellular senescence has emerged as an important driver of aging and age-related disease in the kidney. The activity of ß-galactosidase at pH 6 (SA-ß-Gal) is a classic maker of senescence in cellular biology; however, the predictive role of kidney tissue SA-ß-Gal on eGFR loss in chronic kidney disease (CKD) is still not understood. We retrospectively studied the expression of SA-ß-Gal in kidney biopsies obtained in a cohort [n = 22] of incident patients who were followed up for 3 years as standard of care. SA-ß-Gal staining was approximately fourfold higher in the tubular compartment of patients with CKD vs. controls [26.0 ± 9 vs. 7.4 ± 6% positive tubuli in patients vs. controls; p < 0.025]. Tubular expressions of SA-ß-Gal, but not proteinuria, at the time of biopsy correlated with eGFR loss at the follow up; moreover, SA-ß-Gal expression in more than 30% of kidney tubules was associated with fast progressive kidney disease. In conclusion, our study shows that SA-ß-Gal is upregulated in the kidney tubular compartment of adult patients affected by CKD and suggests that tubular SA-ß-Gal is associated with accelerated loss of renal function.

Biopsy-proven acute tubulointerstitial nephritis in patients treated with immune checkpoint inhibitors: a pooled analysis of case reports.

Introduction: Acute kidney injury (AKI) in cancer patients receiving immune checkpoint inhibitors (ICIs) may recognize multiple causes. Here, we reviewed cases of biopsy-proven acute tubulointerstitial nephritis (ATIN) to describe the clinical characteristics and outcomes of this condition. Method: We conducted a pooled analysis of clinical cases of ICI-related biopsy-proven ATIN up to 1 May 2022. We collected data on clinical characteristics, AKI, biopsy findings, laboratory examinations, and renal outcomes. Results: Eighty-five patients (61.4 ± 19 years, 56 male) were evaluated. Melanoma was the most prevalent diagnosis (51%), followed by non-small cell lung cancer (30%). ICI treatment consisted of PD-1, PDL-1 (nivolumab, pembrolizumab, atezolizumab), and CTLA-4 inhibitors (i) (ipilimumab) or combination PD-1i+CTLA4i. Renal toxicity developed after a median of four cycles of therapy. Fifty-one patients (65.5%) developed the most severe form of AKI- stage 3, including five patients requiring dialysis. All the 19 patients treated with dual ICI blockade developed AKI-stage 3, compared with 29 patients out of the 60 receiving a single agent (p<0.001). Most events were managed with corticosteroids associated with ICI withdrawal. In 15 patients ICI was restarted, but in six (40%) AKI recurred. Overall, 32 patients (40%) presented a complete renal recovery, which chance was inversely associated with dual ICI blockade (OR 0.15, 95CI 0.03-0.7, p=0.01). Conclusion: ICI-related ATIN may develop late after the therapy initiation, presenting as severe AKI, particularly in patients with dual ICI blockade. Although this complication may be partially reversible, concerns remain about the renal function sequelae and the possibility of restarting ICI treatment.

Multifaceted relationship between diabetes and kidney diseases: Beyond diabetes.

Diabetes mellitus is one of the most common causes of chronic kidney disease. Kidney involvement in patients with diabetes has a wide spectrum of clinical presentations ranging from asymptomatic to overt proteinuria and kidney failure. The development of kidney disease in diabetes is associated with structural changes in multiple kidney compartments, such as the vascular system and glomeruli. Glomerular alterations include thickening of the glomerular basement membrane, loss of podocytes, and segmental mesangiolysis, which may lead to microaneurysms and the development of pathognomonic Kimmelstiel-Wilson nodules. Beyond lesions directly related to diabetes, awareness of the possible coexistence of nondiabetic kidney disease in patients with diabetes is increasing. These nondiabetic lesions include focal segmental glomerulosclerosis, IgA nephropathy, and other primary or secondary renal disorders. Differential diagnosis of these conditions is crucial in guiding clinical management and therapeutic approaches. However, the relationship between diabetes and the kidney is bidirectional; thus, new-onset diabetes may also occur as a complication of the treatment in patients with renal diseases. Here, we review the complex and multifaceted correlation between diabetes and kidney diseases and discuss clinical presentation and course, differential diagnosis, and therapeutic oppor-tunities offered by novel drugs.

Diagnosing Fabry nephropathy: the challenge of multiple kidney disease.

Fabry disease (FD) is an X-linked inherited lysosomal disorder due to a deficiency of the enzyme alpha-galactosidase A (α-gla) due to mutations in the GLA gene. These mutations result in plasma and lysosome accumulation of glycosphingolipids, leading to progressive organ damage and reduced life expectancy. Due to the availability of specific disease-modifying treatments, proper and timely diagnosis and therapy are essential to prevent irreversible complications. However, diagnosis of FD is often delayed because of the wide clinical heterogeneity of the disease and multiple organ involvement developing in variable temporal sequences. This observation is also valid for renal involvement, which may manifest with non-specific signs, such as proteinuria and chronic kidney disease, which are also common in many other nephropathies. Moreover, an additional confounding factor is the possibility of the coexistence of FD with other kidney disorders. Thus, suspecting and diagnosing FD nephropathy in patients with signs of kidney disease may be challenging for the clinical nephrologist. Herein, also through the presentation of a unique case of co-occurrence of autosomal dominant polycystic kidney disease and FD, we review the available literature on cases of coexistence of FD and other renal diseases and discuss the implications of these conditions. Moreover, we highlight the clinical, laboratory, and histological elements that may suggest clinical suspicion and address a proper diagnosis of Fabry nephropathy.

Daratumumab in the treatment of C3 glomerulopathy with monoclonal gammopathy: a case report and literature review.

Although rare, C3 glomerulopathy (C3G) is increasingly recognized thanks to the currently available diagnostic skills. C3G is not a single disease but a group of disorders with distinct pathogenesis and progression. Thus, an essential step for its management remains an in-depth characterization of the specific form and the identification of underlying conditions, which may also impact treatment choices as well. Among these entities, an emerging condition is the association of C3G with monoclonal gammopathy, which confers poor outcomes. Overall, diagnosis of C3G remains challenging, and determining the appropriate treatment remains unclear. Conventional immunosuppressive therapy has proven ineffective in such cases, while clone-directed therapies have shown promising results in small interventional studies and case series. Here, we report a case of a patient affected by C3G with monoclonal gammopathy of renal significance who experienced rapid deterioration of kidney function requiring replacement therapy. After the failure of first-line treatment, a switch to the anti-CD38 therapy with daratumumab resulted in the progressive improvement of the patient's kidney function, leading to the discontinuation of hemodialysis after approximately 10 months. Serial renal biopsies were also performed to study the disease's evolution in response to the treatment. Based on the description of this single case, we have comprehensively reviewed available studies on daratumumab use in patients with C3G associated with monoclonal gammopathy to provide insights for the design of prospective studies which aim to enhance the management of such poor prognosis disease.

The Contribution of Muscle Innate Immunity to Uremic Cachexia.

Protein energy wasting (PEW) is a common complication both in chronic kidney disease (CKD) and end-stage kidney disease (ESKD). Of note, PEW is one of the stronger predictors of morbidity and mortality in this patient population. The pathogenesis of PEW involves several mechanisms, including anorexia, insulin resistance, acidosis and low-grade inflammation. In addition, "sterile" muscle inflammation contributes to PEW at an advanced CKD stage. Both immune and resident muscle cells can activate innate immunity; thus, they have critical roles in triggering "sterile" tissue inflammation. Toll-like receptor 4 (TLR4) can detect endogenous danger-associated molecular patterns generated or retained in blood in uremia and induce a sterile muscle inflammatory response via NF-κB in myocytes. In addition, TLR4, though the activation of the NLRP3 inflammasome, links the sensing of metabolic uremic stress in muscle to the activation of pro-inflammatory cascades, which lead to the production of IL-1ß and IL-18. Finally, uremia-induced accelerated cell senescence is associated with a secretory phenotype that favors fibrosis in muscle. Targeting these innate immune pathways could lead to novel therapies for CKD-related PEW.

Homocysteine exchange across skeletal muscle in patients with chronic kidney disease.

Sites and mechanisms regulating the supply of homocysteine (Hcy) to the circulation are unexplored in humans. We studied the exchange of Hcy across the forearm in CKD patients (n = 17, eGFR 20 ± 2 ml/min), in hemodialysis (HD)-treated patients (n = 14) and controls (n = 9). Arterial Hcy was ~ 2.5 folds increased in CKD and HD patients (p < 0.05-0.03 vs. controls). Both in controls and in patients Hcy levels in the deep forearm vein were consistently greater (+~7%, p < 0.05-0.01) than the corresponding arterial levels, indicating the occurrence of Hcy release from muscle. The release of Hcy from the forearm was similar among groups. In all groups arterial Hcy varied with its release from muscle (p < 0.03-0.02), suggesting that muscle plays an important role on plasma Hcy levels. Forearm Hcy release was inversely related to folate plasma level in all study groups but neither to vitamin B12 and IL-6 levels nor to muscle protein net balance. These data indicate that the release of Hcy from peripheral tissue metabolism plays a major role in influencing its Hcy plasma levels in humans and patients with CKD, and that folate is a major determinant of Hcy release.

Among biomarkers of neutrophil activity, matrix metalloproteinases 8 independently predicts remission of metabolic syndrome.

BACKGROUND AND AIMS: Inflammation due to the excess of nutrient intake plays an important role in the pathophysiology of metabolic syndrome (MetS). Here, the potential influence of neutrophils and their degranulation markers on MetS improvement upon dietary and behavioral counselling, has been investigated. Specifically, we aimed at investigating their role as potential predictors of metabolic syndrome improvements. METHODS AND RESULTS: patients with MetS (n = 127) received behavioral and dietary recommendations before follow-up at 6 months. Serum levels of matrix metalloproteinases (MMP)8, MMP9, myeloperoxidase (MPO), tissue inhibitor of MMP (TIMP)-1, TIMP-2, TIMP-3 and resistin were tested at baseline. In the whole cohort, baseline levels of proinflammatory MMP8, MMP9 and MPO increased together with the number of MetS criteria. Seventy-three (57%) patients experienced a reduction in MetS-defining criteria at follow-up. With respect to those with no improvement, such individuals showed lower weight and waist circumference at enrolment, less frequent smoking habits, higher levels of triglycerides and lower circulating MMP8. At logistic regression analysis, baseline MMP8 showed negative predictive ability (odds ratio (OR) 0.979 [0.961-0.997]; p = 0.025) against MetS improvement. Such findings hold true even when included in the backward stepwise logistic regression model confirming MMP8 as an independent predictor (OR 0.970 [0.949-0.993]; p = 0.009). Receiver operating characteristic (ROC) curve confirmed the predictive ability of MMP8 combined in a model including baseline MetS criteria and waist circumference. Bootstrap resampling analysis internally validated our findings. CONCLUSION: Improvement of MetS is independently associated with baseline low MMP-8 levels, suggesting a pivotal role for inflammation in metabolic alteration.

Impact of eGFR rate on 1-year all-cause mortality in patients with stable coronary artery disease.

BACKGROUND: Coronary artery disease (CAD) is a leading cause of mortality and is often complicated by chronic kidney disease. We sought to investigate the prevalence of different degree of estimated glomerular filtration rate (eGFR) reduction, the clinical and bio-humoral correlates, its relationship with therapeutic management, and its predictive role on 1-year all-cause mortality, in patients with stable CAD. METHODS: We studied 4,130 patients with stable CAD recruited in a prospective, observational, nationwide study (START, STable coronary Artery diseases RegisTry) in Italy. Baseline clinical characteristics, pharmacological treatment, and all-cause 1-year mortality were evaluated according to groups of eGFR (<30; 30-59; 60-89; ≥90 ml/min/1.73 m2) at baseline. RESULTS: The presence and the degree of chronic kidney disease entailed an unfavorable risk profile, since it was gradually associated with more comorbidities. Furthermore, progressively lower eGFR values were associated to lower diastolic blood pressure and hemoglobin values. As eGFR lowers, optimal medical treatment and its persistence overtime is reduced. Multivariate analysis showed that progressively lower eGFR significantly correlated with all-cause 1-year mortality [hazard ratio (HR): 1.02; 95% confidence intervals (CI): 1.01-1-03; p = 0.0001]. CONCLUSIONS: Low eGFR is associated with an increasing risk of all-cause mortality in patients with stable CAD. Chronic kidney disease may hamper the optimization of treatment limiting the use of drugs which may favorably impact cardiovascular and renal outcomes.

Myostatin: Basic biology to clinical application.

Myostatin is a member of the transforming growth factor (TGF)-ß superfamily. It is expressed by animal and human skeletal muscle cells where it limits muscle growth and promotes protein breakdown. Its effects are influenced by complex mechanisms including transcriptional and epigenetic regulation and modulation by extracellular binding proteins. Due to its actions in promoting muscle atrophy and cachexia, myostatin has been investigated as a promising therapeutic target to counteract muscle mass loss in experimental models and patients affected by different muscle-wasting conditions. Moreover, growing evidence indicates that myostatin, beyond to regulate skeletal muscle growth, may have a role in many physiologic and pathologic processes, such as obesity, insulin resistance, cardiovascular and chronic kidney disease. In this chapter, we review myostatin biology, including intracellular and extracellular regulatory pathways, and the role of myostatin in modulating physiologic processes, such as muscle growth and aging. Moreover, we discuss the most relevant experimental and clinical evidence supporting the extra-muscle effects of myostatin. Finally, we consider the main strategies developed and tested to inhibit myostatin in clinical trials and discuss the limits and future perspectives of the research on myostatin.

Identification of a plausible serum uric acid cut-off value as prognostic marker of stroke: the Uric Acid Right for Heart Health (URRAH) study.

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting combined (fatal and non-fatal) cerebrovascular (CBV) events in the whole database. The URic acid Right for heArt Health study is a nationwide, multicenter, observational cohort study involving data on subjects aged 18-95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 120.7 ± 61.8 months. A total of 14,588 subjects were included in the analysis. A prognostic cut-off value of SUA able to discriminate combined CBV events (>4.79 mg/dL or >284.91 µmol/L) was identified by means of receiver operating characteristic curve in the whole database. Multivariate Cox regression analysis adjusted for confounders (age, sex, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, body mass index, low-density lipoprotein cholesterol, and use of diuretics) identified an independent association between SUA and combined CBV events in the whole database (HR 1.249, 95% confidence interval, 1.041-1.497, p = 0.016). The results of the present study confirm that SUA is an independent risk marker for CBV events after adjusting for potential confounding variables, including arterial hypertension, and demonstrate that >4.79 mg/dL is a valid prognostic cut-off value.

Association of uric acid with kidney function and albuminuria: the Uric Acid Right for heArt Health (URRAH) Project.

BACKGROUND: Hyperuricemia is commonly observed in patients with chronic kidney disease (CKD). However, a better understanding of the relationship among uric acid (UA) values, glomerular filtration rate (GFR) and albuminuria may shed light on the mechanisms underlying the excess of cardiovascular mortality associated with both chronic kidney disease and hyperuricemia and lead to better risk stratification. Our main goal was to study the relationships between serum uric acid and kidney disease measures (namely estimated GFR [eGFR] and albuminuria) in a large cohort of individuals at cardiovascular risk from the URic acid Right for heArt Health (URRAH) Project database. METHODS: Clinical data of 26,971 individuals were analyzed. Factors associated with the presence of hyperuricemia defined on the basis of previously determined URRAH cutoffs for cardiovascular and all-cause mortality were evaluated through multivariate analysis. Chronic kidney disease was defined as eGFR < 60 ml/min per 1.73 m2 and/or abnormal urinary albumin excretion diagnosed as: (i) microalbuminuria if urinary albumin concentration was > 30 and ≤ 300 mg/L, or if urinary albumin-to-creatinine ratio (ACR) was > 3.4 mg/mmol and ≤ 34 mg/mmol; (ii) macroalbuminuria if urinary albumin concentration was > 300 mg/L, or if ACR was > 34 mg/mmol. RESULTS: Mean age was 58 ± 15 years (51% males, 62% with hypertension and 12% with diabetes), mean eGFR was 81 ml/min per 1.73m22with a prevalence of eGFR < 60 and micro- or macroalbuminuria of 16, 15 and 4%, respectively. Serum uric acid showed a trend towards higher values along with decreasing renal function. Both the prevalence of gout and the frequency of allopurinol use increased significantly with the reduction of eGFR and the increase in albuminuria. Hyperuricemia was independently related to male gender, eGFR strata, and signs of insulin resistance such as body mass index (BMI) and triglycerides. CONCLUSIONS: The lower the eGFR the higher the prevalence of hyperuricemia and gout. In subjects with eGFR < 60 ml/min the occurrence of hyperuricemia is about 10 times higher than in those with eGFR > 90 ml/min. The percentage of individuals treated with allopurinol was below 2% when GFR was above 60 ml/min, it increased to 20% in the presence of CKD 3b and rose further to 35% in individuals with macroalbuminuria.

Serum uric acid, predicts heart failure in a large Italian cohort: search for a cut-off value the URic acid Right for heArt Health study.

OBJECTIVE: To assess the prognostic cut-off values of serum uric acid (SUA) in predicting fatal and morbid heart failure in a large Italian cohort in the frame of the Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension. METHODS: The URic acid Right for heArt Health (URRAH) study is a nationwide, multicentre, cohort study involving data on individuals aged 18-95 years, recruited on a community basis from all regions of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 128 ±â€Š65 months. Incident heart failure was defined on the basis of International Classification of Diseases Tenth Revision codes and double-checked with general practitioners and hospital files. Multivariate Cox regression models having fatal and morbid heart failure as dependent variables, adjusted for sex, age, SBP, diabetes, estimated glomerular filtration rate, smoking habit, ethanol intake, BMI, haematocrit, LDL cholesterol, previous diagnosis of heart failure and use of diuretics as possible confounders, were used to search for an association between SUA as a continuous variable and heart failure. By means of receiver operating characteristic curves, two prognostic cut-off values (one for all heart failure and one for fatal heart failure) were identified as able to discriminate between individuals doomed to develop the event. These cut-off values were used as independent predictors to divide individuals according to prognostic cut-off values in a multivariate Cox models, adjusted for confounders. RESULTS: A total of 21 386 individuals were included in the analysis. In Cox analyses, SUA as a continuous variable was a significant predictor of all [hazard ratio 1.29 (1.23-1.359), P < 0.0001] and fatal [hazard ratio 1.268 (1.121-1.35), P < 0.0001] incident heart failure. Cut-off values of SUA able to discriminate all and fatal heart failure status were identified by mean of receiver operating characteristic curves in the whole database: SUA more than 5.34 mg/dl (confidence interval 4.37-5.6, sensitivity 52.32, specificity 63.96, P < 0.0001) was the univariate prognostic cut-off value for all heart failure, whereas SUA more than 4.89 mg/dl (confidence interval 4.78-5.78, sensitivity 68.29, specificity 49.11, P < 0.0001) for fatal heart failure. The cut-off for all heart failure and the cut-off value for fatal heart failure were accepted as independent predictors in the Cox analysis models, the hazard ratios being 1.645 (1.284-2.109, P < 0.0001) for all heart failure and 1.645 (1.284-2.109, P < 0.0001) for fatal heart failure, respectively. CONCLUSION: The results of the current study confirm that SUA is an independent risk factor for all heart failure and fatal heart failure, after adjusting for potential confounding variables and demonstrate that a prognostic cut-off value can be identified for all heart failure (>5.34 mg/dl) and for fatal heart failure (>4.89 mg/dl).

Kidney disease and all-cause mortality in patients with COVID-19 hospitalized in Genoa, Northern Italy.

BACKGROUND: The prevalence of kidney involvement during SARS-CoV-2 infection has been reported to be high. Nevertheless, data are lacking about the determinants of acute kidney injury (AKI) and the combined effect of chronic kidney disease (CKD) and AKI in COVID-19 patients. METHODS: We collected data on patient demographics, comorbidities, chronic medications, vital signs, baseline laboratory test results and in-hospital treatment in patients with COVID-19 consecutively admitted to our Institution. Chronic kidney disease was defined as eGFR < 60 mL/min per 1.73 m2 or proteinuria at urinalysis within 180 days prior to hospital admission. AKI was defined according to KDIGO criteria. The primary and secondary outcomes were the development of AKI and death. RESULTS: Of 777 patients eligible for the study, acute kidney injury developed in 176 (22.6%). Of these, 79 (45%) showed an acute worsening of a preexisting CKD, and 21 (12%) required kidney replacement therapy. Independent associates of AKI were chronic kidney disease, C-reactive protein (CRP) and ventilation support. Among patients with acute kidney injury, 111 died (63%) and its occurrence increased the risk of death by 60% (HR 1.60 [95% IC 1.21-2.49] p = 0.002) independently of potential confounding factors including hypertension, preexisting kidney damage, and comorbidities. Patients with AKI showed a significantly higher rate of deaths attributed to bleeding compared to CKD and the whole population (7.5 vs 1.5 vs 3.5%, respectively). CONCLUSION: Awareness of kidney function, both preexisting CKD and development of acute kidney injury, may help to identify those patients at increased risk of death.

Increased serum uric acid levels are associated to renal arteriolopathy and predict poor outcome in IgA nephropathy.

BACKGROUND AND AIMS: IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and a leading cause of end stage renal disease (ESRD). In addition to classical progression factors, other atherosclerosis-related factors, including hyperuricemia (HU), have been associated to the renal progression of IgAN. Increased serum uric acid (SUA) levels are well known to be concomitant of cardiovascular and kidney diseases, and have been proposed to be implicated in the development of arteriolar damage (AD). The aim of the present study was to explore the correlation between SUA levels, renal damage and its implication for outcome in IgAN patients. METHODS AND RESULTS: Clinical, laboratory and histologic data of 145 patients with biopsy proven IgAN were collected and retrospectively analyzed to determine the correlation between SUA levels, renal damage and the primary outcome (death or ESRD). Biopsy-proven AD was defined by the presence of arteriolar hyalinosis and/or intimal thickening. HU, defined as the highest SUA gender-specific tertile, was >7.7 mg/dl for males and >6.2 mg/dl for females. The prevalence of AD increased with the increase in the SUA level tertiles (p = 0.02). At logistic regression analysis SUA was independently related to the presence of AD (OR 1.75 [95%CI 1.10-2.93], p = 0.03). HU and AD had a synergic impact on progression of IgAN. Patients having both AD and HU, showed a reduced survival free from the primary outcome as compared to those having only one risk factor or neither (p = 0.01). CONCLUSIONS: SUA levels are independently associated with AD and poor prognosis in patients with IgAN.

Enhanced myostatin expression and signalling promote tubulointerstitial inflammation in diabetic nephropathy.

Myostatin (MSTN), a family member of the transforming growth factor (TGF)-ß super family, has been detected in the tubuli of pig kidney, but its role in the human kidney is not known. In this study we observed upregulation of MSTN mRNA (~8 to 10-fold increase) both in the glomeruli and tubulointerstitium in diabetic nephropathy (DN). In DN, immunoreactive MSTN was mainly localized in the tubuli and interstitium (∼4-8 fold increase), where it colocalized in CD45+ cells. MSTN was also upregulated in the glomeruli and the arterial vessels. Tubulointerstitial MSTN expression was directly related to interstitial fibrosis (r = 0.54, p < 0.01). In HK-2 tubular epithelial cells, both high (30 mmol) glucose and glycated albumin upregulated MSTN mRNA and its protein (p < 0.05-0.01). MSTN-treated HK-2 cells underwent decreased proliferation, together with NF-kB activation and CCL-2 and SMAD 2,3 overexpression. In addition, MSTN induced intracellular ROS release and upregulated NADPH oxidase, effects which were mediated by ERK activation. In conclusion, our data show that MSTN is expressed in the human kidney and overexpressed in DN, mainly in the tubulointerstitial compartment. Our results also show that MSTN is a strong inducer of proximal tubule activation and suggest that MSTN overexpression contributes to kidney interstitial fibrosis in DN.

Long-term blood pressure behavior and progression to end-stage renal disease in patients with immunoglobulin A nephropathy: a single-center observational study in Italy.

BACKGROUND: Antihypertensive treatment by the use of RAAS inhibitors (RAAS-is) is of paramount importance in the management of slowly progressive IgA nephropathy (IgAN). With the aim of better understanding the relationship between BP behavior and progression, we looked at time-averaged SBP and time-averaged proteinuria and renal outcome in a single-center cohort of IgAN patients. METHODS: Among 248 consecutive patients referred to the Clinic of Nephrology of San Martino Hospital from 1996 to 2018 for native renal biopsy with a diagnosis of IgAN, we retrospectively analyzed 145 with available data at baseline and during follow-up. All patients received Supportive Care, 39% were on RAAS-is alone, 45% plus steroids, and 16% plus steroids and immunosuppressors. Renal replacing treatment (RRT) was the primary endpoint. RESULTS: During a mean follow-up of 67 ±â€Š6 months, 23% of study patients (n = 33) progressed to RRT and 6% (n = 9) died. Patients who reached the renal endpoint, had lower baseline eGFR and higher proteinuria and proteinuria indexed at baseline. Moreover, they had higher TA-SBP (139 ±â€Š17 vs. 130 ±â€Š13, P = 0.0016). The incidence of RRT was higher in IgAN patients in the highest time-averaged SBP tertile as compared with the others (32 vs. 23 vs. 9%, χ 6.8, P = 0.033). After adjusting for baseline SBP, baseline and time-averaged proteinuria indexed, MEST-C score, and treatment, the association between TA-SBP and RRT persisted. CONCLUSION: Time-averaged low BP values were independently associated to a decreased risk of renal progression in IgAN with no evidence of a J-curve relationship even at SBP levels below 125 mmHg.