Metalloproteinases as Biomarkers and Sociomarkers in Human Health and Disease.

Metalloproteinases (MPs) are zinc-dependent enzymes with proteolytic activity and a variety of functions in the pathophysiology of human diseases. The main objectives of this review are to analyze a specific family of MPs, the matrix metalloproteinases (MMPs), in the most common chronic and complex diseases that affect patients' social lives and to better understand the nature of the associations between MMPs and the psychosocial environment. In accordance with the PRISMA extension for a scoping review, an examination was carried out. A collection of 24 studies was analyzed, focusing on the molecular mechanisms of MMP and their connection to the manifestation of social aspects in human disease. The complexity of the relationship between MMP and social problems is presented via an interdisciplinary approach based on complexity paradigm as a new approach for conceptualizing knowledge in health research. Finally, two implications emerge from the study: first, the psychosocial states of individuals have a profound impact on their overall health and disease conditions, which implies the importance of adopting a holistic perspective on human well-being, encompassing both physical and psychosocial aspects. Second, the use of MPs as biomarkers may provide physicians with valuable tools for a better understanding of disease when used in conjunction with "sociomarkers" to develop mathematical predictive models.

The Impact of Cholecaciferol Supplementation on Bone Mineral Density in Long-Term Kidney Transplant Recipients.

Although reduced bone mineral density (BMD) is associated with a higher risk of fractures, morbidity, and mortality in kidney transplant patients (KTRs), there is no consensus on optimal treatment for the alterations of BMD in this population. This study aims at assessing the effect of cholecalciferol supplementation on BMD over a follow-up period of 2 years in a cohort of long-term KTRs. Patients with age ≥ 18 years were included and divided into two subgroups based on treatment with bisphosphonate and/or calcimimetics and/or active vitamin D sterols (KTRs-treated) or never treated with the above medications (KTRs-free). BMD was evaluated at lumbar vertebral bodies (LV) and right femoral neck (FN) with standard DEXA at the beginning and end of the study. According to World Health Organization (WHO) criteria, results were expressed as T-score and Z-score. Osteoporosis and osteopenia were defined as T score ≤ -2.5 SD and T score < -1 and >-2.5 SD, respectively. Cholecalciferol was supplemented at a dose of 25,000 IU/week over 12 weeks followed by 1500 IU/day. KTRs-free (n. 69) and KTRs-treated (n. 49) consecutive outpatients entered the study. KTRs-free were younger (p < 0.05), with a lower prevalence of diabetes (p < 0.05) and of osteopenia at FN (46.3 % vs. 61.2 %) compared to KTRs-treated. At the entry none of the study subjects had a sufficient level of cholecalciferol; Z-score and T-score at LV and FN were not different between groups. At the end of the study period, serum cholecalciferol concentration was significantly increased in both groups (p < 0.001); the KTRs-free group presented an improvement in both T-score and Z-score at LV (p < 0.05) as well as a lower prevalence of osteoporotic cases (21.7% vs. 15.9%); in contrast, no changes were recorded in KTR-treated individuals. In conclusion, supplementation with cholecalciferol ameliorated Z-score and T-score at LV in long-term KTRs who had been never treated with active or inactive vitamin D sterols, bisphosphonates, and calcimimetics. Future endeavours are needed to confirm these preliminary findings.

Role of Vitamin K in Chronic Kidney Disease: A Focus on Bone and Cardiovascular Health.

Chronic kidney disease (CKD) is commonly associated with vitamin K deficiency. Some of the serious complications of CKD are represented by cardiovascular disease (CVD) and skeletal fragility with an increased risk of morbidity and mortality. A complex pathogenetic link between hormonal and ionic disturbances, bone tissue and metabolism alterations, and vascular calcification (VC) exists and has been defined as chronic kidney disease-mineral and bone disorder (CKD-MBD). Poor vitamin K status seems to have a key role in the progression of CKD, but also in the onset and advance of both bone and cardiovascular complications. Three forms of vitamin K are currently known: vitamin K1 (phylloquinone), vitamin K2 (menaquinone), and vitamin K3 (menadione). Vitamin K plays different roles, including in activating vitamin K-dependent proteins (VKDPs) and in modulating bone metabolism and contributing to the inhibition of VC. This review focuses on the biochemical and functional characteristics of vitamin K vitamers, suggesting this nutrient as a possible marker of kidney, CV, and bone damage in the CKD population and exploring its potential use for promoting health in this clinical setting. Treatment strategies for CKD-associated osteoporosis and CV disease should include vitamin K supplementation. However, further randomized clinical studies are needed to assess the safety and the adequate dosage to prevent these CKD complications.

Circulating Omentin-1 levels and altered iron balance in chronic haemodialysis patients.

BACKGROUND: Iron deficiency is highly prevalent among patients undergoing chronic haemodialysis (HD) but its correct identification is often problematic as common biomarkers of iron status, such as transferrin saturation (TSAT) and ferritin, can be altered by inflammation or malnutrition. METHODS: In this pilot multicentre study, we aimed at evaluating circulating levels of Omentin-1, a novel fat depot-specific adipokine that is also involved in iron regulation, in a cohort of 85 chronic HD patients with relation to their iron status. RESULTS: Omentin-1 levels in HD were statistically higher than in healthy controls (P = 0.03) and there was a significant, growing trend in all iron parameters across Omentin-1 tertiles (P < 0.001). Compared with patients with optimal iron status, Omentin-1 levels were lower in subjects categorized according to TSAT ≤20% or serum ferritin ≤200 µg/L (both P < 0.001) and even more reduced in 19 patients (22%) simultaneously displaying low levels of both markers (P < 0.001). In this latter group, Omentin-1 levels increased in parallel to all other iron markers after iron correction by i.v. supplementation. At multivariate regression analyses, ferritin (ß = 0.71; P < 0.001) and TSAT (ß = 0.32; P = 0.03) remained the sole independent predictors of Omentin-1 levels. This biomarker also showed a remarkable diagnostic capacity at receiver operating characteristic analyses in identifying iron-depleted HD patients according to a criterion of TSAT ≤20% [area under the curve (AUC) 0.827], ferritin ≤200 µg/L (AUC 0.863) or low levels of both parameters (AUC 0.907). CONCLUSIONS: Findings obtained indicate that Omentin-1 is somewhat involved in iron balance regulation and might be a candidate biomarker for diagnosing and managing altered iron conditions in HD patients.

Bone Mineral Density Changes in Long-Term Kidney Transplant Recipients: A Real-Life Cohort Study of Native Vitamin D Supplementation.

Vitamin D insufficiency has been associated with reduced bone mineral density (BMD) in kidney transplant patients (KTRs). However, the efficacy of vitamin D supplementation on BMD remains poorly defined, especially for long-term KTRs. We aimed to investigate the effect of native vitamin D supplementation on the BMD of KTRs during a 2-year follow-up. Demographic, clinical, and laboratory data were collected. BMD was evaluated with standard DEXA that was performed at baseline (before vitamin D supplementation) and at the end of study period. BMD was assessed at lumbar vertebral bodies (LV) and right femoral neck (FN) by a single operator. According to WHO criteria, results were expressed as the T-score (standard deviation (SD) relative to young healthy adults) and Z-score (SD relative to age-matched controls). Osteoporosis and osteopenia were defined as a T-score ≤ -2.5 SD and a T-score < -1 and a > -2.5 SD, respectively. Based on plasma levels, 25-OH-vitamin D (25-OH-D) was supplemented as recommended for the general population. Data from 100 KTRs were analyzed. The mean study period was 27.7 ± 3.4 months. At study inception, 25-OH-D insufficiency and deficiency were recorded in 65 and 35 patients. At the basal DEXA, the percentage of osteopenia and osteoporosis was 43.3% and 18.6% at LV and 54.1% and 12.2% at FN, respectively. At the end of the study, no differences in the Z-score and T-score gains were observed. During linear mixed model analysis, native vitamin D supplementation was found to have a negative nitration with Z-score changes at the right femoral neck in KTRs (p < 0.05). The mean dose of administered cholecalciferol was 13.396 ± 7.537 UI per week; increased 25-OH-D levels were found (p < 0.0001). Either low BMD or 25-OH-vitamin D concentration was observed in long-term KTRs. Prolonged supplementation with 25-OH-D did not modify BMD, Z-score, or T-score.

Hypoxia-Inducible Factor Stabilizers in End Stage Kidney Disease: "Can the Promise Be Kept?"

Anemia is a common complication of chronic kidney disease (CKD). The prevalence of anemia in CKD strongly increases as the estimated Glomerular Filtration Rate (eGFR) decreases. The pathophysiology of anemia in CKD is complex. The main causes are erythropoietin (EPO) deficiency and functional iron deficiency (FID). The administration of injectable preparations of recombinant erythropoiesis-stimulating agents (ESAs), especially epoetin and darbepoetin, coupled with oral or intravenous(iv) iron supplementation, is the current treatment for anemia in CKD for both dialysis and non-dialysis patients. This approach reduces patients' dependence on transfusion, ensuring the achievement of optimal hemoglobin target levels. However, there is still no evidence that treating anemia with ESAs can significantly reduce the risk of cardiovascular events. Meanwhile, iv iron supplementation causes an increased risk of allergic reactions, gastrointestinal side effects, infection, and cardiovascular events. Currently, there are no studies defining the best strategy for using ESAs to minimize possible risks. One class of agents under evaluation, known as prolyl hydroxylase inhibitors (PHIs), acts to stabilize hypoxia-inducible factor (HIF) by inhibiting prolyl hydroxylase (PH) enzymes. Several randomized controlled trials showed that HIF-PHIs are almost comparable to ESAs. In the era of personalized medicine, it is possible to envisage and investigate specific contexts of the application of HIF stabilizers based on the individual risk profile and mechanism of action.

Reversal of radiocontrast medium toxicity in human renal proximal tubular cells by white grape juice extract.

Radiocontrast media (RCM)-induced nephrotoxicity (CIN) is a major clinical problem accounting for 12% of all hospital-acquired cases of acute kidney injury. The pathophysiology of CIN is not well understood, but direct toxic effects on renal cells have been postulated as contributing to CIN. We have investigated the effect of a white grape (Vitis vinifera) juice extract (WGJe) on human renal proximal tubular (HK-2) cells treated with the radiocontrast medium (RCM) sodium diatrizoate. WGJe caused an increase in phosphorylation of the prosurvival kinases Akt and ERK1/2 in HK-2 cells. Treatment of HK-2 cells with 75 mgI/ml sodium diatrizoate for 2.5h and then further incubation (for 27.5h) after removal of the RCM caused a drastic decrease in cell viability. However, pre-treatment with WGJe, prior to incubation with diatrizoate, dramatically improved cell viability. Analysis of key signaling molecules by Western blotting showed that diatrizoate caused a drastic decrease in phosphorylation of Akt (Ser473), FOXO1 (Thr24) and FOXO3a (Thr32) during the initial 2.5h incubation period, and WGJe pre-treatment caused a reversal of these effects. Further analysis by Western blotting of samples from HK-2 cells cultured for longer periods of time (for up to 27.5h after an initial 2.5h exposure to diatrizoate with or without WGJe pre-treatment) showed that WGJe pre-treatment caused a negative effect on phosphorylation of p38, NF-κB (Ser276) and pERK1/2 whilst having a positive effect on the phosphorylation of Akt, FOXO1/FOXO3a and maintained levels of Pim-1 kinase. WGJe may alleviate RCM toxicity through modulation of signaling molecules that are known to be involved in cell death and cell survival and its possible beneficial effects should be further investigated.

Impact of BMI on cardiovascular events, renal function, and coronary artery calcification.

BACKGROUND/AIMS: High BMI increases the risk of cardiovascular events (CVEs) in the general population. Conflicting results have been reported on the role of BMI on CVEs and on decline of renal function in patients with chronic kidney disease not on dialysis (CKD). This study evaluates the impact of BMI on CVEs, dialysis initiation, and coronary artery calcification (CAC) in CKD patients. METHODS: CKD patients were divided in normal-BMI and high-BMI patients. CVEs, initiation of dialysis, and extent and progression of CAC were assessed. Univariate and multivariable analysis were performed (adjustment variables: age, diabetes, hypertension, gender, CKD stage, serum concentration of hemoglobin, parathyroid hormone, calcium, phosphorus, albumin, C-reactive protein, LDL-cholesterol, total calcium score, 24-hour proteinuria). Patients were followed to the first event (CVE, dialysis) or for 2 years. RESULTS: 471 patients were evaluated. A CVE occurred in 13.5 and 21.3% (p < 0.05) of normal-BMI and high-BMI patients, respectively. High BMI did not increase the risk for CVEs in univariate (HR: 1.86; 95% CI: 0.97-3.54; p = 0.06) or multivariable analysis (HR: 1.36; 95% CI: 0.57-3.14; p = 0.50). High BMI did not increase the risk for initiation of dialysis in univariate (HR: 0.96; 95% CI: 0.58-1.60; p = 0.9) or multivariable analysis (HR: 1.77; 95% CI: 0.82-3.81; p = 0.14). Adding the interaction term (between BMI and glomerular filtration rate) to other variables, the risk of dialysis initiation significantly increased (HR: 3.06; 95% CI: 1.31-7.18; p = 0.01) in high-BMI patients. High BMI was not a predictor of CAC extent or progression. CONCLUSIONS: High BMI was not a predictor of CVEs. High BMI increased the risk for dialysis initiation, but high BMI was not associated to CAC extent and progression. The presence of confounders may underestimate the impact of high BMI on dialysis initiation.

Postdialytic rebound of serum phosphorus: pathogenetic and clinical insights.

To gain insights into postdialytic rebound of serum phosphate (PDR-P), serum phosphate (P), calcium (Ca), and parathyroid hormone (PTH), levels were compared from the end of treatment (T0) to the subsequent 30 to 120 min and up to 68 hr in uremic patients who underwent with crossover modality a single session of two dialytic treatments characterized by different convective removal: standard hemodialysis (HD) and hemodiafiltration (HDF). In HDF, versus HD, P removal was greater (1171 +/- 90 versus 814 +/- 79 mg; P < 0.05) in the presence of similar predialytic P levels (6.0 +/- 0.2 and 5.9 +/- 0.4 mg/dl) and Kt/V (1.35 +/- 0.06 and 1.34 +/- 0.05); however, the serum P values at T0 did not differ (3.0 +/- 0.2 versus 3.3 +/- 0.2 mg/dl). In HDF, PDR-P was more rapid (30 min versus 90 min) and of a greater extent (at T120: +69 +/- 6% versus +31 +/- 4%; P < 0.0001). The higher P levels were maintained throughout the interdialytic period. Ca x P and PTH changed in parallel. Thereafter, patients were randomized to receive either HD or HDF for 3 mo. During this period, in the presence of similar Kt/V, protein intake, and dose of phospate binder, predialytic serum P levels diminished in HDF (from 5.8 +/- 0.2 to 4.4 +/- 0.3 mg/dl; P < 0.05), but they remained unchanged in HD. A similar pattern of changes was detected in Ca x P. Therefore, PDR-P is likely dependent on the mobilization of phosphate from a deep compartment induced by the intradialytic removal of this solute. Enhancement of convective removal acutely amplifies the entity of the phenomenon but allows a better control of Ca-P homeostasis in the medium term.