In vitro anti-lithogenic activity of lime powder regimen (LPR) and the effect of LPR on urinary risk factors for kidney stone formation in healthy volunteers

A review of citrus plants as functional foods and dietary supplements for human health, with an emphasis on meta-analyses, clinical trials, and their chemical composition

Fruits, flowers, leaves, essential oils, hydrosols, and juices of citrus spp. Are utilized to prepare various forms of food products. Along with their nutritional values, in the health industry, different parts of the plants of the citrus genus have been used as supplements or remedies to prevent or control diseases. This review focused on reported meta-analyses and clinical trials on the health benefits of citrus plants as functional foods. Also, chemical compounds of various citrus species were reviewed. The following information sources were used for data collection: Google Scholar, the Web of Science, Scopus, and PubMed. Various keywords, including "citrus AND chemical compounds," "citrus AND phytochemicals," "citrus species," "citrus AND meta-analysis," "nutritional and therapeutical values of citrus spp.," "clinical trials AND citrus," "clinical trials AND Rutaceae," "health benefits of citrus spp.," "citrus edible or non-edible applications," and scientific names of the citrus plants were utilized to collect data for the review. The scientific name and common name of all twenty-eight citrus species, along with any of the above keywords, were also searched in the mentioned databases. Scientific papers and data sources were sought to review and discuss the citrus plant's nutritional and therapeutic importance. Several meta-analyses and clinical trials have reported beneficial effects of citrus spices on a variety of cancer risks, cardiovascular risk factors, neurologic disorders, urinary tract conditions, and gastrointestinal tract conditions. They have shown anxiolytic, antimicrobial, and pain-alleviating effects. Some of them can be helpful in managing obesity and cardiovascular risk factors.

Kidney Stone Prevention

Kidney stone disease (KSD) (alternatively nephrolithiasis or urolithiasis) is a global health care problem that affects almost people in developed and developing countries. Its prevalence has been continuously increasing with a high recurrence rate after stone removal. Although effective therapeutic modalities are available, preventive strategies for both new and recurrent stones are required to reduce physical and financial burdens of KSD. To prevent kidney stone formation, its etiology and risk factors should be first considered. Low urine output and dehydration are the common risks of all stone types, whereas hypercalciuria, hyperoxaluria, and hypocitraturia are the major risks of calcium stones. In this article, up-to-date knowledge on strategies (nutrition-based mainly) to prevent KSD is provided. Important roles of fluid intake (2.5-3.0 L/d), diuresis (>2.0-2.5 L/d), lifestyle and habit modifications (for example, maintain normal body mass index, fluid compensation for working in high-temperature environment, and avoid cigarette smoking), and dietary management [for example, sufficient calcium at 1000-1200 mg/d, limit sodium at 2 or 3-5 g/d of sodium chloride (NaCl), limit oxalate-rich foods, avoid vitamin C and vitamin D supplements, limit animal proteins to 0.8-1.0 g/kg body weight/d but increase plant proteins in patients with calcium and uric acid stone and those with hyperuricosuria, increase proportion of citrus fruits, and consider lime powder supplementation] are summarized. Moreover, uses of natural bioactive products (for example, caffeine, epigallocatechin gallate, and diosmin), medications (for example, thiazides, alkaline citrate, other alkalinizing agents, and allopurinol), bacterial eradication, and probiotics are also discussed. Adv Nutr 2023;x:xx-xx.

Systematic analysis of modulating activities of native human urinary Tamm-Horsfall protein on calcium oxalate crystallization, growth, aggregation, crystal-cell adhesion and invasion through extracellular matrix

Functions of Tamm-Horsfall protein (THP), the most abundant human urinary protein, have been studied for decades. However, its precise roles in kidney stone formation remain controversial. In this study, we aimed to clarify the roles of native human urinary THP in calcium oxalate monohydrate (COM) kidney stone formation. THP was purified from the human urine by adsorption method using diatomaceous earth (DE). Its effects on stone formation processes, including COM crystallization, crystal growth, aggregation, crystal-cell adhesion and invasion through extracellular matrix (ECM), were examined. SDS-PAGE and Western blotting confirmed that DE adsorption yielded 84.9% purity of the native THP isolated from the human urine. Systematic analyses revealed that THP (at 0.4-40 μg/ml) concentration-dependently reduced COM crystal size but did not affect the crystal mass during initial crystallization. At later steps, THP concentration-dependently inhibited COM crystal growth and aggregation, and prevented crystal-cell adhesion only at 40 μg/ml. However, THP did not affect crystal invasion through the ECM. Sequence analysis revealed two large calcium-binding domains (residues 65-107 and 108-149) and three small oxalate-binding domains (residues 199-207, 361-368 and 601-609) in human THP. Immunofluorescence study confirmed the binding of THP to COM crystals. Analyses for calcium-affinity and/or oxalate-affinity demonstrated that THP exerted a high affinity with only calcium, not oxalate. Functional validation revealed that saturation of THP with calcium, not with oxalate, could abolish the inhibitory effects of THP on COM crystal growth, aggregation and crystal-cell adhesion. These data highlight the inhibitory roles of the native human urinary THP in COM crystal growth, aggregation and crystal-cell adhesion, which are the important processes for kidney stone formation. Such inhibitory effects of THP are most likely mediated via its high affinity with calcium ions.

Combined effect of polyacrylic acid and vitamin E in preventing calcium oxalate crystal deposition in the kidneys of experimental hyperoxaluric rats

Our study explores the combined effect of polyacrylic acid and vitamin E as prophylactic and curative agent against ethylene glycol (EG) induced calcium oxalate stone formation in Wistar rats. Male Wistar rats (54) were divided into nine groups, including control. The experimental groups were equally segregated into two for preventive study (4) and curative study (4). Urolithiasis was induced with 0.75% (v/v) EG in drinking water. Polyacrylic acid (10 mg/kg) and vitamin E (300 IU/day) were supplemented from day 1 for preventive and day 30 for curative studies. Restoration of urinary lithogenic factors (calcium, oxalate, phosphate, citrate and magnesium) and renal function (urea and creatinine in serum) by intervening agents were accomplished compared to urolithic rats (P < .001). Abnormal localization and increased expression of Tamm-Horsfall Protein, osteopontin and transferrin were observed in the kidneys of urolithic rats (P < .001) from immunohistochemistry and immunoblotting analysis. Polyacrylic acid and vitamin E supplementation have regulated the expression of the urinary macromolecules. Pro-inflammatory cytokines in kidney were significantly reduced (P < .001) by the intervening agents compared to urolithic rats. Therefore, polyacrylic acid and vitamin E in combination could be a potential formulation for better management of urolithiasis.

Kidney stone proteomics: an update and perspectives

INTRODUCTION

Main problems of kidney stone disease are its increasing prevalence and high recurrence rate after calculi removal in almost all areas around the globe. Despite enormous efforts in the past, its pathogenic mechanisms remain unclear and need further elucidations. Proteomics has thus become an essential tool to unravel such sophisticated disease mechanisms at cellular, subcellular, molecular, tissue, and whole organism levels.

AREAS COVERED

This review provides abrief overview of kidney stone disease followed by updates on proteomics for investigating urinary stone modulators, matrix proteins, cellular responses to different types/doses of calcium oxalate (CaOx) crystals, sex hormones and other stimuli, crystal-cell interactions, crystal receptors, secretome, and extracellular vesicles (EVs), all of which lead to better understanding of the disease mechanisms. Finally, the future challenges and translation of these obtained data to the clinic are discussed.

EXPERT OPINION

Knowledge from urinary proteomics for exploring the important stone modulators (either inhibitors or promoters) will be helpful for early detection of asymptomatic cases for prompt prevention of symptoms, complications, and new stone formation. Moreover, these modulators may serve as the new therapeutic targets in the future for successful treatment and prevention of kidney stone disease by medications or other means of intervention.

Lime powder regimen supplement alleviates urinary metabolic abnormalities in urolithiasis patients

BACKGROUND

Urolithiasis has high recurrent rate after surgical removal within 3 years. Potassium citrate compound is used to prevent stone recurrence but it has intolerable gastrointestinal adverse effects. We conducted a phase 2 clinical study of lime power regimen (LPR), a limeade-based supplement containing potassium and citrate for 6 months period of treatment, to evaluate its effects on biochemical and clinical aspects of recurrent urolithiasis.

METHODS

Seventy-four urolithiasis patients were randomly allocated to receive either LPR or placebo for 6 months in a double-blinded manner. Plasma and 24 h urine samples were collected to measure urinary pH, mineral excretion and urinary total antioxidant status , plasma for creatinine and plasma protein carbonyl, and stone for elemental analysis at the initiation and end-of-treatment (6 month). Adverse effects were recorded.

RESULTS

Administration of LPR significantly increased urinary pH, citrate and potassium excretion. Urinary levels of calcium and oxalate, and plasma protein carbonyl content were reduced, while urinary total antioxidant status was elevated by LPR treatment. Urinary supersaturation was decreased and urinary protein excretion was ameliorated in LPR-treated patients. Gastrointestinal adverse effects were rarely observed. None of the participants developed stone recurrence for the duration of the trial.

CONCLUSION

Lime power regimen is a potential drug to correct urinary metabolic disorders associated with urolithiasis in high risk stone recurrent patients. A phase 3 clinical trial is underway to validate anti-stone recurrence property of LPR in long-term treatment.

Regulation of urinary crystal inhibiting proteins and inflammatory genes by lemon peel extract and formulated citrus bioflavonoids on ethylene glycol induced urolithic rats

The objective of this study is to check the regulation of crystal matrix proteins and inflammatory mediators by citrus bioflavonoids (CB) and Lemon peel (LP) extract in hyperoxaluric rats. The animals were divided into six groups with 6 animals each. Group 1: Control, Group 2: Urolithic (Ethylene glycol (EG)-0.75%); Group 3 & 5: Preventive study (EG + CB (20 mg/kg body weight) and LP (100 mg/kg body weight) extract administration from 0th-7th week) respectively; Group 4 & 6: Curative study (EG + CB and LP extract administration from 4th-7th week) respectively by oral administration. Urinary lithogenic factors (Calcium, oxalate, phosphate and citrate) were normalized in CB & LP supplemented rats, while serum parameters revealed the nephroprotective nature of the intervening agents compared to urolithic rats (p < 0.001). Immunoblotting studies showed significantly increased expression of THP, osteopontin and transferrin in kidneys of urolithic rats (p < 0.001), while preventive and curative study showed near normal expression of these proteins. Expression of NF-κB, TNF-α and IL-6 were raised significantly (p < 0.001), while a very minimal increase in MCP-1 expression was observed in urolithic rats compared to control. Hence, supplementation of CB and LP reduced the crystal promoting factors and provides protection from crystal induced renal damage.