Evaluation of Curcumin's effect on inflammation in hemodialysis patients

The Potential of Naturally Derived Compounds for Treating Chronic Kidney Disease: A Review of Autophagy and Cellular Senescence

Chronic kidney disease (CKD) is characterized by irreversible progressive worsening of kidney function leading to kidney failure. CKD is viewed as a clinical model of premature aging and to date, there is no treatment to reverse kidney damage. The well-established treatment for CKD aims to control factors that may aggravate kidney progression and to provide kidney protection effects to delay the progression of kidney disease. As an alternative, Traditional Chinese Medicine (TCM) has been shown to have fewer adverse effects for CKD patients. However, there is a lack of clinical and molecular studies investigating the mechanisms by which natural products used in TCM can improve CKD. In recent years, autophagy and cellular senescence have been identified as key contributors to aging and age-related diseases. Exploring the potential of natural products in TCM to target these processes in CKD patients could slow disease progression. A better understanding of the characteristics of these natural products and their effects on autophagy and cellular senescence through clinical studies, coupled with the use of these products as complementary therapy alongside mainstream treatment, may maximize therapeutic benefits and minimize adverse effects for CKD patients. While promising, there is currently a lack of thorough research on the potential synergistic effects of these natural products. This review examines the use of natural products in TCM as an alternative treatment for CKD and discusses their active ingredients in terms of renoprotection, autophagy, and cellular senescence.

Potential Effects of Bioactive Compounds of Plant-Based Foods and Medicinal Plants in Chronic Kidney Disease and Dialysis: A Systematic Review

BACKGROUND

The bioactive components of plant foods and medicinal plants have attracted interest due to their potential impact on the progression of chronic kidney disease (CKD) and outcomes.

OBJECTIVE

This study aimed to conduct a critical and quantitative systematic review of randomized clinical trials (RCTs) investigating the potential effects of selected phytochemicals from plant-based foods and medicinal plants in CKD and dialysis patients.

METHODS

The review included studies that related plant-based bioactive compounds (curcumin, propolis, sulforaphane, betalain, catechins, rhein, emodin, aloe-emodin, flavonoids, and triptolide) and medicinal plants (green tea, rhubarb, Astragalus membranaceus, and Tripterygium wilfordii Hook F) in CKD and dialysis patients. A literature search was conducted in PubMed, LILACS, Embase, Scopus, and WOS between December 2022 and October 2024. This review was performed according to the PRISMA flowchart and was registered in PROSPERO (595162).

RESULTS

In the eight RCTs conducted with curcumin, anti-inflammatory, antioxidant, and microbiota-modulating properties were reported. As for propolis, in three RCTs, anti-inflammatory, anti-proteinuric, and renal-protective properties were reported. Sulforaphane in one RCT showed antioxidant and cardiovascular benefits, and in another RCT no effects were observed. In one RCT, genistein was shown to be a potential anti-inflammatory agent and improved nutritional status. Allicin in two RCTs showed cardioprotective, antioxidant, anti-inflammatory, and lipid-lowering effects. Finally, beetroot showed a vasodilator effect in one RCT. As for the medicinal plants, green tea, rhubarb, Astragalus membranaceus, and Tripterygium Wilfordii Hook F, in six RCTs they showed antioxidant, anti-inflammatory, cardioprotective, antiproteinuric, and renoprotective properties.

CONCLUSIONS

These results suggest that bioactive compounds of plant-based foods and medicinal plants have promising effects in terms of preventing or treating CKD progression and appear to improve inflammation and antioxidant capacity and support cardiovascular benefits and renoprotective effects; however, it is recommended that further studies be carried out.

Is Curcumin Intake Really Effective for Chronic Inflammatory Metabolic Disease? A Review of Meta-Analyses of Randomized Controlled Trials

This review aimed to examine the effects of curcumin on chronic inflammatory metabolic disease by extensively evaluating meta-analyses of randomized controlled trials (RCTs). We performed a literature search of meta-analyses of RCTs published in English in PubMed®/MEDLINE up to 31 July 2023. We identified 54 meta-analyses of curcumin RCTs for inflammation, antioxidant, glucose control, lipids, anthropometric parameters, blood pressure, endothelial function, depression, and cognitive function. A reduction in C-reactive protein (CRP) levels was observed in seven of ten meta-analyses of RCTs. In five of eight meta-analyses, curcumin intake significantly lowered interleukin 6 (IL-6) levels. In six of nine meta-analyses, curcumin intake significantly lowered tumor necrosis factor α (TNF-α) levels. In five of six meta-analyses, curcumin intake significantly lowered malondialdehyde (MDA) levels. In 14 of 15 meta-analyses, curcumin intake significantly reduced fasting blood glucose (FBG) levels. In 12 of 12 meta-analyses, curcumin intake significantly reduced homeostasis model assessment of insulin resistance (HOMA-IR). In seven of eight meta-analyses, curcumin intake significantly reduced glycated hemoglobin (HbA1c) levels. In eight of ten meta-analyses, curcumin intake significantly reduced insulin levels. In 14 of 19 meta-analyses, curcumin intake significantly reduced total cholesterol (TC) levels. Curcumin intake plays a protective effect on chronic inflammatory metabolic disease, possibly via improved levels of glucose homeostasis, MDA, TC, and inflammation (CRP, IL-6, TNF-α, and adiponectin). The safety and efficacy of curcumin as a natural product support the potential for the prevention and treatment of chronic inflammatory metabolic diseases.

Curcumin prevents high glucose-induced stimulatory effects of renal cell secretome on fibroblast activation via mitigating intracellular free radicals and TGF-β secretion

Diabetic kidney disease (DKD) is a leading cause of kidney failure. However, the involvement of renal fibroblasts and their communications with renal epithelial cells during DKD remain poorly understood. We investigated the potential role of renal proximal tubular epithelial cells (PTECs) in renal fibroblast activation that might lead to DKD. Additionally, the protective effects of curcumin, a known antioxidant, against renal fibroblast activation induced by high glucose-treated PTECs were investigated. Secretome was collected from HK-2 PTECs under normal glucose, high glucose, high glucose pretreated/cotreated with curcumin, or osmotic control condition for 24 h. Such secretome was then used to treat BHK-21 renal fibroblasts for 24 h. BHK-21 cells treated with high glucose-induced secretome had increased levels of fibroblast activation markers, including spindle index, F-actin, α-smooth muscle actin (α-SMA), fibronectin, collagen I, matrix metalloproteinase-2 (MMP-2) and MMP-9, as compared with normal glucose and osmotic control conditions. However, all these increases were successfully mitigated by curcumin. In addition, high glucose markedly increased intracellular reactive oxygen species (ROS) and transforming growth factor-β (TGF-β) secretion, but did not affect the secretion of platelet-derived growth factor A (PDGFA) and interleukin-1β (IL-1β), in HK-2 renal cells as compared with normal glucose and osmotic control conditions. Both intracellular ROS and secreted TGF-β levels were successfully mitigated by curcumin. Therefore, curcumin prevents the high glucose-induced stimulatory effects of renal cell secretome on fibroblast activation, at least in part, via mitigating intracellular ROS and TGF-β secretion.

Chronic Kidney Disease Diets for Kidney Failure Prevention: Insights from the IL-11 Paradigm

Nearly every fifth adult in the United States and many older adults worldwide are affected by chronic kidney disease (CKD), which can progress to kidney failure requiring invasive kidney replacement therapy. In this review, we briefly examine the pathophysiology of CKD and discuss emerging mechanisms involving the physiological resolution of kidney injury by transforming growth factor beta 1 (TGFβ1) and interleukin-11 (IL-11), as well as the pathological consequences of IL-11 overproduction, which misguides repair processes, ultimately culminating in CKD. Taking these mechanisms into account, we offer an overview of the efficacy of plant-dominant dietary patterns in preventing and managing CKD, while also addressing their limitations in terms of restoring kidney function or preventing kidney failure. In conclusion, this paper outlines novel regeneration strategies aimed at developing a reno-regenerative diet to inhibit IL-11 and promote repair mechanisms in kidneys affected by CKD.

The Effects of Curcumin Administration on Carotid Intima-Media Thickness and Pulse Wave Velocity in Diabetic Hemodialysis Patients: A Randomized, Double-Blinded, Placebo-Controlled Trial

Background

Prior studies have reported that curcumin is inversely associated with reduced markers of atherosclerosis risk, including carotid intima-media thickness (CIMT). This study was designed to assess the effects of curcumin on CIMT and pulse wave velocity (PWV) in diabetic hemodialysis (HD) patients.

Methods

This randomized, double-blinded, placebo-controlled trial was conducted on 39 diabetic HD patients. People were assigned to receive curcumin or placebo (starch) for 24 weeks. Individuals in the curcumin group (n = 26) received 80 mg/day. CIMT and PWV levels were taken at baseline and after 24 weeks of intervention.

Results

After 24 weeks of intervention, curcumin intake did not affect mean levels of left (P = 0.83) and right (P = 0.47) CIMT and maximum levels of left (P = 0.84) and right (P = 0.11) CIMT, and PWV (P = 0.12) compared to the placebo. Furthermore, within-group difference demonstrated a significant reduction in mean levels of PWV (P = 0.01) in the curcumin group. We did not observe any significant change in C-reactive protein (CRP) concentrations after curcumin intake (P = 0.69).

Conclusions

Curcumin intake did not affect mean levels of left and right CIMT and maximum levels of left and right CIMT, PWV, and CRP levels compared to the placebo. Additionally, within-group difference demonstrated a significant reduction in mean levels of PWV in the curcumin group.This trial was registered at www.irct.ir as http://www.irct.ir: IRCT20200527047584N1.

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

Reactive oxygen species, toxicity, oxidative stress, and antioxidants: chronic diseases and aging

A physiological level of oxygen/nitrogen free radicals and non-radical reactive species (collectively known as ROS/RNS) is termed oxidative eustress or "good stress" and is characterized by low to mild levels of oxidants involved in the regulation of various biochemical transformations such as carboxylation, hydroxylation, peroxidation, or modulation of signal transduction pathways such as Nuclear factor-κB (NF-κB), Mitogen-activated protein kinase (MAPK) cascade, phosphoinositide-3-kinase, nuclear factor erythroid 2-related factor 2 (Nrf2) and other processes. Increased levels of ROS/RNS, generated from both endogenous (mitochondria, NADPH oxidases) and/or exogenous sources (radiation, certain drugs, foods, cigarette smoking, pollution) result in a harmful condition termed oxidative stress ("bad stress"). Although it is widely accepted, that many chronic diseases are multifactorial in origin, they share oxidative stress as a common denominator. Here we review the importance of oxidative stress and the mechanisms through which oxidative stress contributes to the pathological states of an organism. Attention is focused on the chemistry of ROS and RNS (e.g. superoxide radical, hydrogen peroxide, hydroxyl radicals, peroxyl radicals, nitric oxide, peroxynitrite), and their role in oxidative damage of DNA, proteins, and membrane lipids. Quantitative and qualitative assessment of oxidative stress biomarkers is also discussed. Oxidative stress contributes to the pathology of cancer, cardiovascular diseases, diabetes, neurological disorders (Alzheimer's and Parkinson's diseases, Down syndrome), psychiatric diseases (depression, schizophrenia, bipolar disorder), renal disease, lung disease (chronic pulmonary obstruction, lung cancer), and aging. The concerted action of antioxidants to ameliorate the harmful effect of oxidative stress is achieved by antioxidant enzymes (Superoxide dismutases-SODs, catalase, glutathione peroxidase-GPx), and small molecular weight antioxidants (vitamins C and E, flavonoids, carotenoids, melatonin, ergothioneine, and others). Perhaps one of the most effective low molecular weight antioxidants is vitamin E, the first line of defense against the peroxidation of lipids. A promising approach appears to be the use of certain antioxidants (e.g. flavonoids), showing weak prooxidant properties that may boost cellular antioxidant systems and thus act as preventive anticancer agents. Redox metal-based enzyme mimetic compounds as potential pharmaceutical interventions and sirtuins as promising therapeutic targets for age-related diseases and anti-aging strategies are discussed.

Effect of Curcumin Consumption on Inflammation and Oxidative Stress in Patients on Hemodialysis: A Literature Review

Advanced chronic kidney disease (CKD) stages lead to exacerbated inflammation and oxidative stress. Patients with CKD in stage 5 need renal hemodialysis (HD) to remove toxins and waste products. However, this renal replacement therapy is inefficient in controlling inflammation. Regular curcumin consumption has been shown to reduce inflammation and oxidative stress in subjects with chronic pathologies, suggesting that the daily intake of curcumin may alleviate these conditions in HD patients. This review analyzes the available scientific evidence regarding the effect of curcumin intake on oxidative stress and inflammation in HD patients, focusing on the mechanisms and consequences of HD and curcumin consumption. The inclusion of curcumin as a dietary therapeutic supplement in HD patients has shown to control the inflammation status. However, the optimal dose and oral vehicle for curcumin administration are yet to be determined. It is important to consider studies on curcumin bioaccessibility to design effective oral administration vehicles. This information will contribute to the achievement of future nutritional interventions that validate the efficacy of curcumin supplementation as part of diet therapy in HD.

Role of Turmeric and Curcumin in Prevention and Treatment of Chronic Diseases: Lessons Learned from Clinical Trials

Turmeric (Curcuma longa) has been used for thousands of years for the prevention and treatment of various chronic diseases. Curcumin is just one of >200 ingredients in turmeric. Almost 7000 scientific papers on turmeric and almost 20,000 on curcumin have been published in PubMed. Scientific reports based on cell culture or animal studies are often not reproducible in humans. Therefore, human clinical trials are the best indicators for the prevention and treatment of a disease using a given agent/drug. Herein, we conducted an extensive literature survey on PubMed and Scopus following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The keywords "turmeric and clinical trials" and "curcumin and clinical trials" were considered for data mining. A total of 148 references were found to be relevant for the key term "turmeric and clinical trials", of which 70 were common in both PubMed and Scopus, 44 were unique to PubMed, and 34 were unique to Scopus. Similarly, for the search term "curcumin and clinical trials", 440 references were found to be relevant, of which 70 were unique to PubMed, 110 were unique to Scopus, and 260 were common to both databases. These studies show that the golden spice has enormous health and medicinal benefits for humans. This Review will extract and summarize the lessons learned about turmeric and curcumin in the prevention and treatment of chronic diseases based on clinical trials.

Curcumin Supplementation and Human Disease: A Scoping Review of Clinical Trials

Medicinal properties of turmeric (Curcuma longa L.), a plant used for centuries as an anti-inflammatory, are attributed to its polyphenolic curcuminoids, where curcumin predominates. Although "curcumin" supplements are a top-selling botanical with promising pre-clinical effects, questions remain regarding biological activity in humans. To address this, a scoping review was conducted to assess human clinical trials reporting oral curcumin effects on disease outcomes. Eight databases were searched using established guidelines, yielding 389 citations (from 9528 initial) that met inclusion criteria. Half focused on obesity-associated metabolic disorders (29%) or musculoskeletal disorders (17%), where inflammation is a key driver, and beneficial effects on clinical outcomes and/or biomarkers were reported for most citations (75%) in studies that were primarily double-blind, randomized, and placebo-controlled trials (77%, D-RCT). Citations for the next most studied disease categories (neurocognitive [11%] or gastrointestinal disorders [10%], or cancer [9%]), were far fewer in number and yielded mixed results depending on study quality and condition studied. Although additional research is needed, including systematic evaluation of diverse curcumin formulations and doses in larger D-RCT studies, the preponderance of current evidence for several highly studied diseases (e.g., metabolic syndrome, osteoarthritis), which are also clinically common, are suggestive of clinical benefits.

The protective effects of curcumin on depression: Genes, transcription factors, and microRNAs involved

BACKGROUND

We aim to identify the molecular mechanisms for curcumin's anti-depressant properties, including genes, transcription factors, and miRNAs.

METHODS

The Comparative Toxicogenomics Database, GeneMania, Metascape, MIENTURNET, and Cytoscape software were used as important data approaches in this study.

RESULTS

Curcumin may have an anti-depressant effect via the relevant genes: ADORA2A, ALB, BDNF, FGF2, GLO1, GSK3B, IL6, MIF, NOS1, PTGS2, RELN, SELP, SOD1, and NR3C1. Co-expression (50.7 %) and physical interactions (28.7 %) were the primary relationships discovered by gene network analysis. The key pathways involved in curcumin's protective function against depression were "spinal cord injury", "regulation of apoptotic signaling pathway", "positive regulation of protein phosphorylation", "folate metabolism", "neuroinflammation and glutamatergic signaling", and "inflammation response". We also observed 74 miRNAs associated with depression that are targeted by curcumin, with hsa-miR-146a-5p having the greatest expression and interaction. PLSCR1, SNAI1, ZNF267, ATF3, and GTF2B were the most important transcription factors that regulated four curcumin-targeted genes. Curcumin's physicochemical characteristics and pharmacokinetics are consistent with its antidepressant effects due to its high gastrointestinal absorption, which did not remove it from the CNS, and its ability to penetrate the blood-brain barrier. Curcumin also inhibits CYP1A9 and CYP3A4.

LIMITATIONS

A toxicogenomic design in silico was applied.

CONCLUSIONS

Our findings suggest that therapy optimization and further research into curcumin's pharmacological properties are required before it may be utilized to treat depression.

The effects of curcumin-containing supplements on inflammatory biomarkers in hemodialysis patients: A systematic review and meta-analysis

In the past decade, the effect of curcumin or turmeric supplementation on many aspects of health status in different populations has been evaluated. In the present study, a systematic review and meta-analysis were conducted to estimate the effect of curcumin administration on inflammatory markers in hemodialysis (HD) patients. A systematic search was performed in MEDLINE, EMBASE, Scopus, and Clarivate Analytics Web of Science databases from 1997 until June2022 for terms related to curcumin/turmeric and hemodialysis (HD). Randomized, double-blind/single-blind studies examining the effects of curcumin/turmeric on the inflammation of HD participants older than 18 years were considered eligible for inclusion. Data were pooled using the weighted mean difference (WMD) and 95% CI as the summary statistic, considering a random-effects analysis model. The data that were pooled from nine studies with 472 patients indicated that curcumin-containing supplement had significant effect on serum C-reactive protein (CRP) levels (WMD = -3.3 mg/L; 95% CI: -5.4 to -1.3; p < 0.001, I²  = 76.7%, 8 studies, 467 participants), and interlukine-6 (IL-6) levels (SMD: -0.4; 95% CI: -0.8 to -0.07; p = 0.02, I²  = 31.6%, 3 studies, 153 participants) compared control group. Although curcumin intervention could not change tumor neurosis factor-α (TNF-α) concentration (SMD = -0.3; 95% CI: -0.7 to 0.04; p = 0.08, I²  = 25.3%, 3 studies, 153 participants), when compared with the placebo group. Our study's main limitations were small number of studies, overall high risk of bias in the included trials, and high heterogeneity in some results. The present meta-analysis suggested that intervention with curcumin-containing supplements was associated with a significant reduction in serum hs-CRP and IL-6 concentrations in HD patients. The curcumin intervention in the reduction of hs-CRP levels was greater than the minimal clinically important difference (MCID) for CRP (0.5 mg/L), which can be helpful in physicians' clinical decisions.

Turmeric supplementation with piperine is more effective than turmeric alone in attenuating oxidative stress and inflammation in hemodialysis patients: A randomized, double-blind clinical trial

PURPOSE

Turmeric has renop rotective effects that can act to reduce oxidative stress and inflammation in hemodialysis (HD) patients. Piperine has been indicated as a bioavailability enhancer of turmeric and consequently of its biological effects. However, data on the efficacy of the turmeric/piperine combination in HD patients are limited. We aimed to verify whether turmeric supplementation in combination with piperine has a superior effect to turmeric alone in increasing antioxidant capacity and reducing oxidative stress and inflammation in HD patients.

METHODS

This randomized, double-blind clinical trial was conducted in HD patients (age 20-75 years). Patients were supplemented with turmeric (3 g/day) or turmeric/piperine (3 g turmeric + 2 mg piperine/day) for 12 weeks. Malondialdehyde (MDA), antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), high-sensitivity C-reactive protein (hs-CRP), and ferritin were evaluated at baseline and the end of the study.

RESULTS

There was a reduction in the MDA and ferritin levels in the turmeric/piperine group and in the comparison between groups at the end of the study [MDA: -0.08(-0.14/0.01) nmol/mL versus -0.003(-0.10/0.26) nmol/mL, p = 0.003; ferritin: -193.80 ± 157.29 mg/mL versus 51.99 ± 293.25 mg/mL, p = 0.018]. In addition, GPx activity reduced in the turmeric group (p = 0.029). No changes were observed for CAT, GR, and hs-CRP.

CONCLUSION

Turmeric plus piperine was superior to turmeric alone in decreasing MDA and ferritin levels. The use of a combination of turmeric and piperine as a dietary intervention may be beneficial for modulating the status oxidative and inflammation in HD patients.

BRAZILIAN REGISTRY OF CLINICAL TRIALS NUMBER

RBR-2t5zpd; Registration Date: May 2, 2018.

Randomized, double-blinded, controlled clinical trial of the effect of captopril, telmisartan and their combination on systemic inflammation of patients on hemodialysis

To evaluate individual and combined effect of captopril and telmisartan on systemic inflammation markers of hemodialysis (HD) patients. Randomized, double-blinded, controlled clinical trial. Patients on HD at least 2 months, with arteriovenous fistula, were randomly allocated to groups: (1) captopril/placebo (N 13); (2) telmisartan/placebo (N 13); (3) captopril + telmisartan (N 12); or (4) placebo/placebo (N 12). During 3 months, patients received oral drugs as follows: captopril 50 mg/day, telmisartan 80 mg/day or placebo. Patients excluded if they had conditions or were on drugs potentially influencing on inflammation. Clinical and biochemical evaluations were performed monthly. Serum tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6), and C-reactive protein (CRP) were measured at 0, 1 and 3 months. Baseline, demographic, clinical and biochemical variables were comparable between groups. Baseline versus final inflammatory markers were: captopril/placebo TNFα, 2.47 (0.1-4.5) versus 1.73 (0.3-3.8) pg/ml; IL-6, 17.03 (7.2-23) versus 7.90 (0.7-19) pg/ml; CRP, 4.21 (1.6-18) versus 5.9 (3.0-28) mg/l; telmisartan/placebo TNFα, 3.03 (2.3-4.6) versus 1.70 (1.2-2.0) pg/ml; IL-6, 14.10 (5.5-23) versus 9.85 (6.2-13) pg/ml; CRP, 5.74 (2.1-13) versus 10.60 (1.5-27) mg/l; captopril + telmisartan TNFα, 1.43 (0.7-5.4) versus 0.40 (0.1-2.1) pg/ml; IL-6, 10.05 (4.9-23) versus 4.00 (0.7-7.7) pg/ml (p < 0.05); CRP, 3.26 (0.7-12) versus 2.83 (0.6-6.5) mg/l; placebo/placebo TNFα, 3.13 (1.6-5.6) versus 1.64 (1.6-2.3) pg/ml; IL-6, 8.12 (5.4-16) versus 7.60 (2.4-15) pg/ml; CRP, 5.23 (1.9-16) versus 3.13 (1.5-18) mg/l. Monotherapy with captopril or telmisartan display a trend, but their combined treatment significantly decreased serum levels of IL-6. No remarkable changes on TNFα and CRP were observed.

The effects of curcumin-containing supplementations on inflammatory markers and lipid profiles in patients with chronic kidney diseases: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

An evaluation the effects of curcumin on inflammatory markers and lipid profiles among patients with chronic kidney diseases (CKD).

METHODS

The electronic databases such as PubMed, and Scopus were searched systematically up until 12 December 2021. To evaluate the quality of the included studies, the Cochrane risk-of-bias tool for randomized trials was utilized. Likewise, data pooling was performed using a random effects model, also called a variance components model. Also, the findings were calculated as weighted mean difference (WMD) with a 95% confidence interval (CI).

RESULTS

In the end, this meta-analysis comprised a total number of nine studies. Curcumin intake significantly reduced total cholesterol (TC) (WMD=-13.77 mg/dL; 95% CI, -26.77, -0.77; p=0.04) and tumor necrosis factor alpha (TNF-α) (WMD=-18.87 pg/mL; 95% CI, -28.36, -9.38; p<0.001) compared with controls. The results did not confirm the significant effect of curcumin intake on triglyceride (TG) (WMD=-6.37 mg/dL; 95% CI, -26.59, 13.85; p=0.54), low-density lipoproteins (LDL-C) (WMD=-5.65 mg/dL; 95% CI, -20.81, 9.50; p=0.46), high-density lipoprotein (HDL-C) (WMD=0.16 mg/dL; 95% CI, -2.55, 2.88; p=0.91), and C-reactive protein (CRP) (WMD=-0.13 mg/L; 95% CI, -3.25, 3.30; p=0.93).

CONCLUSIONS

Our study showed that curcumin significantly impacts TC and TNF levels in CKD patients.

COVID-19, cytokines, inflammation, and spices: How are they related?

BACKGROUND

Cytokine storm is the exaggerated immune response often observed in viral infections. It is also intimately linked with the progression of COVID-19 disease as well as associated complications and mortality. Therefore, targeting the cytokine storm might help in reducing COVID-19-associated health complications. The number of COVID-19 associated deaths (as of January 15, 2021; https://www.worldometers.info/coronavirus/) in the USA is high (1199/million) as compared to countries like India (110/million). Although the reason behind this is not clear, spices may have some role in explaining this difference. Spices and herbs are used in different traditional medicines, especially in countries such as India to treat various chronic diseases due to their potent antioxidant and anti-inflammatory properties.

AIM

To evaluate the literature available on the anti-inflammatory properties of spices which might prove beneficial in the prevention and treatment of COVID-19 associated cytokine storm.

METHOD

A detailed literature search has been conducted on PubMed for collecting information pertaining to the COVID-19; the history, origin, key structural features, and mechanism of infection of SARS-CoV-2; the repurposed drugs in use for the management of COVID-19, and the anti-inflammatory role of spices to combat COVID-19 associated cytokine storm.

KEY FINDINGS

The literature search resulted in numerous in vitro, in vivo and clinical trials that have reported the potency of spices to exert anti-inflammatory effects by regulating crucial molecular targets for inflammation.

SIGNIFICANCE

As spices are derived from Mother Nature and are inexpensive, they are relatively safer to consume. Therefore, their anti-inflammatory property can be exploited to combat the cytokine storm in COVID-19 patients. This review thus focuses on the current knowledge on the role of spices for the treatment of COVID-19 through suppression of inflammation-linked cytokine storm.

Effect of curcumin on C-reactive protein as a biomarker of systemic inflammation: An updated meta-analysis of randomized controlled trials

It has been suggested that curcumin is a potential agent for lowering the levels of C-reactive protein (CRP) and high-sensitivity CRP (hs-CRP), as markers of inflammation. In the current meta-analysis, we attempted to clarify the efficacy of curcumin supplementation in lowering the concentrations of CRP and hs-CRP in patients with autoinflammatory conditions. Nine studies were found evaluating the effect of curcumin on CRP levels, while 23 studies were identified for hs-CRP. CRP concentration was decreased significantly compared to the placebo (WMD = -3.67 mg/L, 95% CI = -6.96 to -0.38, p = 0.02). There was a significant effect of curcumin at dose ≤1,000 mg/day on the CRP concentration. CRP concentration significantly decreased after >10-week intervention compared with placebo.hs-CRP concentration in the intervention group was significantly lower than that of placebo group. A significant effect of curcumin consumption was detected on the serum level of hs-CRP in studies with prescribing ≤1,000 mg/day, and those with ≤10-week duration of intervention. Curcumin consumption resulted in a reduction of hs-CRP in a non-linear fashion with stronger effects with less than 2000 mg curcumin per day. Curcumin seems to be beneficial in decreasing the hs-CRP and CRP levels in proinflammatory settings.

Antioxidant and anti-inflammatory response to curcumin supplementation in hemodialysis patients: A randomized, double-blind, placebo-controlled clinical trial

BACKGROUND AND OBJECTIVES

Hemodialysis (HD) patients are vulnerable to malnutrition and cardiovascular complications due to many factors, including oxidative stress and inflammation. Curcumin supplementation is associated with attenuation of proinflammatory cytokines and increased activity of antioxidant enzymes, but its effects in HD patients are unknown. This study aimed to evaluate the effect of curcumin supplementation on oxidative stress and inflammation in HD patients.

METHODS

This randomized, double-blind, placebo-controlled trial enrolled 43 HD patients and divided them into two groups: supplemented with curcumin (1 g/day) or placebo (corn starch) for 12 weeks. Demographic information and blood samples were taken at the start and the end of the study to determine serum malondialdehyde (MDA) concentrations, antioxidant enzyme activity, and high-sensitivity C-reactive protein (hs-CRP).

RESULTS

The curcumin group showed a significant increase in catalase activity [Δ = 1.13 ± 2.87 versus Δ = -1.08 ± 2.68; p = 0.048] and preserved glutathione peroxidase activity [Δ = -4.23 ± 11.50 versus Δ = -14.44 ± 13.96; p < 0.01] compared with the placebo group. However, no significant changes were found in MDA concentrations, glutathione reductase activity, and hs-CRP concentrations after the intervention.

CONCLUSION

Curcumin supplementation for 12 weeks had potential effects on antioxidant response, but it was not enough to reduce oxidative stress markers and inflammation in HD patients. This trial was registered at EnsaiosClínicos.gov.br under registration number RBR-2t5zpd.

Effect of curcumin on proinflammatory cytokines: A meta-analysis of randomized controlled trials

It has been suggested that curcumin has the potential for lowering inflammation. In the current meta-analysis, we attempted to clarify the efficacy of curcumin/turmeric supplementation in reducing concentrations of interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-α in patients with an inflammatory background. The main databases were searched to identify eligible trials evaluating the effect of curcumin in reducing IL-1, IL-6, IL-8, and TNF-α in serum up to March 2021. The effect sizes for weighted mean difference (WMD) and 95% confidence intervals (CI) were calculated. Overall, 32 randomized controlled trials (RCTs) were included. There was a significant decrease in the serum levels of IL-1 (WMD = -2.33 pg/ml, 95% CI = -3.33 to -1.34, P < 0.001) and TNF-α (WMD = -1.61 pg/ml, 95% CI = -2.72, -0.51, P < 0.001) compared to the placebo group following treatment. Nonetheless, curcumin/turmeric supplementation was non-significantly associated with reduced levels of IL-6 (WMD = -0.33 pg/ml, 95% CI = -0.99-0.34, P = 0.33) and increased levels of IL-8 (WMD = 0.52 pg/ml, 95% CI = -1.13-2.17, P = 0.53). The dose-responses analysis indicated that curcumin/turmeric supplementation resulted in IL-1 and IL-8 alteration in a non-linear model. Subgroup analysis according to duration and dose of treatment and target population revealed diverse outcomes. Curcumin could have a beneficial effect in reducing the proinflammatory cytokines IL-1 and TNF-α, but not IL-6 and IL-8 levels.

Herbal antioxidants in dialysis patients: a review of potential mechanisms and medical implications

The consumption of exogenous antioxidants isolated from herbal extracts has shown beneficial effects on ameliorating dialysis-related complications through debilitating oxidative stress and inflammatory process. Many clinical studies available in public databases have reported the improved consequences of dialysis in patients supplemented with herbal antioxidants. Exploration of such data offers great possibilities for gaining insights into the potential mechanisms and medical implications of herbal antioxidants. In this work, the mechanisms and implications of some famous bioactive substances including silymarin, curcumin, resveratrol, emodin, and quercetin on the consequences of dialysis in chronic kidney disease (CKD) patients were explored. The protective features of silymarin are due to the flavonoid complex silybin. Curcumin is an active element from the root of curcuma longa with extensive beneficial properties, including antioxidant, anti-inflammatory activity, and inhibitory effects on cell apoptosis. Resveratrol can reduce the oxidative stress by neutralization of free radicals. Emodin is known as a natural anthraquinone derivative isolated from Chinese herbs. Finally, quercetin has been reported to exhibit several properties including antioxidant, anti-diabetic, analgesic, antihistaminic, antiviral, cholesterol reducer, and renal hemodynamic modulator. However, potential mechanisms and medical implications of the aforementioned herbal antioxidants seem to be more complicated, that is, more studies are required in this field.

The effects of nanocurcumin supplementation on inflammation in hemodialysis patients: A randomized controlled trial

INTRODUCTION

Serum levels of several pro-inflammatory cytokines are higher in hemodialysis patients compared to healthy people. Curcumin has been shown to be able to decrease cytokines levels in nonuremic subjects. Our goal was to evaluate the effect of nanocurcumin administration on cytokines levels in hemodialysis patients.

METHODS

The study was performed over a 3 months period on 54 hemodialysis patients who had been randomized to receive either nanocurcumin or placebo. Serum levels and gene expressions of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) were evaluated using enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR).

FINDINGS

Serum levels of IL-6 and TNF-α were similar in the two groups at baseline but were lower after 12 weeks of treatment with nanocurcumin compared to placebo (P = 0.024 for IL-6 and 0.02 for TNF). In the group given nanocurcumin, serum levels of both cytokines decreased substantially (P < 0.001 for each), whereas they were unchanged in the group given placebo. Gene expression for each cytokine in peripheral blood mononuclear cells (PBMCs) was reduced at 12 weeks vs. baseline in the group given nanocurcumin, and changes in gene expression correlated with changes in serum level for each of the two cytokines.

DISCUSSION

The results indicate that nanocurcumin supplementation reduces both serum levels and gene expression of IL-6 and TNF-α in hemodialysis patients. The feasibility and potential clinical benefits of nanocurcumin treatment to reduce inflammation in hemodialysis patients warrant further study.

Functional foods modulating inflammation and metabolism in chronic diseases: a systematic review

Chronic diseases are responsible for approximately 71% global deaths. These are characterized by chronic low-grade inflammation and metabolic alterations. "Functional foods" have been attributed with anti-inflammatory properties, demonstrated in cell lines and murine models; however, studies in humans are inconclusive. The purpose of this systematic review is to identify clinical trials that analyzed changes in inflammatory and metabolic mediators, in response to consumption of specific functional foods. A total of 3581 trials were screened and 88 were included for this review. Foods identified to regulate inflammation included cranberries, grapes, pomegranate, strawberries, wheat, whole grain products, low fat dairy products, yogurt, green tea, cardamom, turmeric, soy foods, almonds, chia seeds, flaxseed, pistachios, algae oil, flaxseed oil and grape seed oil. Clinical trials that focus on a dietary pattern rich in functional foods are necessary to explore if the additive effect of these foods lead to more clinically relevant outcomes.

The Use of Curcumin for the Treatment of Renal Disorders: A Systematic Review of Randomized Controlled Trials

Chronic kidney disease (CKD) is one of the significant causes of morbidity and mortality worldwide, which could develop and progress to end-stage renal disease. Increased inflammation and reduced antioxidant capacity commonly occur in CKD and hemodialysis patients. Curcumin is a natural bioactive compound with antioxidant and anti-inflammatory properties. This systematic review was undertaken with the main aim of assessing the effects of curcumin/turmeric supplementation on renal diseases based on clinical trials. A comprehensive search was performed in PubMed/MEDLINE, Scopus, ISI Web of Science, and Google Scholar from inception up to April 6, 2020 to identify clinical trials assessing the effects of curcumin or turmeric alone, or in combination with other herbs or nutrients on renal diseases. Twelve studies met the eligibility criteria. These randomized controlled trials (RCTs) comprised 631 patients with either chronic kidney diseases (CKD), hemodialysis, diabetic proteinuria and nephropathy, and lupus nephritis. Curcumin/turmeric supplementation had favorable effects on renal diseases, particularly in terms of inflammation and oxidative stress. However, with the exception for proteinuria, their impact on clinical parameters, such as blood urea nitrogen, creatinine, glomerular filtration rate (GFR), and serum albumin, was weak and not significant. No serious adverse effects were reported following curcumin/turmeric supplementation. Within the limitations of this review, it can be concluded that curcumin/turmeric supplementation might have some beneficial effects on inflammatory and oxidative stress parameters of patients but no considerable positive impact on clinical outcomes of kidney diseases, apart from proteinuria.

Anti-inflammatory effects of oral supplementation with curcumin: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

Chronic inflammation is a major contributor to the development of noncommunicable diseases. Curcumin, a bioactive polyphenol from turmeric, is a well-known anti-inflammatory agent in preclinical research. Clinical evidence remains inconclusive because of discrepancies regarding optimal dosage, duration, and formulation of curcumin.

OBJECTIVE

The aim of this systematic review, conducted and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and checklist, was to evaluate the efficacy of curcumin supplementation on systemic inflammatory mediators, comparing dose, duration, and bioavailability status of interventions.

DATA SOURCES

The Medline, CINAHL, EMBASE, Scopus, and Cochrane literature databases were searched from 1980 to May-end 2019. Randomized controlled trials investigating effects of dietary curcumin on inflammatory mediators in humans not receiving anti-inflammatory treatment were eligible for inclusion. Two authors independently assessed titles and abstracts of identified articles for potential eligibility and respective, retrieved, full-text articles; disagreements were resolved by a third author. Evidence quality was critically appraised using the Quality Criteria Checklist for Primary Research.

DATA EXTRACTION

Thirty-two trials (N = 2,038 participants) were included and 28 were meta-analyzed using a random-effects model; effect sizes were expressed as Hedges' g (95%CI).

DATA ANALYSIS

Pooled data (reported here as weighted mean difference [WMD]; 95%CI) showed a reduction in C-reactive protein (-1.55 mg/L; -1.81 to -1.30), interleukin-6 (-1.69 pg/mL, -2.56 to -0.82), tumor necrosis factor α (-3.13 pg/mL; -4.62 to -1.64), IL-8 (-0.54 pg/mL; -0.82 to -0.28), monocyte chemoattractant protein-1 (-2.48 pg/mL; -3.96 to -1.00), and an increase in IL-10 (0.49 pg/mL; 0.10 to 0.88), with no effect on intracellular adhesion molecule-1.

CONCLUSION

These findings provide evidence for the anti-inflammatory effects of curcumin and support further investigation to confirm dose, duration, and formulation to optimize anti-inflammatory effects in humans with chronic inflammation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42019148682.

Biochemistry, Safety, Pharmacological Activities, and Clinical Applications of Turmeric: A Mechanistic Review

Turmeric (Curcuma longa L.) is a popular natural drug, traditionally used for the treatment of a wide range of diseases. Its root, as its most popular part used for medicinal purposes, contains different types of phytochemicals and minerals. This review summarizes what is currently known on biochemistry, safety, pharmacological activities (mechanistically), and clinical applications of turmeric. In short, curcumin is considered as the fundamental constituent in ground turmeric rhizome. Turmeric possesses several biological activities including anti-inflammatory, antioxidant, anticancer, antimutagenic, antimicrobial, antiobesity, hypolipidemic, cardioprotective, and neuroprotective effects. These reported pharmacologic activities make turmeric an important option for further clinical research. Also, there is a discussion on its safety and toxicity.

Imbalance of Th22/Treg cells causes microinflammation in uremic patients undergoing hemodialysis

BACKGROUND

Regulatory T (Treg) cells are of critical functionality in immune activation and inflammation in uremic patients undergoing hemodialysis (HD). A disruption in balance of Treg cells has potency to elicit infectious disease progression. Here, we examined possible association between ratio imbalance of Th22/Treg cells and microinflammation in uremic patients undergoing HD.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated to allow measurement of the percentage of Th22 cells and Treg cells using flow cytometry. Subsequently, serum levels of related cytokines, interleukin (IL) 22 (IL-22) and IL-10 and inflammatory factors, C-reactive protein (CRP), (TNF-α), IL-6 were determined via enzyme-linked immunosorbent assay (ELISA). Then relationships among dialysis time, microinflammation status (CRP) and dialysis adequacy (immunoreactive parathyroid hormone (iPTH), urea clearance index (Kt/V), β2-MG, serum calcium, and serum phosphorus) were evaluated. Finally, correlation between microinflammation status and dialysis adequacy was analyzed with Pearson's correlation coefficient.

RESULTS

An increased percentage of Th22 and a decreased percentage of Treg cells were evident in uremic patients undergoing HD. Serum levels of IL-22, CRP, TNF-α, and IL-6 were increased, while IL-10 serum level was reduced. An imbalance of Th22/Treg cells was associated with microinflammation status in uremic patients undergoing HD. Furthermore, prolongation of the dialysis time, the microinflammation status and dialysis adequacy were changed. Increased dialysis adequacy was observed to correlate with alleviated microinflammation of uremic patients undergoing HD.

CONCLUSIONS

Conjointly, an imbalance of Th22/Treg cells may be a potential cause responsible for uremia occurrence, which in turn indicates that uremia could be effectively alleviated by altering the ratio of Th22/Treg cells.

Oral turmeric/curcumin effects on inflammatory markers in chronic inflammatory diseases: A systematic review and meta-analysis of randomized controlled trials

Turmeric extract or active component curcumin may have anti-inflammatory effects in people with chronic inflammatory diseases. The effect of turmeric or curcumin on a wide range of inflammatory markers has not been evaluated in a systematic review. We performed a systematic review of randomized controlled trials (RCTs) evaluating the effects of oral turmeric or curcumin on inflammatory markers (CRP, hsCRP, IL-1, IL-6, TNF) in patients with a wide range of chronic inflammatory diseases. Pubmed, EMBASE, Scopus, the Web of Science, and the Cochrane library were evaluated until June 2018. Random effects meta-analyses with inverse variance methods and stratified by turmeric or curcumin were performed. Effects were expressed as mean differences (MD) and their 95% confidence intervals (CI). Risk of bias of RCTs was evaluated with the Cochrane tool. Nineteen RCTs were identified; included patients had rheumatic diseases, advanced chronic kidney disease with hemodialysis, metabolic syndrome, and cardiovascular diseases. Turmeric was the intervention in 5 RCTs (n = 356) and curcumin/curcuminoids in 14 RCTs (n = 988). Follow up times ranged between 4 and 16 weeks. One RCT had high risk of bias. In comparison to controls, turmeric or curcumin did not significantly decrease levels of CRP (MD -2.71 mg/L, 95%CI -5.73 to 0.31, p = 0.08, 5 studies), hsCRP (MD -1.44 mg/L, 95%CI -2.94 to 0.06, p = 0.06, 6 studies), IL-1 beta (MD -4.25 pg/mL, 95%CI -13.32 to 4.82, p = 0.36, 2 studies), IL-6 (MD -0.71 pg/mL, 95%CI -1.68 to 0.25, p = 0.15), and TNF alpha (MD -1.23 pg/mL, 95%CI -3.01 to 0.55, p = 0.18, 7 studies). There were no differences between turmeric and curcumin interventions. High heterogeneity of effects was observed for all markers across studies, except hsCRP. Other inflammatory markers such as IL-1 alpha, TNF beta, IL-17, and IL-22 had scarce data. Turmeric or curcumin did not decrease several inflammatory markers in patients with chronic inflammatory diseases.