Tackling Counterfeit Drugs: The Challenges and Possibilities.

Drugs that have been manufactured or packaged fraudulently are referred to as counterfeit/fake/spurious/falsified drugs because they either lack active ingredients or have the incorrect dosages. Counterfeiting of drugs has become a global issue with which the whole world is grappling. The World Health Organization states the frightening figure in which almost 10.5% of the medications worldwide are either subpar or fake. Although developing and low-income countries are the targets of the large-scale drug counterfeiting activities, fake/substandard drugs are also making their way into developed nations including the USA, Canada, and European countries. Counterfeiting of drugs is leading to not only economic loss but is also playing its part in the morbidity and mortality of patients. The recent COVID-19 pandemic fuelled the demand for certain categories of medicines such as antipyretics, remdesivir, corticosteroids, vaccines, etc., thus increasing the demand and manufacture of subpar/fake medicines. This review articulates the current trends and global impact of drug counterfeiting, current and potential measures for its prevention and the role of different stakeholders in tackling the menace of drug counterfeiting.

Evaluating the potential of tauroursodeoxycholic acid as add-on therapy in amelioration of streptozotocin-induced diabetic kidney disease.

The bile acid tauroursodeoxycholic acid (TUDCA) is of natural origin and is used in traditional Chinese medicine for centuries. Earlier its use was limited to biliary disorders but owing to its pleiotropic effects dietary TUDCA supplementation is under clinical trials for diseases including type 1 and 2 diabetic complications. The current study aims to evaluate the potential and underlying molecular mechanism of the TUDCA as a monotherapy and as an add-on therapy to telmisartan, an angiotensin II type 1 receptor (AT1R) blocker against diabetic kidney disease (DKD). We employed both in-vitro and in-vivo approaches where NRK-52E cells were incubated with high glucose, and DKD was induced in Wistar rats using streptozotocin (55 mg/kg, i.p.). After 4 weeks, animals were administered with TUDCA (250 mg/kg, i.p.), telmisartan (10 mg/kg, p.o.), and their combination for 4 weeks. Plasma was collected for the biochemical estimation and kidneys were used for immunoblotting, PCR, and histopathological analysis. Similarly, for in-vitro experiments, cells were exposed to 1000 µM of TUDCA and 10 µM of telmisartan, and their combination, followed by cell lysate collection and immunoblotting analysis. We observed that the addition of TUDCA to conventional telmisartan treatment was more effective in restoring the renal function decline and suppressing the apoptotic and fibrotic signaling as compared to monotherapies of AT1R blocker and ER stress inhibitor. The results implicate the utility of traditionally used TUDCA as a potential renoprotective compound. Since, both TUDCA and telmisartan are approved for clinical usage, thus concomitant administration of them could be a novel therapeutic strategy against DKD.

Endoplasmic Reticulum Stress and Renin-Angiotensin System Crosstalk in Endothelial Dysfunction.

BACKGROUND: Vascular endothelial dysfunction (VED) significantly results in catastrophic cardiovascular diseases with multiple aetiologies. Variations in vasoactive peptides, including angiotensin II and endothelin 1, and metabolic perturbations like hyperglycaemia, altered insulin signalling, and homocysteine levels result in pathogenic signalling cascades, which ultimately lead to VED. Endoplasmic reticulum (ER) stress reduces nitric oxide availability, causes aberrant angiogenesis, and enhances oxidative stress pathways, consequently promoting endothelial dysfunction. Moreover, the renin-angiotensin system (RAS) has widely been acknowledged to impact angiogenesis, endothelial repair and inflammation. Interestingly, experimental studies at the preclinical level indicate a possible pathological link between the two pathways in the development of VED. Furthermore, pharmacological modulation of ER stress ameliorates angiotensin-II mediated VED as well as RAS intervention either through inhibition of the pressor arm or enhancement of the depressor arm of RAS, mitigating ER stress-induced endothelial dysfunction and thus emphasizing a vital crosstalk. CONCLUSION: Deciphering the pathway overlap between RAS and ER stress may open potential therapeutic avenues to combat endothelial dysfunction and associated diseases. Several studies suggest that alteration in a component of RAS may induce ER stress or induction of ER stress may modulate the RAS components. In this review, we intend to elaborate on the crosstalk of ER stress and RAS in the pathophysiology of VED.

Klotho in kidney diseases: a crosstalk between the renin-angiotensin system and endoplasmic reticulum stress.

Klotho is a transmembrane anti-ageing protein that exists in three forms, i.e. α-Klotho, ß-Klotho and γ-Klotho, with distinct organ-specific expression and functions in the body. Here we focus on α-Klotho (hereafter Klotho), abundantly expressed by the distal and proximal convoluted tubules of the kidney. A significant decline in systemic and renal Klotho levels is a new hallmark for kidney disease progression. Emerging research portrays Klotho as a promising diagnostic and therapeutic target for diabetic and non-diabetic kidney disease. Even so, the underlying mechanisms of Klotho regulation and the strategies to restore its systemic and renal levels are still lacking. Angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers are the current standard of care for kidney diseases, but the molecular mechanisms for their nephroprotective action are still ambiguous. Moreover, endoplasmic reticulum (ER) stress also plays a crucial role in kidney disease progression. Few studies have claimed that the renin-angiotensin-aldosterone system (RAAS) has a direct relation with ER stress generation and vice versa in kidney disease. Interestingly, RAAS and ER stress modulation are associated with Klotho regulation in kidney disease. Here we focus on how the RAAS and ER stress connect with Klotho regulation in kidney disease. We also discuss Klotho and ER stress in an alliance with the concept of haemodynamic and metabolic overload in kidney disease. In addition, we highlight novel approaches to implement Klotho as a therapeutic target via RAAS and ER stress modulation for the treatment of diabetic and non-diabetic kidney diseases.

Klotho restoration via ACE2 activation: A potential therapeutic strategy against acute kidney injury-diabetes comorbidity.

Acute kidney injury (AKI) is a collection of clinical syndromes with persistent increases in morbidity and mortality rates. Hyperglycemia is a risk factor for AKI development. Renin-angiotensin-aldosterone system (RAS) disequilibrium and Klotho downregulation also play a pivotal role in the pathogenesis of AKI. Moreover, the relationship between Klotho and ACE2 (a component of non-conventional RAS) regulation in AKI remains an unexplored area of research. Hence, in this study, we investigated ACE2 and Klotho regulation in AKI using ischemic Wistar rats and NRK52E cells under normal and hyperglycemic conditions. Our findings suggested that hyperglycemia exacerbates renal ischemia-reperfusion injury (IRI)/hypoxia-reperfusion injury (HRI) induced AKI. Systemic and renal Klotho deficiency is a novel hallmark of AKI. Additionally, ACE2 is a protective component of the RAS, and its inhibition/deficiency leads to inflammation, apoptosis, Klotho downregulation, and thus AKI development. However, ACE2 activation resulted in the amelioration of AKI. Importantly, ACE2 plays an important role in Klotho upregulation, which might act as an intermediate for ACE2-mediated reno-protection. In conclusion, ACE2 activator i.e. DIZE restored endogenous ACE2-Ang-(1-7)-Klotho level, inhibited apoptosis and inflammation, and ameliorates IRI/HRI induced AKI under diabetic and non-diabetic conditions. Hence, in future, targeting ACE2-Ang-(1-7)-Klotho axis may prove a novel therapeutic strategy against AKI, where further preclinical and clinical investigations are required to verify the clinical potential of this finding.

Cyproheptadine, a SET7/9 inhibitor, reduces hyperglycaemia-induced ER stress alleviating inflammation and fibrosis in renal tubular epithelial cells.

CONTEXT: Persistent hyperglycaemia increases SET7/9 expression and endoplasmic reticulum (ER) stress which causes inflammation, apoptosis, and fibrosis in renal tubular epithelial cells leading to diabetic kidney disease (DKD). OBJECTIVE: Current study explores the renoprotective potential of a novel SET7/9 inhibitor, Cyproheptadine, and the underlying molecular mechanisms in hyperglycaemia-induced renal tubular epithelial cell injury. METHODS: Change in expression of SET7/9, histone H3 lysine (K4) monomethylation (H3K4Me1), inflammatory, fibrotic, and ER stress proteins were evaluated in-vivo and in-vitro. NRK-52E cells were used to study the preventive effect of Cyproheptadine against hyperglycaemia-induced ER stress and subsequent inflammation and fibrosis. RESULTS: SET7/9 and H3K4Me1 expression significantly increased with ER stress, inflammation, apoptosis, and fibrosis, in-vivo and in-vitro under hyperglycaemia. However, the cells treated with Cyproheptadine showed significant suppression of H3K4Me1 and reduction in ER stress, inflammation, apoptosis, and fibrosis. CONCLUSION: Cyproheptadine prevented hyperglycaemia-induced renal fibrosis and inflammation by reducing H3K4Me1 expression and ER stress.

Long non-coding RNAs as emerging regulators of miRNAs and epigenetics in diabetes-related chronic kidney disease.

Diabetes is one of the major cause of chronic kidney disease (CKD), including "diabetic nephropathy," and is an increasingly prevalent accelerator of the progression of non-diabetic forms of CKD. The long non-coding RNAs (lncRNAs) have come into the limelight in the past few years as one of the emerging weapons against CKD in diabetes. Available data over the past few years demonstrate the interaction of lncRNAs with miRNAs and epigenetic machinery. Interestingly, the evolving data suggest that lncRNAs play a vital role in diabetes-associated CKD by regulation of epigenetic enzymes such as DNA methyltransferase, histone deacetylases, and histone methyltransferases. LncRNAs are also engaged in the regulation of several miRNAs in diabetic nephropathy. Hence this review will elaborate on the association between lncRNAs and their interaction with epigenetic regulators involved in different aspects and thus the progression of CKD in diabetes.

Inhibition of endoplasmic reticulum stress combined with activation of angiotensin-converting enzyme 2: novel approach for the prevention of endothelial dysfunction in type 1 diabetic rats.

Persistent hyperglycemia in type 1 diabetes triggers numerous signaling pathways, which may prove deleterious to the endothelium. As hyperglycemia damages the endothelial layer via multiple signaling pathways, including enhanced oxidative stress, downregulation of angiotensin-converting enzyme 2 signaling, and exacerbation of endoplasmic reticulum (ER) stress, it becomes difficult to prevent injury using monotherapy. Thus, the present study was conceived to evaluate the combined effect of ER stress inhibition along with angiotensin-converting enzyme 2 activation, two major contributors to hyperglycemia-induced endothelial dysfunction, in preventing endothelial dysfunction associated with type 1 diabetes. Streptozotocin-induced diabetic animals were treated with either diminazene aceturate (5 mg·kg-1 per day, p.o.) or tauroursodeoxycholic acid, sodium salt (200 mg·kg-1 per day i.p.), or both for 4 weeks. Endothelial dysfunction was evaluated using vasoreactivity assay, where acetylcholine-induced relaxation was assessed in phenylephrine pre-contracted rings. Combination therapy significantly improved vascular relaxation when compared with diabetic control as well as monotherapy. Restoration of nitrite levels along with prevention of collagen led to improved vasodilatation. Moreover, there was an overall reduction in aortic oxidative stress. We conclude that by simultaneously inhibiting ER stress and activating angiotensin-converting enzyme 2 deleterious effects of hyperglycemia on endothelium were significantly alleviated. This could serve as a novel strategy for the prevention of endothelial dysfunction.

Epigenetic restoration of endogenous Klotho expression alleviates acute kidney injury-diabetes comorbidity.

AIMS: The present study aimed at exploring the mechanisms behind Klotho regulation in hyperglycemia augmented AKI. In addition, epigenetic ways to restore the Klotho expression in AKI-diabetes comorbidity have been evaluated. MAIN METHODS: Bilateral ischemia-reperfusion injury (IRI) and chemical hypoxia-reperfusion injury (HRI) were developed in diabetic rats and, NRK52E cells under high glucose conditions respectively, to mimic the AKI condition. Plasma, urine, tubular lysate of the kidney and NRK52E cell lysate were used for biochemical, ELISA, histology, immunoblotting, RT-PCR and RNA interference studies. KEY FINDINGS: Hyperglycemia significantly aggravated IRI/HRI induced AKI as evidenced by biochemical and histological results. We also observed a significant increase in expressions of kidney specific histone deacetylases (HDACs), apoptotic and inflammatory proteins, and decrease in levels of endogenous Klotho, H3K9Ac and H3K27Ac proteins in hyperglycemic IRI/HRI groups. SIGNIFICANCE: Diabetes comorbidity exaggerates AKI, where endogenous Klotho loss could be a potential connecting link. However, kidney-specific HDACs inhibition showed reno-protection via restoring the endogenous Klotho loss and thus prevention of inflammation and apoptosis, which could prove to be a potential therapeutic strategy against diabetes-AKI comorbidity.

Klotho: A possible mechanism of action of SGLT2 inhibitors preventing episodes of acute kidney injury and cardiorenal complications of diabetes.

Diabetes and cardiorenal comorbidities are major global health concerns, with high economic burdens and mortality rates. Sodium glucose co-transporter-2 inhibitors (SGLT2is) are novel US Food and Drug Administration (FDA)-approved antihyperglycemics with unexpected protective potential against cardiorenal diseases in patients with or without type 2 diabetes mellitus (T2DM). Despite initial concerns, the incidence of episodes of acute kidney injury (AKI) was significantly lower in patients taking SGLT2i compared with other therapies or placebo. Evolving data suggest a link between SGLT2is and the anti-aging protein Klotho in the amelioration of diabetes and cardiorenal diseases. Here, we consider Klotho and SGLT2is as a novel therapeutic approach for the management of AKI and other cardiorenal complications in patients with or without diabetes.

Epigenetic and non-epigenetic regulation of Klotho in kidney disease.

Klotho is a novel renoprotective anti-aging protein available in membrane-bound or soluble form. Klotho is expressed in brain, pancreas, and other solid organs but shows highest expression levels in the kidney. Klotho sustains normal kidney physiology but Klotho regulation also contributes to the progression of kidney disease. Systemic and intrarenal levels of Klotho fall drastically during acute kidney injury, kidney fibrosis, diabetic nephropathy, and other forms of chronic kidney disease, etc. Moreover, exogenous supplementation or overexpression of endogenous Klotho attenuates kidney disease. The regulation of endogenous Klotho expression involves epigenetic as well as non-epigenetic mechanisms. The epigenetic modifications such as DNA methylation, post-translational histone modifications, miRNAs regulate the change in Klotho expression in kidney disease. Non-epigenetic mechanisms such as ER stress, Wnt signaling, activation of the renin angiotensin system (RAS), excessive reactive oxygen species and cytokine generation, albumin overload, and PPAR-γ signaling also contribute to Klotho regulation. Evolving evidence highlight the capacity of natural products to regulate Klotho expression in kidney disease. All these preclinical data suggest that Klotho could be a novel biomarker as well as therapeutic target. Here we review the different mechanisms of Klotho regulation in the context of Klotho as a biomarker and potential therapeutic agent.

Role of SET7/9 in the progression of ischemic renal injury in diabetic and non-diabetic rats.

SET domain with lysine methyltransferase 7/9 (Set7/9), a histone lysine methyltransferase (HMT), recently suggested to exert a critical role among kidney disorders, whereas its role in diabetes associated IRI co-morbidity remains complete elusive. The present study aimed to understand the role of SET7/9 and histone methylation in regulation of inflammatory signaling under IRI in diabetes mellitus and non-diabetic rats. Our results demonstrated that IRI caused renal dysfunction via increased blood urea nitrogen (BUN) levels in ND and DM rats. The NF-κB mediated inflammatory cascade like increased p-NF-κB, reduced IκBα levels followed by enhanced leukocyte infiltration as shown by increased MCP-1 expressions. IRI results in increased histone H3 methylation at lysine 4 and 36 (H3K4Me2, H3K36Me2), and decreased histone H3 methylation at lysine 9. Additionally, IRI increased the protein and mRNA expression of H3K4Me2 specific histone methyltransferase-SET7/9 in DM and ND rats. The abovementioned results remain prominent in DM rats compared to ND rats followed by IRI. Further, treatment with a novel SET7/9 inhibitor; cyproheptadine, significantly improved renal functioning via reducing the BUN levels in ND and DM rats. Hence, this study demonstrated the role of SET7/9 in mediating active transcription via H3K4Me2, ultimately regulated the NFκB-mediated inflammatory cascade. Therefore, SET7/9 can be explored as novel target for drug development against IRI under DM and ND conditions.

Evidence for Use or Disuse of Renin-Angiotensin System Modulators in Patients Having COVID-19 With an Underlying Cardiorenal Disorder.

Coronavirus disease 19 (COVID-19) originated in Wuhan, China, in December 2019 has been declared pandemic by World Health Organization due to an exponential rise in the number of infected and deceased persons across the globe. Emerging reports suggest that susceptibility and mortality rates are higher in patients with certain comorbidities when compared to the average population. Cardiovascular diseases and diabetes are important risk factors for a lethal outcome of COVID-19. Extensive research ensuing the outbreak of coronavirus-related severe acute respiratory syndrome in the year 2003, and COVID-19 recently revealed a role of renin-angiotensin system (RAS) components in the entry of coronavirus wherein angiotensin-converting enzyme 2 (ACE2) had garnered the significant attention. This raises the question whether the use of RAS inhibitors, the backbone of treatment of cardiovascular, neurovascular, and kidney diseases could increase the susceptibility for coronavirus infection or unfortunate outcomes of COVID-19. Thus, currently, there is a lack of consensus regarding the effects of RAS inhibitors in such patients. Moreover, expert bodies like American Heart Association, American College of Cardiology, and so on have now released official statements that RAS inhibitors must be continued, unless suggested otherwise by a physician. In this brief review, we will elaborate on the role of RAS and ACE2 in pathogenesis of COVID-19. Moreover, we will discuss the potential effect of the use and disuse of RAS inhibitors in patients having COVID-19 with cardiometabolic comorbidities.

'PARP'ing fibrosis: repurposing poly (ADP ribose) polymerase (PARP) inhibitors.

Fibrosis is a wound-healing process that results in tissue scarring and organ dysfunction. Several novel mechanisms of fibrogenesis have been discovered recently. In this review, we focus on the role of poly-ADP ribose polymerase (PARP) in major organ fibrosis, such as lungs, heart, liver, and kidneys. PARP is a dynamic enzyme that modulates different cellular proteins by the addition of PAR groups and mediates an array of cellular events in both normal physiological and pathophysiological states. The US Food and Drug Administration (FDA) and European Medicines Agency (EMA) recently approved several PARP inhibitors, such as olaparib, niraparib, talazoparib, and rucaparib, for the treatment of ovarian and germline BRCA-mutant breast cancers. Consequently, repurposing these drugs could provide an opportunity to counter organ fibrosis.

Cocos nucifera and metformin combination for modulation of diabetic symptoms in streptozotocin induced diabetic rats.

BACKGROUND: Cocos nucifera, belonging to Arecaceae family, holds quite an importance in the Indian traditional medicinal system. C.nucifera inflorescence (CnI) has been reported in the literature to be useful in the treatment of diarrhoea, dysentery, diabetes, and dyspepsia. In this study, we aimed to evaluate the efficacy of CnI as an adjuvant with metformin in ameliorating Type-2 diabetes mellitus (T2-DM). OBJECTIVES: To evaluate antidiabetic activity of CnI in combination with metformin in Streptozotocin (STZ) induced diabetic rats. MATERIALS AND METHODS: Diabetes was induced in male Wistar rats using streptozotocin (45 mg/kg; i.p.). Plasma glucose level (PGL) was estimated after 72 h of STZ injection. Ethanolic extract of CnI (250 mg/kg and 500 mg/kg) per se and in combination with metformin (22.5 mg/kg) was administered orally once daily to rats for a period of 28 days. PGL level was estimated on 7th, 14th and 21st day followed by Oral Glucose Tolerance Test (OGTT) and PGL both on the 28th day of treatment. DPPH assay was performed to evaluate antioxidant activity of CnI extract. RESULTS: Extract of CnI (250 mg/kg and 500 mg/kg alone and the combination of extract (250 mg/kg) along with metformin (22.5 mg/kg) significantly decreased PGL (p < 0.0001) on 7th, 14th, 21st and 28th days. Histopathological analysis of pancreatic tissue showed that treatment with CnI extract per se and in combination with metformin improved the damaged architecture of pancreas. CONCLUSION: The combination therapy of CnI and metformin produced a significant antidiabetic effect than that of the extract alone and provides a scientific rationale for their use in antidiabetic therapy as an adjuvant.

ER stress response mediates diabetic microvascular complications.

Endoplasmic reticulum (ER) homeostasis orchestrates the folding, modification, and trafficking of secretory and membrane proteins to the Golgi compartment, thus governing cellular functions. Alterations in ER homeostasis result in the activation of signaling pathways, such as the unfolded protein response (UPR), to regain ER homeostasis. Nevertheless, failure of UPR leads to activation of autophagy-mediated cell death. Several recent studies emphasized the association of the ER stress (ERS) response with the initiation and progression of diabetes. In this review, we highlight the contribution of the ERS response, such as UPR and autophagy, in the initiation and progression of diabetes and associated microvascular complications, including diabetic nephropathy (DN), retinopathy, and neuropathy, in various experimental models, as well as in humans. We highlight the ERS as a putative therapeutic target for the treatment of diabetic microvascular complications and, thus, the urgent need for the development of improved synthetic and natural inhibitors of ERS.

Concurrent neprilysin inhibition and renin-angiotensin system modulations prevented diabetic nephropathy.

AIMS: Renin-angiotensin system (RAS) and natriuretic peptides system (NPS) perturbations govern the development of diabetic nephropathy (DN). Hence, in search of a novel therapy against DN, present study targeted both, NPS and RAS simultaneously using a neprilysin inhibitor (NEPi) in combination with either angiotensin receptor blocker (ARB) or angiotensin-converting enzyme 2 (ACE2) activator. METHODS: We induced diabetes in male Wistar rats by a single dose of streptozotocin (55 mg/kg, i.p.). After four weeks, we treated diabetic rats with thiorphan, telmisartan or diminazene aceturate (Dize) 0.1, 10, 5 mg/kg/day, p.o. alone as monotherapy, or both thiorphan/telmisartan or thiorphan/Dize as combination therapy, for four weeks. Then, plasma and urine biochemistry were performed, and kidneys from all the groups were collected and processed separately for histopathology, ELISA and Western blotting. KEY FINDINGS: Proposed combination therapies attenuated metabolic perturbations, prevented renal functional decline, and normalised adverse alterations in renal ACE, ACE2, Ang-II, Ang-(1-7), neprilysin and cGMP levels in diabetic rats. Histopathological evaluation revealed a significant reduction in glomerular and tubulointerstitial fibrosis by combination therapies. Importantly, combination therapies inhibited inflammatory, profibrotic and apoptotic signalling, way better than respective monotherapies, in preventing DN. CONCLUSION: Renoprotective potential of thiorphan (NEPi)/telmisartan (ARB) and thiorphan/Dize (ACE2 activator) combination therapies against the development of DN is primarily attributed to normalisation of RAS and NPS components and inhibition of pathological signalling related to inflammation, fibrosis, and apoptosis. Hence, we can conclude that NEPi/ARB and NEPi/ACE2 activator combination therapies might be new therapeutic strategies in preventing DN.

Diabetic nephropathy: The regulatory interplay between epigenetics and microRNAs.

Diabetic nephropathy (DN) is still one of the leading causes of end-stage renal disease despite the emergence of different therapies to counter the metabolic, hemodynamic and fibrotic pathways, implicating a prominent role of genetic and epigenetic factors in its progression. Epigenetics is the study of changes in the expression of genes which may be inheritable and does not involve a change in the genome sequence. Thrust areas of epigenetic research are DNA methylation and histone modifications. Noncoding RNAs (ncRNAs), particularly microRNAs (miRNAs) control the expression of genes via post-transcriptional mechanisms. However, the regulation by epigenetic mechanisms and miRNAs are not completely distinct. A number of emerging reports have revealed the interplay between epigenetic machinery and miRNA expression, particularly in cancer. Further research has proved that a feedback loop exists between miRNA expression and epigenetic regulation in disorders including DN. Studies showed that different miRNAs (miR-200, miR-29 etc.) were found to be regulated by epigenetic mechanisms viz. DNA methylation and histone modifications. Conversely, miRNAs (miR-301, miR-449 etc.) themselves modulated levels of DNA methyltranferases (DNMTs) and Histone deacetylases (HDACs), enzymes vital to epigenetic modifications. With already few FDA approved epigenetic -modulating drugs (Vorinostat, Decitabine) in the market and miRNA therapeutic drugs under clinical trial it becomes imperative to analyze the possible interaction between the two classes of drugs in the modulation of a disease process. The purpose of this review is to articulate the interplay between miRNA expression and epigenetic modifications with a particular focus on its impact on the development and progression of DN.

Curcumin and folic acid abrogated methotrexate induced vascular endothelial dysfunction.

Methotrexate, an antifolate drug widely used in rheumatoid arthritis, psoriasis, and cancer, is known to cause vascular endothelial dysfunction by causing hyperhomocysteinemia, direct injury to endothelium or by increasing the oxidative stress (raising levels of 7,8-dihydrobiopterin). Curcumin is a naturally occurring polyphenol with strong antioxidant and anti-inflammatory action and therapeutic spectra similar to that of methotrexate. This study was performed to evaluate the effects of curcumin on methotrexate induced vascular endothelial dysfunction and also compare its effect with that produced by folic acid (0.072 µg·g(-1)·day(-1), p.o., 2 weeks) per se and in combination. Male Wistar rats were exposed to methotrexate (0.35 mg·kg(-1)·day(-1), i.p.) for 2 weeks to induce endothelial dysfunction. Methotrexate exposure led to shedding of endothelium, decreased vascular reactivity, increased oxidative stress, decreased serum nitrite levels, and increase in aortic collagen deposition. Curcumin (200 mg·kg(-1)·day(-1) and 400 mg·kg(-1)·day(-1), p.o.) for 4 weeks prevented the increase in oxidative stress, decrease in serum nitrite, aortic collagen deposition, and also vascular reactivity. The effects were comparable with those produced by folic acid therapy. The study shows that curcumin, when concomitantly administered with methotrexate, abrogated its vascular side effects by preventing an increase in oxidative stress and abating any reduction in physiological nitric oxide levels.