Trans-10,cis-12-conjugated linoleic acid worsens renal pathology and alters cyclooxygenase derived oxylipins in obesity-associated nephropathy

Triazine herbicide prometryn alters epoxide hydrolase activity and increases cytochrome P450 metabolites in murine livers via lipidomic profiling

Oxylipins are a group of bioactive fatty acid metabolites generated via enzymatic oxygenation. They are notably involved in inflammation, pain, vascular tone, hemostasis, thrombosis, immunity, and coagulation. Oxylipins have become the focus of therapeutic intervention since they are implicated in many conditions, such as nonalcoholic fatty liver disease, cardiovascular disease, and aging. The liver plays a crucial role in lipid metabolism and distribution throughout the organism. Long-term exposure to pesticides is suspected to contribute to hepatic carcinogenesis via notable disruption of lipid metabolism. Prometryn is a methylthio-s-triazine herbicide used to control the growth of annual broadleaf and grass weeds in many cultivated plants. The amounts of prometryn documented in the environment, mainly waters, soil and plants used for human and domestic consumption are significantly high. Previous research revealed that prometryn decreased liver development during zebrafish embryogenesis. To understand the mechanisms by which prometryn could induce hepatotoxicity, the effect of prometryn (185 mg/kg every 48 h for seven days) was investigated on hepatic and plasma oxylipin levels in mice. Using an unbiased LC-MS/MS-based lipidomics approach, prometryn was found to alter oxylipins metabolites that are mainly derived from cytochrome P450 (CYP) and lipoxygenase (LOX) in both mice liver and plasma. Lipidomic analysis revealed that the hepatotoxic effects of prometryn are associated with increased epoxide hydrolase (EH) products, increased sEH and mEH enzymatic activities, and induction of oxidative stress. Furthermore, 9-HODE and 13-HODE levels were significantly increased in prometryn treated mice liver, suggesting increased levels of oxidation products. Together, these results support that sEH may be an important component of pesticide-induced liver toxicity.

Conjugated linoleic acid (CLA) reduces HFD-induced obesity by enhancing BAT thermogenesis and iWAT browning via the CD36-AMPK pathway

The antiobesity effect of conjugated linoleic acid (CLA) has been reported. However, the underlying mechanisms have not been fully clarified. Thus, this study aimed to investigate the effects of CLA on thermogenesis of interscapular brown adipose tissue (iBAT) and browning of inguinal subcutaneous white adipose tissue (iWAT) and explore the possible signaling pathway. The in vivo results showed that CLA enhanced the O2 consumption and heat production in HFD (high-fat diet)-fed female mice by roughly 38%. Meanwhile, CLA increased the average iBAT temperature by 2°C at the room temperature and cold exposure, respectively. Correspondingly, CLA caused 1.6- and 2.4-fold increases in the expression of UCP1 (uncoupling protein 1) of BAT and iWAT, respectively, suggesting the activated iBAT thermogenesis and iWAT browning in HFD-fed female mice. Meanwhile, CLA could promote the formation of brown and beige adipocytes in differentiated stromal vascular cells (SVCs) isolated from iBAT and iWAT (the expressions of UCP1 were promoted by about twofold changes). In possible mechanisms, CLA stimulated the expression of CD36 and the activation of the AMPK pathway in mice iBAT and iWAT as well as the differentiated SVCs. However, inhibition of CD36 and AMPK (adenosine 5'-monophosphate-activated protein kinase) abolished the promotive effects of CLA on brown and beige adipocytes formation. Hence, we showed that CLA reduced HFD-induced obesity through enhancing iBAT thermogenesis and iWAT browning via the  CD36-AMPK pathway.

Anti-apoptotic effect of HeidihuangWan in renal tubular epithelial cells via PI3K/Akt/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Heidihuang Wan (HDHW) is a classic Chinese herbal formula, which was first recorded in the "Suwen Bingji Qiyi Baoming Collection" written by Liu Wansu during the Jin Dynasty (1115-1234 AD). It is commonly used clinically for the treatment of kidney diseases and its curative effect is stable. Previous animal experiments have confirmed that HDHW can effectively improve renal fibrosis. However, the underlying pharmacological mechanism remains unclear.

AIMS OF THIS STUDY

Renal tubular epithelial cell (RTEC) apoptosis is one of the main pathological features of renal fibrosis. This study aimed to observe the effect and underlying mechanism of HDHW on the apoptosis of RTECs to further explore the pathological mechanism of HDHW against renal fibrosis.

MATERIALS AND METHODS

We examined the HDHW composition in rat serum. In vitro, we first screened out the optimal intervention concentration of HDHW on RTECs using the MTT assay. Hypoxia/reoxygenation was then used to induce apoptosis of RTECs (H/R-RTECs), which were divided into H/R-RTEC, astragaloside IV (positive control), HDHW, and RTECs groups. After 48 h of drug intervention, apoptosis of RTECs was detected using flow cytometry and protein expression was detected by western blotting. The 5/6 nephrectomy rat model was constructed and divided into the normal control, 5/6 nephrectomy, HDHW, and astragaloside IV groups. After 8 weeks of treatment, TUNEL staining was used to detect cell apoptosis, and western blotting was used to detect protein expression.

RESULTS

HDHW downregulated the expression of pro-apoptotic proteins Bax and Caspase3, up-regulated the expression of anti-apoptotic protein Bcl-2, activated the PI3K/Akt/mTOR signaling pathway, and reversed the early apoptosis of RTECs, thereby resisting the apoptosis of RTECs.

CONCLUSION

HDHW inhibits apoptosis of RTECs by modulating the PI3K/Akt/mTOR signaling pathway. This study provides experimental evidence for the anti-fibrotic effect of HDHW on the kidneys and partially elucidates its pharmacological mechanism of action.

Heidihuangwan alleviates renal fibrosis in rats with 5/6 nephrectomy by inhibiting autophagy

Renal fibrosis is a common pathway for the progression of various chronic kidney diseases (CKD), and the formation and deterioration will eventually lead to end-stage renal failure, which brings a heavy medical burden to the world. HeidihuangWan (HDHW) is a herbal formulation with stable and reliable clinical efficacy in the treatment of renal fibrosis. However, the mechanism of HDHW in treating renal fibrosis is not clear. In this study, we aimed to investigate the mechanism of HDHW to improve renal fibrosis. Wistar rats were randomly divided into the normal control group, 5/6 Nephrectomy group, astragaloside IV (AS-IV) group, HDHW group, and HDHW + IGF-1R inhibitor (JB1) group. Except for the normal control group, the rat renal fibrosis model was established by 5/6 nephrectomy and intervened with drugs for 8 weeks. Blood samples were collected to evaluate renal function. Hematoxylin-Eosin (HE), Periodic Acid-Schiff (PAS), Modified Masson’s Trichrome (Masson) staining were used to evaluate the pathological renal injury, and immunohistochemistry and Western blotting were used to detect the protein expression of renal tissue. The results showed that HDHW was effective in improving renal function and reducing renal pathological damage. HDHW down-regulated the levels of fibrosis marker proteins, including α-smooth muscle actin (α-SMA), vimentin, and transforming growth factors–β(TGF-β), which in turn reduced renal fibrosis. Further studies showed that HDHW down-regulated the expression of autophagy-related proteins Beclin1 and LC3II, indicating that HDHW inhibited autophagy. In addition, we examined the activity of the class I phosphatidylinositol-3 kinase (PI3K)/serine-threonine kinase (Akt)/mTOR pathway, an important signaling pathway regulating autophagy, and the level of insulin-like growth factor 1 (IGF-1), an upstream activator of PI3K/Akt/mTOR. HDHW upregulated the expression of IGF-1 and activated the PI3K/Akt/mTOR pathway, which may be a vital pathway for its inhibition of autophagy. Application of insulin-like growth factor 1 receptor (IGF-1R) inhibitor further confirmed that the regulation of autophagy and renal fibrosis by HDHW was associated with IGF-1-mediated activation of the PI3K/Akt/mTOR pathway. In conclusion, our study showed that HDHW inhibited autophagy by upregulating IGF-1 expression, promoting the binding of IGF-1 to IGF-1R, and activating the PI3K/Akt/mTOR signaling pathway, thereby reducing renal fibrosis and protecting renal function. This study provides support for the application and further study of HDHW.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

Alterations of specific lipid groups in serum of obese humans: a review

Obesity is a major contributor to the dysfunction of liver, cardiac, pulmonary, endocrine and reproductive system, as well as a component of metabolic syndrome. Although development of obesity-related disorders is associated with lipid abnormalities, most previous studies dealing with the problem in question were limited to routinely determined parameters, such as serum concentrations of triacylglycerols, total cholesterol, low-density and high-density lipoprotein cholesterol. Many authors postulated to extend the scope of analysed lipid compounds and to study obesity-related alterations in other, previously non-examined groups of lipids. Comprehensive quantitative, structural and functional analysis of specific lipid groups may result in identification of new obesity-related alterations. The review summarizes available evidence of obesity-related alterations in various groups of lipids and their impact on health status of obese subjects. Further, the role of diet and endogenous lipid synthesis in the development of serum lipid alterations is discussed, along with potential application of various lipid compounds as risk markers for obesity-related comorbidities.

Conjugated linoleic acid rat pretreatment reduces renal damage in ischemia/reperfusion injury: Unraveling antiapoptotic mechanisms and regulation of phosphorylated mammalian target of rapamycin

SCOPE

Conjugated linoleic acids (CLAs) are dietary components with beneficial effects on human health. The aim of this study was to evaluate the potential benefits of CLA pretreatment in a rat model of renal ischemia/reperfusion injury (IRI).

METHODS AND RESULTS

Animals were treated with CLAs (200 mg/kg/day) or water for two weeks prior to sham surgery or to surgery to induce IRI. Renal function, oxidative stress, apoptosis, and cell proliferation markers, were evaluated. Moreover, kidney sections were submitted to histological evaluation. IRI induced increased serum creatinine, blood urea nitrogen, fractional sodium excretion, malondialdehyde, Bax, and phosphorylated mammalian target of rapamycin (P-mTOR), and decreased clearance of creatine, superoxide dismutase and catalase activities, and Bax in comparison with control groups. CLA prefeeding restored, at least in part, the above reported markers to normal levels, increased the anti-apoptotic protein, B-cell lymphoma 2 (Bcl-2), and reduce the histological damage.

CONCLUSION

The results suggest that the decreased renal tissue damage and improved renal function and oxidative stress, in rats pretreated with CLAs before renal IRI induction, could be associated with downregulation of Bax and P-mTOR, and upregulation of Bcl-2. CLAs pretreatment resulted to protect against IRI through the regulation of signaling pathways involved in apoptosis.