Renoprotective and haemodynamic effects of adiponectin and peroxisome proliferator-activated receptor agonist, pioglitazone, in renal vasculature of diabetic Spontaneously hypertensive rats

The Many Facets of PPAR-γ Agonism in Obesity and Associated Comorbidities: Benefits, Risks, Challenges, and Future Directions

PURPOSE OF REVIEW

Obesity is strongly associated with cardiometabolic disorders and certain malignancies, emphasizing the key role of adipose tissue in human health. While incretin mimetics have shown effectiveness in glycemic control and weight loss, a holistic strategy for combating obesity and associated comorbidities remains elusive. This review explores peroxisome proliferator-activated receptor gamma (PPAR-γ) agonism as a potential therapeutic approach, highlighting its benefits, addressing its limitations, and outlining future directions for developing more effective treatment strategies.

RECENT FINDINGS

Both natural and synthetic PPAR-γ agonists hold significant therapeutic potential as insulin sensitizers, while also demonstrating anti-inflammatory properties and playing a critical role in regulating lipid metabolism. However, the clinical use of natural agonists is limited by poor bioavailability, while synthetic agents like thiazolidinediones are associated with adverse effects, including fluid retention, weight gain, and bone loss. Current research is focused on developing modified, tissue-specific PPAR-γ agonists, as well as dual PPAR-α/PPAR-γ agonists, with improved safety profiles to mitigate these side effects. Nanotechnology-based drug delivery systems also hold promise for enhancing bioavailability and therapeutic efficacy. Furthermore, the transformative potential of machine learning and artificial intelligence offers opportunities to accelerate advancements in this field. PPAR-γ agonists exhibit significant potential in addressing metabolic syndrome, cardiovascular disease, and cancer. However, their clinical use is restricted by safety concerns and suboptimal pharmacokinetics. Innovations in modified PPAR-γ agonists, nanotechnology-based delivery systems, and computational tools hold promise for creating safer and more effective therapeutic options for obesity and its associated disorders.

Oxidative Stress in Kidney Injury and Hypertension

Hypertension (HTN) is a major contributor to kidney damage, leading to conditions such as nephrosclerosis and hypertensive nephropathy, significant causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). HTN is also a risk factor for stroke and coronary heart disease. Oxidative stress, inflammation, and activation of the renin-angiotensin-aldosterone system (RAAS) play critical roles in causing kidney injury in HTN. Genetic and environmental factors influence the susceptibility to hypertensive renal damage, with African American populations having a higher tendency due to genetic variants. Managing blood pressure (BP) effectively with treatments targeting RAAS activation, oxidative stress, and inflammation is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD. Interactions between genetic and environmental factors impacting kidney function abnormalities are central to HTN development. Animal studies indicate that genetic factors significantly influence BP regulation. Anti-natriuretic mechanisms can reset the pressure-natriuresis relationship, requiring a higher BP to excrete sodium matched to intake. Activation of intrarenal angiotensin II receptors contributes to sodium retention and high BP. In HTN, the gut microbiome can affect BP by influencing energy metabolism and inflammatory pathways. Animal models, such as the spontaneously hypertensive rat and the chronic angiotensin II infusion model, mirror human essential hypertension and highlight the significance of the kidney in HTN pathogenesis. Overproduction of reactive oxygen species (ROS) plays a crucial role in the development and progression of HTN, impacting renal function and BP regulation. Targeting specific NADPH oxidase (NOX) isoforms to inhibit ROS production and enhance antioxidant mechanisms may improve renal structure and function while lowering blood pressure. Therapies like SGLT2 inhibitors and mineralocorticoid receptor antagonists have shown promise in reducing oxidative stress, inflammation, and RAAS activity, offering renal and antihypertensive protection in managing HTN and CKD. This review emphasizes the critical role of NOX in the development and progression of HTN, focusing on its impact on renal function and BP regulation. Effective BP management and targeting oxidative stress, inflammation, and RAAS activation, is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD.

Mesoporous silica and alumina nanoparticles to improve drug delivery of pioglitazone on diabetic type 1 nephropathy in rats

Background and purpose

Diabetic nephropathy leads to end-stage renal disease. The present study aimed to evaluate the prophylactic effect of pioglitazone-loaded mesoporous silica and alumina scaffold on renal function and the underlying mechanisms in streptozotocin-induced diabetic rats.

Experimental approach

The mesoporous nanoparticles were synthesized by chemical methods from tetraethylorthosilicate and aluminum isopropoxide and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The soaking method was applied to load pioglitazone into the mesoporous silica and alumina. Subsequently, the most capable formulation was evaluated for lipid profile, blood glucose, renal function biomarkers, malondialdehyde, and kidney histopathological changes in diabetic rats.

Findings/Results

Pioglitazone loaded in the mesoporous included a superior release of about 80%. No interaction was observed in Fourier transform infrared spectroscopy and X-ray diffraction was shown crystalline. Scanning electron microscopy showed the size of the nanometer in the range of 100 - 300 nm. Mesoporous silica containing the drug significantly decreased urinary parameters, triglycerides, low-density lipoprotein, blood urea nitrogen, blood glucose, malondialdehyde, and creatinine. In addition, it showed increased high-density lipoprotein, significantly. The renal histopathological changes indicated improvement compared with the untreated diabetic group.

Conclusion and implications

It was concluded that the mesoporous was potent to serve as a promising drug carrier and a platform aimed at the delivery of poorly water-soluble drugs for improving oral bioavailability. Furthermore, it has the potential to provide a beneficial effect on the changes in diabetic parameters.

Interaction between Nuclear Receptor and Alpha-Adrenergic Agonist Subtypes in Metabolism and Systemic Hemodynamics of Spontaneously Hypertensive Rats

Partial and full PPAR-γ agonists have shown promising effects and antihypertensive and antidiabetic agents through increased plasma adiponectin concentration. This study is aimed at examining the role of PPAR-γ, alpha-adrenoceptors, and adiponectin receptors in the modulation of vasopressor responses to angiotensin II (Ang II) and adrenergic agonists, after a subset treatment of partial and full PPAR-γ agonists, each individually, and also when coupled with adiponectin in SHRs. The antioxidant potential and metabolic indices for these animals were also determined. Group I (WKY) and group II (SHR) were designated as normotensive control and hypertensive control, respectively. Groups III (SHR) and IV (SHR) received irbesartan (30 mg/kg) and pioglitazone (10 mg/kg) orally for 28 days, and groups V (SHR), VI (SHR), and VII (SHR) were treated with adiponectin (2.5 μg/kg) intraperitoneally alone, in combination with irbesartan, and in combination with pioglitazone, respectively, from days 21 to 28 only. On day 29, sodium pentobarbitone (60 mg/kg) was used to anesthetize all test animals, and systemic hemodynamic and plasma adiponectin concentrations and in vitro and in vivo antioxidant potential were measured. As compared to the WKY control, the SHR control group's noninvasive blood pressure and basal mean arterial pressure were significantly greater, along with increased arterial stiffness, lower plasma nitric oxide, adiponectin concentration, and antioxidant enzyme levels (all P < 0.05). However, they were gradually normalized by single drug treatments in all groups, and to a greater extent in the SHR + Irb + Adp group (P < 0.05). In the acute study, the dose dependant mean arterial pressure responses to intravenously administered adrenergic agonists and angiotensin-II were significantly larger in SHRs as compared to WKY by 20-25%. Adiponectin alone and in combination significantly blunted vasopressor responses to these alpha-adrenergic agonists in the SHR + Pio + Adp group by 63%, whereas attenuated responses to ANG-II administration to 70% in SHR + Irb + Adp. In conclusion, the combined treatment of adiponectin with PPAR-agonists reduced the systemic vascular responses to adrenergic agonists and improved arterial stiffness. This an evidence of the interaction of adiponectin receptors, PPAR-γ, alpha-adrenoceptors, and ANG-II in the systemic vasculature of SHRs. A significant level of synergism has also been proved among full PPAR-γ agonists and adiponectin receptors.

Umbilical artery ultrasound haemodynamics combined with serum adiponectin levels can aid in predicting adverse pregnancy outcomes in patients with severe pre-eclampsia

Severe pre-eclampsia is a leading cause of maternal and perinatal morbidity and mortality. This retrospective study explored pregnancy outcome predictive values of umbilical artery Doppler with serum adiponectin in severe pre-eclampsia. Fasting elbow venous blood was collected from 118 severe pre-eclampsia patients [maternal systolic pressure ≥ 160 mmHg and/or diastolic pressure ≥ 110 mmHg + minimal proteinuria, 56; mild hypertension + heavy proteinuria (≥2 g/24 h or random urinary protein ≥ 2+), 42; no proteinuria but new-onset hypertension + diseases of heart/lung/liver/kidney/other organs or abnormalities in blood/digestive/nervous systems, placental foetus involved, 20] and 90 controls (18.5-24.9 kg/m²) in the first morning of admission. Serum adiponectin and resistance/pulsatility indexes were separately measured and correlatively analysed by Pearson's coefficient analysis. Adverse outcomes included maternal primary postpartum haemorrhage and placental abruption, neonatal asphyxia, low birth weight, foetal distress, foetal growth restriction. In severe pre-eclampsia, serum adiponectin (downregulated) was negatively-correlated with resistance/pulsatility indexes (upregulated). The area under the curve of umbilical artery Doppler with serum adiponectin for predicting adverse outcomes of severe pre-eclampsia was 0.6545 (specificity 60.27%, sensitivity 60.00%). In conclusion, umbilical artery Doppler with serum adiponectin predicts adverse pregnancy outcomes in severe pre-eclampsia.Impact statementWhat is already known on this subject? Sad levels were lowered in sPE patients. UA ultrasound hemodynamic parameters can predict adverse pregnancy outcomes.What do the results of this study add? Our study revealed that ultrasonic hemodynamic indexes of UA combined with Sad levels had better efficacy in predicting pregnancy outcomes in patients with sPE, and our study is expected to improve the accuracy of clinical prediction of adverse outcomes in sPE patients.What are the implications of these findings for clinical practice and/or further research? Through the combined detection of multiple indicators of the foetus in the mother, our study expects to be able to monitor and predict the growth of the foetus in the mother more accurately in clinical practice, avoid excessive intervention or untimely intervention, and reduce the incidence of perinatal adverse pregnancy outcomes.

Trinity of inflammation, innate immune cells and cross-talk of signalling pathways in tumour microenvironment

Unresolved inflammation is a pathological consequence of persistent inflammatory stimulus and perturbation in regulatory mechanisms. It increases the risk of tumour development and orchestrates all stages of tumorigenesis in selected organs. In certain cancers, inflammatory processes create the appropriate conditions for neoplastic transformation. While in other types, oncogenic changes pave the way for an inflammatory microenvironment that leads to tumour development. Of interest, hallmarks of tumour-promoting and cancer-associated inflammation are striking similar, sharing a complex network of stromal (fibroblasts and vascular cells) and inflammatory immune cells that collectively form the tumour microenvironment (TME). The cross-talks of signalling pathways initially developed to support homeostasis, change their role, and promote atypical proliferation, survival, angiogenesis, and subversion of adaptive immunity in TME. These transcriptional and regulatory pathways invariably contribute to cancer-promoting inflammation in chronic inflammatory disorders and foster "smouldering" inflammation in the microenvironment of various tumour types. Besides identifying common target sites of numerous cancer types, signalling programs and their cross-talks governing immune cells' plasticity and functional diversity can be used to develop new fate-mapping and lineage-tracing mechanisms. Here, we review the vital molecular mechanisms and pathways that establish the connection between inflammation and tumour development, progression, and metastasis. We also discussed the cross-talks between signalling pathways and devised strategies focusing on these interaction mechanisms to harness synthetic lethal drug combinations for targeted cancer therapy.

Activation of PPAR-γ prevents TERT-mediated pulmonary vascular remodeling in MCT-induced pulmonary hypertension

Background

It has been demonstrated that elevated telomerase reverse transcriptase (TERT) expression or activity is implicated in pulmonary hypertension (PH). In addition, activation of peroxisome-proliferator-activated receptor γ (PPAR-γ) has been found to prevent PH progression. However, the molecular mechanism responsible for the protective effect of PPAR-γ activation on TERT expression in the pathogenesis of PH remains unknown. This study was performed to address these issues.

Methods

Intraperitoneal injection of monocrotaline (MCT) was used to establish PH. BIBR1532 was applied to inhibit the activity of telomerase. The right ventricular systolic pressure (RVSP) and histological analysis were used to detect the development of PH. The protein levels of p-Akt, t-Akt, c-Myc and TERT were determined by western blotting. Pharmacological inhibition of TERT by BIBR1532 effectively suppressed RVSP, RVHI and the WT% in MCT-induced PH rats.

Results

Pharmacological inhibition of Akt/c-Myc pathway by LY294002 diminished TERT upregulation, RVSP, RVHI and WT% in MCT-PH rats. Activation of PPAR-γ by pioglitazone inhibited p-Akt and c-Myc expressions and further downregulated TERT, thus to reduced RVSP, RVHI and WT% in MCT-treated PH rats.

Conclusions

In conclusion, TERT upregulation contributes to PH development in MCT-treated rats. Activation of PPAR-γ prevents pulmonary arterial remodeling through Akt/c-Myc/TERT axis suppression.

Alternatively Spliced Landscape of PPARγ mRNA in Podocytes Is Distinct from Adipose Tissue

Podocytes are highly differentiated epithelial cells, and their structural and functional integrity is compromised in a majority of glomerular and renal diseases, leading to proteinuria, chronic kidney disease, and kidney failure. Traditional agonists (e.g., pioglitazone) and selective modulators (e.g., GQ-16) of peroxisome-proliferator-activated-receptor-γ (PPARγ) reduce proteinuria in animal models of glomerular disease and protect podocytes from injury via PPARγ activation. This indicates a pivotal role for PPARγ in maintaining glomerular function through preservation of podocytes distinct from its well-understood role in driving insulin sensitivity and adipogenesis. While its transcriptional role in activating adipokines and adipogenic genes is well-established in adipose tissue, liver and muscle, understanding of podocyte PPARγ signaling remains limited. We performed a comprehensive analysis of PPARγ mRNA variants due to alternative splicing, in human podocytes and compared with adipose tissue. We found that podocytes express the ubiquitous PPARγ Var 1 (encoding γ1) and not Var2 (encoding γ2), which is mostly restricted to adipose tissue and liver. Additionally, we detected expression at very low level of Var4, and barely detectable levels of other variants, Var3, Var11, VartORF4 and Var9, in podocytes. Furthermore, a distinct podocyte vs. adipocyte PPAR-promoter-response-element containing gene expression, enrichment and pathway signature was observed, suggesting differential regulation by podocyte specific PPARγ1 variant, distinct from the adipocyte-specific γ2 variant. In summary, podocytes and glomeruli express several PPARγ variants, including Var1 (γ1) and excluding adipocyte-specific Var2 (γ2), which may have implications in podocyte specific signaling and pathophysiology. This suggests that that new selective PPARγ modulators can be potentially developed that will be able to distinguish between the two forms, γ1 and γ2, thus forming a basis of novel targeted therapeutic avenues.

Crosstalk relationship between adiponectin receptors, PPAR-γ and α-adrenoceptors in renal vasculature of diabetic WKYs

Hypoadiponectinemia is associated with renal dysfunctions. Irbesartan and pioglitazone activate Peroxisome proliferator-activated gamma receptor (PPAR-γ) as partial and full agonists. We investigated a crosstalk interaction and synergistic action between adiponectin receptors, PPAR-γ agonists in attenuating renal hemodynamics to adrenergic agonists in diabetic Wistar Kyoto rats (WKY). Streptozotocin (40 mg/kg) was used to induce diabetes, whereas, pioglitazone (10 mg/kg/day), irbesartan (30 mg/kg/day) administered orally for 28 days and adiponectin intraperitoneally (2.5 μg/kg/day) for last 7 days. Metabolic and plasma samples were analyzed on days 0, 8, 21, and 28. During the acute study (day 29), renal vasoconstrictor actions to adrenergic agonists and angiotensin-II were determined. Diabetic WKYs had lower plasma adiponectin, higher creatinine clearance, urinary and fractional sodium excretion but were normalized to a greater extent in pioglitazone and adiponectin combined treatment. Responses to intra-renal administration of adrenergic agonists including noradrenaline (NA), phenylephrine (PE), methoxamine (ME), and angiotensin-II (ANG-II) were larger in diabetic WKY, but significantly blunted with adiponectin treatment in diabetic WKYs to 35-40%, and further reduced by 65-70% in combination with pioglitazone. Attenuation to ANG-II responses in adiponectin and combination with irbesartan was 30-35% and 75-80%, respectively (P < 0.05). Pharmacodynamically, a crosstalk interaction exists between PPAR-γ, adiponectin receptors (adipo R1 & R2), alpha adrenoceptors, and angiotensin-I (ATI) receptors in the renal vasculature of diabetic WKYs. Exogenously administered adiponectin with full PPAR-γ agonist substantially attenuated renal hemodynamics and improved excretory functions, signifying their renoprotective action. Additionally, a degree of synergism exists between adiponectin and pioglitazone to a large extent compared to combination therapy with irbesartan (partial PPAR-γ agonist) in attenuating the renal vascular receptiveness to adrenergic agonists.