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Angiotensin II Type 1 Receptor Blockade Improves β-Cell Function and Glucose Tolerance in a Mouse Model of Type 2 Diabetes Kwan Yi Chu 1 , Tung Lau 1 , Per-Ola Carlsson 2 and Po Sing Leung 1 1 Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China 2 Departments of Medical Cell Biology and Medical Sciences, Uppsala University, Uppsala, Sweden Address correspondence and reprint requests to Professor P. S. Leung, PhD, Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong. E-mail: psleung{at}cuhk.edu.hk Abstract We identified an angiotensin-generating system in pancreatic islets and found that exogenously administered angiotensin II, after binding to its receptors (angiotensin II type 1 receptor [AT1R]), inhibits insulin release in a manner associated with decreased islet blood flow and (pro)insulin biosynthesis. The present study tested the hypothesis that there is a change in AT1R expression in the pancreatic islets of the obesity-induced type 2 diabetes model, the db/db mouse, which enables endogenous levels of angiotensin II to impair islet function. Islets from 10-week-old db/db and control mice were isolated and investigated. In addition, the AT1R antagonist losartan was administered orally to 4-week-old db/db mice for an 8-week period. We found that AT1R mRNA was upregulated markedly in db/db islets and double immunolabeling confirmed that the AT1R was localized to β-cells. Losartan selectively improved glucose-induced insulin release and (pro)insulin biosynthesis in db/db islets. Oral losartan treatment delayed the onset of diabetes, and reduced hyperglycemia and glucose intolerance in db/db mice, but did not affect the insulin sensitivity of peripheral tissues. The present findings indicate that AT1R antagonism improves β-cell function and glucose tolerance in young type 2 diabetic mice. Whether islet AT1R activation plays a role in the pathogenesis of human type 2 diabetes remains to be determined. AT1R, angiotensin II type 1 receptor KRBB, Krebs-Ringer bicarbonate buffer OGTT, oral glucose tolerance test RAS, renin-angiotensin system Footnotes Accepted November 10, 2005. Received August 8, 2005. DIABETES

Hypertension is the leading risk factor for cerebral small vessel disease. We aimed to determine whether antihypertensive drug classes differentially affect microvascular function in people with small vessel disease. We did a multicentre, open-label, randomised crossover trial with blinded endpoint assessment at five specialist centres in Europe. We included participants aged 18 years or older with symptomatic sporadic small vessel disease or cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and an indication for antihypertensive treatment. Participants were randomly assigned (1:1:1) to one of three sequences of antihypertensive treatment using a computer-generated multiblock randomisation, stratified by study site and patient group. A 2-week washout period was followed by three 4-week periods of oral monotherapy with amlodipine, losartan, or atenolol at approved doses. The primary endpoint was change in cerebrovascular reactivity (CVR) determined by blood oxygen level-dependent MRI response to hypercapnic challenge in normal-appearing white matter from the end of washout to the end of each treatment period. Efficacy analyses were done by intention-to-treat principles in all randomly assigned participants who had at least one valid assessment for the primary endpoint, and analyses were done separately for participants with sporadic small vessel disease and CADASIL. This trial is registered at ClinicalTrials.gov, NCT03082014, and EudraCT, 2016-002920-10, and is terminated. Between Feb 22, 2018, and April 28, 2022, 75 participants with sporadic small vessel disease (mean age 64·9 years [SD 9·9]) and 26 with CADASIL (53·1 years [7·0]) were enrolled and randomly assigned to treatment. 79 participants (62 with sporadic small vessel disease and 17 with CADASIL) entered the primary efficacy analysis. Change in CVR did not differ between study drugs in participants with sporadic small vessel disease (mean change in CVR 1·8 × 10–4%/mm Hg [SE 20·1; 95% CI –37·6 to 41·2] for amlodipine; 16·7 × 10–4%/mm Hg [20·0; –22·3 to 55·8] for losartan; –7·1 × 10–4%/mm Hg [19·6; –45·5 to 31·1] for atenolol; poverall=0·39) but did differ in patients with CADASIL (15·7 × 10–4%/mm Hg [SE 27·5; 95% CI –38·3 to 69·7] for amlodipine; 19·4 × 10–4%/mm Hg [27·9; –35·3 to 74·2] for losartan; –23·9 × 10–4%/mm Hg [27·5; –77·7 to 30·0] for atenolol; poverall=0·019). In patients with CADASIL, pairwise comparisons showed that CVR improved with amlodipine compared with atenolol (–39·6 × 10–4%/mm Hg [95% CI –72·5 to –6·6; p=0·019) and with losartan compared with atenolol (–43·3 × 10–4%/mm Hg [–74·3 to –12·3]; p=0·0061). No deaths occurred. Two serious adverse events were recorded, one while taking amlodipine (diarrhoea with dehydration) and one while taking atenolol (fall with fracture), neither of which was related to study drug intake. 4 weeks of treatment with amlodipine, losartan, or atenolol did not differ in their effects on cerebrovascular reactivity in people with sporadic small vessel disease but did result in differential treatment effects in patients with CADASIL. Whether antihypertensive drug classes differentially affect clinical outcomes in people with small vessel diseases requires further research. EU Horizon 2020 programme.

Cancer and stromal cells actively exert physical forces (solid stress) to compress tumour blood vessels, thus reducing vascular perfusion. Tumour interstitial matrix also contributes to solid stress, with hyaluronan implicated as the primary matrix molecule responsible for vessel compression because of its swelling behaviour. Here we show, unexpectedly, that hyaluronan compresses vessels only in collagen-rich tumours, suggesting that collagen and hyaluronan together are critical targets for decompressing tumour vessels. We demonstrate that the angiotensin inhibitor losartan reduces stromal collagen and hyaluronan production, associated with decreased expression of profibrotic signals TGF-β1, CCN2 and ET-1, downstream of angiotensin-II-receptor-1 inhibition. Consequently, losartan reduces solid stress in tumours resulting in increased vascular perfusion. Through this physical mechanism, losartan improves drug and oxygen delivery to tumours, thereby potentiating chemotherapy and reducing hypoxia in breast and pancreatic cancer models. Thus, angiotensin inhibitors —inexpensive drugs with decades of safe use — could be rapidly repurposed as cancer therapeutics. Hyaluronan is a component of the tumour extracellular matrix. Here, Chauhan et al . show that hyaluronan increases blood pressure in collagen-rich tumours by compressing vessel walls, and that reducing the level of hyaluranon with an angiotensin II inhibitor increases blood flow and drug penetrance in tumours.

This study aimed to determine whether early administration of drugs that block the renin–angiotensin system slows the progression of change in glomerular mesangial fractional volume and retinopathy progression of two steps or more, according to the retinopathy severity scale. Early blockade of the renin–angiotensin system did not modify nephropathy progression in patients with type 1 diabetes but had important effects in slowing retinopathy. Early blockade of the renin–angiotensin system did not modify nephropathy progression in patients with type 1 diabetes but had important effects in slowing retinopathy. Diabetic nephropathy, responsible for more than 45% of cases of end-stage renal disease in the United States, 1 may be structurally advanced once albuminuria becomes detectable. 2 , 3 Blockers of the renin–angiotensin system are more effective than other antihypertensive agents in slowing nephropathy progression in patients who have proteinuria, diabetes mellitus, and a reduced glomerular filtration rate (GFR), 4 – 6 and such blockers can also decrease proteinuria in patients with diabetes. 7 Although the reduction of proteinuria in patients with diabetes has been associated with a reduction in the rate of decline in GFR in small studies, 8 this association has not been systematically tested; . . .

Photothermal therapy (PTT) is a promising therapeutic procedure with minimal side effects, which can not only kill tumor directly but also cause immunogenic cell death (ICD). However, most solid tumors, including neuroblastoma, are abundant in fibroblasts, which limit the penetration and delivery of nanoparticles. Losartan is an antihypertensive drug approved by the FDA, and it has been proved to have the effect of breaking down excessive ECM network. In this study, we investigated the application and potential mechanism of the combination of mesoporous platinum nanoparticles (MPNs) and losartan in the PTT of neuroblastoma by establishing neuroblastoma models in vitro and in vivo. Compared to the MPNs group without 808 nm laser irradiation, Neuro-2a cells pretreated with PTT and losartan showed lower survival rates, increased surface calreticulin, and higher release of HMGB1 and ATP. The group also exhibited the highest anti-tumor efficacy in vivo, with a tumor suppression ratio of approximately 80%. Meanwhile, we found that CD3 T cells, CD4 T cells and CD8 T cells from the peripheral blood of experimental group mice were significantly higher than control groups, and CD8 PD-1 cells were significantly lower than those in MPNs + Los group and Los + laser group. And the expression of PD-1 and α-SMA in Neuro-2a tumors tissue was reduced. Furthermore, losartan could reduce damage of liver function caused by MPNs and laser treatment. This study demonstrated that losartan-induced fibroblasts ablation increased the penetration of MPNs into tumors. Enhanced penetration allowed PTT to kill more tumor cells and synergistically activate immune cells, leading to ICD, indicating the great promise of the strategy for treating neuroblastoma in vivo.

In ovarian cancer patients, tumor fibrosis and angiotensin-driven fibrogenic signaling have been shown to inversely correlate with survival. We sought to enhance drug delivery and therapeutic efficacy by remodeling the dense extracellular matrix in two orthotopic human ovarian carcinoma xenograft models. We hypothesized that targeting the angiotensin signaling axis with losartan, an approved angiotensin system inhibitor, could reduce extracellular matrix content and the associated “solid stress,” leading to better anticancer therapeutic effect. We report here four translatable findings: (i) losartan treatment enhances the efficacy of paclitaxel—a drug used for ovarian cancer treatment—via normalizing the tumor microenvironment, resulting in improved vessel perfusion and drug delivery; (ii) losartan depletes matrix via inducing antifibrotic miRNAs that should be tested as candidate biomarkers of response or resistance to chemotherapy; (iii) although losartan therapy alone does not reduce tumor burden, it reduces both the incidence and the amount of ascites formed; and (iv) our retrospective analysis revealed that patients receiving angiotensin system inhibitors concurrently with standard treatment for ovarian cancer exhibited 30 mo longer overall survival compared with patients on other antihypertensives. Our findings provide the rationale and supporting data for a clinical trial on combined losartan and chemotherapy in ovarian cancer patients.

Tumor stiffness is a critical factor influencing cancer progression, therapeutic resistance, and drug delivery. This study investigates the role of mechanical normalization in breast cancer therapy through the anti-fibrotic action of losartan, an angiotensin II type 1 receptor blocker. We developed a comprehensive multiphysics model integrating tumor cell proliferation, oxygen transport, interstitial fluid dynamics, and losartan pharmacokinetics/pharmacodynamics (PK/PD). Simulations demonstrate that losartan reduces tumor stiffness by up to 28%, enhances oxygenation by 8%, and increases tumor porosity by ~45%, thereby enhancing drug penetration and interstitial transport. Furthermore, tumor cell concentration decreased by 88%, reflecting the drug’s dual anti-proliferative and pro-apoptotic effects. Spatial analyses revealed heterogeneity in stiffness reduction and drug response, emphasizing the importance of tumor geometry and perfusion. Our findings support the potential of losartan as a mechanotherapeutic adjuvant to enhance standard cancer treatments by remodeling the tumor microenvironment and overcoming mechanical barriers to therapy.

Pirfenidone (PFD), one acceptable medication for treating idiopathic pulmonary fibrosis (IPF), is not well tolerated by patients at full doses. Hence, employing of some approaches such as combination therapy may be applicable for increasing therapeutic efficacy of PFD. Losartan (LOS), an angiotensin II receptor antagonist, could be a suitable candidate for combination therapy because of its stabilizing effect on the pulmonary function of IPF patients. Therefore, this study aimed to investigate the effects of LOS in combination with PFD on bleomycin (BLM)-induced lung fibrosis in rats. BLM-exposed rats were treated with LOS alone or in combination with PFD. The edema, pathological changes, level of transforming growth factor-β (TGF-β1), collagen content, and oxidative stress parameters were assessed in the lung tissues. Following BLM exposure, the inflammatory response, collagen levels, and antioxidant markers in rat lung tissues were significantly improved by PFD, and these effects were improved by combination with LOS. The findings of this in vivo study suggest that the combined administration of PFD and LOS may provide more potent protection against IPF than single therapy through boosting its anti-inflammatory, anti-fibrotic, and anti-oxidant effects. These results hold promise in developing a more effective therapeutic strategy for treating of lung fibrosis.

The dense collagen network in tumors significantly reduces the penetration and efficacy of nanotherapeutics. We tested whether losartan—a clinically approved angiotensin II receptor antagonist with noted antifibrotic activity—can enhance the penetration and efficacy of nanomedicine. We found that losartan inhibited collagen I production by carcinoma-associated fibroblasts isolated from breast cancer biopsies. Additionally, it led to a dose-dependent reduction in stromal collagen in desmoplastic models of human breast, pancreatic, and skin tumors in mice. Furthermore, losartan improved the distribution and therapeutic efficacy of intratumorally injected oncolytic herpes simplex viruses. Finally, it also enhanced the efficacy of i.v. injected pegylated liposomal doxorubicin (Doxil). Thus, losartan has the potential to enhance the efficacy of nanotherapeutics in patients with desmoplastic tumors.

Many studies have shown that alterations in the gut microbiota are associated with hypertension. Our study aimed to observe the characteristics of the gut microbiota in hypertension and to further explore whether drug molecules can play a therapeutic role in hypertension by interfering with the gut microbiota. We evaluated the differences in the composition of the gut microbiota in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Meanwhile, three first-line cardiovascular disease (CVD) drugs, losartan, atorvastatin, and aspirin, were used to treat the SHR in order to observe their effects on the gut microbiota in SHR. The 16S rDNA results showed that the diversity and richness of the gut microbiota in SHR were significantly reduced compared with that of the WKY, the Firmicutes/Bacteroidetes ratio was increased, the abundances of Bifidobacterium and short chain fatty acids (SCFAs)-producing bacteria decreased, and the abundance of lactate-producing bacteria increased. In addition to lowering the blood pressure, losartan increased the abundances of Alistipes, Bacteroides, and Butyricimonas in SHR, reduced the abundances of Ruminococcaceae, Streptococcus, and Turicibacter, reduced the Firmicutes/Bacteroidetes ratio, and rebalanced the gut microbiota. Losartan also increased the abundances of Bifidobacterium and SCFAs-producing bacteria and reduced the abundance of lactate-producing bacteria. However, atorvastatin and aspirin had no significant effect on the gut microbiota in SHR. The above results showed that losartan could change the characteristics of the gut microbiota in hypertension and rebalance the gut microbiota, which may be related to lowering the blood pressure. Atorvastatin and aspirin have no significant influence on the gut microbiota in SHR.