Development Of Interstitial Fibrosis Research Articles

Abstract We118: Phosphoglycerate Dehydrogenase Gene Therapy for Dilated Cardiomyopathy

Introduction: Dilated cardiomyopathy (DCM) is a multifaceted cardiac disorder affecting approximately 1 in 250 to 2000 individuals and stands as a predominant cause of heart failure. Despite advancements in identifying genetic mutations associated with DCM, the precise mechanisms driving its pathogenesis are unknown, translating to the lack of disease-modifying interventions. Hypothesis: Modulating serine biosynthesis and one-carbon metabolism in cardiomyocytes by forced expression of Phosphoglycerate Dehydrogenase ( PHGDH) will ameliorate cardiac dysfunction in DCM and halt the disease progression. Methods: We developed a gene therapy vector expressing the PHGDH gene, controlled by a chicken cardiac-specific promoter (cardiac troponin T, cTnT) (AAV9.cTnT.hPHGDH). We delivered this construct via an AAV-based gene transfer approach using the cardiotropic adeno-associated virus serotype-9 in the TM54 DCM mouse – a well-established transgenic mouse that expresses a mutant tropomyosin cDNA (Tpm1 p. E54K; Tm54) under the control of the cardiac αMHC promoter. At 6 weeks old, when the animals exhibit DCM, they were treated with AAV9.cTnT.hPHGDH or control (AAV9.cTnT.GFP). Serial echocardiography was employed to assess heart function for 10 weeks. Morphometric data including heart weight, body weight, and tibia length were recorded. Subsequently, WGA and picrosirius red staining were performed to evaluate cardiomyocyte size and fibrosis, respectively. Finally, metabolic changes were assessed by untargeted metabolomics. Results: AAV9.cTnT.hPHGDH treatment of DCM TM54 mice improved the systolic function and halted the progression of DCM compared to the control mice. Furthermore, PHGDH treatment prevented the development of interstitial fibrosis and cardiomyocyte hypertrophy. Finally, these functional and structural improvements correlate with metabolic rewiring of the glucose metabolism in the DCM heart. Conclusion: These findings suggest that metabolic rewiring of the glucose metabolism by enhancing serine biosynthesis and one-carbon metabolism in the DCM heart may be cardioprotective. Thus, PHGDH gene therapy may be a novel therapeutic approach for DCM and heart failure.

Transcription factor Twist1 drives fibroblast activation to promote kidney fibrosis via signaling proteins Prrx1/TNC

The transcription factor Twist1 plays a vital role in normal development in many tissue systems and continues to be important throughout life. However, inappropriate Twist1 activity has been associated with kidney injury and fibrosis, though the underlying mechanisms involved remain incomplete. Here, we explored the role of Twist1 in regulating fibroblast behaviors and the development kidney fibrosis. Initially Twist1 protein and activity was found to be markedly increased within interstitial myofibroblasts in fibrotic kidneys in both humans and rodents. Treatment of rat kidney interstitial fibroblasts with transforming growth factor-β1 (a profibrotic factor) also induced Twist1 expression in vitro. Gain- and loss-of-function experiments supported that Twist1 signaling was responsible for transforming growth factor-β1-induced fibroblast activation and fetal bovine serum-induced fibroblast proliferation. Mechanistically, Twist1 protein promoted kidney fibroblast activation by driving the expression of downstream signaling proteins, Prrx1 and TNC. Twist1 directly enhanced binding to the promoter of Prrx1 but not TNC, whereas the promoter of TNC was directly bound by Prrx1. Finally, mice with fibroblast-specific deletion of Twist1 exhibited less Prrx1 and TNC protein abundance, interstitial extracellular matrix deposition and kidney inflammation in both the unilateral ureteral obstruction and ischemic-reperfusion injury-induced kidney fibrotic models. Inhibition of Twist1 signaling with Harmine, a β-carboline alkaloid, improved extracellular matrix deposition in both injury models. Thus, our results suggest that Twist1 signaling promotes the activation and proliferation of kidney fibroblasts, contributing to the development of interstitial fibrosis, offering a potential therapeutic target for chronic kidney disease.

The influence of endurance exercise training on myocardial fibrosis and arrhythmogenesis in a coxsackievirus B3 myocarditis mouse model

Nonischaemic myocardial fibrosis is associated with cardiac dysfunction, malignant arrhythmias and sudden cardiac death. In the absence of a specific aetiology, its finding as late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging is often attributed to preceding viral myocarditis. Athletes presenting with ventricular arrhythmias often have nonischaemic LGE. Previous studies have demonstrated an adverse effect of exercise on the course of acute viral myocarditis. In this study, we have investigated, for the first time, the impact of endurance training on longer-term outcomes such as myocardial fibrosis and arrhythmogenicity in a murine coxsackievirus B3 (CVB)-induced myocarditis model. Male C57BL/6J mice (n = 72) were randomly assigned to 8 weeks of forced treadmill running (EEX) or no exercise (SED). Myocarditis was induced 2 weeks later by a single intraperitoneal injection with CVB, versus vehicle in the controls (PBS). In a separate study, mice (n = 30) were subjected to pretraining for 13 weeks (preEEX), without continuation of exercise during myocarditis. Overall, continuation of exercise resulted in a milder clinical course of viral disease, with less weight loss and better preserved running capacity. CVB-EEX and preEEX-CVB mice tended to have a lower mortality rate. At sacrifice (i.e. 6 weeks after inoculation), the majority of virus was cleared from the heart. Histological assessment demonstrated prominent myocardial inflammatory infiltration and cardiomyocyte loss in both CVB groups. Inflammatory lesions in the CVB-EEX group contained higher numbers of pro-inflammatory cells (iNOS-reactive macrophages and CD8+ T lymphocytes) compared to these in CVB-SED. Treadmill running during myocarditis increased interstitial fibrosis [82.4% (CVB-EEX) vs. 56.3% (CVB-SED); P = 0.049]. Additionally, perivascular and/or interstitial fibrosis with extensive distribution was more likely to occur with exercise [64.7% and 64.7% (CVB-EEX) vs. 50% and 31.3% (CVB-SED); P = 0.048]. There was a numerical, but not significant, increase in the number of scars per cross-section (1.9 vs. 1.2; P = 0.195), with similar scar distribution and histological appearance in CVB-EEX and CVB-SED. In vivo electrophysiology studies did not induce sustained monomorphic ventricular tachycardia, only nonsustained (usually polymorphic) runs. Their cumulative beat count and duration paralleled the increased fibrosis between CVB-EEX and CVB-SED, but the difference was not significant (P = 0.084 for each). Interestingly, in mice that were subjected to pretraining only without continuation of exercise during myocarditis, no differences between pretrained and sedentary mice were observed at sacrifice (i.e. 6 weeks after inoculation and training cessation) with regard to myocardial inflammation, fibrosis, and ventricular arrhythmogenicity. In conclusion, endurance exercise during viral myocarditis modulates the inflammatory process with more pro-inflammatory cells and enhances perivascular and interstitial fibrosis development. The impact on ventricular arrhythmogenesis requires further exploration.

Pulmonary fibrosis after a new coronavirus infection - versions and controversies: A review

Fibrosis is a dynamic process characterized by a typical cascade of events as a result of overexpressed repair of connective tissue in response to injury, and manifested by excessive accumulation of extracellular matrix. The development of fibrosis is a determining factor in the pathogenesis, clinical course and prognosis of many diseases, among which interstitial lung diseases occupy a special place. According to a large Russian registry (ClinicalTrials.gov: NCT04492384), in a third of patients with COVID-19, the volume of lung parenchyma involvement exceeds 50% (CT 3-4). The rapid growth in the number of patients who have had a coronavirus infection with lung damage has raised the issues of its long-term consequences to the number of the most relevant in internal medicine of the current time. Often, in the outcome of a coronavirus infection, patients retain clinical and functional changes that are similar to interstitial lung diseases of a different origin, the prognosis of which is determined by the development of interstitial fibrosis and the rate of its progression. This article is an attempt to consider topical issues of fibrogenesis in patients who have undergone a new coronavirus infection through the prism of polar data on immunobiology, clinical course and prognosis.

Renal Pathology of Ciliopathies.

Renal ciliopathies are a group of genetic disorders that affect the function of the primary cilium in the kidney, as well as other organs. Since primary cilia are important for regulation of cell signaling pathways, ciliary dysfunction results in a range of clinical manifestations, including renal failure, cyst formation, and hypertension. We summarize the current understanding of the pathophysiological and pathological features of renal ciliopathies in childhood, including autosomal dominant and recessive polycystic kidney disease, nephronophthisis, and Bardet-Biedl syndrome, as well as skeletal dysplasia associated renal ciliopathies. The genetic basis of these disorders is now well-established in many cases, with mutations in a large number of cilia-related genes such as PKD1, PKD2, BBS, MKS, and NPHP being responsible for the majority of cases. Renal ciliopathies are broadly characterized by development of interstitial fibrosis and formation of multiple renal cysts which gradually enlarge and replace normal renal tissue, with each condition demonstrating subtle differences in the degree, location, and age-related development of cysts and fibrosis. Presentation varies from prenatal diagnosis of congenital multisystem syndromes to an asymptomatic childhood with development of complications in later adulthood and therefore clinicopathological correlation is important, including increasing use of targeted genetic testing or whole genome sequencing, allowing greater understanding of genetic pathophysiological mechanisms.

Effect of Spironolactone on Kidney Function in Kidney Transplant Recipients (the SPIREN trial): A Randomized Placebo-Controlled Clinical Trial.

Long-term kidney allograft survival is hampered by progressive interstitial fibrosis and tubular atrophy. The SPIREN trial tested the hypothesis that the mineralocorticoid receptor antagonist spironolactone stabilizes kidney function and attenuates glomerular barrier injury in kidney transplant patients treated with calcineurin inhibitors. Randomized, placebo-controlled, double blind clinical trial including 188 prevalent kidney transplant patients. Patients were randomized to spironolactone or placebo for three years. Glomerular filtration rate was measured along with proteinuria and kidney fibrosis. The primary endpoint was change in measured glomerular filtration rate. Secondary outcomes were 24h proteinuria, kidney allograft fibrosis and cardiovascular events. Measured glomerular filtration rates, 24h proteinuria and blood pressure were determined yearly. Kidney biopsies were collected at baseline and after two years (n=48). Fibrosis was evaluated by quantitative stereology and classified according to Banff. The groups were comparable at baseline except for slightly older allografts in the spironolactone group. Spironolactone reduced measured glomerular filtration rates (up to -7.6 (95% CI -10.9;-4.3) ml/min compared to placebo) independently of time since transplantation and blood pressure with no impact on the kidney function curve over time and reduced 24h proteinuria after one year. There was no significant effect of spironolactone on the development of interstitial fibrosis. Spironolactone added to standard therapy for three years in kidney transplant patients did not improve kidney function, long-term proteinuria or interstitial fibrosis.

ACOX1 deficiency-induced lipid metabolic disorder facilitates chronic interstitial fibrosis development in renal allografts

Chronic interstitial fibrosis presents a significant challenge to the long-term survival of transplanted kidneys. Our research has shown that reduced expression of acyl-coenzyme A oxidase 1 (ACOX1), which is the rate-limiting enzyme in the peroxisomal fatty acid β-oxidation pathway, contributes to the development of fibrosis in renal allografts. ACOX1 deficiency leads to lipid accumulation and excessive oxidation of polyunsaturated fatty acids (PUFAs), which mediate epithelial–mesenchymal transition (EMT) and extracellular matrix (ECM) reorganization respectively, thus causing fibrosis in renal allografts. Furthermore, activation of Toll-like receptor 4 (TLR4)-nuclear factor kappa-B (NF-κB) signaling induced ACOX1 downregulation in a DNA methyltransferase 1 (DNMT1)-dependent manner. Overconsumption of PUFA resulted in endoplasmic reticulum (ER) stress, which played a vital role in facilitating ECM reorganization. Supplementation with PUFAs contributed to delayed fibrosis in a rat model of renal transplantation. The study provides a novel therapeutic approach that can delay chronic interstitial fibrosis in renal allografts by targeting the disorder of lipid metabolism.

Modulation of myocardial inflammation, fibrosis development and ventricular arrhythmogenicity by endurance exercise in murine coxsackievirus B3 myocarditis

Abstract Aims Nonischaemic myocardial fibrosis is associated with progressive deterioration of myocardial function and forms the substrate for arrhythmias in atria and ventricles. In the absence of a specific aetiology, its origin is commonly attributed to preceding viral myocarditis. Athletes presenting with ventricular arrhythmias often demonstrate nonischaemic fibrosis on magnetic resonance imaging. Previous translational studies have shown an adverse effect of exercise on the course of acute viral myocarditis. Nevertheless, the effect on myocardial fibrosis development, a frequent and important consequence of viral myocarditis, has not yet been investigated. In the present study, we evaluate for the first time the impact of endurance exercise on longer-term myocardial inflammation, myocardial fibrosis and arrhythmogenicity using a murine viral myocarditis model. Methods and results Male C57BL/6J mice (11 weeks of age, n=72) were randomly assigned to 8 weeks of treadmill running (EEX) or without exercise (SED). Two weeks into the study (training or control), animals were injected intraperitoneally with either coxsackievirus B3 to induce acute viral myocarditis (CVB) or vehicle (PBS). Exercising myocarditis mice showed lower mortality (11% vs. 27%), albeit without statistical significance (P=0.23). At sacrifice (i.e. 6 weeks after inoculation), prominent myocardial inflammatory infiltration and cardiomyocyte loss was observed in both CVB groups, without difference on semiquantitative histological scoring. Nevertheless, the infiltrating cells in the CVB-EEX group were more often proinflammatory in nature (predominantly iNOS-reactive macrophages and positive CD8+/CD4+ ratio) compared to these in CVB-SED (predominantly arginase-1-reactive macrophages and higher CD4+/CD8+ ratio). In addition, the EEX group showed more haemosiderin-laden macrophages and spindled fibroblasts as signs of organisation. At that time, the majority of virus was cleared from the heart. Treadmill running during myocarditis enhanced development of interstitial fibrosis (with limited or extensive distribution)(82.4% in CVB-EEX vs. 56.3% in CVB-SED; P=0.049) and perivascular and/or interstitial fibrosis with extensive distribution (64.7% & 64.7% in CVB-EEX vs. 50% & 31.3% in CVB-SED; P=0.048). The highest scar counts were observed in CVB-EEX, but the mean count (1.9 vs. 1.2; P=0.19) did not significantly differ between the myocarditis groups. In CVB-EEX, the lesions contained denser and more organised collagen bundles. In vivo electrophysiology studies showed similar ventricular arrhythmia inducibility (P>0.20) and arrhythmia burden (P=0.49) in the myocarditis groups, although the longest arrhythmias and highest cumulative burden occurred in CVB-EEX. Conclusion Endurance exercise training during viral myocarditis modulates the longer-term inflammatory process and promotes perivascular and interstitial fibrosis development, potentially enhancing ventricular arrhythmogenicity.

Abstract 16888: Reduced Diastolic Myocardial Strain From Interstitial Fibrosis Dissociates the Myocardial Transcriptional Response to Transient Increases in Left Ventricular End-Diastolic Filling Pressure (LVEDP)

Objective: Brief repetitive pressure overload (RPO) in swine leads to interstitial fibrosis and reduced diastolic left ventricular (LV) compliance in the absence of LV hypertrophy. The present study determined whether LV compliance influences the transcriptional response to elevated LVEDP. Methods: Brief pressure overload was produced with phenylephrine (1-2 hours) to elevate LVEDP from 11.4±1.2 mmHg to 30.3±2.4 mmHg in normal hearts (n=6) and from 12.3±0.9 mmHg to 30.0±1.6 mmHg after 2 weeks of daily RPO (n=8). Interstitial fibrosis was quantified using picrosirius red staining. Whole tissue RNA-seq was performed on RNA isolated from LV samples collected 24 hours after increased LVEDP in each group vs. unstressed controls (n=10). Transcripts were mapped to Ensembl Sscrofa 11.1 gene index, aligned with Salmon, and mapped to human homologs using Biomart. Differential expression analysis was performed with DESeq2 package and gene ontology was performed using DAVID. Genes were considered differentially expressed (DEG) if the absolute value of log2fc was > 0.477 (∼33% change) and a p < 0.05. Results: Chronic RPO increased interstitial fibrosis (12.9±1.8% vs. 6.5±1.5% in normals; p<0.05) and markedly reduced diastolic circumferential strain (1.5±2.7% vs. 20.3±4.4% in normals; p<0.05). Stretch activated genes ANP and BNP were significantly upregulated with increased LVEDP in normal hearts (fc 35.8 and 14.3; both p<9x10 – 9 ), but not in hearts after RPO (fc 1.4 and 1.8; both p-ns). Among the 15,133 total genes expressed, increased LVEDP induced 3,534 DEGs in normal hearts. Top gene ontology enriched pathways included ECM, cytoskeleton, cell junction, and microtubules. In contrast, there was a marked reduction in DEGs (117) observed when LVEDP was elevated in the stiff LV after RPO. Conclusions: Elevated LVEDP in the normal heart leads to many DEGs including the ECM and cytoskeleton proteins involved in reducing LV compliance. In contrast, after RPO and the development of interstitial fibrosis, there is a marked attenuation of the transcriptional response to increased LVEDP. These data support the notion that myocardial strain rather than pressure is the primary physiological determinant of the transcriptional response to pressure overload.

Main Cardiac Histopathologic Alterations in the Acute Phase of Trypanosoma cruzi Infection in a Murine Model.

Symptoms in the acute phase of Chagas disease are usually mild and nonspecific. However, after several years, severe complications like dilated heart failure and even death may arise in the chronic phase. Due to the lack of specific symptoms in the acute phase, the aim of this work was to describe and analyze the cardiac histopathology during this phase in a CD1 mouse model by assessing parasitism, fibrotic damage, and the presence and composition of a cellular infiltrate, to determine its involvement in the pathogenesis of lesions in the cardiac tissue. Our results indicate that the acute phase lasts about 62 days post-infection (dpi). A significant increase in parasitemia was observed since 15 dpi, reaching a maximum at 33 dpi (4.1 × 106). The presence of amastigote nests was observed at 15-62 dpi, with a maximum count of 27 nests at 35 dpi. An infiltrate consisting primarily of macrophages and neutrophils was found in the cardiac tissue within the first 30 days, but the abundance of lymphocytes showed an 8 ≥ fold increase at 40-62 dpi. Unifocal interstitial fibrosis was identified after 9 dpi, which subsequently showed a 16 ≥ fold increase at 40-60 dpi, along with a 50% mortality rate in the model under study. The increased area of fibrotic lesions revealed progression in the extent of fibrosis, mainly at 50-62 dpi. The presence of perivasculitis and thrombus circulation disorders was seen in the last days (62 dpi); finally, cases of myocytolysis were observed at 50 and 62 dpi. These histopathological alterations, combined with collagen deposition, seem to lead to the development of interstitial fibrosis and damage to the cardiac tissue during the acute phase of infection. This study provides a more complete understanding of the patterns of histopathological abnormalities involved in the acute phase, which could help the development of new therapies to aid the preclinical tests of drugs for their application in Chagas disease.

Abstract P1049: The Impact Of Endurance Exercise On Longer-term Myocardial Fibrosis Development And Ventricular Arrhythmogenicity In Murine Coxsackievirus B3 Myocarditis

Aims: Diagnostic work-up of athletes often reveals nonischaemic myocardial fibrosis, which is associated with cardiac dysfunction and malignant arrhythmias. Its isolated finding on magnetic resonance imaging is commonly attributed to preceding viral myocarditis. Previous murine studies have shown a negative effect of exercise early in the course of viral myocarditis. In this study, we investigate, for the first time, the impact of endurance exercise on myocardial fibrosis development and arrhythmogenicity in a murine viral myocarditis model. Methods & Results: Eleven-week-old male C57BL/6J mice (n=72) were randomised to 8 weeks of treadmill running (EEX) or without exercise (SED). After 2 weeks, animals received a single injection with either coxsackievirus B3 to induce acute viral myocarditis (CVB) or vehicle as control (PBS). Exercise resulted in a milder clinical disease course, with less weight loss and better preserved running capacity. In addition, mortality was lower in exercising myocarditis mice (11 vs. 27%), however without statistical significance (P=0.23). Exercise during myocarditis increased the occurrence of interstitial fibrosis (limited or extensive distribution) at sacrifice ( i.e. 6 weeks after inoculation)(82.4% in CVB-EEX vs. 56.3% in CVB-SED; P=0.049). Additionally, exercise enhanced development of perivascular and/or interstitial fibrosis with extensive distribution (64.7% & 64.7% in CVB-EEX vs. 50% & 31.3% in CVB-SED; P=0.048). CVB-EEX animals demonstrated more myocardial scars on average, albeit not significantly (1.9 vs. 1.2; P=0.19), with similar scar distribution. Despite manifest fibrotic remodelling, collagen and fibrogenetic genes were not upregulated in the myocarditis groups at the time of sacrifice. In vivo right ventricular programmed electrical stimulation showed comparable ventricular arrhythmia inducibility in the myocarditis groups (P>0.20). The longest arrhythmias and highest cumulative arrhythmia burden occurred in CVB-EEX, however, without reaching statistical significance when compared to CVB-SED (P=0.49). Conclusion: Endurance exercise during viral myocarditis enhances perivascular and interstitial fibrosis development, which may promote ventricular arrhythmogenicity.

Targeting Cellular Senescence in Organ Transplantation.

Targeting Cellular Senescence in Organ Transplantation.

Knockdown of histone deacetylase 1 in fibroblasts and pericytes prevents renal interstitial fibrosis after ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI), one form of acute kidney failure, often occurs after cardiovascular or renal surgery where there is a decline in blood flow through the kidney. This injury causes damage to renal cells and can lead to the formation of interstitial fibrosis, which will increase the risk of chronic kidney disease. The histone deacetylases (HDAC) protein family controls the expression of genes via epigenetic regulation of deacetylating histone lysine residues. We published that within an hour of bilateral IRI, in male mice, there was an increase of HDAC1 in the epithelium and interstitial cells. Moreover, inhibition of HDAC1 prior to IRI resulted in attenuated interstitial fibrosis. Myofibroblasts secrete collagen contributing significantly to wound healing as well as the development of interstitial fibrosis and these cells are predominantly differentiated fibroblasts and pericytes. We hypothesized that the knockdown of HDAC1 in fibroblasts and pericytes will attenuate interstitial fibrosis in the kidney after IRI. Male control (HDAC1fl/fl) and iFibroblastHDAC1KO (HDAC1fl/fl, Col1A2-CreER, hemizygous mice) were used in the experiment. The mice underwent bilateral renal artery and vein clamping for 18 minutes to induce IRI or sham surgery. Acute kidney injury was confirmed by serum creatinine measurements and determination of glomerular filtration rate (GFR) by transcutaneous FITC-sinistrin clearance 24 hours after injury. GFR was measured weekly for 4 weeks at which point the blood and kidneys were collected for analysis. Renal interstitial fibrosis was quantified by measuring the percentage coverage area of collagen stained by picrosirius red staining. 24 hours after surgery, IRI mice serum creatinine levels were greater in control mice 0.53 mg/dl ± 0.17, n = 9, and iFibHDAC1KO IRI mice 0.25 mg/dl ± 0.053, n = 10, compared to sham mice (control 0.084 mg/dl ± 0.008, n = 5, KO 0.098 mg/dl ± 0.006, n = 4, Pgenotype = 0.3, Psurgery = 0.028, Pinteraction = 0.25). This agreed with the measured GFR that was significantly reduced in the IRI mice (control IRI = 426 ul/min/100g ± 132, KO IRI = 529 ul/min/100g ± 116, Sham control = 1180 ul/min/100g ± 178, sham KO = 1188 ul/min/100g ± 156, Pgenotype = 0.71, Psurgery = 0.0003, Pinteraction = 0.75). The percentage of the collagen-positive area was significantly higher in control than in sham mice (p = 0.0011), while there was no noticeable difference (p = 0.9) between iFibHDAC1KO and sham mice (control IRI = 1.2 % ± 0.2, KO IRI = 0.47% ± 0.12, sham control = 0.35% ± 0.085, sham KO = 0.401% ± 0.073). In conclusion, HDAC1 is activated by IRI in the myofibroblast and promotes interstitial fibrosis. Funding resources: NIH NIDDK R01DK126664, UAB-UCSD O'Brien Center, and the Priya Nagar M.D. Foundation. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

High glucose induces an activated state of partial epithelial-mesenchymal transition in human primary tubular cell cultures.

Tubulointerstitial fibrosis is observed in diabetic nephropathy. It is still debated whether tubular cells, undergoing epithelial-mesenchymal transition (EMT) in high glucose (HG) conditions, may contribute to interstitial fibrosis development. In this study, we investigated the phenotypic and molecular EMT-like changes and the alteration of inflammatory and fibrogenic secretome induced by HG in human primary tubular cell cultures. Taking advantage of this in vitro cell model composed of proximal and distal tubular cells, we showed that HG-treated tubular cells acquired a fibroblast-like morphology with increased cytoplasmic stress fibers, maintaining the expression of the epithelial markers specific of proximal and distal tubular cells. HG increased Snail1, miRNA210 and Vimentin mesenchymal markers, decreased N-cadherin expression and migration ability of primary tubular cells, while E-cadherin expression and focal adhesion distribution were not affected. Furthermore, HG treatment of tubular cells altered the inflammatory cytokine secretion creating a secretome able to enhance the proliferation and migration of fibroblasts. Our findings show that HG promotes an activated state of partial EMT in human tubular primary cells and induces a pro-inflammatory and pro-fibrogenic microenvironment, supporting the active role of tubular cells in diabetic nephropathy onset.

Beclin-1 dependent autophagy improves renal outcomes following Unilateral Ureteral Obstruction (UUO) injury.

Interstitial Fibrosis and Tubular Atrophy (IFTA) is the most common cause of long-term graft failure following renal transplant. One of the hallmarks of IFTA is the development of interstitial fibrosis and loss of normal renal architecture. In this study, we evaluated the role of autophagy initiation factor Beclin-1 in protecting against post-renal injury fibrosis. Adult male wild type (WT) C57BL/6 mice were subjected to Unilateral Ureteral Obstruction (UUO), and kidney tissue samples were harvested at 72-hour, 1- and 3-week post-injury. The UUO-injured and uninjured kidney samples were examined histologically for fibrosis, autophagy flux, inflammation as well activation of the Integrated Stress Response (ISR). We compared WT mice with mice carrying a forced expression of constitutively active mutant form of Beclin-1, Becn1F121A/F121A . In all experiments, UUO injury induces a progressive development of fibrosis and inflammation. These pathological signs were diminished in Becn1F121A/F121A mice. In WT animals, UUO caused a strong blockage of autophagy flux, indicated by continuously increases in LC3II accompanied by an over 3-fold accumulation of p62 1-week post injury. However, increases in LC3II and unaffected p62 level by UUO were observed in Becn1F121A/F121A mice, suggesting an alleviation of disrupted autophagy. Beclin-1 F121A mutation causes a significant decrease in phosphorylation of inflammatory STING signal and limited production of IL6 and IFNγ, but had little effect on TNF-α, in response to UUO. Furthermore, activation of ISR signal cascade was detected in UUO-injured in kidneys, namely the phosphorylation signals of elF2S1 and PERK in addition to the stimulated expression of ISR effector ATF4. However, Becn1F121A/F121A mice did not reveal signs of elF2S1 and PERK activation under the same condition and had a dramatically reduced ATF level at 3-week post injury. The results suggest that UUO causes a insufficient, maladaptive renal autophagy, which triggered downstream activation of inflammatory STING pathway, production of cytokines, and pathological activation of ISR, eventually leading to the development of fibrosis. Enhancing autophagy via Beclin-1 improved renal outcomes with diminished fibrosis, via underlying mechanisms of differential regulation of inflammatory mediators and control of maladaptive ISR.

Трансформуючий фактор росту- β1 в формуванні патологічного ремоделювання серця при артеріальній гіпертензії з цукровим діабетом 2 типу та ожирінням

The purpose of the study was to investigate the role of transforming growth factor-β1 in the formation of pathological remodeling of the left ventricle of the heart in patients with arterial hypertension with and without type 2 diabetes mellitus against the background of abdominal obesity. Materials and methods. 58 patients with arterial hypertension of the II stage, 2-3 degree with abdominal obesity of the I-III degree were involved in the examination, of which 32 had type 2 diabetes. The control group consisted of 14 healthy people. Structural indicators of the heart were studied using an echocardiographic study. Determination of the level of transforming growth factor-β1 in blood serum was carried out by the immunoenzymatic method. Results and discussion. It was established that in the groups of patients with arterial hypertension with type 2 diabetes mellitus and abdominal obesity and arterial hypertension with abdominal obesity, probable differences in transforming growth factor-β1 between types of cardiac remodeling were not detected. Probable differences in the levels of transforming growth factor-β1 in CGLS and EGLS were established only between the groups of the examined and probably differed from the control group, which indicates a significant influence of abdominal obesity on the development of adverse remodeling, both in arterial hypertension with type 2 diabetes mellitus and with arterial hypertension without it. However, the most pronounced changes in transforming growth factor-β1 were observed in subjects with impaired carbohydrate metabolism (type 2 diabetes mellitus), which allows us to consider hyperglycemia as an additional factor in the formation of pathological geometry of the heart. Conclusion. The data obtained as a result of the study may indicate that in the formation of pathological types of cardiac remodeling in patients with arterial hypertension with abdominal obesity, from the point of view of the development of interstitial fibrosis, a significant contribution belongs to the transforming growth factor-β1, which is a key factor in the formation of hypertrophy of the myocardium of the left ventricle. Along with this, additional factors of the formation of cardiac remodeling should be noted in case of violation of carbohydrate metabolism in arterial hypertension with type 2 diabetes mellitus on the background of abdominal obesity. The association of a probable increase in the levels of transforming growth factor-β1 in concentric hypertrophy of the left ventricle and eccentric hypertrophy of the left ventricle and the consequences of hyperglycemia significantly increases the cardiovascular risk, which determines the expediency of earlier therapeutic intervention

Inhibition of TRIF-Dependent Inflammation Decelerates Afterload-Induced Myocardial Remodeling.

Pressure-overload-induced cardiac hypertrophy represents one cause of the development of heart failure. The aim of this study is to characterize the influence of the TIR-domain-containing adapter-inducing interferon-β (TRIF) during afterload-induced myocardial remodeling. After trans-aortic constriction (TAC), cardiac pressure overload leads to an early increase in MyD88- (Myeloid differentiation primary response gene 88) and TRIF-dependent cytokines. The maximum cytokine expression appeared within the first week and decreased to its control level within five weeks. While cardiomyocyte hypertrophy was comparable, the myocardial accumulation of the inflammatory cells was lower in TRIF−/−mice. At d7, TRIF deficiency reduced transcription factors and TRIF-dependent cytokines. Through the modulation of the TGF-β-signaling pathway and anti-fibrotic microRNAs, TRIF was involved in the development of interstitial fibrosis. The absence of TRIF was associated with a decreased expression of proapoptotic proteins. In echocardiography and working heart analyses, TRIF deficiency slowed left-ventricular wall thickening, myocardial hypertrophy, and reduces the ejection fraction. In summary, TRIF is an important adapter protein for the release of inflammatory cytokines and the accumulation of inflammatory cells in the early stage of maladaptive cardiac remodeling. TRIF is involved in the development of cardiac fibrosis by modulating inflammatory and fibrotic signal transduction pathways.

MO608: INV-202, A CB1 Receptor Blocker, Reduces Renal Injury in A Murine Model of Streptozotocin (STZ)-Induced Type-1 Diabetes

Abstract BACKGROUND AND AIMS Renal diseases remain a burden for Public Health and chronic kidney disease (CKD) affects several millions of individuals worldwide. Diabetic Nephropathy (DN) is the most frequent consequence of diabetes and is characterized by an increase in urinary albumin excretion and progressive loss of renal function associated with glomerular basement membrane thickening, mesangial expansion, nodular glomerular sclerosis and tubulointerstitial fibrosis. To date, there are few treatments that can prevent its progression. Indeed, current therapeutic approaches including RAAS blockers, SGLT2 inhibitors or both approaches combined do not fully abrogate DN progression. A growing body of experimental evidence suggests that modulation of the endocannabinoid system, and in particular its type 1 receptor (CB1R), may be a therapeutic tool in the management of CKD and more particularly DN. CB1R blockade represents a potential therapeutic modality in the fight against obesity, diabetes and their metabolic sequelae. In kidney, CB1R inhibition promotes a reduction in albuminuria, renal fibrosis and preserves renal function in both obesity-induced and diabetic nephropathy in mice mainly through a direct action of CB1R in podocytes and/or proximal tubules. INV-202 is a peripherally acting Cannabinoid receptor-1 (CB1r) inverse agonist that is under clinical development for the treatment of diseases associated with diabetes and metabolic syndrome. Here we report the effects of INV-202 on renal function and associated parameters in a preclinical model of diabetic nephropathy. METHOD Twelve weeks after the initiation of diabetes using streptozotocin, C57BL6/J mice (8 per treatment group) were randomized to receive a daily oral dose of INV-202, 0.3 mg/kg and 3 mg/kg or vehicle for 4 weeks. Five mice not treated with STZ were used as a nondiabetic control. At the end of treatment, animals were sacrificed. Urinary albumin-to-creatinine ratio (ACR), renal matrix remodelling, glomerular filtration and interstitial fibrosis were assessed in addition to glucose levels, body weight and organ weights. RESULTS After 28 days of treatment, there was no significant effect on hyperglycemia or body weight with either dose of INV-202. Renal and hepatic weights were reduced while heart weight was unaffected. This remained true when normalizing for tibial length. Compared with vehicle-treated diabetic mice, INV-202-challenged mice displayed a marked decrease in many clinical features of DN such as albuminuria, albumin-to-creatinine ratio, urinary urea, loss of glomerular filtration rate and renal hypertrophy. Interestingly, we also found an improvement in both podocyte and proximal tubular cells morphology and health markers that were likely responsible for the improvement previously mentioned. In addition, INV-202 led to a downregulation of the angiotensin II receptor expression as well as a reduced urinary excretion, suggesting an inhibitory effect of this compound on the angiotensin II-mediated renal dysfunction in the context of DN. Furthermore, INV-202 also led to a drastic reduction in renal inflammation and oxidative stress markers that are known to be highly involved in the pathogenesis of DN. Finally, despite the limitation of our model in regard to interstitial fibrosis development, we could observe a marked anti-fibrotic effect of INV-202. CONCLUSION Treatment with INV-202 reduced the progression of nephropathy in STZ-induced diabetic mice. Improvements in kidney size, function and histology, with corresponding gene expression, were noted with both doses of INV-202. Further work to explore the effect of INV-202 in humans is warranted.

Single-cell transcriptomics provides insights into hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a genetic heart disease that is characterized by unexplained segmental hypertrophy that is usually most pronounced in the septum. While sarcomeric gene mutations are often the genetic basis for HCM, the mechanistic origin for the heterogeneous remodeling remains largely unknown. A better understanding of the gene networks driving the cardiomyocyte (CM) hypertrophy is required to improve therapeutic strategies. Patients suffering from HCM often receive a septal myectomy surgery to relieve outflow tract obstruction due to hypertrophy. Using single-cell RNA sequencing (scRNA-seq) on septal myectomy samples from patients with HCM, we identify functional links between genes, transcription factors, and cell size relevant for HCM. The data show the utility of using scRNA-seq on the human hypertrophic heart, highlight CM heterogeneity, and provide a wealth of insights into molecular events involved in HCM that can eventually contribute to the development of enhanced therapies.

Adefovir accumulation in the renal interstitium triggers mast cell degranulation and promotes renal interstitial fibrosis

Organic anion transporters 1 (OAT1) and OAT3 are responsible for transporting adefovir (ADV) into renal tubular epithelial cells. Our previous research found that ADV accumulated in the renal interstitium and caused renal interstitial fibrosis when Oat1/3 were inhibited by OATs inhibitor probenecid for long-term. Mast cells (MCs) in the interstitial space are considered to be key drivers of renal fibrosis. The current work investigated the effect of ADV on MCs in vitro and during the development of interstitial fibrosis in rats. Results indicate that ADV triggers chymase release from cultured RBL-2H3 mast cells in a time-and concentration-dependent manner. Angiotensin II (Ang II) in renal interstitium is generated mainly by chymase, renin and other products released from MCs, and has a direct effect on fibrosis through the angiotensin receptor. The concentrations of Ang II and fibrosis was significantly increased after administration of ADV alone or with probenecid for 4 weeks. The MCs membrane stabilizer sodium cromoglycate (SCG) and the angiotensin receptor antagonist Valsartan (VAL) could ameliorate ADV-induced nephrotoxicity. Additionally, SCG or VAL could reduce the accumulation of ADV in the renal interstitium by upregulating the expression of Oat1/3 and multidrug resistance-associated protein 4. Therefore, ADV accumulation in the renal interstitium could promote the degranulation of interstitial MCs and drive the development of renal fibrosis. SCG or VAL could ameliorate ADV-associated fibrosis by decreasing degranulation of MCs and accelerating renal clearance of ADV.