Progressive Interstitial Fibrosis Research Articles

#1449 Maturation of tertiary lymphoid structures in progressive kidney damage due to chronic phosphate load

Abstract Background and Aims We have recently shown that a high phosphate diet (HPD) in mice leads to an increase in FGF23 levels and causes progressive tubular damage and interstitial fibrosis with increased accumulation of macrophages and concomitant perivascular immune cell aggregates in the corticomedullary zone. Such tertiary lymphoid structures (TLS) can develop as a result of chronic inflammation and have already been described in lupus nephritis and IgA nephropathy, among others. In our model, the question arose to what extent damage to the proximal tubule is temporally associated with the development and maturation of TLS and which factors favor TLS development. Method Wild-type mice were fed HPD for 1, 2, 3, 4 and 6 months and the kidneys of each were compared with those of mice on a normal phosphate diet (NPD). To evaluate the effect of high FGF23 ± phosphate, Fgf23 was overexpressed in mice on NPD and HPD using an adeno-associated virus (AAV-Fgf23), and hypophosphatemic Hyp mice were used. Results An increased tubular damage score was seen after only two months of HPD. In parallel, perivascular immune cell clusters developed in the corticomedullary zone and in the renal cortex, which were characterized by aggregates of CD45R+ B cells and CD3+ T cells, as well as LYVE1+ lymphatic vessels after three months of HPD and were accompanied by increased expression of venous markers (Plvap, Aplnr, EphB4) and cell adhesion molecules (Sell, Vcam1, Madcam1). Further analyses showed a time-dependent induction of the immunofibroblast-derived chemokines Cxcl13 and Ccl19, as well as the lymphotoxins Lta and Ltb, which are important for the differentiation of immunofibroblasts into follicular dendritic cells (FDC) and follicular reticular cells (FRC). Already after four months of HPD, proliferating B-cell clusters with FDCs, FRCs located in T-cell clusters, podoplanin+ networks, high endothelial venules, plasma cells and increased IgD synthesis indicated fully mature TLS, while tubular damage and fibrosis continued to increase until six months of HPD. Compared to AAV-Fgf23 mice on NPD, only AAV-Fgf23 animals on HPD developed tubular damage with fibrosis and fully mature TLS. Hypophosphatemic Hyp mice with high FGF23 showed neither signs of tubular damage nor the development of TLS. Conclusion The development of renal TLS due to chronic high phosphate load coincides with the development of tubular damage, with earlier maturation of TLS and progression of tubular damage.

Immune checkpoint activity exacerbate renal interstitial fibrosis progression by enhancing PD-L1 expression in renal tubular epithelial cells

Renal interstitial fibrosis (RIF) is often associated with inflammatory cell infiltration and no effective therapy. Programmed death cell-1 (PD-1) and its ligand PD-L1 were playing critical roles in T cell coinhibition and exhaustion, but the role in RIF is unclear. Here the data analyses of serum from 122 IgA nephrology (IgAN) patients showed that high level of soluble PD-1(sPD-1) was an independent risk factor for RIF and renal function progression. PD-L1 was also overexpressed in renal interstitial tissues from both IgAN patients with high level of sPD-1 and the unilateral ureteral obstruction (UUO) mouse. PD-L1 was significantly overexpressed in HK-2 cells with upregulated collagen and α-SMA when stimulated by inflammation or hypoxia in vitro. Additionally, matrix metalloproteinases (MMP-2) could increase the level of sPD-1 in culture supernatant when added in co-culture system of HK-2 and jurkat cells, which implied serum sPD-1 of IgAN might be cleaved by MMP-2 from T cells infiltrated into the tubulointerstitial inflammatory microenvironment. Crucially, injection of PD-L1 fusion protein, the blocker of sPD-1, could ameliorate kidney fibrosis in UUO mice by increasing T cell coinhibition and exhaustion, suggesting the therapeutic potential of PD-L1 fusion targeting for renal fibrosis. Take together, it reveals a novel causal role of sPD-1 in serum and PD-L1 of renal interstitial tissues in the development of renal fibrosis of IgAN, and targeting sPD-1 in serum by PD-L1 fusion protein is a potential therapeutic approach to prevent renal fibrosis of IgAN.

Rictor/mTORC2 signalling contributes to renal vascular endothelial-to-mesenchymal transition and renal allograft interstitial fibrosis by regulating BNIP3-mediated mitophagy.

Renal allograft interstitial fibrosis/tubular atrophy (IF/TA) constitutes the principal histopathological characteristic of chronic allograft dysfunction (CAD) in kidney-transplanted patients. While renal vascular endothelial-mesenchymal transition (EndMT) has been verified as an important contributing factor to IF/TA in CAD patients, its underlying mechanisms remain obscure. Through single-cell transcriptomic analysis, we identified Rictor as a potential pivotal mediator for EndMT. This investigation sought to elucidate the role of Rictor/mTORC2 signalling in the pathogenesis of renal allograft interstitial fibrosis and the associated mechanisms. The influence of the Rictor/mTOR2 pathway on renal vascular EndMT and renal allograft fibrosis was investigated by cell experiments and Rictor depletion in renal allogeneic transplantation mice models. Subsequently, a series of assays were conducted to explore the underlying mechanisms of the enhanced mitophagy and the ameliorated EndMT resulting from Rictor knockout. Our findings revealed a significant activation of the Rictor/mTORC2 signalling in CAD patients and allogeneic kidney transplanted mice. The suppression of Rictor/mTORC2 signalling alleviated TNFα-induced EndMT in HUVECs. Moreover, Rictor knockout in endothelial cells remarkably ameliorated renal vascular EndMT and allograft interstitial fibrosis in allogeneic kidney transplanted mice. Mechanistically, Rictor knockout resulted in an augmented BNIP3-mediated mitophagy in endothelial cells. Furthermore, Rictor/mTORC2 facilitated the MARCH5-mediated degradation of BNIP3 at the K130 site through K48-linked ubiquitination, thereby regulating mitophagy activity. Subsequent experiments also demonstrated that BNIP3 knockdown nearly reversed the enhanced mitophagy and mitigated EndMT and allograft interstitial fibrosis induced by Rictor knockout. Consequently, our study underscores Rictor/mTORC2 signalling as a critical mediator of renal vascular EndMT and allograft interstitial fibrosis progression, exerting its impact through regulating BNIP3-mediated mitophagy. This insight unveils a potential therapeutic target for mitigating renal allograft interstitial fibrosis.

Understanding the Roles of Non-coding RNAs and Exosomal Non-Coding RNAs in Diabetic Nephropathy.

One of the greatest serious side effects of diabetes is diabetic nephropathy (DN), which is also the key factor in the sometimes-deadly diabetic end-stage renal disease. Progressive renal interstitial fibrosis is closely associated with oxidative stress, and the extracellular matrix is typically a feature of DN. Some RNAs formed by genome transcription that are not translated into proteins are recognized as noncoding RNAs. It has been shown that ncRNAs control apoptosis, inflammatory response, cell proliferation, autophagy, and other pathogenic processes, contributing to the pathogenesis of DN. Exosomes are nano-carriers vesicles that variety in size from 40 to 160 nm. Exosomes are widely present and dispersed in different bodily fluids, plentiful in nucleic acids, lipids, and proteins (microRNA, mRNA, tRNA, lncRNA, circRNA, etc.). Exosomes play a crucial role as messengers for cellular communication. They transport and transmit key signaling molecules, participate in the transfer of information and materials between cells, control cellular physiological processes, and are carefully linked to the beginning and development of many diseases. Herein, we summarized the role of different ncRNAs in DN. Moreover, we highlighted the role of the exosomal form of ncRNAs in the DN pathogenesis.

Effect of Spironolactone on Kidney Function in Kidney Transplant Recipients: 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.

Outcomes of lung transplantation in patients with telomere-related forms of progressive fibrosing interstitial lung disease pulmonary fibrosis: A systematic review

Outcomes of lung transplantation in patients with telomere-related forms of progressive fibrosing interstitial lung disease pulmonary fibrosis: A systematic review

Wild-type S100A3 and S100A13 restore calcium homeostasis and mitigate mitochondrial dysregulation in pulmonary fibrosis patient-derived cells

Patients with digenic S100A3 and S100A13 mutations exhibited an atypical and progressive interstitial pulmonary fibrosis, with impaired intracellular calcium homeostasis and mitochondrial dysfunction. Here we provide direct evidence of a causative effect of the mutation on receptor mediated calcium signaling and calcium store responses in control cells transfected with mutant S100A3 and mutant S100A13. We demonstrate that the mutations lead to increased mitochondrial mass and hyperpolarization, both of which were reversed by transfecting patient-derived cells with the wild type S100A3 and S100A13, or extracellular treatment with the recombinant proteins. In addition, we demonstrate increased secretion of inflammatory mediators in patient-derived cells and in control cells transfected with the mutant-encoding constructs. These findings indicate that treatment of patients’ cells with recombinant S100A3 and S100A13 proteins is sufficient to normalize most of cellular responses, and may therefore suggest the use of these recombinant proteins in the treatment of this devastating disease.

Development of renal fibrosis in patients with chronic kidney disease: Mechanisms, biomarkers, and clinical implications

CKD is a global health concern with significant implications for patients' well-being, morbidity, and mortality. The underlying mechanism of CKD development often involves progressive interstitial fibrosis. Understanding the processes and factors influencing fibrogenesis is crucial. This review aims to analyze recent literature on the pathophysiological mechanisms, early diagnosis, prevention, and treatment of renal fibrosis in CKD patients. It explores various aspects of kidney fibrogenesis, highlighting key pathogenic factors and signaling pathways that warrant further investigation.
 The review emphasizes the potential of urinary uromodulin (uUmod) as a biomarker for early renal fibrosis diagnosis and delves into the role of anemia, kidney hypoxia, vitamin D, and unique aspects of fibrosis development in diabetic kidney disease patients. Furthermore, it underscores the importance of inhibiting the renin-angiotensin-aldosterone system (RAAS) as a strategy for fibrosis prevention and attenuation.

Variants in FGF10 cause early onset of severe childhood interstitial lung disease: A detailed description of four affected children.

Fibroblast growth factor 10 (FGF10) is a signaling molecule with a well-established role for lung branching morphogenesis. Rare heterozygous, deleterious variants in the FGF10 gene are known causes of the lacrimo-auriculo-dento-digital (LADD) syndrome and aplasia of lacrimal and salivary glands.Previous studies indicate that pathogenic variants in FGF10 can cause childhood Interstitial Lung Disease (chILD) due to severe diffuse developmental disorders of the lung, but detailed reports on clinical presentation and follow-up of affected children are lacking. We describe four children with postnatal onset of chILD and heterozygous variants in FGF10, each detected by exome or whole genome sequencing. All children presented with postnatal respiratory failure. Two children died within the first 2 days of life, one patient died at age of 12 years due to right heart failure related to severe pulmonary hypertension (PH) and one patient is alive at age of 6years, but still symptomatic. Histopathological analysis of lung biopsies from the two children with early postpartum demise revealed diffuse developmental disorder representing acinar dysplasia and interstitial fibrosis. Sequential biopsies of the child with survival until the age of 12 years revealed alveolar simplification and progressive interstitial fibrosis. Our report extends the phenotype of FGF10-related disorders to early onset chILD with progressive interstitial lung fibrosis and PH. Therefore, FGF10-related disorder should be considered even without previously described syndromic stigmata in children with postnatal respiratory distress, not only when leading to death in the neonatal period but also in case of persistent respiratory complaints and PH.

UCP1 alleviates renal interstitial fibrosis progression through oxidative stress pathway mediated by SIRT3 protein stability

BackgroundRenal interstitial fibrosis is a common pathway for the progressive development of chronic renal diseases (CKD) with different etiology, and is the main pathological basis leading to end-stage renal disease. Although the current research on renal interstitial fibrosis is gradually deepening, the diagnosis and treatment methods are still very lacking. Uncoupling protein 1 (UCP1) is a nuclear encoded protein in mitochondria inner membrane and plays an important role in regulating energy metabolism and mitochondrial homeostasis. However, the biological significance of UCP1 and potential regulatory mechanisms in the development of CKD remain unclear.MethodsUnilateral ureteral obstruction (UUO) model was used to construct the animal model of renal fibrosis, and TGF-β1 stimulation of HK2 cells was used to construct the vitro model of renal fibrosis. UCP1 expression was detected by Western blot, immunoblot analysis and immunohistochemistry. UCP1 was upregulated by UCP1 overexpressing lentivirus and UCP1 agonist CL316243. Western blot and immunofluorescence were used to detect epithelial mesenchymal transition (EMT)-related markers, such as collagen I, fibronectin, antioxidant enzyme SOD2 and CAT. Reactive oxygen species (ROS) production was detected by ROS detection kit. SIRT3 knockdown was performed by siRNA.ResultsThis study presents that UCP1 is significantly downregulated in patients with renal fibrosis and UUO model. Further studies discover that UCP1 overexpression and CL316243 treatments (UCP1 agonists) reversed EMT and extracellular matrix (ECM) accumulation in renal fibrosis models in vivo and in vitro. Simultaneously, UCP1 reduced the ROS production by increasing the stability of SIRT3. When SIRT3 was knocked down, the production of ROS decreased.ConclusionsElevating the expression of UCP1 can inhibit the occurrence of oxidative stress by stabilizing SIRT3, thereby reducing EMT and ECM accumulation, and ultimately alleviating renal interstitial fibrosis. It will provide new instructions and targets for the treatment of CKD.

Determination of serum KIM-1 in patients with chronic kidney injury

Background: Chronic kidney disease (CKD) affects more than 800 million people worldwide and is one of the leading non-communicable causes of death. Despite being a latent issue, once renal damage has started, the disease can rapidly progress to an advanced stage. Aims and Objectives: Currently, the most commonly used markers for the diagnosis of renal disease are non-specific and insensitive. As a result, the goal of the current study is to investigate whether KIM-1 could be a precise and sensitive biomarker for identifying early kidney injury in CKD patients. Materials and Methods: This case–control study recruited 155 participants from the Index Medical College Hospital v Research Centre, Indore, Madhya Pradesh, based on inclusion and exclusion criteria. 150 non-CKD subjects matched for age and sex were also taken from the hospital. The levels of KIM-1 were compared between CKD and non-CKD participants. Serum creatinine, urea, and creatinine clearance were also measured. Results: The levels of KIM-1 were substantially higher in CKD patients than in non-CKD participants. In addition, a negative relationship between KIM-1 and creatinine clearance was observed with a P<0.05. Conclusion: KIM-1 is a precise and sensitive kidney injury biomarker that can identify early kidney injury in CKD and contribute to the progression of interstitial fibrosis in kidney disease.

Nicotine promotes renal interstitial fibrosis via upregulation of XIAP in an alpha7-nAChR-dependent manner

Renal fibrosis, characterized by excessive accumulation of the extracellular matrix in the renal tubulointerstitium, can lead to chronic kidney disease (CKD), resulting in a heavy burden on families and society. Clinical studies have shown that smoking is closely associated with CKD deterioration in patients with diabetes, hypertension, polycystic kidney disease, and kidney transplantation. However, the mechanism of action of nicotine in renal fibrosis pathogenesis remains largely unknown. X-linked inhibitor of apoptosis (XIAP), a member of the inhibitor of apoptosis protein (IAP) family, is involved in apoptosis, necroptosis, autophagy, and immune response. Here, the upregulated expression of XIAP and α7 nicotine acetylcholine receptor (α7-nAChR) was determined in the kidneys of the CKD smoking group in human and animal studies. A significant positive correlation between XIAP and cotinine was observed. In addition, the nuclear translocation and transcriptional activity of SP1 were promoted when nicotine bound to α7-nAChR, resulting in XIAP overexpression and renal interstitial fibrosis progression. This phenotype can be reversed by the nicotine receptor subtype α7-nAChR antagonists methyllycaconitine. Our results revealed the complex underlying mechanism of nicotine in promoting renal fibrosis by altering SP1 nucleocytoplasmic translocation and regulating XIAP expression. These results provide novel insights into the pathogenesis and treatment of CKD.

Overview of aristolochic acid nephropathy: an update.

Aristolochic acid nephropathy (AAN) is a rapidly progressive renal interstitial fibrosis caused by medical or environmental exposure to aristolochic acid (AA). Since the outbreak of AAN in Belgium was reported nearly 30 years ago, the safety of herbal remedies has drawn considerable attention, and AAN has become a global public health problem. Breakthroughs have been made to better understand the disease, including the toxicity of AAs, the possible mechanisms of AAN, the disease patterns, and the pathological features; however, some critical problems remain unresolved. Because of the insidious onset of the disease, the incidence of AAN and the prevalence of exposure to AAs are unknown and might be largely underestimated. During the past decades, AA-containing herbs have been strictly administrated in many regions and the occurrence of AAN has declined sharply, yet cases of AAN are still sporadically reported. Despite the progress in the understanding of the disease's pathogenesis, there is no effective treatment for delaying or reversing the renal deterioration caused by AAN. Therefore, the risk of exposure to AAs should be taken seriously by public health workers and clinicians. In this review, we updated the latest data on AAN, summarized the advances throughout these years, and put forward some challenges for future research.

#4043 FABRY DISEASE: A RARE ENTITY IN THE NEPHROLOGY SETTING

Abstract Background and Aims Fabry disease is a rare genetic disorder that affects multiple organs, including the kidneys. It is characterized by the accumulation of globotriaosylceramide (Gb3) in various tissues and organs, leading to progressive interstitial fibrosis and renal dysfunction. We aim to determine the renal manifestations of Fabry disease in particular the histological aspects. Method This study analyzed 9 patients with Fabry disease and renal involvement in a retrospective, single-center analysis. Clinical and biological data, as well as histologic findings, were collected based on patient's observations. Results Data was collected from 9 patients, including 7 males and 2 females, with an average age at diagnosis of 25.2 years (ranging from 17 to 32 years). All patients showed depleted activity of alpha 1 glycosidase, confirming the diagnosis. Acrosyndrome and vascular cutaneous lesions (angiokeratomas) were the dominant signs at admission with respectively (n=7; n=4), with only 3 patients being identified through familial screening without symptoms. Uncontrolled Hypertension was noted in 2 patients. Renal manifestations included renal hyperfiltration in 2 cases, isolated proteinuria in 4 patients, and renal failure in 3 others with a mean serum creatinine levels of 240 ± 36 µmol/l. Four patients underwent renal biopsy, which showed characteristic lesions of Fabry disease with sphingolipid accumulation and tubular cell vacuolization. Thickening of the glomerular capillary walls was observed in one patient. Interstitial fibrosis and tubular atrophy were noted in 3 patients. All patients received enzyme replacement therapy. Angiotensin-converting enzyme inhibitors (ACEi) and/or angiotensin II receptors blockers (ARB) were uses in 6 patients. Five patients progressed to terminal stage of renal failure requiring dialysis after an average follow-up period of 13±2.7 years. Four patients died from cardiovascular complications. Conclusion Early recognition and diagnosis of Fabry disease from the onset of glomerular hyperfiltration and albuminuria are crucial for the initiation of appropriate treatment and management, which can help to delay the progression of renal and other organ damage.

Evaluation of Interstitial Fibrosis and Tubular Atrophy (IFTA) in Renal Allograft Biopsies:- Comparison of Visual Analysis with Morphometric Quantification and its Correlation with Renal Function

ABSTRACT Introduction: With the increase in number of allografts being performed, the frequency of chronic allograft nephropathy (CAN) has also increased. It is characterized clinically by a progressive decline in glomerular filtration rate, and histologically, by a progressive interstitial fibrosis (IF) and tubular atrophy (TA) which can even be seen in recipients with good allograft function. Objectives: To compare visual analysis with morphometric quantification of interstitial fibrosis and tubular atrophy (IFTA) in renal allograft biopsies and its correlation with renal function. Materials and Methods: A total of 29 renal allograft biopsies were evaluated for fibrosis and tubular atrophy by light microscopy by visual method on Masson’s trichrome-stained and PAS-stained sections, respectively, as well as by computer-assisted morphometry. IFTA was graded as per Banff working classification of renal allograft pathology, which includes a four-point estimate of the prevalence of IF (ci score) and for tubular atrophy (ct score). The estimation of IF and TA by the two methods was correlated with the renal function state; the serum creatinine level. Result: The percentage of IFTA showed statistically significant correlation between manual and morphometric methods (P < 0.001). Each of the method was correlated with serum creatinine level. IF showed a good correlation with serum creatinine by both the methods; however, no correlation could be established between TA and serum creatinine by either method. Conclusion: When calculating scoring IFTA as per Banff criteria, by either the visual method or the morphometric method, there was a significant correlation between the two methods. However when expressed only as a percentage of total area, the visual method was associated with slight overestimation of both the parameters.

Interstitial lung disease and mycobacteriosis in children with inherited CCR2 deficiency

Tissue-resident alveolar macrophages are important for lung homeostasis and innate immunity. They originate from fetal monocytes and are maintained in the lung through self-renewal or may arise from recruited circulating monocytes. Disturbance of alveolar macrophage function, their numbers or loss of GM-CSF signaling can all underlie pulmonary alveolar proteinosis (PAP). Here, we report eight patients (aged 8–21 years) from four kindreds and three ancestries suffering from recurrent pneumonia, progressive interstitial fibrosis, and PAP. All patients are deficient for the monocyte-chemoattractant protein-1 (CCL-2) receptor 2 (CCR2). Five patients are homozygous and three are compound heterozygous for private or rare CCR2 variants. The variants are loss-of-function for Ca2 +-release and cell migration upon CCL-2 stimulation, when tested by overexpression in monocytic THP-1 cells. Moreover, CCL-2-dependent migration and Ca2+-release of the patients’ monocytes are abolished, while their plasma CCL-2 levels are elevated. Yet, CCR2-deficient cells respond normally to GM-CSF. In addition, the counts, frequencies, and transcriptomes of blood lymphoid and myeloid subsets are normal. Mice deficient for CCR2 display alveolar septal wall thickening and increased number of alveolar type II cells producing surfactant protein C causing increased lung tissue hysteresis. CCR2-deficient mice are vulnerable to mycobacteria, with impaired attraction of blood monocytes to infected tissues. These findings suggest that human CCR2 is essential for the recruitment of monocytes to both pulmonary alveoli and tissues infected with mycobacteria.

Tracing causes of tubule atrophy in vivo

Acute kidney injury (AKI) is a known risk factor for chronic kidney disease (CKD). The mechanisms for AKI-CKD transition may involve failed tubule repair and progressive interstitial fibrosis but are incompletely understood. Which events lead to failed tubule repair? Can injury spread over time? And are these processes steered by myofibroblasts and fibrotic tissue remodeling?Here, we combined serial intravital 2-photon microscopy and a novel model of partial ischemia-reperfusion injury (partial IRI), which allowed us to investigate injured tissue alongside uninjured tissue in the same kidney and over time. Thus, we occluded only one branch of the left renal artery for 21 min, rendering half the kidney ischemic. We then tracked tubule necrosis and remodeling alongside myofibroblast dynamics for up to 3 weeks. Necrotic cell death was detected by in vivo propidium iodide staining. PDGFRβ-CreERT2-Salsa6F mice (N=5) identified main myofibroblast precursor cells, by tdTomato-expression. Myofibroblast-differentiation was confirmed by ex vivo αSMA staining. Proximal tubule (PT) function was assessed by in vivo uptake of fluorescent albumin.Necrotic cell death was solely detectable upon reperfusion. Border areas in between post-ischemic and non-ischemic tissue presented severely necrotic PTs alongside uninjured PTs. From 1 day after partial IRI, we observed formation of granular casts in the lumen of necrotic tubules, which 1-2 days later also appeared in initially non-necrotic PTs downstream. Tubule necrosis and granular cast accumulation preceded thinned epithelium that lacked albumin endocytosis (day 3-7) and recruitment of myofibroblasts (peaking D4-10). Of note, non-necrotic tubules, without granular cast accumulation, didn’t remodel nor recruit myofibroblasts.Among all remodeling tubule segments, 24% turned atrophic. Importantly, preceding necrotic cell death was higher in atrophic than in recovering tubules (55±13% vs. 39±18% necrotic cells/total segment cell number, (mean±SD), p<.0001). Preceding granular casts accounted for 38±15% vs. 12±11% (mean ±SD) of the luminal area in atrophic and recovering tubules, respectively (p<.0001). Ex vivo staining for pro-fibrotic VCAM-1 demonstrated selective positivity in atrophic tubules, which appeared scattered at D8 while at D21, entire atrophic tubules stained positive (n=3, each). Consistently, we detected persistent myofibroblast enclosure of atrophic tubule, while recruitment around recovered PTs resolved by day 14 (50±21% vs. 23±18% of coverage, p<.001).Tracking the same tubules in vivo and over time, we demonstrated early proximal tubule necrosis, which induced luminal granular cast formation and injury propagation. These events preceded myofibroblast accumulation and predicted tubule atrophy. We further documented de novo expression of pro-inflammatory VCAM-1 and persistent myofibroblast recruitment selectively in atrophic tubules, suggesting an active role of this tubule state in AKI-CKD transition. Novo Nordisk Foundation, Augustinus Foundation, Aarhus University Research Foundation (AUFF) 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.

Joubert Syndrome and Renal Implication

AbstractTwenty-five to 30% of patients with Joubert syndrome (JS) have renal involvement. Two forms of renal disease (RD) have traditionally been described. The less common form is the Dekaban–Arima syndrome, a JS RD that includes congenital blindness and occasional encephalocele. The other, more common RD is juvenile nephronophthisis (NPHP), that presents a progressive interstitial fibrosis, associated with small cysts at the corticomedullary junction. NPHP is the most frequent genetic cause for end-stage RD in the first three decades of life. Symptoms start at approximately 6 years of age with urine concentrating defects, polydipsia, polyuria, and secondary enuresis.

The Progression of Interstitial Fibrosis and Tubular Atrophy at 6 Months Is an Independent Predictor of Poor Graft Outcomes in Kidney Transplant Recipients.

We studied implantation and 6-mo surveillance biopsies and examined the association between the progression of IFTA (ΔIFTA) and a composite of censored graft loss or doubling of serum creatinine in 248 adult kidney recipients. The percentage of patients with ΔIFTA of 1 or ≥2 was 35% and 22%, respectively. Positive ΔIFTA was a risk factor for the composite endpoint (hazard ratio, 1.36; 95% confidence interval, 1.03-1.79). This estimate was robust to adjustment for recipient and donor baseline characteristics, baseline IFTA, tacrolimus levels, and rejection status. ΔIFTA was associated with decreased estimated glomerular filtration rate at 3 and 5 y. IFTA+i was a predictor in the cohort; however, IFTA progression was not limited to those with a mononuclear cell interstitial inflammation (Banff "i") score above zero. Notably, donor age was a predictor of IFTA at 6 mo, but not of ΔIFTA, whereas rejection, donor diabetes, and recipient smoking status were. Progression of IFTA at 6 mo can predict outcomes. ΔIFTA was not related to donor age but may be linked to other risk factors influencing decision-making for donor versus recipient selection.

Kif26b contributes to the progression of interstitial fibrosis via migration and myofibroblast differentiation in renal fibroblast.

Kinesin family member 26b (Kif26b) is essential for kidney development, and its deletion in mice leads to kidney agenesis. However, the roles of this gene in adult settings remain elusive. Thus, this study aims to investigate the role of Kif26b in the progression of renal fibrosis. A renal fibrosis model with adenine administration using Kif26b heterozygous mice and wild-type mice was established. Renal fibrosis and the underlying mechanism were investigated. The underlying pathways and functions of Kif26b were evaluated in an in vitro model using primary renal fibroblasts. Kif26b heterozygous mice were protected from renal fibrosis with adenine administration. Renal expressions of connective tissue growth factor (CTGF) and myofibroblast accumulation were reduced in Kif26b heterozygous mice. The expression of nonmuscle myosin heavy chain II (NMHCII), which binds to the C-terminus of Kif26b protein, was also suppressed in Kif26b heterozygous mice. The in vitro study revealed reduced expressions of CTGF, α-smooth muscle actin, and myosin heavy chain 9 (Myh9) via transfection with siRNAs targeting Kif26b in renal fibroblasts (RFB). RFBs, which were transfected by the expression vector of Kif26b, demonstrated higher expressions of these genes than non-transfected cells. Finally, Kif26b suppression and NMHCII blockage led to reduced abilities of migration and collagen gel contraction in renal fibroblasts. Taken together, Kif26b contributes to the progression of interstitial fibrosis via migration and myofibroblast differentiation through Myh9 in the renal fibrosis model. Blockage of this pathway at appropriate timing might be a therapeutic approach for renal fibrosis.