Tamoxifen attenuates renal fibrosis in human kidney slices and rats subjected to unilateral ureteral obstruction

3D Humanized Bioprinted Tubulointerstitium Model to Emulate Renal Fibrosis In Vitro

Chronic kidney disease (CKD) leads to a gradual loss of kidney function, with fibrosis as pathological endpoint, which is characterized by extracellular matrix (ECM) deposition and remodeling. Traditionally, in vivo models are used to study interstitial fibrosis, through histological characterization of biopsy tissue. However, ethical considerations and the 3Rs (replacement, reduction, and refinement) regulations emphasizes the need for humanized 3D in vitro models. This study introduces a bioprinted in vitro model which combines primary human cells and decellularized and partially digested extracellular matrix (ddECM). A protocol was established to decellularize kidney pig tissue and the ddECM was used to encapsulate human renal cells. To investigate fibrosis progression, cells were treated with transforming growth factor beta 1 (TGF-β1), and the mechanical properties of the ddECM hydrogel were modulated using vitamin B2 crosslinking. The bioprinting perfusable model replicates the renal tubulointerstitium. Results show an increased Young's modulus over time, together with the increase of ECM components and cell dedifferentiation toward myofibroblasts. Multiple fibrotic genes resulted upregulated, and the model closely resembled fibrotic human tissue in terms of collagen deposition. This 3D bioprinted model offers a more physiologically relevant platform for studying kidney fibrosis, potentially improving disease progression research and high-throughput drug screening.

Targeted delivery of galunisertib using machine perfusion reduces fibrogenesis in an integrated ex vivo renal transplant and fibrogenesis model

BACKGROUND AND PURPOSE

Fibrosis in kidney allografts is a major post-transplant complication that contributes to graft failure. Lately, multiple potent inhibitors of fibrosis-related pathways have been developed such as galunisertib, an inhibitor of the transforming growth factor-beta (TGF-β/TGFβ1) signalling pathway. This drug, however, poses risks for adverse effects when administered systemically. Therefore, we devised a new repurposing strategy in which galunisertib is administered ex vivo. We combined machine perfusion and tissue slices to explore the antifibrotic effects of galunisertib in renal grafts.

EXPERIMENTAL APPROACH

Porcine kidneys were subjected to 30 min of warm ischaemia, 24 h of oxygenated hypothermic machine perfusion and 6 h of normothermic machine perfusion with various treatments (i.e. untreated control, TGFβ1, galunisertib or TGFβ1 + galunisertib; n = 8 kidneys per group). To determine whether effects persisted upon ceasing treatment, kidney slices were prepared from respective kidneys and incubated for 48 h.

KEY RESULTS

Galunisertib treatment improved general viability without negatively affecting renal function or elevating levels of injury markers or by-products of oxidative stress during perfusion. Galunisertib also reduced inflammation and, more importantly, reduced the onset of fibrosis after 48 h of incubation.

CONCLUSIONS AND IMPLICATIONS

Our findings demonstrate the value of using machine perfusion for administering antifibrotic drugs such as galunisertib, proving it to be an effective example of repurposing.

Pharmacotherapy of urethral stricture

Urethral stricture is characterized by the chronic formation of fibrous tissue, leading to the narrowing of the urethral lumen. Despite the availability of various endoscopic treatments, the recurrence of urethral strictures remains a common challenge. Postsurgery pharmacotherapy targeting tissue fibrosis is a promising option for reducing recurrence rates. Although drugs cannot replace surgery, they can be used as adjuvant therapies to improve outcomes. In this regard, many drugs have been proposed based on the mechanisms underlying the pathophysiology of urethral stricture. Ongoing studies have obtained substantial progress in treating urethral strictures, highlighting the potential for improved drug effectiveness through appropriate clinical delivery methods. Therefore, this review summarizes the latest researches on the mechanisms related to the pathophysiology of urethral stricture and the drugs to provide a theoretical basis and new insights for the effective use and future advancements in drug therapy for urethral stricture.

Tamoxifen Alters TGF-β1/Smad Signaling in Vocal Fold Injury

OBJECTIVES

Effective treatments for vocal fold fibrosis remain elusive. Tamoxifen (TAM) is a selective estrogen receptor modulator and was recently reported to have antifibrotic actions. We hypothesized that TAM inhibits vocal fold fibrosis via altered transforming growth factor beta 1 (TGF-β1) signaling. Both in vitro and in vivo approaches were employed to address this hypothesis.

METHODS

In vitro, vocal fold fibroblasts were treated with TAM (10-8 or 10-9  M) ± TGF-β1 (10 ng/ml) to quantify cell proliferation. The effects of TAM on genes related to fibrosis were quantified via quantitative real-time polymerase chain reaction. In vivo, rat vocal folds were unilaterally injured, and TAM was administered by oral gavage from pre-injury day 5 to post-injury day 7. The rats were randomized into two groups: 0 mg/kg/day (sham) and 50 mg/kg/day (TAM). Histological changes were examined on day 56 to assess tissue architecture.

RESULTS

TAM (10-8  M) did not affect Smad3, Smad7, Acta2, or genes related to extracellular matrix metabolism. TAM (10-8 or 10-9  M) + TGF-β1, however, significantly increased Smad7 and Has3 expression and decreased Col1a1 and Acta2 expression compared to TGF-β1 alone. In vivo, TAM significantly increased lamina propria area, hyaluronic acid concentration, and reduced collagen deposition compared to sham treatment.

CONCLUSIONS

TAM has antifibrotic potential via the regulation of TGF-β1/Smad signaling in vocal fold injury. These findings provide foundational data to develop innovative therapeutic options for vocal fold fibrosis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:2248-2254, 2023.

Tamoxifen associated to the conservative CKD treatment promoted additional antifibrotic effects on experimental hypertensive nephrosclerosis

CKD progression depends on the activation of an intricate set of hemodynamic and inflammatory mechanisms, promoting renal leukocyte infiltration, inflammation and fibrosis, leading to renal function loss. There are currently no specific drugs to detain renal fibrogenesis, which is a common end-point for different nephropathies. Clinical therapy for CKD is mostly based on the management of hypertension and proteinuria, partially achieved with renin-angiotensin-aldosterone system (RAAS) blockers, and the control of inflammation by immunosuppressive drugs. The aim of the present study was to verify if the administration of tamoxifen (TAM), an estrogen receptor modulator, clinically employed in the treatment of breast cancer and predicted to exert antifibrotic effects, would promote additional benefits when associated to a currently used therapeutic scheme for the conservative management of experimental CKD. Wistar rats underwent the NAME model of hypertensive nephrosclerosis, obtained by daily oral administration of a nitric oxide synthesis inhibitor, associated to dietary sodium overload. The therapeutic association of TAM to losartan (LOS), and mofetil mycophenolate (MMF) effectively reduced the severe hypertension, marked albuminuria and glomerular damage exhibited by NAME animals. Moreover, the association also succeeded in limiting renal inflammation in this model, and promoted further reduction of ECM interstitial accumulation and renal fibrosis, compared to the monotherapies. According to our results, the association of TAM to the currently used conservative treatment of CKD added significant antifibrotic effects both in vivo and in vitro, and may represent an alternative to slow the progression of chronic nephropathy.

Research progress on the mechanism of renal interstitial fibrosis in obstructive nephropathy

Renal fibrosis is a common result for various chronic kidney diseases developing to the end stage. It is a pathological process characterized by the destruction of normal kidney structure and the subsequent replacement with fibrous tissue, which primarily involves fibroblast proliferation and extracellular matrix deposition. Obstruction is a common cause of renal fibrosis, and obstructive renal fibrosis is a common disease in urology. Obstructive renal fibrosis, characterized by its insidious onset, is the result of a complex interplay of multiple factors. These factors encompass renal tubular epithelial cell injury, the presence of a hypoxic microenvironment in affected kidney tissue, inflammatory cell infiltration, release of inflammatory mediators, and the release of renal fibrosis growth factors, among others. This paper reviews the research progress on the mechanism and treatment of renal interstitial fibrosis.

Estrogen receptor β attenuates renal fibrosis by suppressing the transcriptional activity of Smad3

Renal fibrosis (RF) is a common pathway leading to chronic kidney disease (CKD), which lacks effective treatment. While estrogen receptor beta (ERβ) is known to be present in the kidney, its role in RF remains unclear. The present study aimed to investigate the role and underlying mechanism of ERβ during RF progression in patients and animal models with CKD. We found that ERβ was highly expressed in the proximal tubular epithelial cells (PTECs) in healthy kidneys but its expression was largely lost in patients with immunoglobin A nephropathy (IgAN) and in mice with unilateral ureter obstruction (UUO) and subtotal nephrectomy (5/6Nx). ERβ deficiency markedly exacerbated, whereas ERβ activation by WAY200070 and DPN attenuated RF in both UUO and 5/6Nx mouse models, suggesting a protective role of ERβ in RF. In addition, ERβ activation inhibited TGF-β1/Smad3 signaling, while loss of renal ERβ was associated with overactivation of the TGF-β1/Smad3 pathway. Furthermore, deletion or pharmacological inhibition of Smad3 prevented the loss of ERβ and RF. Mechanistically, activation of ERβ competitively inhibited the association of Smad3 with the Smad-binding element, thereby downregulating the transcription of the fibrosis-related genes without altering Smad3 phosphorylation in vivo and in vitro. In conclusion, ERβ exerts a renoprotective role in CKD by blocking the Smad3 signaling pathway. Thus, ERβ may represent as a promising therapeutic agent for RF.

Tamoxifen Affects Aquaporin-3 Expression and Subcellular Localization in Rat and Human Renal Collecting Ducts

Sex hormones play an important role in the regulation of water homeostasis, and we have previously shown that tamoxifen (TAM), a selective estrogen receptor modulator (SERM), affects the regulation of aquaporin (AQP)-2. In this study, we investigated the effect of TAM on the expression and localization of AQP3 in collecting ducts using various animal, tissue, and cell models. The impact of TAM on AQP3 regulation was studied in rats subjected to 7 days of unilateral ureteral obstruction (UUO), with the rats fed a lithium-containing diet to induce nephrogenic diabetes insipidus (NDI), as well as in human precision-cut kidney slices (PCKS). Moreover, intracellular trafficking of AQP3 after TAM treatment was investigated in Madin-Darby Canine Kidney (MDCK) cells stably expressing AQP3. In all models, the expression of AQP3 was evaluated by Western blotting, immunohistochemistry and qPCR. TAM administration attenuated UUO-induced downregulation of AQP3 and affected the localization of AQP3 in both the UUO model and the lithium-induced NDI model. In parallel, TAM also affected the expression profile of other basolateral proteins, including AQP4 and Na/K-ATPase. In addition, TGF-β and TGF-β+TAM treatment affected the localization of AQP3 in stably transfected MDCK cells, and TAM partly attenuated the reduced AQP3 expression in TGF-β exposed human tissue slices. These findings suggest that TAM attenuates the downregulation of AQP3 in a UUO model and a lithium-induced NDI model and affects the intracellular localization in the collecting ducts.

An animal-free preclinical drug screening platform based on human precision-cut kidney slices

OBJECTIVE

Renal fibrosis is one of the main pathophysiological processes underlying the progression of chronic kidney disease and kidney allograft failure. In the past decades, overwhelming efforts have been undertaken to find druggable targets for the treatment of renal fibrosis, mainly using cell- and animal models. However, the latter often do not adequately reflect human pathogenesis, obtained results differ per strain within a given species, and the models are associated with considerable discomfort for the animals. Therefore, the objective of this study is to implement the 3Rs in renal fibrosis research by establishing an animal-free drug screening platform for renal fibrosis based on human precision-cut kidney slices (PCKS) and by limiting the use of reagents that are associated with significant animal welfare concerns.

RESULTS

Using Western blotting and gene expression arrays, we show that transforming growth factor-β (TGF-β) induced fibrosis in human PCKS. In addition, our results demonstrated that butaprost, SC-19220 and tamoxifen - all putative anti-fibrotic compounds - altered TGF-β-induced pro-fibrotic gene expression in human PCKS. Moreover, we observed that all compounds modulated fairly distinct sets of genes, however they all impacted TGF-β/SMAD signaling. In conclusion, this study revealed that it is feasible to use an animal-free approach to test drug efficacy and elucidate mechanisms of action.

Estrogen Signaling Influences Nephron Segmentation of the Zebrafish Embryonic Kidney

Despite significant advances in understanding nephron segment patterning, many questions remain about the underlying genes and signaling pathways that orchestrate renal progenitor cell fate choices and regulate differentiation. In an effort to identify elusive regulators of nephron segmentation, our lab conducted a high-throughput drug screen using a bioactive chemical library and developing zebrafish, which are a conserved vertebrate model and particularly conducive to large-scale screening approaches. 17β-estradiol (E2), which is the dominant form of estrogen in vertebrates, was a particularly interesting hit from this screen. E2 has been extensively studied in the context of gonad development, but roles for E2 in nephron development were unknown. Here, we report that exogenous estrogen treatments affect distal tubule composition, namely, causing an increase in the distal early segment and a decrease in the neighboring distal late. These changes were noted early in development but were not due to changes in cell dynamics. Interestingly, exposure to the xenoestrogens ethinylestradiol and genistein yielded the same changes in distal segments. Further, upon treatment with an estrogen receptor 2 (Esr2) antagonist, PHTPP, we observed the opposite phenotypes. Similarly, genetic deficiency of the Esr2 analog, esr2b, revealed phenotypes consistent with that of PHTPP treatment. Inhibition of E2 signaling also resulted in decreased expression of essential distal transcription factors, irx3b and its target irx1a. These data suggest that estrogenic compounds are essential for distal segment fate during nephrogenesis in the zebrafish pronephros and expand our fundamental understanding of hormone function during kidney organogenesis.

Exploring Porcine Precision-Cut Kidney Slices as a Model for Transplant-Related Ischemia-Reperfusion Injury

Marginal donor kidneys are more likely to develop ischemia-reperfusion injury (IRI), resulting in inferior long-term outcomes. Perfusion techniques are used to attenuate IRI and improve graft quality. However, machine perfusion is still in its infancy, and more research is required for optimal conditions and potential repairing therapies. Experimental machine perfusion using porcine kidneys is a great way to investigate transplant-related IRI, but these experiments are costly and time-consuming. Therefore, an intermediate model to study IRI would be of great value. We developed a precision-cut kidney slice (PCKS) model that resembles ischemia-reperfusion and provides opportunities for studying multiple interventions simultaneously. Porcine kidneys were procured from a local slaughterhouse, exposed to 30 min of warm ischemia, and cold preserved. Subsequently, PCKS were prepared and incubated under various conditions. Adenosine triphosphate (ATP) levels and histological tissue integrity were assessed for renal viability and injury. Slicing did not influence tissue viability, and PCKS remained viable up to 72 h incubation with significantly increased ATP levels. Hypothermic and normothermic incubation led to significantly higher ATP levels than baseline. William’s medium E supplemented with Ciprofloxacin (and Amphotericin-B) provided the most beneficial condition for incubation of porcine PCKS. The porcine PCKS model can be used for studying transplant IRI.

Axl-inhibitor bemcentinib alleviates mitochondrial dysfunction in the unilateral ureter obstruction murine model

Renal fibrosis is a progressive histological manifestation leading to chronic kidney disease (CKD) and associated with mitochondrial dysfunction. In previous work, we showed that Bemcentinib, an Axl receptor tyrosine kinase inhibitor, reduced fibrosis development. In this study, to investigate its effects on mitochondrial dysfunction in renal fibrosis, we analysed genome‐wide transcriptomics data from a unilateral ureter obstruction (UUO) murine model in the presence or absence of bemcentinib (n = 6 per group) and SHAM‐operated (n = 4) mice. Kidney ligation resulted in dysregulation of mitochondria‐related pathways, with a significant reduction in the expression of oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), citric acid cycle (TCA), response to reactive oxygen species and amino acid metabolism‐related genes. Bemcentinib treatment increased the expression of these genes. In contrast, AKT/PI3K signalling pathway genes were up‐regulated upon UUO, but bemcentinib largely inhibited their expression. At the functional level, ligation reduced mitochondrial biomass, which was increased upon bemcentinib treatment. Serum metabolomics analysis also showed a normalizing amino acid profile in UUO, compared with SHAM‐operated mice following bemcentinib treatment. Our data suggest that mitochondria and mitochondria‐related pathways are dramatically affected by UUO surgery and treatment with Axl‐inhibitor bemcentinib partially reverses these effects.