Simulated physiological stretch-induced proliferation of human bladder smooth muscle cells is regulated by MMPs

Pirfenidone improves voiding function by suppressing bladder fibrosis in underactive bladder rats

Underactive bladder (UAB), characterized by a complex set of symptoms with few treatment options, can significantly reduce the quality of life of affected people. UAB is characterized by hyperplasia and fibrosis of the bladder wall as well as decreased bladder compliance. Pirfenidone is a powerful anti-fibrotic agent that inhibits the progression of fibrosis in people with idiopathic pulmonary fibrosis. In the current study, we evaluated the efficacy of pirfenidone in the treatment of bladder fibrosis in a UAB rat model. UAB was induced by crushing damage to nerve bundles in the major pelvic ganglion. Forty-two days after surgery, 1 mL distilled water containing pirfenidone (100, 300, or 500 mg/kg) was orally administered once every 2 days for a total of 10 times for 20 days to the rats in the pirfenidone-treated groups. Crushing damage to the nerve bundles caused voiding dysfunction, resulting in increased bladder weight and the level of fibrous related factors in the bladder, leading to UAB symptoms. Pirfenidone treatment improved urinary function, increased bladder weight and suppressed the expression of fibrosis factors. The results of this experiment suggest that pirfenidone can be used to ameliorate difficult-to-treat urological conditions such as bladder fibrosis. Therefore, pirfenidone treatment can be considered an option to improve voiding function in patient with incurable UAB.

Single-cell atlas of keratoconus corneas revealed aberrant transcriptional signatures and implicated mechanical stretch as a trigger for keratoconus pathogenesis

Keratoconus is a common ectatic corneal disorder in adolescents and young adults that can lead to progressive visual impairment or even legal blindness. Despite the high prevalence, its etiology is not fully understood. In this study, we performed single-cell RNA sequencing (scRNA-Seq) analysis on 39,214 cells from central corneas of patients with keratoconus and healthy individuals, to define the involvement of each cell type during disease progression. We confirmed the central role of corneal stromal cells in this disease, where dysregulation of collagen and extracellular matrix (ECM) occurred. Differential gene expression and histological analyses revealed two potential novel markers for keratoconus stromal cells, namely CTSD and CTSK. Intriguingly, we detected elevated levels of YAP1 and TEAD1, the master regulators of biomechanical homeostasis, in keratoconus stromal cells. Cyclical mechanical experiments implicated the mechanical stretch in prompting protease production in corneal stromal cells during keratoconus progression. In the epithelial cells of keratoconus corneas, we observed reduced basal cells and abnormally differentiated superficial cells, unraveling the corneal epithelial lesions that were usually neglected in clinical diagnosis. In addition, several elevated cytokines in immune cells of keratoconus samples supported the involvement of inflammatory response in the progression of keratoconus. Finally, we revealed the dysregulated cell-cell communications in keratoconus, and found that only few ligand-receptor interactions were gained but a large fraction of interactional pairs was erased in keratoconus, especially for those related to protease inhibition and anti-inflammatory process. Taken together, this study facilitates the understanding of molecular mechanisms underlying keratoconus pathogenesis, providing insights into keratoconus diagnosis and potential interventions.

Recurrent Urinary Tract Infection: A Mystery in Search of Better Model Systems

Urinary tract infections (UTIs) are among the most common infectious diseases worldwide but are significantly understudied. Uropathogenic E. coli (UPEC) accounts for a significant proportion of UTI, but a large number of other species can infect the urinary tract, each of which will have unique host-pathogen interactions with the bladder environment. Given the substantial economic burden of UTI and its increasing antibiotic resistance, there is an urgent need to better understand UTI pathophysiology - especially its tendency to relapse and recur. Most models developed to date use murine infection; few human-relevant models exist. Of these, the majority of in vitro UTI models have utilized cells in static culture, but UTI needs to be studied in the context of the unique aspects of the bladder's biophysical environment (e.g., tissue architecture, urine, fluid flow, and stretch). In this review, we summarize the complexities of recurrent UTI, critically assess current infection models and discuss potential improvements. More advanced human cell-based in vitro models have the potential to enable a better understanding of the etiology of UTI disease and to provide a complementary platform alongside animals for drug screening and the search for better treatments.

The role of interleukin-6/interleukin-6 receptor signaling in the mechanical stress-induced extracellular matrix remodeling of bladder smooth muscle

Extracellular matrix (ECM) remodeling is strongly associated with pathological changes induced by bladder outlet obstruction (BOO). In this study, we investigated the role of interleukin-6 (IL-6) in mechanical stretch-induced ECM remodeling of bladder smooth muscle. To construct a BOO animal model, the urethras of female Sprague-Dawley rats were partially ligated. In addition, increased hydrostatic pressure and mechanical stretching were applied to human bladder smooth muscle cells (HBSMCs) as an in vitro model. The expression of rat inflammatory genes was analyzed using DNA microarrays. We used quantitative RT-PCR (qRT-PCR) and immunohistochemical staining to detect IL-6 in the bladder smooth muscle of rats. To determine the specificity of IL-6, small interfering ribonucleic acid (siRNA) transfection and IL-6 receptor inhibitor (SC144) were applied to HBSMCs. qRT-PCR with siRNA transfection was also used to determine the specificity of downstream signaling. Moreover, western blotting was conducted to verify the expression results. In the animal model, the expression of ECM components and inflammatory genes was significantly upregulated. The expression of IL-6 was increased at both the mRNA level and the protein level in BOO rats. In vitro, hydrostatic pressure, and mechanical stretching both promoted MMP7 and MMP11 expression. Additionally, downregulation of collagen III occurred in both the hydrostatic pressure group and the mechanical stretch group. However, the expression of fibronectin exhibited opposing patterns between the hydrostatic pressure and mechanical stretch groups. The application of targeted siRNA transfection and an inhibitor (SC144) that targeted IL-6 significantly reversed the changes in MMP7 and MMP11 under mechanical stress and partially increased the expression of collagen III and fibronectin. In summary, IL-6 participated in the ECM remodeling of HBSMCs under mechanical stress, indicating that IL-6 may play an essential role in BOO.
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β-Adrenoceptors regulate matrix metalloproteinase expression in human urothelial cells under hydrostatic pressure

The bladder wall is constantly subjected to intravesical pressure during the filling and voiding cycles. An imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) under elevated intravesical pressure contributes to pathological changes in the bladder. To investigate the changes in human urothelial cells (HUCs) under elevated intravesical pressure, this study analyzed the effect of β-adrenoceptor signaling on the expression of MMPs and TIMPs in HUCs exposed to pathological hydrostatic pressure (HP) (70 cm H₂ O) for 6 hours. Quantitative polymerase chain reaction, Western blot analysis, and cell fluorescence staining were used to explore the effect of β-adrenoceptor signaling on the expression of MMPs and TIMPs in HUCs after agonist and/or antagonist treatment. The expression levels of β₂ - and β₃ -adrenoceptor, MMP1, and MMP2 were greatly downregulated, while the expression of TIMP1 was greatly upregulated. Formoterol and BRL 37344, which are agonists of β₂ - and β₃ -adrenoceptor, respectively, significantly increased MMP1 and MMP2 expression under 70 cm H₂ O. As a classic downstream pathway of β₂ - and β₃ -adrenoceptor, protein kinase A (PKA) signaling inhibited MMP1 and MMP2 expression by regulating cAMP response element binding protein (CREB) activity. MMP1 and MMP2 expression in HUCs under 70 cm H₂ O was modified by β₂ - and β₃ -adrenoceptor via the PKA/CREB pathway. This outcome suggests that MMPs likely participate in the pathological effects of elevated intravesical pressure. The underlying mechanism of β₂ - and β₃ -adrenoceptor in elevated intravesical pressure was also revealed; this mechanism constitutes a new potential therapeutic target for partial bladder outlet obstruction.