Role of Reactive Oxygen Species in TGF-β1-Induced Mitogen-Activated Protein Kinase Activation and Epithelial-Mesenchymal Transition in Renal Tubular Epithelial Cells

A recombinant plasmid encoding human hepatocyte growth factor promotes healing of combined radiation-trauma skin injury involved in regulating Nrf2 pathway in mice

Combined radiation-trauma skin injury represents a severe and intractable condition that urgently requires effective therapeutic interventions. In this context, hepatocyte growth factor (HGF), a multifunctional growth factor with regulating cell survival, angiogenesis, anti-inflammation and antioxidation, may be valuable for the treatment of combined radiation-trauma injury. This study investigated the protective effects of a recombinant plasmid encoding human HGF (pHGF) on irradiated human immortalized keratinocytes (HaCaT) cells in vitro, and its capability to promote the healing of combined radiation-trauma injuries in mice. The pHGF radioprotection on irradiated HaCaT cells in vitro was assessed by cell viability, the expression of Nrf2, Bcl-2 and Bax, as well as the secretion of inflammatory cytokines. In vivo therapeutic treatment, the irradiated mice with full-thickness skin wounds received pHGF local injection. The injuries were appraised based on relative wound area, pathology, immunohistochemical detection, terminal deoxynucleotidyl transferase dUTP nick end labelling assay and cytokine content. The transfection of pHGF increased the cell viability and Nrf2 expression in irradiated HaCaT cells. pHGF also significantly upregulated Bcl-2 expression, decreased the Bax/Bcl-2 ratio and inhibited the expression of interleukin-1β and tumor necrosis factor-α in irradiated cells. Local pHGF injection in vivo caused high HGF protein expression and noticeable accelerated healing of combined radiation-trauma injury. Moreover, pHGF administration upregulated Nrf2, vascular endothelial growth factor, Bcl-2 expression, downregulated Bax expression and mitigated inflammatory response. In conclusion, the protective effect of pHGF may be related to inhibiting apoptosis and inflammation involving by upregulating Nrf2. Local pHGF injection distinctly promoted the healing of combined radiation-trauma injury and demonstrates potential as a gene therapy intervention for combined radiation-trauma injury in clinic.

The functions of hydrogen sulfide on the urogenital system of both males and females: from inception to the present

Hydrogen sulfide (H2S) is known as a chemical gas in nature with both enzymatic and non-enzymatic biosynthesis in different human organs. A couple of studies have demonstrated the function of H2S in regulating the homeostasis of the human body. Additionally, they have shown its synthesis, measurement, chemistry, protective effects, and interaction in various aspects of scientific evidence. Furthermore, many researches have demonstrated the beneficial impacts of H2S on genital organs and systems. According to various studies, it is recognized that H2S-producing enzymes and the endogenous production of H2S are expressed in male and female reproductive systems in different mammalian species. The main goal of this comprehensive review is to assess the potential therapeutic impacts of this gasotransmitter in the male and female urogenital system and find underlying mechanisms of this agent. This narrative review investigated the articles that were published from the 1970s to 2022. The review's primary focus is the impacts of H2S on the male and female urogenital system. Medline, CINAHL, PubMed, and Google scholar databases were searched. Keywords used in this review were "Hydrogen sulfide," "H2S," "urogenital system," and "urogenital tract". Numerous studies have demonstrated the therapeutic and protective effects of sodium hydrosulfide (Na-HS) as an H2S donor on male and female infertility disorders. Furthermore, it has been observed that H2S plays a significant role in improving different diseases such as ameliorating sperm parameters. The specific localization of H2S enzymes in the urogenital system provides an excellent opportunity to comprehend its function and role in various disorders related to this system. It is noteworthy that H2S has been demonstrated to be produced in endocrine organs and exhibit diverse activities. Moreover, it is important to recognize that alterations in H2S biosynthesis are closely linked to endocrine disorders. Therefore, hormones can be pivotal in regulating H2S production, and H2S synthesis pathways may aid in establishing novel therapeutic strategies. H2S possesses pharmacological effects on essential disorders, such as anti-inflammation, anti-apoptosis, and anti-oxidant activities, which render it a valuable therapeutic agent for human urogenital disease. Furthermore, this agent shows promise in ameliorating the detrimental effects of various male and female diseases. Despite the limited clinical research, studies have demonstrated that applying H2S as an anti-oxidant source could ameliorate adverse effects of different conditions in the urogenital system. More clinical studies are required to confirm the role of this component in clinical settings.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

Tonic ErbB signaling underlies TGFβ-induced activation of ERK and is required for lens cell epithelial to myofibroblast transition

Fibrosis is a major, but incompletely understood, component of many diseases. The most common vision-disrupting complication of cataract surgery involves differentiation of residual lens cells into myofibroblasts. In serum-free primary cultures of lens epithelial cells (DCDMLs), inhibitors of either ERK or of ErbB signaling prevent TGFβ from upregulating both early (fibronectin) and late (αSMA) markers of myofibroblast differentiation. TGFβ stimulates ERK in DCDMLs within 1.5 h. Kinase inhibitors of ErbBs, but not of several other growth factor receptors in lens cells, reduce phospho ERK to below basal levels in the absence or presence of TGFβ. This effect is attributable to constitutive ErbB activity playing a major role in regulating the basal levels pERK. Additional studies support a model in which TGFβ-generated reactive oxygen species serve to indirectly amplify ERK signaling downstream of tonically active ErbBs to mediate myofibroblast differentiation. ERK activity is in turn essential for expression of ErbB1 and ErbB2, major inducers of ERK signaling. By mechanistically linking TGFβ, ErbB, and ERK signaling to myofibroblast differentiation, our data elucidate a new role for ErbBs in fibrosis and reveal a novel mode by which TGFβ directs lens cell fate.

Role of platelet factor 4 in arteriovenous fistula maturation failure: What do we know so far?

The rate of arteriovenous fistula (AVF) maturation failure remains unacceptably high despite continuous efforts on technique improvement and careful pre-surgery planning. In fact, half of all newly created AVFs are unable to be used for hemodialysis (HD) without a salvage procedure. While vascular stenosis in the venous limb of the access is the culprit, the underlying factors leading to vascular narrowing and AVF maturation failure are yet to be determined. We have recently demonstrated that AVF non-maturation is associated with post-operative medial fibrosis and fibrotic stenosis, and post-operative intimal hyperplasia (IH) exacerbates the situation. Multiple pathological processes and signaling pathways are underlying the stenotic remodeling of the AVF. Our group has recently indicated that a pro-inflammatory cytokine platelet factor 4 (PF4/CXCL4) is upregulated in veins that fail to mature after AVF creation. Platelet factor 4 is a fibrosis marker and can be detected in vascular stenosis tissue, suggesting that it may contribute to AVF maturation failure through stimulation of fibrosis and development of fibrotic stenosis. Here, we present an overview of the how PF4-mediated fibrosis determines AVF maturation failure.

Hirudin in the Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is a common public health concern. The global burden of CKD is increasing due to the high morbidity and mortality associated with it, indicating the shortcomings of therapeutic drugs at present. Renal fibrosis is the common pathology of CKD, which is characterized by glomerulosclerosis, renal tubular atrophy, and renal interstitial fibrosis. Natural hirudin is an active ingredient extracted from Hirudo medicinalis, which has been found to be the strongest natural specific inhibitor of thrombin. Evidence based on pharmacological data has shown that hirudin has important protective effects in CKD against diabetic nephrology, nephrotic syndrome, and renal interstitial fibrosis. The mechanisms of hirudin in treating CKD are mainly related to inhibiting the inflammatory response, preventing apoptosis of intrinsic renal cells, and inhibiting the interactions between thrombin and protease-activated receptors. In this review, we summarize the function and beneficial properties of hirudin for the treatment of CKD, and its underlying mechanisms.

TGFβ2 mediates oxidative stress-induced epithelial-to-mesenchymal transition of bladder smooth muscle

Bladder outlet obstruction (BOO) is the primary clinical manifestation of benign prostatic hyperplasia, the most common urinary system disease in elderly men, and leads to associated lower urinary tract symptoms. Although BOO is reportedly associated with increased systemic oxidative stress (OS), the underlying mechanism remains unclear. The elucidation of this mechanism is the primary aim of this study. A Sprague-Dawley rat model of BOO was constructed and used for urodynamic monitoring. The bladder tissue of rats was collected and subjected to real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR), histological examination, and immunohistochemical staining. Through bioinformatics prediction, we found that transforming growth factor β2 (TGFβ2) expression was upregulated in rats with BOO compared with normal bladder tissue. In vitro analyses using primary bladder smooth muscle cells (BSMCs) revealed that hydrogen peroxide (H2O2) induced TGFβ2 expression. Moreover, H2O2 induced epithelial-to-mesenchymal transition (EMT) by reducing E-cadherin, an endothelial marker and CK-18, a cytokeratin maker, and increasing mesenchymal markers, including N-cadherin, vimentin, and α-smooth muscle actin (α-SMA) levels. The downregulation of TGFβ2 expression in BSMCs using siRNA technology alleviated H2O2-induced changes in EMT marker expression. The findings of the study indicate that TGFβ2 plays a crucial role in BOO by participating in OS-induced EMT in BSMCs.

Progress in understanding of relationship between inflammation and tumors

Over the past decade, there has been clear evidence that inflammation plays a key role in tumorigenesis. Tumor extrinsic inflammation is caused by many factors, including bacterial and viral infections, autoimmune diseases, obesity, smoking, excessive alcohol consumption, etc., all of which can increase cancer risk and stimulate malignant progression. Conversely, inflammation inherent in cancer or caused by cancer can be triggered by cancer-initiating mutations and can promote malignant progression through recruitment and activation of inflammatory cells. Both exogenous and endogenous inflammation can lead to immunosuppression, thus providing a preferred opportunity for tumor development. Studies have confirmed that chronic inflammation is involved in various steps of tumorigenesis, including cell transformation, promotion, survival, prolifer-ation, invasion, angiogenesis, and metastasis. Recent research has shed new light on the molecular and cellular circuits between inflammation and cancer. Two pathways have been preliminarily identified: Intrinsic and extrinsic. In the intrinsic pathway, genetic events leading to tumors initiate the expression of inflammatory related programs and guide the construction of the inflammatory microenvironment. In the extrinsic pathway, inflammatory conditions promote the development of cancer. This article reviews the recent progress in the understanding of the relationship between inflammation and tumors.

Epithelial-mesenchymal transition in age-associated thymic involution: Mechanisms and therapeutic implications

The thymus is a critical immune organ with endocrine and immune functions that plays important roles in the physiological and pathological processes of the body. However, with aging, the thymus undergoes degenerative changes leading to decreased production and output of naive T cells and the secretion of thymic hormones and related cytokines, thereby promoting the occurrence and development of various age-associated diseases. Therefore, identifying essential processes that regulate age-associated thymic involution is crucial for long-term control of thymic involution and age-associated disease progression. Epithelial-mesenchymal transition (EMT) is a well-established process involved in organ aging and functional impairment through tissue fibrosis in several organs, such as the heart and kidney. In the thymus, EMT promotes fibrosis and potentially adipogenesis, leading to thymic involution. This review focuses on the factors involved in thymic involution, including oxidative stress, inflammation, and hormones, from the perspective of EMT. Furthermore, current interventions for reversing age-associated thymic involution by targeting EMT-associated processes are summarized. Understanding the key mechanisms of thymic involution through EMT as an entry point may promote the development of new therapies and clinical agents to reverse thymic involution and age-associated disease.

Suppressing epithelial-mesenchymal-transition blue light therapy for reducing macrophage-mediated cancerous pulmonary fibrosis: An in-vitro study

Lung cancer is the leading killer among all types of cancer globally. As a key factor, epithelial-mesenchymal transition (EMT) plays a crucial role in pathological fibrosis and lung cancer metastasis. This study endeavors to investigate the effect of blue light at specific wavelengths of 405 nm and 415 nm (54 J/cm2 ) on EMT induced by TGF-β1 in A549 cells. The results revealed that the blue light irradiation reduced the morphological characteristics of EMT in the A549 cells, and cell-to-cell connections were weakened significantly. Molecular analysis showed upregulation of epithelial marker E-cadherin and downregulation of EMT marker vimentin. Additionally, exposure to blue light irradiation at 405 nm and 415 nm significantly decelerated the ability of invasion and migration. Moreover, cell viability was also investigated. Based on these findings, blue light can serve as a useful therapeutic option for inhibiting EMT in cases of lung cancer and fibrotic lung disease.

Polysulfide nanoparticles inhibit fibroblast-to-myofibroblast transition via extracellular ROS scavenging and have potential anti-fibrotic properties

This paper is about the effects of reactive oxygen species (ROS) - and of their nanoparticle-mediated extracellular removal - in the TGF-β1-induced differentiation of fibroblasts (human dermal fibroblasts - HDFa) to more contractile myofibroblasts, and in the maintenance of this phenotype. Here, poly(propylene sulfide) (PPS) nanoparticles have been employed on 2D and 3D in vitro models, showing extremely low toxicity and undergoing negligible internalization, thereby ensuring an extracellular-only action. Firstly, PPS nanoparticles abrogated ROS-mediated downstream molecular events such as glutathione oxidation, NF-κB activation, and heme oxidase-1 (HMOX) overexpression. Secondly, PPS nanoparticles were also capable to inhibit, prevent and reverse the TGF-β1-induced upregulation of key biomechanical elements, such as ED-a fibronectin (EF-A FN) and alpha-smooth muscle actin (α-SMA), respectively markers of protomyofibroblastic and of myofibroblastic differentiation. We also confirmed that ROS alone are ineffective promoters of the myofibroblastic transition, although their presence contributes to its stabilization. Finally, the particles also countered TGF-β1-induced matrix- and tissue-level phenomena, e.g., the upregulation of collagen type 1, the development of aberrant collagen type 1/3 ratios and the contracture of HDFa 3D-seeded fibrin constructs. In short, experimental data at molecular, cellular and tissue levels show a significant potential in the use of PPS nanoparticles as anti-fibrotic agents.

The Interplay of Autophagy and Oxidative Stress in the Kidney: What Do We Know?

BACKGROUND

Autophagy, as an indispensable metabolism, plays pivotal roles in maintaining intracellular homeostasis. Nutritional stress, amino acid deficiency, oxidative stress, and hypoxia can trigger its initiation. Oxidative stress in the kidney activates essential signal molecules, like mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), and silent mating-type information regulation 2 homolog-1 (SIRT1), to stimulate autophagy, ultimately leading to degradation of intracellular oxidative substances and damaged organelles. Growing evidence suggests that autophagy protects the kidney from oxidative stress during acute ischemic kidney injury, chronic kidney disease, and even aging.

SUMMARY

This review emphasizes the cross talk between reactive oxygen species (ROS) signaling pathways and autophagy during renal homeostasis and chronic kidney disease according to the current latest research and provides therapeutic targets during kidney disorders by adjusting autophagy and suppressing oxidative stress.

KEY MESSAGES

ROS arise through an imbalance of oxidation and antioxidant defense mechanisms, leading to impaired cellular and organ function. Targeting the overproduction of ROS and reactive nitrogen species, reducing the antioxidant enzyme activity and the recovery of the prooxidative-antioxidative balance provide novel therapeutic regimens to contribute to recovery in acute and chronic renal failure. Although, in recent years, great progress has been made in understanding the molecular mechanisms of oxidative stress and autophagy in acute and chronic renal failure, the focus on clinical therapies is still in its infancy. The growing number of studies on the interactive mechanisms of oxidative stress-mediated autophagy will be of great importance for the future treatment and prevention of kidney diseases.

External Validation of the Nelson Equation for Kidney Function Decline in Patients with Acute Ischemic Stroke or Transient Ischemic Attack

Background

There is a close brain-kidney interaction following ischemic cerebrovascular disease. The new-onset kidney injury after stroke leads to severe neurological deficits and poor functional outcomes. We aimed to validate the Nelson equation for predicting the new-onset and long-term kidney function decline in patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA).

Methods

A total of 3169 patients were enrolled in the Third China National Stroke Registry, whose baseline estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m². The outcome of interest was the incident eGFR< 60 mL/min/1.73 m² at 3 months. The prediction equation of participants with or without diabetes was validated respectively. The receiver operating characteristic curve (AUC) evaluated prediction performance. The Delong test compared the Nelson equation performance with the O'Seaghdha equation and the Chien equation. Continuous net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were determined to evaluate the incremental effect.

Results

During the 3-mo follow-up period, among 1151 patients with diabetes, there were 31 cases (2.7%) of reduced eGFR. Meanwhile, among 2018 non-diabetic patients, there were 23 cases (1.1%) of reduced eGFR. The Nelson equation showed good discrimination and was well-calibrated in patients with diabetes (AUC 0.82, Hosmer-Lemeshow test p = 0.67) or without diabetes (AUC 0.82, Hosmer-Lemeshow test p = 0.09). The performance of the Nelson equation was superior to other equation, as increased continuous NRI (diabetic, 0.64; non-diabetic, 1.13) and IDI (diabetic, 0.10; non-diabetic, 0.13) to the Chien equation.

Conclusion

The Nelson equation reliably predicted the risks of the new-onset and long-term kidney function decline in patients with AIS or TIA, which could help clinicians screen high-risk patients and improve clinical care.

Renal fibrosis in type 2 cardiorenal syndrome: An update on mechanisms and therapeutic opportunities

Cardiorenal syndrome (CRS) is a state of coexisting heart failure and renal insufficiency in which acute or chronic dysfunction of the heart or kidney lead to acute or chronic dysfunction of the other organ.It was found that renal fibrosis is an important pathological process in the progression of type 2 CRS to end-stage renal disease, and progressive renal impairment accelerates the deterioration of cardiac function and significantly increases the hospitalization and mortality rates of patients. Previous studies have found that Hemodynamic Aiteration, RAAS Overactivation, SNS Dysfunction, Endothelial Dysfunction and Imbalance of natriuretic peptide system contribute to the development of renal disease in the decompensated phase of heart failure, but the exact mechanisms is not clear. Therefore, in this review, we focus on the molecular pathways involved in the development of renal fibrosis due to heart failure and identify the canonical and non-canonical TGF-β signaling pathways and hypoxia-sensing pathways, oxidative stress, endoplasmic reticulum stress, pro-inflammatory cytokines and chemokines as important triggers and regulators of fibrosis development, and summarize the therapeutic approaches for the above signaling pathways, including SB-525334 Sfrp1, DKK1, IMC, rosarostat, 4-PBA, etc. In addition, some potential natural drugs for this disease are also summarized, including SQD4S2, Wogonin, Astragaloside, etc.

Endoplasmic reticulum stress-triggered ferroptosis via the XBP1-Hrd1-Nrf2 pathway induces EMT progression in diabetic nephropathy

Diabetic nephropathy (DN) is characterized by tubulointerstitial fibrosis caused by epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells. Although ferroptosis promotes DN development, the specific pathological process that is affected by ferroptosis in DN remains unclear. Herein, EMT-related changes, including increased α-smooth muscle actin (α-SMA) and Vimentin expression and decreased E-cadherin expression, were observed in the renal tissues of streptozotocin-induced DN mice and high glucose-cultured human renal proximal tubular (HK-2) cells. Treatment with ferrostatin-1 (Fer-1) ameliorated these changes and rescued renal pathological injury in diabetic mice. Interestingly, endoplasmic reticulum stress (ERS) was activated during EMT progression in DN. Inhibiting ERS improved the expression of EMT-associated indicators and further rescued the characteristic changes in ferroptosis caused by high glucose, including reactive oxygen species (ROS) accumulation, iron overload, increased lipid peroxidation product generation, and reduced mitochondrial cristae. Moreover, overexpression of XBP1 increased Hrd1 expression and inhibited NFE2-related factor 2 (Nrf2) expression, which could enhance cell susceptibility to ferroptosis. Co-immunoprecipitation (Co-IP) and ubiquitylation assays indicated that Hrd1 interacted with and ubiquitinated Nrf2 under high-glucose conditions. Collectively, our results demonstrated that ERS triggers ferroptosis-related EMT progression through the XBP1-Hrd1-Nrf2 pathway, which provides new insights into potential mechanisms for delaying EMT progression in DN.

Nr4a1 promotes renal interstitial fibrosis by regulating the p38 MAPK phosphorylation

BACKGROUND

Renal interstitial fibrosis (RIF) is a common pathway to end-stage renal disease regardless of the initial etiology. Currently, the molecular mechanisms for RIF remains not fully elucidated. Nuclear receptor subfamily 4 group A member 1(Nr4a1), a member of the NR4A subfamily of nuclear receptors, is a ligand-activated transcription factor. The role of Nr4a1 in RIF remains largely unknown.

METHODS

In this study, we determined the role and action mechanism of Nr4a1 in RIF. We used unilateral ureteral obstruction (UUO) mice and transforming growth factor (TGF)-β1-treated human renal proximal tubular epithelial cells (HK-2 cells) as in vivo and in vitro models of RIF. A specific Nr4a1 agonist Cytosporone B (Csn-B) was applied to activate Nr4a1 both in vivo and in vitro, and Nr4a1 small interfering RNA was applied in vitro. Renal pathological changes were evaluated by hematoxylin and eosin and Masson staining, and the expression of fibrotic proteins including fibronectin (Fn) and collagen-I (Col-I), and phosphorylated p38 MAPK was measure by immunohistochemical staining and western blot analysis.

RESULTS

The results showed that Nr4a1 was upregulated in UUO mouse kidneys, and was positively correlated with the degree of interstitial kidney injury and the levels of fibrotic proteins. Csn-B treatment aggravated UUO-induced renal interstitial fibrosis, and induced p38 MAPK phosphorylation. In vitro, TGF-β induced Nr4a1 expression, and Nr4a1 downregulation prevented TGF-β1-induced expression of Fn and Col-I and the activation of p38 MAPK. Csn-B induced fibrotic proteins expression and p38 MAPK phosphorylation, and moreover Csn-B induced fibrotic proteins expression was abrogated by treatment with p38 MAPK inhibitor SB203580. We provided further evidence that Csn-B treatment promoted cytoplasmic accumulation of Nr4a1.

CONCLUSION

The findings in the present study indicate that Nr4a1 promotes renal fibrosis potentially through activating p38 MAPK kinase.

Canagliflozin ameliorates epithelial-mesenchymal transition in high-salt diet-induced hypertensive renal injury through restoration of sirtuin 3 expression and the reduction of oxidative stress

Hypertensive nephropathy is characterized by long-term damage to renal tissues by chronic uncontrolled hypertension, and ultimately leads to the development of renal fibrosis. The epithelial-mesenchymal transition (EMT) potentially contributes to the promotion of renal fibrosis in chronic kidney disease (CKD). In this study, we investigated the potential roles of canagliflozin (Cana) on renal EMT and oxidative stress through its effects on sirtuin 3 (SIRT3) expression. High-salt diet (HSD)-induced Dahl salt-sensitive rats hypertensive renal injury led to decreased SIRT3 expression and an increase in EMT and oxidative stress. In contrast, Cana administration rescued SIRT3 expression, decreased both EMT and levels of oxidative stress, and ameliorated renal injury. Furthermore, we compared the antihypertensive and renoprotective properties of Cana when combined with irbesartan (Irb), a renin-angiotensin system (RAS) blocker. We concluded that administration of Cana in combination with Irb had a significantly greater effect in lowering systolic blood pressure when compared to Cana monotherapy. However, no statistical differences were observed between combined therapy and monotherapy groups with regards to the lowering of diastolic blood pressure and renoprotection. Utilizing the human renal proximal tubular epithelial cell line (HK-2), Angiotensin II (AngⅡ) induced HK-2 negatively regulated the expression of SIRT3, FOXO3a, catalase, and promoted EMT, all of which were reversed by Cana. Furthermore, SIRT3 silencing abolished Cana-mediated rescue of forkhead box O3a (FOXO3a) and catalase expression and Cana-mediated suppression of EMT in AngⅡ induced HK-2. Taken together, Cana acts as a renoprotective agent by suppressing EMT in the pathology of renal fibrosis via interaction with the SIRT3-FOXO3a pathway.

Antrodia camphorata and coenzyme Q0 , a novel quinone derivative of Antrodia camphorata, impede HIF-1α and epithelial-mesenchymal transition/metastasis in human glioblastoma cells

Antrodia camphorata (AC) and Coenzyme Q₀ (CoQ₀ ), a novel quinone derivative of AC, exhibits antitumor activities. The present study evaluated EMT/metastasis inhibition and autophagy induction aspects of AC and CoQ₀ in human glioblastoma (GBM8401) cells. Our findings revealed that AC treatment (0-150 μg/mL) hindered tumor cell proliferation and migration/invasion in GBM8401 cells. Notably, AC treatment inhibited HIF-1α and EMT by upregulating epithelial marker protein E-cadherin while downregulating mesenchymal proteins Twist, Slug, Snail, and β-catenin. There was an appearance of the autophagy markers LC3-II and p62/SQSTM1, while ATG4B was downregulated by AC treatment. We also found that CoQ₀ (0-10 μM) could inhibit migration and invasion in GBM8401 cells. In particular, E-cadherin was elevated and N-cadherin, Vimentin, Twist, Slug, and Snail, were reduced upon CoQ₀ treatment. In addition, MMP-2/-9 expression and Wnt/β-catenin pathways were downregulated. Furthermore, autophagy inhibitors 3-MA or CQ reversed the CoQ₀ -elicited suppression of migration/invasion and metastasis-related proteins (Vimentin, Snail, and β-catenin). Results suggested autophagy-mediated antiEMT and antimetastasis upon CoQ₀ treatment. CoQ₀ inhibited HIF-1α and metastasis in GBM8401 cells under normoxia and hypoxia. HIF-1α knockdown using siRNA accelerated CoQ₀ -inhibited migration. Finally, CoQ₀ exhibited a prolonged survival rate in GBM8401-xenografted mice. Treatment with Antrodia camphorata/CoQ₀ inhibited HIF-1α and EMT/metastasis in glioblastoma.

Effect of melatonin on oxidative stress indicators in animal models of fibrosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Imbalance of oxidative stress has been detected in a range of fibrotic diseases. Melatonin as an indoleamine hormone plays an important role in regulating the circadian rhythm of human, while in recent years, its antioxidant effect has also attracted increasing attention. This study aimed to perform a systematic review and meta-analysis to comprehensively evaluate the antioxidant effect of melatonin in animal models of fibrosis.

METHODS

The PubMed, Cochrane Library, EMBASE, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang database, China Science and Technology Journal Database (VIP), and SinoMed databases were searched from inception to March 1st, 2022 to retrieve eligible studies that evaluated the effect of melatonin supplementation on the levels of malondialdehyde (MDA), lipid peroxidation (LPO), nitric oxide (NO), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), and catalase (CAT) in animal models of fibrosis.

RESULTS

A total of 64 studies were included in this meta-analysis. The results showed that melatonin supplementation significantly reduced the levels of oxidative indicators including MDA (P < 0.00001), LPO (P < 0.00001) and NO (P < 0.0001), and elevated the levels of antioxidant indicators including GSH (P < 0.00001), GPx (P < 0.00001) and SOD (P < 0.00001) in fibrotic diseases.

CONCLUSIONS

Our research findings showed that melatonin supplementation could significantly reduce the levels of oxidative indicators including MDA, LPO and NO and elevate the levels of antioxidant indicators including GSH, GPx and SOD so as to correct oxidative stress in animal models of fibrosis. However, no significant changes were observed in CAT level. More clinical studies are needed to further confirm the beneficial role of melatonin in fibrotic diseases.

Campylobacter jejuni Modulates Reactive Oxygen Species Production and NADPH Oxidase 1 Expression in Human Intestinal Epithelial Cells

Campylobacter jejuni is the major bacterial cause of foodborne gastroenteritis worldwide. Mechanistically, how this pathogen interacts with intrinsic defence machinery of human intestinal epithelial cells (IECs) remains elusive. To address this, we investigated how C. jejuni counteracts the intracellular and extracellular reactive oxygen species (ROS) in IECs. Our work shows that C. jejuni differentially regulates intracellular and extracellular ROS production in human T84 and Caco-2 cells. C. jejuni downregulates the transcription and translation of nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase (NOX1), a key ROS-generating enzyme in IECs and antioxidant defence genes CAT and SOD1. Furthermore, inhibition of NOX1 by diphenylene iodonium (DPI) and siRNA reduced C. jejuni ability to interact, invade, and intracellularly survive within T84 and Caco-2 cells. Collectively, these findings provide mechanistic insight into how C. jejuni modulates the IEC defence machinery.

Clinical Radiobiology for Radiation Oncology

This chapter is focused on radiobiological aspects at the molecular, cellular, and tissue level which are relevant for the clinical use of ionizing radiation (IR) in cancer therapy. For radiation oncology, it is critical to find a balance, i.e., the therapeutic window, between the probability of tumor control and the probability of side effects caused by radiation injury to the healthy tissues and organs. An overview is given about modern precision radiotherapy (RT) techniques, which allow optimal sparing of healthy tissues. Biological factors determining the width of the therapeutic window are explained. The role of the six typical radiobiological phenomena determining the response of both malignant and normal tissues in the clinic, the 6R’s, which are Reoxygenation, Redistribution, Repopulation, Repair, Radiosensitivity, and Reactivation of the immune system, is discussed. Information is provided on tumor characteristics, for example, tumor type, growth kinetics, hypoxia, aberrant molecular signaling pathways, cancer stem cells and their impact on the response to RT. The role of the tumor microenvironment and microbiota is described and the effects of radiation on the immune system including the abscopal effect phenomenon are outlined. A summary is given on tumor diagnosis, response prediction via biomarkers, genetics, and radiomics, and ways to selectively enhance the RT response in tumors. Furthermore, we describe acute and late normal tissue reactions following exposure to radiation: cellular aspects, tissue kinetics, latency periods, permanent or transient injury, and histopathology. Details are also given on the differential effect on tumor and late responding healthy tissues following fractionated and low dose rate irradiation as well as the effect of whole-body exposure.

Dapagliflozin alleviates renal fibrosis in a mouse model of adenine-induced renal injury by inhibiting TGF-β1/MAPK mediated mitochondrial damage

Renal fibrosis is a common pathological outcome of various chronic kidney diseases, and as yet, there is no specific treatment. Dapagliflozin has shown renal protection in some clinical trials as a glucose-lowering drug, but its role and mechanism on renal fibrosis remain unclear. In this study, we used a 0.2% adenine diet-induced renal fibrosis mouse model to investigate whether dapagliflozin could protect renal function and alleviate renal fibrosis in this animal model. In vivo, we found that dapagliflozin's protective effect on renal fibrosis was associated with 1) sustaining mitochondrial integrity and respiratory chain complex expression, maintained the amount of mitochondria; 2) improving fatty acid oxidation level with increased expression of CPT1-α, PPAR-α, ACOX1, and ACOX2; 3) reducing inflammation and oxidative stress, likely via regulation of IL-1β, IL-6, TNF-α, MCP-1, cxcl-1 expression, and glutathione (GSH) activity, superoxide dismutase (SOD) and malondialdehyde (MDA) levels; and 4) inhibiting the activation of the TGF-β1/MAPK pathway. In HK2 cells treated with TGF-β1, dapagliflozin reduced the expression of FN and α-SMA, improved mitochondrial respiratory chain complex expression, and inhibited activation of the TGF-β1/MAPK pathway.

An Overview of Epithelial-to-Mesenchymal Transition and Mesenchymal-to-Epithelial Transition in Canine Tumors: How Far Have We Come?

Historically, pre-clinical and clinical studies in human medicine have provided new insights, pushing forward the contemporary knowledge. The new results represented a motivation for investigators in specific fields of veterinary medicine, who addressed the same research topics from different perspectives in studies based on experimental and spontaneous animal disease models. The study of different pheno-genotypic contexts contributes to the confirmation of translational models of pathologic mechanisms. This review provides an overview of EMT and MET processes in both human and canine species. While human medicine rapidly advances, having a large amount of information available, veterinary medicine is not at the same level. This situation should provide motivation for the veterinary medicine research field, to apply the knowledge on humans to research in pets. By merging the knowledge of these two disciplines, better and faster results can be achieved, thus improving human and canine health.

Inhibition of Ureteral Stricture by Pirfenidone-Loaded Nanoparticle-Coated Ureteral Stents with Slow-Release Pirfenidone

Introduction

Ureteral stricture caused by iatrogenic ureteral injury induced ureteral injury is more common and challenging to recover quickly. The effective prevention of ureteral stricture due to iatrogenic ureteral injury-induced ureteral damage is a current challenge for urologists. The purpose of this study was to evaluate the effectiveness of nanoparticle/pirfenidone complex-coated ureteral stents with slow-release pirfenidone for the prevention of ureteral stricture in rabbits. In this study, we developed a nanoparticle/pirfenidone complex-coated ureteral stent to deliver pirfenidone into the injured ureter to inhibit ureteral stricture.

Methods

Twelve New Zealand rabbits were divided into four groups: Sham, US, US+ Unmodified ureteral stent, and US+NP/PFD ureteral stent; we constructed an irreversible electroporation model of ureteral injury in rabbits and placed unmodified ureteral stents and nanoparticle/pirfenidone complex-coated ureteral stents into the ureter. Two weeks later, we euthanized the rabbits and removed their bilateral kidneys and ureters. We evaluated the effect of ureteral stent prophylaxis by gross specimen observation, section staining, and Western Blot.

Results

We found that the nanoparticle/pirfenidone complexes could adhere uniformly to the surface of the ureteral stent. After placement into the ureter, the nanoparticle/pirfenidone complexes were able to remain on the surface of the ureteral stent. We found nanoparticle/pirfenidone complexes could diffuse in the ureteral epithelial tissue two weeks after the order. The study showed that nanoparticle/pirfenidone complex-coated ureteral stents placed into the ureter showed significantly less stenosis due to fibrosis than in US control rabbits and rabbits treated with unmodified ureteral stents.

Conclusion

We used a novel platform based on nanoparticle/pirfenidone complex-coated ureteral stents for local and sustained delivery of pirfenidone, which can effectively deliver pirfenidone to the tissue and can slowly control the release of pirfenidone. Therefore, combining ureteral stents with nanoparticle/pirfenidone complexes was an effective measure to prevent ureteral stricture.

"In medio stat virtus": Insights into hybrid E/M phenotype attitudes

Epithelial-mesenchymal plasticity (EMP) refers to the ability of cells to dynamically interconvert between epithelial (E) and mesenchymal (M) phenotypes, thus generating an array of hybrid E/M intermediates with mixed E and M features. Recent findings have demonstrated how these hybrid E/M rather than fully M cells play key roles in most of physiological and pathological processes involving EMT. To this regard, the onset of hybrid E/M state coincides with the highest stemness gene expression and is involved in differentiation of either normal and cancer stem cells. Moreover, hybrid E/M cells are responsible for wound healing and create a favorable immunosuppressive environment for tissue regeneration. Nevertheless, hybrid state is responsible of metastatic process and of the increasing of survival, apoptosis and therapy resistance in cancer cells. The present review aims to describe the main features and the emerging concepts regulating EMP and the formation of E/M hybrid intermediates by describing differences and similarities between cancer and normal hybrid stem cells. In particular, the comprehension of hybrid E/M cells biology will surely advance our understanding of their features and how they could be exploited to improve tissue regeneration and repair.

Gambogenic acid alleviates kidney fibrosis via epigenetic inhibition of EZH2 to regulate Smad7-dependent mechanism

BACKGROUND

Epigenetics regulating gene expression plays important role in kidney fibrosis. Natural products originating from diverse sources including plants and microorganisms are capable to influence epigenetic modifications. Gambogenic acid (GNA) is a caged xanthone extracted from gamboge resin, exudation of Garcinia hanburyi Hook.f., and the effect of GNA on kidney fibrosis with its underlying mechanism on epigenetics remains unknown.

PURPOSE

This study aimed to explore the role of GNA against kidney fibrogenesis by histone methylation mediating gene expression.

METHODS

Two experimental mice of unilateral ureteral obstruction (UUO) and folic acid (FA) were given two dosages of GNA (3 and 6 mg/kg/d). TGF-β1 was used to stimulate mouse tubular epithelial (TCMK-1) cells and siRNAs were transfected to verify the underlying mechanisms of GNA. Histological changes were evaluated by HE, MASSON stainings, immunohistochemistry and immunofluorescence. Western blot and qPCR were used to measure protein/gene transcription levels.

RESULTS

GNA dose-dependently alleviated UUO-induced kidney fibrosis and FA-induced kidney early fibrosis, indicated by the pathology and fibrotic factor changes (α-SMA, collagen I, collagen VI, and fibronectin). Mechanically, GNA reduced enhancer of zeste homolog 2 (EZH2) and H3K27me3, promoted Smad7 transcription, and inhibited TGF-β/Smad3 fibrotic signaling in injured kidneys. Moreover, with TGF-β1-induced EZH2 increasing, GNA suppressed α-SMA, fibronectin and collagen levels in tubular epithelial TCMK-1 cells. Although partially decreasing EZH2, GNA did not influence fibrotic signaling in Smad7 siRNA-transfected TCMK-1 cells.

CONCLUSION

Epigenetic inhibition of EZH2 by GNA ameliorated kidney fibrogenesis via regulating Smad7-meidated TGF-β/Smad3 signaling.

Treatment of myocardial interstitial fibrosis in pathological myocardial hypertrophy

Pathological myocardial hypertrophy can be caused by a variety of diseases, mainly accompanied by myocardial interstitial fibrosis (MIF), which is a diffuse and patchy process, appearing as a combination of interstitial micro-scars and perivascular collagen fiber deposition. Different stimuli may trigger MIF without cell death by activating a variety of fibrotic signaling pathways in mesenchymal cells. This manuscript summarizes the current knowledge about the mechanism and harmful outcomes of MIF in pathological myocardial hypertrophy, discusses the circulating and imaging biomarkers that can be used to identify this lesion, and reviews the currently available and potential future treatments that allow the individualized management of patients with pathological myocardial hypertrophy.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Mitochondrial oxidative stress in the tumor microenvironment and cancer immunoescape: foe or friend?

The major concept of "oxidative stress" is an excess elevated level of reactive oxygen species (ROS) which are generated from vigorous metabolism and consumption of oxygen. The precise harmonization of oxidative stresses between mitochondria and other organelles in the cell is absolutely vital to cell survival. Under oxidative stress, ROS produced from mitochondria and are the major mediator for tumorigenesis in different aspects, such as proliferation, migration/invasion, angiogenesis, inflammation, and immunoescape to allow cancer cells to adapt to the rigorous environment. Accordingly, the dynamic balance of oxidative stresses not only orchestrate complex cell signaling events in cancer cells but also affect other components in the tumor microenvironment (TME). Immune cells, such as M2 macrophages, dendritic cells, and T cells are the major components of the immunosuppressive TME from the ROS-induced inflammation. Based on this notion, numerous strategies to mitigate oxidative stresses in tumors have been tested for cancer prevention or therapies; however, these manipulations are devised from different sources and mechanisms without established effectiveness. Herein, we integrate current progress regarding the impact of mitochondrial ROS in the TME, not only in cancer cells but also in immune cells, and discuss the combination of emerging ROS-modulating strategies with immunotherapies to achieve antitumor effects.

Renalase Challenges the Oxidative Stress and Fibroproliferative Response in COVID-19

The hallmark of the coronavirus disease 2019 (COVID-19) pathophysiology was reported to be an inappropriate and uncontrolled immune response, evidenced by activated macrophages, and a robust surge of proinflammatory cytokines, followed by the release of reactive oxygen species, that synergistically result in acute respiratory distress syndrome, fibroproliferative lung response, and possibly even death. For these reasons, all identified risk factors and pathophysiological processes of COVID-19, which are feasible for the prevention and treatment, should be addressed in a timely manner. Accordingly, the evolving anti-inflammatory and antifibrotic therapy for severe COVID-19 and hindering post-COVID-19 fibrosis development should be comprehensively investigated. Experimental evidence indicates that renalase, a novel amino-oxidase, derived from the kidneys, exhibits remarkable organ protection, robustly addressing the most powerful pathways of cell trauma: inflammation and oxidative stress, necrosis, and apoptosis. As demonstrated, systemic renalase administration also significantly alleviates experimentally induced organ fibrosis and prevents adverse remodeling. The recognition that renalase exerts cytoprotection via sirtuins activation, by raising their NAD⁺ levels, provides a “proof of principle” for renalase being a biologically impressive molecule that favors cell protection and survival and maybe involved in the pathogenesis of COVID-19. This premise supports the rationale that renalase's timely supplementation may prove valuable for pathologic conditions, such as cytokine storm and related acute respiratory distress syndrome. Therefore, the aim for this review is to acknowledge the scientific rationale for renalase employment in the experimental model of COVID-19, targeting the acute phase mechanisms and halting fibrosis progression, based on its proposed molecular pathways. Novel therapies for COVID-19 seek to exploit renalase's multiple and distinctive cytoprotective mechanisms; therefore, this review should be acknowledged as the thorough groundwork for subsequent research of renalase's employment in the experimental models of COVID-19.

Trimetazidine Reduces Cardiac Fibrosis in Rats by Inhibiting NOX2-Mediated Endothelial-to-Mesenchymal Transition

Purpose

Methods

Results

Conclusion

Pharmacological and Genetic Inhibition of HDAC4 Alleviates Renal Injury and Fibrosis in Mice

Histone deacetylase 4 (HDAC4) has been shown to be involved in cell proliferation, differentiation, and migration and is associated with a variety of cancers. However, the role of HDAC4 in renal fibrogenesis and its mechanisms are unclear. We assessed the role of HDAC4 and possible mechanisms of fibrosis in a murine model of kidney injury induced by unilateral ureteral obstruction (UUO) using tasquinimod, a highly selective HDAC4 inhibitor, and knockout mice with depletion of HDAC4 in renal tubular cells. UUO injury resulted in increased expression of HDAC4 and fibrotic proteins fibronectin and α-smooth muscle actin, while treatment with tasquinimod or knockout of HDAC4 significantly reduced their expression. Pharmacological and genetic inhibition of HDAC4 also decreased tubular epithelial cell arrest in the G2/M phase of the cell cycle, expression of transforming growth factor-β1 and phosphorylation of Smad3, signal transducer and activator of transcription 3, and extracellular signal-regulated kinase 1/2 in the injured kidney. Moreover, tasquinimod treatment or HDAC4 deletion inhibited UUO-induced renal tubular cell injury and apoptosis as indicated by reduced expression of neutrophil gelatinase-associated lipocalin, Bax, and inhibition of caspase-3. Finally, administration of tasquinimod or knockdown of HDAC4 prevented injury-related repression of Klotho, a renoprotective protein. Our results indicate that HDAC4 is critically involved in renal tubular injury and fibrosis and suggest that HDAC4 is a potential therapeutic target for treatment of chronic fibrotic kidney disease.

Research Progress of Chinese Herbal Medicine Intervention in Renal Interstitial Fibrosis

Chronic kidney diseases usually cause renal interstitial fibrosis, the prevention, delay, and treatment of which is a global research hotspot. However, no definite treatment options are available in modern medicine. Chinese herbal medicine has a long history, rich varieties, and accurate treatment effects. Hitherto, many Chinese herbal medicine studies have emerged to improve renal interstitial fibrosis. This paper reviews the mechanisms of renal interstitial fibrosis and recent studies on the disease intervention with Chinese herbal medicine through literature search, intend to reveal the importance of Chinese herbal medicine in renal interstitial fibrosis. The results show that Chinese herbal medicine can improve renal interstitial fibrosis, and the effects of Chinese herbal medicine on specific pathological mechanisms underlying renal interstitial fibrosis have been explored. Additionally, the limitations and advantages of Chinese herbal medicine in the treatment of renal interstitial fibrosis, possible research directions, and new targets of Chinese herbal medicine are discussed to provide a basis for studies of renal interstitial fibrosis.

Sirtuins and Hypoxia in EMT Control

Epithelial–mesenchymal transition (EMT), a physiological process during embryogenesis, can become pathological in the presence of different driving forces. Reduced oxygen tension or hypoxia is one of these forces, triggering a large number of molecular pathways with aberrant EMT induction, resulting in cancer and fibrosis onset. Both hypoxia-induced factors, HIF-1α and HIF-2α, act as master transcription factors implicated in EMT. On the other hand, hypoxia-dependent HIF-independent EMT has also been described. Recently, a new class of seven proteins with deacylase activity, called sirtuins, have been implicated in the control of both hypoxia responses, HIF-1α and HIF-2α activation, as well as EMT induction. Intriguingly, different sirtuins have different effects on hypoxia and EMT, acting as either activators or inhibitors, depending on the tissue and cell type. Interestingly, sirtuins and HIF can be activated or inhibited with natural or synthetic molecules. Moreover, recent studies have shown that these natural or synthetic molecules can be better conveyed using nanoparticles, representing a valid strategy for EMT modulation. The following review, by detailing the aspects listed above, summarizes the interplay between hypoxia, sirtuins, and EMT, as well as the possible strategies to modulate them by using a nanoparticle-based approach.

Toward Human Models of Cardiorenal Syndrome in vitro

Heart and kidney diseases cause high morbidity and mortality. Heart and kidneys have vital functions in the human body and, interestingly, reciprocally influence each other’s behavior: pathological changes in one organ can damage the other. Cardiorenal syndrome (CRS) is a group of disorders in which there is combined dysfunction of both heart and kidney, but its underlying biological mechanisms are not fully understood. This is because complex, multifactorial, and dynamic mechanisms are likely involved. Effective treatments are currently unavailable, but this may be resolved if more was known about how the disease develops and progresses. To date, CRS has actually only been modeled in mice and rats in vivo. Even though these models can capture cardiorenal interaction, they are difficult to manipulate and control. Moreover, interspecies differences may limit extrapolation to patients. The questions we address here are what would it take to model CRS in vitro and how far are we? There are already multiple independent in vitro (human) models of heart and kidney, but none have so far captured their dynamic organ-organ crosstalk. Advanced in vitro human models can provide an insight in disease mechanisms and offer a platform for therapy development. CRS represents an exemplary disease illustrating the need to develop more complex models to study organ-organ interaction in-a-dish. Human induced pluripotent stem cells in combination with microfluidic chips are one powerful tool with potential to recapitulate the characteristics of CRS in vitro. In this review, we provide an overview of the existing in vivo and in vitro models to study CRS, their limitations and new perspectives on how heart-kidney physiological and pathological interaction could be investigated in vitro for future applications.

Mitochondria preserve an autarkic one-carbon cycle to confer growth-independent cancer cell migration and metastasis

Metastasis is the most common cause of death in cancer patients. Canonical drugs target mainly the proliferative capacity of cancer cells, which leaves slow-proliferating, persistent cancer cells unaffected. Metabolic determinants that contribute to growth-independent functions are still poorly understood. Here we show that antifolate treatment results in an uncoupled and autarkic mitochondrial one-carbon (1C) metabolism during cytosolic 1C metabolism impairment. Interestingly, antifolate dependent growth-arrest does not correlate with decreased migration capacity. Therefore, using methotrexate as a tool compound allows us to disentangle proliferation and migration to profile the metabolic phenotype of migrating cells. We observe that increased serine de novo synthesis (SSP) supports mitochondrial serine catabolism and inhibition of SSP using the competitive PHGDH-inhibitor BI-4916 reduces cancer cell migration. Furthermore, we show that sole inhibition of mitochondrial serine catabolism does not affect primary breast tumor growth but strongly inhibits pulmonary metastasis. We conclude that mitochondrial 1C metabolism, despite being dispensable for proliferative capacities, confers an advantage to cancer cells by supporting their motility potential.

Chemotherapeutic antifolates, such as methotrexate (MTX), impair cancer cell proliferation by inhibiting nucleotide synthesis. Here, the authors show that MTX sustains an autarkic mitochondrial one-carbon metabolism leading to serine synthesis to promote cancer cell migration and metastasis.

Epithelial-mesenchymal transition in organ fibrosis development: current understanding and treatment strategies

Organ fibrosis is a process in which cellular homeostasis is disrupted and extracellular matrix is excessively deposited. Fibrosis can lead to vital organ failure and there are no effective treatments yet. Although epithelial–mesenchymal transition (EMT) may be one of the key cellular mechanisms, the underlying mechanisms of fibrosis remain largely unknown. EMT is a cell phenotypic process in which epithelial cells lose their cell-to-cell adhesion and polarization, after which they acquire mesenchymal features such as infiltration and migration ability. Upon injurious stimulation in different organs, EMT can be triggered by multiple signaling pathways and is also regulated by epigenetic mechanisms. This narrative review summarizes the current understanding of the underlying mechanisms of EMT in fibrogenesis and discusses potential strategies for attenuating EMT to prevent and/or inhibit fibrosis. Despite better understanding the role of EMT in fibrosis development, targeting EMT and beyond in developing therapeutics to tackle fibrosis is challenging but likely feasible.

Thrombospondins in human aortic aneurysms

Thrombospondins are a family of matricellular proteins with a multimeric structure that is known to be involved in several biological and pathological processes. Their relationship with vascular disorders has raised special interest recently. Aortic aneurysms are related to the impairment of vascular remodeling, in which extracellular matrix proteins seem to play an important role. Thus, research in thrombospondins, and their potential role in aneurysm development is progressively gaining importance. Nevertheless, studies showing thrombospondin dysregulation in human samples are still scarce. Although studies performed in vitro and in vivo models are essential to understand the molecular mechanisms and pathways underlying the disorder, descriptive studies in human samples are also necessary to ascertain their real value as biomarkers and/or novel therapeutic targets. The present article reviews the latest findings regarding the role of thrombospondins in aortic aneurysm development, paying particular attention to the studies performed in human samples.

Insights into the cytoprotective potential of Bergenia ligulata against oxalate-induced oxidative stress and epithelial-mesenchymal transition (EMT) via TGFβ1/p38MAPK pathway in human renal epithelial cells

Oxalate exposure to human renal epithelial cells triggers a vicious cycle of oxidative stress leading to cellular injury and deposition of calcium oxalate crystals on the injured cells. This results in further oxidative damage causing inflammation and loss of cell-cell adhesion factors, ultimately leading to irreparable kidney damage. However, these events can be attenuated or prevented by plants rich in antioxidants used in the traditional system of medicine for treatment of kidney stones. To delineate the mechanism by which Bergenia ligulata extract exerts its cytoprotective role in oxalate-induced injury we designed this study. Our results revealed that oxalate-injured HK2 cells cotreated with ethanolic extract of Bergenia ligulata displayed increased viability, reduced oxidative stress due to lowered production of intracellular reactive oxygen species (ROS) and decreased apoptosis. We also observed lowered markers of inflammation, along with increased expression of epithelial marker E-cadherin and decreased expression of mesenchymal markers Vimentin, F-actin, Transforming growth factor beta 1 (TGF-β1) and EMT-related proteins in renal tubular epithelial cells through immunocytochemistry, real-time PCR and western blotting. Our findings collectively suggest that by reducing oxidative stress, modulating crystal structure and preventing crystal-cell adhesion, B. ligulata inhibits the EMT pathway by downregulating the various mediators and thereby exerts its cytoprotective effect.

Connexin32 ameliorates epithelial-to-mesenchymal-transition in diabetic renal tubular via inhibiting NOX4

Renal tubulointerstitial fibrosis (RIF), characterized by epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells (TECs), is the main cause of diabetic renal fibrosis. Oxidative stress plays a pivotal role in the development of diabetic RIF. Connexin32 (Cx32), prominently expressed in renal TECs, has emerged as an important player in the regulation of oxidative stress. However, the role of Cx32 in diabetic RIF has not been explored yet. Here, we showed that adenovirus-mediated Cx32 overexpression suppressed EMT to ameliorate RIF and renal function in STZ-induced diabetic mice, while knockout (KO) of Cx32 exacerbated RIF in diabetic mice. Moreover, overexpression of Cx32 inhibited EMT and the production of extra cellular matrix (ECM) in high glucose (HG) induced NRK-52E cells, whereas knockdown of Cx32 showed the opposite effects. Furthermore, we showed that NOX4, the main source of ROS in renal tubular, was down-regulated by Cx32. Mechanistically, Cx32 down-regulated the expression of PKC alpha in a carboxyl-terminal-dependent manner, thereby inhibiting the phosphorylation at Thr147 of p22phox triggered by PKC alpha, which ultimately repressed the formation of the p22phox-NOX4 complex to reduce the protein level of NOX4. Thus, we establish Cx32 as a novel target and confirm the protection mechanism in RIF.

Iron-Dependent Mitochondrial Dysfunction Contributes to the Pathogenesis of Pulmonary Fibrosis

Although the pathogenesis of pulmonary fibrosis remains unclear, it is known to involve epithelial injury and epithelial-mesenchymal transformation (EMT) as a consequence of cigarette smoke (CS) exposure. Moreover, smoking deposits iron in the mitochondria of alveolar epithelial cells. Iron overload in mitochondria causes the Fenton reaction, leading to reactive oxygen species (ROS) production, and ROS leakage from the mitochondria induces cell injury and inflammation in the lungs. Nevertheless, the mechanisms underlying iron metabolism and pulmonary fibrosis are yet to be elucidated. In this study, we aimed to determine whether iron metabolism and mitochondrial dysfunction are involved in the pathogenesis of pulmonary fibrosis. We demonstrated that administration of the iron chelator deferoxamine (DFO) reduced CS-induced pulmonary epithelial cell death, mitochondrial ROS production, and mitochondrial DNA release. Notably, CS-induced cell death was reduced by the administration of an inhibitor targeting ferroptosis, a unique iron-dependent form of non-apoptotic cell death. Transforming growth factor-β-induced EMT of pulmonary epithelial cells was also reduced by DFO. The preservation of mitochondrial function reduced Transforming growth factor-β-induced EMT. Furthermore, transbronchial iron chelation ameliorated bleomycin-induced pulmonary fibrosis and leukocyte migration in a murine model. Our findings indicate that iron metabolism and mitochondrial dysfunction are involved in the pathogenesis of pulmonary fibrosis. Thus, they may be leveraged as new therapeutic targets for pulmonary fibrosis.

Targeting Oxidative Stress as a Therapeutic Approach for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease characterized by an abnormal reepithelialisation, an excessive tissue remodelling and a progressive fibrosis within the alveolar wall that are not due to infection or cancer. Oxidative stress has been proposed as a key molecular process in pulmonary fibrosis development and different components of the redox system are altered in the cellular actors participating in lung fibrosis. To this respect, several activators of the antioxidant machinery and inhibitors of the oxidant species and pathways have been assayed in preclinical in vitro and in vivo models and in different clinical trials. This review discusses the role of oxidative stress in the development and progression of IPF and its underlying mechanisms as well as the evidence of oxidative stress in human IPF. Finally, we analyze the mechanism of action, the efficacy and the current status of different drugs developed to inhibit the oxidative stress as anti-fibrotic therapy in IPF.

TGF-β/Smad signaling pathway plays a crucial role in patulin-induced pro-fibrotic changes in rat kidney via modulation of slug and snail expression

Patulin (PAT) is a mycotoxin that contaminates a variety of food and foodstuffs. Earlier in vitro and in vivo findings have indicated that kidney is one of the target organs for PAT-induced toxicity. However, no study has evaluated the chronic effects of PAT exposure at environmentally relevant doses or elucidated the detailed mechanism(s) involved. Here, using in vitro and in vivo experimental approaches, we delineated the mechanism/s involved in pro-fibrotic changes in the kidney after low-dose chronic exposure to PAT. We found that non-toxic concentrations (50 nM and 100 nM) of PAT to normal rat kidney cells (NRK52E) caused a higher generation of reactive oxygen species (ROS) (mainly hydroxyl (•OH), peroxynitrite (ONOO^-), and hypochlorite radical (ClO-). PAT exposure caused the activation of mitogen-activated protein kinases (MAPKs) and its downstream c-Jun/Fos signaling pathways. Moreover, our chromatin immunoprecipitation (ChIP) analysis suggested that c-Jun/Fos binds to the promoter region of Transforming growth factor beta (TGF-β₁) and possibly induces its expression. Results showed that PAT-induced TGF-β₁ further activates the TGF-β₁/smad signaling pathways. Higher activation of slug and snail transcription factors further modulates the regulation of pro-fibrotic molecules. Similarly, in vivo results showed that PAT exposure to rats through gavage at 25 and 100 μg/kg b. wt had higher levels of kidney injury/toxicity markers namely vascular endothelial growth factor (VEGF), kidney Injury Molecule-1 (Kim-1), tissue inhibitor of metalloproteinase-1 (Timp-1), and clusterin (CLU). Additionally, histopathological analysis indicated significant alterations in renal tubules and glomeruli along with collagen deposition in PAT-treated rat kidneys. Overall, our data provide evidence of the involvement of ROS mediated MAPKs and TGF-β₁/smad pathways in PAT-induced pro-fibrotic changes in the kidney via modulation of slug and snail expression.

Reactive Oxygen Species: Do They Play a Role in Adaptive Immunity?

The immune system protects the host from a plethora of microorganisms and toxins through its unique ability to distinguish self from non-self. To perform this delicate but essential task, the immune system relies on two lines of defense. The innate immune system, which is by nature fast acting, represents the first line of defense. It involves anatomical barriers, physiological factors as well as a subset of haematopoietically-derived cells generically call leukocytes. Activation of the innate immune response leads to a state of inflammation that serves to both warn about and combat the ongoing infection and delivers the antigenic information of the invading pathogens to initiate the slower but highly potent and specific second line of defense, the adaptive immune system. The adaptive immune response calls on T lymphocytes as well as the B lymphocytes essential for the elimination of pathogens and the establishment of the immunological memory. Reactive oxygen species (ROS) have been implicated in many aspects of the immune responses to pathogens, mostly in innate immune functions, such as the respiratory burst and inflammasome activation. Here in this mini review, we focus on the role of ROS in adaptive immunity. We examine how ROS contribute to T-cell biology and discuss whether this activity can be extrapolated to B cells.

Chronic Hematuria Increases Chronic Kidney Injury and Epithelial-Mesenchymal Transition in 5/6 Nephrectomy Rats

Chronic kidney disease (CKD) is a common outcome of many kidney diseases. Interstitial fibrosis and tubular atrophy (IFTA) is a histologic hallmark of CKD. Hematuria is a common symptom in many human kidney diseases. Free hemoglobin may affect tubular epithelial cells by generating reactive oxygen species (ROS). Epithelial–mesenchymal transition (EMT) of the tubular epithelial cells has been shown to play an important role in the IFTA development. The aim of this study was to determine the effects of chronic hematuria on the CKD progression in 5/6 nephrectomy (5/6NE) rat model of CKD. 5/6 NE rats were treated with oral warfarin (0.5 mg/kg/day) or vehicle (control). The animals were monitored for 26 weeks, while prothrombin time (PT), serum creatinine (SCr), and hematuria were measured weekly. Staining for iron, trichrome, and EMT (vimentin, E-cadherin, smooth muscle actin) markers was performed on the remnant kidneys. ROS were detected in the kidneys by protein carbonyl assay and immunohistochemistry for heme oxygenase 1 (HMOX1), at the end of the study. Apoptosis was detected by TUNEL assay. Warfarin treatment resulted in a PT increase 1.5–2.5 times from control and an increase in hematuria and SCr. Histologically, warfarin-treated animals had more iron-positive tubular epithelial cells and increased IFTA as compared to control (42.9 ± 17% vs. 18.3 ± 2.6%). ROS were increased in the kidney in warfarin-treated rats. The number of tubules that show evidence of EMT was significantly higher in warfarin-treated 5/6NE as compared to control 5/6NE rats. The number of apoptotic tubular epithelial cells was higher in warfarin-treated 5/6 NE rats. Chronic hematuria results in increased iron-positive tubular epithelial cells, EMT, apoptosis, and more prominent IFTA in CKD rats. Our data suggest an important role of chronic hematuria in the progression of CKD.

Correlation between Oxidative Stress and Transforming Growth Factor-Beta in Cancers

The downregulation of reactive oxygen species (ROS) facilitates precancerous tumor development, even though increasing the level of ROS can promote metastasis. The transforming growth factor-beta (TGF-β) signaling pathway plays an anti-tumorigenic role in the initial stages of cancer development but a pro-tumorigenic role in later stages that fosters cancer metastasis. TGF-β can regulate the production of ROS unambiguously or downregulate antioxidant systems. ROS can influence TGF-β signaling by enhancing its expression and activation. Thus, TGF-β signaling and ROS might significantly coordinate cellular processes that cancer cells employ to expedite their malignancy. In cancer cells, interplay between oxidative stress and TGF-β is critical for tumorigenesis and cancer progression. Thus, both TGF-β and ROS can develop a robust relationship in cancer cells to augment their malignancy. This review focuses on the appropriate interpretation of this crosstalk between TGF-β and oxidative stress in cancer, exposing new potential approaches in cancer biology.

β-Endosulfan-mediated induction of pro-fibrotic markers in renal (HK-2) cells in vitro: A new insight in the pathogenesis of chronic kidney disease of unknown etiology

Chronic kidney disease of unknown etiology (CKDu), manifested clinically as tubulo interstitial fibrosis, has emerged as the second major cause of chronic kidney disease (CKD) in the Indian subcontinent and various agrochemicals have been implicated in its occurance. Among the agrochemicals organochlorine pesticides particularly endosulfan is well known for its toxicity and recent residue analysis have shown its presence in the blood samples of general population. In this present study, we have investigated the consequences of endosulfan exposure at a concentration (0.01 μM) equivalent to their highest reported presence in human blood sample of some CKDu patients, to human renal proximal tubular epithelial (HK-2) cell line with regard to ROS generation and expression of profibrotic and epithelial to mesenchymal (EMT) markers in order to find out endosulfan's ability to induce profibrotic changes in renal cell. We demonstrated a significant increase in intracellular ROS generation and increased expression of TGF-β1 when cells were incubated with β-endosulfan (0.01 μM) indicating occurrence of oxidative stress and fibrotic process. Again, decreased expression of epithelial marker E-cadherin and increase in the expression of mesenchymal marker α-smooth muscle actin (α-SMA) suggest possible onset of EMT process. Pre-treatment with 5 mM concentration of anti-oxidant N-acetyl cysteine partially attenuated the above process. In conclusion, these findings suggest possible involvement of β-endosulfan in the development of CKDu through oxidative stress and profibrotic signaling.

Therapeutic effect of neohesperidin on TNF-α-stimulated human rheumatoid arthritis fibroblast-like synoviocytes

During the pathogensis of rheumatoid arthritis (RA), activated RA fibroblast-like synoviocytes (RA-FLSs) combines similar proliferative features as tumor and inflammatory features as osteoarthritis, which eventually leads to joint erosion. Therefore, it is imperative to research and develop new compounds, which can effectively inhibit abnormal activation of RA-FLSs and retard RA progression. Neohesperidin (Neo) is a major active component of flavonoid compounds with anti-inflammation and anti-oxidant properties. In this study, the anti-inflammation, anti-migration, anti-invasion, anti-oxidant and apoptosis-induced effects of Neo on RA-FLSs were explored to investigate the underlying mechanism. The results suggested that Neo decreased the levels of interleukin IL-1β, IL-6, IL-8, TNF-α, MMP-3, MMP-9 and MMP-13 in FLSs. Moreover, Neo blocked the activation of the MAPK signaling pathway. Furthermore, treatment with Neo induced the apoptosis of FLSs, and inhibited the migration of FLSs. It was also found that Neo reduced the accumulation of reactive oxygen species (ROS) induced by TNF-α. Taken together, our results highlighted that Neo may act as a potential and promising therapeutic drug for the management of RA.

Nano-Graphene Oxide-Promoted Epithelial-Mesenchymal Transition of Human Retinal Pigment Epithelial Cells through Regulation of Phospholipase D Signaling

Nano-graphene oxide (Nano-GO) is an extensively studied multifunctional carbon nanomaterial with attractive applications in biomedicine and biotechnology. However, few studies have been conducted to assess the epithelial-to-mesenchymal transition (EMT) in the retinal pigment epithelium (RPE). We aimed to determine whether Nano-GO induces EMT by regulating phospholipase D (PLD) signaling in human RPE (ARPE-19) cells. The physicochemical characterization of Nano-GO was performed using a Zetasizer, X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy. RPE cell viability assays were performed, and the migratory effects of RPE cells were evaluated. RPE cell collagen gel contraction was also determined. Intracellular reactive oxygen species (ROS) levels were determined by fluorescence microscopy and flow cytometry. Immunofluorescence staining and western blot analysis were used to detect EMT-related protein expression. Phospholipase D (PLD) enzymatic activities were also measured. Nano-GO significantly enhanced the scratch-healing ability of RPE cells, indicating that the RPE cell migration ability was increased. Following Nano-GO treatment, the RPE cell penetration of the chamber was significantly promoted, suggesting that the migratory ability was strengthened. We also observed collagen gel contraction and the generation of intracellular ROS in RPE cells. The results showed that Nano-GO induced collagen gel contraction and intracellular ROS production in RPE cells. Moreover, immunofluorescence staining and western blot analysis revealed that Nano-GO significantly regulated key molecules of EMT, including epithelial-cadherin, neural-cadherin, α-smooth muscle actin, vimentin, and matrix metalloproteinases (MMP-2 and MMP-9). Interestingly, Nano-GO-induced RPE cell migration and intracellular ROS production were abrogated in PLD-knockdown RPE cells, indicating that PLD activation played a crucial role in the Nano-GO-induced RPE EMT process. We demonstrate for the first time that Nano-GO promotes RPE cell migration through PLD-mediated ROS production. We provide preliminary evidence to support the hypothesis that Nano-GO has adverse health effects related to RPE damage.

Redox signaling pathways in unilateral ureteral obstruction (UUO)-induced renal fibrosis

Unilateral ureteral obstruction (UUO) is an experimental rodent model that mimics renal fibrosis associated with obstructive nephropathy in an accelerated manner. After UUO, the activation of the renin-angiotensin system (RAS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) and mitochondrial dysfunction lead to reactive oxygen species (ROS) overproduction in the kidney. ROS are secondary messengers able to induce post-translational modifications (PTMs) in redox-sensitive proteins, which activate or deactivate signaling pathways. Therefore, in UUO, it has been proposed that ROS overproduction causes changes in said pathways promoting inflammation, oxidative stress, and apoptosis that contribute to fibrosis development. Furthermore, mitochondrial metabolism impairment has been associated with UUO, contributing to renal damage in this model. Although ROS production and oxidative stress have been studied in UUO, the development of renal fibrosis associated with redox signaling pathways has not been addressed. This review focuses on the current information about the activation and deactivation of signaling pathways sensitive to a redox state and their effect on mitochondrial metabolism in the fibrosis development in the UUO model.