TWEAK, a multifunctional cytokine in kidney injury. Kidney Int. 2011;80:708-718. [PMID: 21697814 DOI: 10.1038/ki.2011.180]

Protein crotonylation: Basic research and clinical diseases

Crotonylation is an importantly conserved post-translational modification, which is completely different from acetylation. In recent years, it has been confirmed that crotonylation occurs on histone and non-histone. Crotonylated Histone primarily affects gene expression through transcriptional regulation, while non-histone Crotonylation mainly regulates protein functions including protein activity, localization, and stability, as well as protein-protein interactions. The change in protein expression and function will affect the physiological process of cells and even cause disease. Reviewing previous studies, this article summarizes the mechanisms of histone and non-histone crotonylation in regulating diseases and cellular physiological processes to explore the possibility of precise regulation of crotonylation sites as potential targets for disease treatment.

Transcriptome Analysis of BAFF/BAFF-R System in Murine Nephrotoxic Serum Nephritis

Chronic kidney disease (CKD) is an emerging cause for morbidity and mortality worldwide. Acute kidney injury (AKI) can transition to CKD and finally to end-stage renal disease (ESRD). Targeted treatment is still unavailable. NF-κB signaling is associated with CKD and activated by B cell activating factor (BAFF) via BAFF-R binding. In turn, renal tubular epithelial cells (TECs) are critical for the progression of fibrosis and producing BAFF. Therefore, the direct involvement of the BAFF/BAFF-R system to the pathogenesis of CKD is conceivable. We performed non-accelerated nephrotoxic serum nephritis (NTN) as the CKD model in BAFF KO (B6.129S2-Tnfsf13btm1Msc/J), BAFF-R KO (B6(Cg)-Tnfrsf13ctm1Mass/J) and wildtype (C57BL/6J) mice to analyze the BAFF/BAFF-R system in anti-glomerular basement membrane (GBM) disease using high throughput RNA sequencing. We found that BAFF signaling is directly involved in the upregulation of collagen III as BAFF ko mice showed a reduced expression. However, these effects were not mediated via BAFF-R. We identified several upregulated genes that could explain the effects of BAFF in chronic kidney injury such as Txnip, Gpx3, Igfbp7, Ccn2, Kap, Umod and Ren1. Thus, we conclude that targeted treatment with anti-BAFF drugs such as belimumab may reduce chronic kidney damage. Furthermore, upregulated genes may be useful prognostic CKD biomarkers.

Combined Plasma Olink Proteomics and Transcriptomics Identifies CXCL1 and TNFRSF12A as Potential Predictive and Diagnostic Inflammatory Markers for Acute Kidney Injury

Acute kidney injury (AKI) poses a significant global public health challenge. Current methods for detecting AKI rely on monitoring changes in serum creatinine (Scr), blood urea nitrogen (BUN), urinary output and some commonly employed biomarkers. However, these indicators are usually neither specific nor sensitive to AKI, especially in cases of mild kidney injury. AKI is accompanied by severe inflammatory reactions, resulting in the upregulation of numerous inflammation-associated proteins in the plasma. Plasma biomarkers are a noninvasive method for detecting kidney injury, and to date, plasma inflammation-associated cytokines have not been adequately studied in AKI patients. The objective of our research was to identify novel inflammatory biomarkers for AKI. We utilized Olink proteomics to analyze the alterations in plasma inflammation-related proteins in the serum of healthy mice (n = 2) or mice treated with cisplatin (n = 6). Additionally, transcriptome datasets for the lipopolysaccharide (LPS), cisplatin, and ischemia‒reperfusion injury (IRI) groups were obtained from the National Center of Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database. We calculated the intersection of differentially expressed proteins (DEPs) and genes (DEGs) from both datasets. In the Olink proteomics analysis, the AKI group had significantly greater levels of 11 DEPs than did the control group. In addition, 56 common upregulated DEGs were obtained from the transcriptome dataset. The expression of CXCL1 and TNFRSF12A overlapped across all the datasets. The transcription and protein expression levels of CXCL1 and TNFRSF12A were detected in vivo. The gene and protein levels of CXCL1 and TNFRSF12A were significantly increased in different AKI mouse models and clinical patients, suggesting that these genes and proteins could be potential specific biomarkers for the identification of AKI.

Retrospective cohort study to evaluate the continuous use of anticholesterolemics and diuretics in patients with COVID-19

Purpose

The purpose of this study is to evaluate the interference of the continuous use of drug classes in the expression of biomarkers during the first week of hospitalization and in the prognosis of patients with COVID-19.

Methods

The patients diagnosed with COVID-19 and confirmed with SARS-CoV-2 by RT-qPCR assay underwent the collection of fasting whole blood samples for further analysis. Other data also extracted for this study included age, sex, clinical symptoms, related comorbidities, smoking status, and classes of continuous use. Routine serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, C-reactive protein, N-terminal fragment of B-type natriuretic peptide, and cardiac troponin, were measured.

Results

In this cross-sectional study, a total of 176 patients with COVID-19 hospitalizations were included. Among them, 155 patients were discharged (88.5%), and 21 patients died (12%). Among the drug classes evaluated, we verified that the continuous use of diuretic 4.800 (1.853-11.67) (p = 0.0007) and antihypercholesterolemic 3.188 (1.215-7.997) (p = 0.0171) drug classes presented a significant relative risk of death as an outcome when compared to the group of patients who were discharged. We evaluated biomarkers in patients who used continuous antihypercholesterolemic and diuretic drug classes in the first week of hospitalization. We observed significant positive correlations between the levels of CRP with cardiac troponin (r = 0.714), IL-6 (r = 0.600), and IL-10 (r = 0.900) in patients who used continuous anticholesterolemic and diuretic drug classes and were deceased. In these patients, we also evaluated the possible correlations between the biomarkers AST, NT-ProBNP, cardiac troponin, IL-6, IL-8, and IL-10. We observed a significantly negative correlations in AST levels with NT-ProBNP (r = -0.500), cardiac troponin (r = -1.00), IL-6 (r = -1.00), and IL-10 (r = -1.00) and a positive correlation with IL-8 (r = 0.500). We also observed significant negative correlation in the levels of NT-ProBNP with IL-10 (r = -0.800) and a positive correlation with cardiac troponin (r = 0.800). IL-6 levels exhibited positive correlations with cardiac troponin (r = 0.800) and IL-10 (r = 0.700).

Conclusion

In this study, we observed that hospitalized COVID-19 patients who continued using anticholesterolemic and diuretic medications showed a higher number of correlations between biomarkers, indicating a poorer clinical prognosis. These correlations suggest an imbalanced immune response to injuries caused by SARS-CoV-2.

Tweak/Fn14 system is involved in rhabdomyolysis-induced acute kidney injury

BACKGROUND

Rhabdomyolysis is a severe clinical syndrome associated to acute kidney injury (AKI) and chronic kidney disease (CKD). TWEAK/Fn14 signaling axis regulates renal inflammation and tubular cell death. However, the functional role of TWEAK/Fn14 in rhabdomyolysis remains unknown.

METHODS

Rhabdomyolysis was induced in wild-type, TWEAK- and Fn14-deficient mice or mice treated with TWEAK blocking antibody. Renal injury, inflammation, fibrosis and cell death were assessed. Additionally, we performed in vivo and in vitro studies to explore the possible signalling pathways involved in Fn14 regulation.

FINDINGS

Fn14 renal expression was increased in mice with rhabdomyolysis, correlating with decline of renal function. Mechanistically, myoglobin (Mb) induced Fn14 expression via ERK and p38 pathway, whereas Nrf2 activation diminished Mb-mediated Fn14 upregulation in cultured renal cells. TWEAK or Fn14 genetic depletion ameliorated rhabdomyolysis-associated loss of renal function, histological damage, tubular cell death, inflammation, and expression of both tubular and endothelial injury markers. Deficiency of TWEAK or Fn14 also decreased long-term renal inflammation and fibrosis in mice with rhabdomyolysis. Finally, pharmacological treatment with a blocking TWEAK antibody diminished the expression of acute renal injury markers and cell death and lessened residual kidney fibrosis and chronic inflammation in rhabdomyolysis.

INTERPRETATION

TWEAK/Fn14 axis participates in the pathogenesis of rhabdomyolysis-AKI and subsequent AKI-CKD transition. Blockade of this signaling pathway may represent a promising therapeutic strategy for reducing rhabdomyolysis-mediated renal injury.

FUNDING

Spanish Ministry of Science and Innovation, ISCIII and Junta de Andalucía.

Targeting the TWEAK-Fn14 pathway prevents dysfunction in cardiac calcium handling after acute kidney injury

Heart and kidney have a closely interrelated pathophysiology. Acute kidney injury (AKI) is associated with significantly increased rates of cardiovascular events, a relationship defined as cardiorenal syndrome type 3 (CRS3). The underlying mechanisms that trigger heart disease remain, however, unknown, particularly concerning the clinical impact of AKI on cardiac outcomes and overall mortality. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor fibroblast growth factor-inducible 14 (Fn14) are independently involved in the pathogenesis of both heart and kidney failure, and recent studies have proposed TWEAK as a possible therapeutic target; however, its specific role in cardiac damage associated with CRS3 remains to be clarified. Firstly, we demonstrated in a retrospective longitudinal clinical study that soluble TWEAK plasma levels were a predictive biomarker of mortality in patients with AKI. Furthermore, the exogenous application of TWEAK to native ventricular cardiomyocytes induced relevant calcium (Ca2+ ) handling alterations. Next, we investigated the role of the TWEAK-Fn14 axis in cardiomyocyte function following renal ischaemia-reperfusion (I/R) injury in mice. We observed that TWEAK-Fn14 signalling was activated in the hearts of AKI mice. Mice also showed significantly altered intra-cardiomyocyte Ca2+ handling and arrhythmogenic Ca2+ events through an impairment in sarcoplasmic reticulum Ca2+ -adenosine triphosphatase 2a pump (SERCA2a ) and ryanodine receptor (RyR2 ) function. Administration of anti-TWEAK antibody after reperfusion significantly improved alterations in Ca2+ cycling and arrhythmogenic events and prevented SERCA2a and RyR2 modifications. In conclusion, this study establishes the relevance of the TWEAK-Fn14 pathway in cardiac dysfunction linked to CRS3, both as a predictor of mortality in patients with AKI and as a Ca2+ mishandling inducer in cardiomyocytes, and highlights the cardioprotective benefits of TWEAK targeting in CRS3. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Emerging significance and therapeutic targets of ferroptosis: a potential avenue for human kidney diseases

Kidney diseases remain one of the leading causes of human death and have placed a heavy burden on the medical system. Regulated cell death contributes to the pathology of a plethora of renal diseases. Recently, with in-depth studies into kidney diseases and cell death, a new iron-dependent cell death modality, known as ferroptosis, has been identified and has attracted considerable attention among researchers in the pathogenesis of kidney diseases and therapeutics to treat them. The majority of studies suggest that ferroptosis plays an important role in the pathologies of multiple kidney diseases, such as acute kidney injury (AKI), chronic kidney disease, and renal cell carcinoma. In this review, we summarize recently identified regulatory molecular mechanisms of ferroptosis, discuss ferroptosis pathways and mechanisms of action in various kidney diseases, and describe the protective effect of ferroptosis inhibitors against kidney diseases, especially AKI. By summarizing the prominent roles of ferroptosis in different kidney diseases and the progress made in studying ferroptosis, we provide new directions and strategies for future research on kidney diseases. In summary, ferroptotic factors are potential targets for therapeutic intervention to alleviate different kidney diseases, and targeting them may lead to new treatments for patients with kidney diseases.

Mitochondrial Dysfunction in the Cardio-Renal Axis

Cardiovascular disease (CVD) frequently complicates chronic kidney disease (CKD). The risk of all-cause mortality increases from 20% to 500% in patients who suffer both conditions; this is referred to as the so-called cardio-renal syndrome (CRS). Preclinical studies have described the key role of mitochondrial dysfunction in cardiovascular and renal diseases, suggesting that maintaining mitochondrial homeostasis is a promising therapeutic strategy for CRS. In this review, we explore the malfunction of mitochondrial homeostasis (mitochondrial biogenesis, dynamics, oxidative stress, and mitophagy) and how it contributes to the development and progression of the main vascular pathologies that could be affected by kidney injury and vice versa, and how this knowledge may guide the development of novel therapeutic strategies in CRS.

Fibrosis of Peritoneal Membrane, Molecular Indicators of Aging and Frailty Unveil Vulnerable Patients in Long-Term Peritoneal Dialysis

Peritoneal membrane status, clinical data and aging-related molecules were investigated as predictors of long-term peritoneal dialysis (PD) outcomes. A 5-year prospective study was conducted with the following endpoints: (a) PD failure and time until PD failure, (b) major cardiovascular event (MACE) and time until MACE. A total of 58 incident patients with peritoneal biopsy at study baseline were included. Peritoneal membrane histomorphology and aging-related indicators were assessed before the start of PD and investigated as predictors of study endpoints. Fibrosis of the peritoneal membrane was associated with MACE occurrence and earlier MACE, but not with the patient or membrane survival. Serum α-Klotho bellow 742 pg/mL was related to the submesothelial thickness of the peritoneal membrane. This cutoff stratified the patients according to the risk of MACE and time until MACE. Uremic levels of galectin-3 were associated with PD failure and time until PD failure. This work unveils peritoneal membrane fibrosis as a window to the vulnerability of the cardiovascular system, whose mechanisms and links to biological aging need to be better investigated. Galectin-3 and α-Klotho are putative tools to tailor patient management in this home-based renal replacement therapy.

TWEAK-Fn14-RelB Signaling Cascade Promotes Stem Cell-like Features that Contribute to Post-Chemotherapy Ovarian Cancer Relapse

Disease recurrence in high-grade serous ovarian cancer may be due to cancer stem-like cells (CSC) that are resistant to chemotherapy and capable of reestablishing heterogeneous tumors. The alternative NF-κB signaling pathway is implicated in this process; however, the mechanism is unknown. Here we show that TNF-like weak inducer of apoptosis (TWEAK) and its receptor, Fn14, are strong inducers of alternative NF-κB signaling and are enriched in ovarian tumors following chemotherapy treatment. We further show that TWEAK enhances spheroid formation ability, asymmetric division capacity, and expression of SOX2 and epithelial-to-mesenchymal transition genes VIM and ZEB1 in ovarian cancer cells, phenotypes that are enhanced when TWEAK is combined with carboplatin. Moreover, TWEAK in combination with chemotherapy induces expression of the CSC marker CD117 in CD117- cells. Blocking the TWEAK-Fn14-RelB signaling cascade with a small-molecule inhibitor of Fn14 prolongs survival following carboplatin chemotherapy in a mouse model of ovarian cancer. These data provide new insights into ovarian cancer CSC biology and highlight a signaling axis that should be explored for therapeutic development.

IMPLICATIONS

This study identifies a unique mechanism for the induction of ovarian cancer stem cells that may serve as a novel therapeutic target for preventing relapse.

Ginkgolide A downregulates transient receptor potential (melastatin) 2 to protect cisplatin-induced acute kidney injury in rats through the TWEAK/Fn14 pathway: Ginkgolide A improve acute renal injury

PURPOSE

In order to seek effective drugs for treating cisplatin-induced acute renal injury and explore the corresponding potential mechanism.

METHODS

Mouse kidney injury model was established by intraperitoneal injection of 20 mg/kg cisplatin. The temporal expression of TRPM2 and the regulation of Ginkgolide A on its expression were analyzed by western blot. In order to perform the mechanical analysis, we used TRPM2-KO knockout mice. In this study, we evaluated the repair effect of GA on acute kidney injury through renal function factors, inflammatory factors and calcium and potassium content. Pathological injury and cell apoptosis were detected by H&E and TUNEL, respectively.

RESULT

Ginkgolide A inhibited inflammatory reaction and excessive oxidative stress, reduced renal function parameters, and improved pathological injury. Meanwhile, we also found that the repair effect of Ginkgolide A on renal injury is related to TRPM2, and Ginkgolide A downregulated TRPM2 expression and inactivated TWEAK/Fn14 pathway in cisplatin-induced renal injury model. We also found that inhibition of TWEAK/Fn14 pathway was more effective in TRPM2-KO mice than TRPM2-WT mice.

CONCLUSION

Ginkgolide A was the effective therapeutic drug for cisplatin-induced renal injury through acting on TRPM2, and TWEAK/Fn14 pathway was the downstream pathway of Ginkgolide A in acute renal injury, and Ginkgolide A inhibited TWEAK/Fn14 pathway in cisplatin-induced renal injury model.

Cellular Landscapes of Nondiseased Human Cardiac Valves From End-Stage Heart Failure-Explanted Heart

BACKGROUND

Exploring the mechanisms of valvular heart disease at the cellular level may be useful to identify new therapeutic targets; however, the comprehensive cellular landscape of nondiseased human cardiac valve leaflets remains unclear.

METHODS

The cellular landscapes of nondiseased human cardiac valve leaflets (5 aortic valves, 5 pulmonary valves, 5 tricuspid valves, and 3 mitral valves) from end-stage heart failure patients undergoing heart transplantation were explored using single-cell RNA sequencing. Bioinformatics was used to identify the cell types, describe the cell functions, and investigate cellular developmental trajectories and interactions. Differences among the 4 types of cardiac valves at the cellular level were summarized. Pathological staining was performed to validate the key findings of single-cell RNA sequencing. An integrative analysis of our single-cell data and published genome-wide association study-based and bulk RNA sequencing-based data provided insights into the cell-specific contributions to calcific aortic valve diseases.

RESULTS

Six cell types were identified among 128 412 cells from nondiseased human cardiac valve leaflets. Valvular interstitial cells were the largest population, followed by myeloid cells, lymphocytes, valvular endothelial cells, mast cells, and myofibroblasts. The 4 types of cardiac valve had distinct cellular compositions. The intercellular communication analysis revealed that valvular interstitial cells were at the center of the communication network. The integrative analysis of our single-cell RNA sequencing data revealed key cellular subpopulations involved in the pathogenesis of calcific aortic valve diseases.

CONCLUSIONS

The cellular landscape differed among the 4 types of nondiseased cardiac valve, which might explain their differences in susceptibility to pathological remodeling and valvular heart disease.

The Evolution of Hypovolemic and Euvolemic Hyponatremia Coincides with an Inflammatory Status in Patients with COVID-19: An Observational Cohort Study

We evaluated the hospital evolution of hyponatremia and inflammation markers in patients with coronavirus disease 2019 (COVID-19). The hospital evolutions of a cohort of adult patients with COVID-19 pneumonia and hyponatremia were retrospectively analyzed. Data of the admission day, 2nd–3rd and 7th–10th day of hospitalization, and of the discharge day were collected. Comparative and multivariate analyzes were developed, and Hazzard ratio (HR) with 95% confidence intervals (95% CI) were calculated. Of the 172 hospitalized patients with COVID-19, 49 of them (28.5%) had hyponatremia, which were analyzed. A total of 32/49 (65.3%) patients were male, and 22/49 (44.9%) euvolemic. Mean age: 69.9 ± 14.7 years. All patients had high inflammatory markers at admission. Of the total patients with hyponatremia at admission, only 26.2% remained hyponatremic at the 7th–10th day of hospitalization. Improvement in serum sodium (SNa) coincided with improvement in inflammatory markers during hospitalization, in both euvolemic and hypovolemic hyponatremic patients. A higher serum creatinine at admission was independently associated with mortality (HR: 12.23, 95% CI: 2 to 25.6) in hyponatremic COVID-19 patients. In conclusion, both hypovolemic and euvolemic hyponatremia in COVID-19 patients occurred in an inflammation status, and improved as inflammation decreased.

Crosstalk between TBK1/IKKε and the type I interferon pathway contributes to tubulointerstitial inflammation and kidney tubular injury

The type I interferon (TI-IFN) pathway regulates innate immunity, inflammation, and apoptosis during infection. However, the contribution of the TI-IFN pathway or upstream signaling pathways to tubular injury in kidney disease is poorly understood. Upon observing evidence of activation of upstream regulators of the TI-IFN pathway in a transcriptomics analysis of murine kidney tubulointerstitial injury, we have now addressed the impact of the TI-IFN and upstream signaling pathways on kidney tubulointerstitial injury. In cultured tubular cells and kidney tissue, IFNα/β binding to IFNAR activated the TI-IFN pathway and recruited antiviral interferon-stimulated genes (ISG) and NF-κB-associated proinflammatory responses. TWEAK and lipopolysaccharide (LPS) signaled through TBK1/IKKε and IRF3 to activate both ISGs and NF-κB. In addition, TWEAK recruited TLR4 to stimulate TBK1/IKKε-dependent ISG and inflammatory responses. Dual pharmacological inhibition of TBK1/IKKε with amlexanox decreased TWEAK- or LPS-induced ISG and cytokine responses, as well as cell death induced by a complex inflammatory milieu that included TWEAK. TBK1 or IRF3 siRNA prevented the TWEAK-induced ISG and inflammatory gene expression while IKKε siRNA did not. In vivo, kidney IFNAR and IFNβ were increased in murine LPS and folic acid nephrotoxicity while IFNAR was increased in human kidney biopsies with tubulointerstitial damage. Inhibition of TBK1/IKKε with amlexanox or IFNAR neutralization decreased TI-IFN pathway activation and protected from kidney injury induced by folic acid or LPS. In conclusion, TI-IFNs, TWEAK, and LPS engage interrelated proinflammatory and antiviral responses in tubular cells. Moreover, inhibition of TBK1/IKKε with amlexanox, and IFNAR targeting, may protect from tubulointerstitial kidney injury.

Hyponatremia and SARS-CoV-2 infection: A narrative review

A novel rapid spreading and changing virus called SARS-CoV-2 appeared in Wuhan city in December 2019. It was announced by the World Health Organization (WHO) as a pandemic disease in March 2020. It commonly presents with respiratory symptoms; however, it may be asymptomatic. Electrolyte abnormalities are not uncommon features of SARS-CoV-2 infection. Hyponatremia is one of these electrolyte disturbances among SARS-CoV-2 patients, and it may produce symptoms such as weakness and seizure as the initial presenting symptoms. The underlying mechanism(s) of hyponatremia due to SARS-CoV-2 infection is (are) not established. The aim of this review is to evaluate the possible mechanism of hyponatremia in patients with COVID-19. Understanding and categorizing the hyponatremia in these patients will lead to better treatment and correction of the hyponatremia. A review of the literature between December 2019 and March 2022 was conducted searching for the possible reported mechanism(s) of hyponatremia in SARS-CoV-2. Although SIADH is the commonly reported cause of hyponatremia in SARS-CoV-2 infection, other causes such as diarrhea, vomiting, and kidney salt loss must be considered before SIADH.

Fn14 exacerbates acute lung injury by activating the NLRP3 inflammasome in mice

BACKGROUND

Uncontrolled inflammation is an important factor in the occurrence and development of acute lung injury (ALI). Fibroblast growth factor-inducible 14 (Fn14), a plasma membrane-anchored receptor, takes part in the pathological process of a variety of acute and chronic inflammatory diseases. However, the role of Fn14 in ALI has not yet been elucidated. This study aimed to investigate whether the activation of Fn14 exacerbated lipopolysaccharide (LPS)-induced ALI in mice.

METHODS

In vivo, ALI was induced by intratracheal LPS-challenge combined with/without Fn14 receptor blocker aurintricarboxylic acid (ATA) treatment in C57BL/6J mice. Following LPS administration, the survival rate, lung tissue injury, inflammatory cell infiltration, inflammatory factor secretion, oxidative stress, and NLRP3 inflammasome activation were assessed. In vitro, primary murine macrophages were used to evaluate the underlying mechanism by which Fn14 activated the NLRP3 inflammasome. Lentivirus was used to silence Fn14 to observe its effect on the activation of NLRP3 inflammasome in macrophages.

RESULTS

In this study, we found that Fn14 expression was significantly increased in the lungs of LPS-induced ALI mice. The inhibition of Fn14 with ATA downregulated the protein expression of Fn14 in the lungs and improved the survival rate of mice receiving a lethal dose of LPS. ATA also attenuated lung tissue damage by decreasing the infiltration of macrophages and neutrophils, reducing inflammation, and suppressing oxidative stress. Importantly, we found that ATA strongly inhibited the activation of NLRP3 inflammasome in the lungs of ALI mice. Furthermore, in vitro, TWEAK, a natural ligand of Fn14, amplified the activation of NLRP3 inflammasome in the primary murine macrophage. By contrast, inhibition of Fn14 with shRNA decreased the expression of Fn14, NLRP3, Caspase-1 p10, and Caspase-1 p20, and the production of IL-1β and IL-18. Furthermore, the activation of Fn14 promoted the production of reactive oxygen species and inhibited the activation of Nrf2-HO-1 in activated macrophages.

CONCLUSIONS

Our study first reports that the activation of Fn14 aggravates ALI by amplifying the activation of NLRP3 inflammasome. Therefore, blocking Fn14 may be a potential way to treat ALI.

Lysophosphatidic Acid Is a Proinflammatory Stimulus of Renal Tubular Epithelial Cells

Chronic kidney disease (CKD) refers to a spectrum of diseases defined by renal fibrosis, permanent alterations in kidney structure, and low glomerular-filtration rate. Prolonged epithelial-tubular damage involves a series of changes that eventually lead to CKD, highlighting the importance of tubular epithelial cells in this process. Lysophosphatidic acid (LPA) is a bioactive lipid that signals mainly through its six cognate LPA receptors and is implicated in several chronic inflammatory pathological conditions. In this report, we have stimulated human proximal tubular epithelial cells (HKC-8) with LPA and 175 other possibly pathological stimuli, and simultaneously detected the levels of 27 intracellular phosphoproteins and 32 extracellular secreted molecules with multiplex ELISA. This quantification revealed a large amount of information concerning the signaling and the physiology of HKC-8 cells that can be extrapolated to other proximal tubular epithelial cells. LPA responses clustered with pro-inflammatory stimuli such as TNF and IL-1, promoting the phosphorylation of important inflammatory signaling hubs, including CREB1, ERK1, JUN, IκΒα, and MEK1, as well as the secretion of inflammatory factors of clinical relevance, including CCL2, CCL3, CXCL10, ICAM1, IL-6, and IL-8, most of them shown for the first time in proximal tubular epithelial cells. The identified LPA-induced signal-transduction pathways, which were pharmacologically validated, and the secretion of the inflammatory factors offer novel insights into the possible role of LPA in CKD pathogenesis.

Kidney injury and oxidative damage alleviation by Zingiber officinale: pharmacokinetics and protective approach in a combined murine model of osteoporosis

Ginger (Zingiber officinale) is considered as a nutraceutical spice, which possesses several health promotion and benefits. This study was carried out to investigate the phyto-chemical composition, the antioxidant capacities, the drug-likeness, and pharmacokinetic properties of ginger extract on kidney injury-associated osteoporosis in rats. Phenolic and flavonoid contents were assessed by standard chemical analysis methods and HPLC. In vivo protective effect was based on the use of female rats to evaluate the effect on renal injury as a result of combined osteoporosis using biochemical markers, oxidative status, and histological analyses. Results showed that ZO contained appreciable amounts of phenolics and flavonoids and it exhibited high scavenging activity. Ovariectomy-associated corticotherapy induced severe renal injury marked by altered biochemical markers (creatinine, urea, and uric acid), reduced GFR, significative oxidative damage signs, and disrupted antioxidant status in the combined osteoporotic rats. The histopathological examination revealed structural modifications of kidney tissues. However, all these changes were reversed following the use of ZO. These results confirm the renoprotective and antioxidant potential of ginger against renal injuries in osteoporotic rats.

Hyponatremia in COVID‐19 patients: Experience from Bangladesh

Background

The purpose of the study was to measure the prevalence of hyponatremia and its association with clinical and laboratory characteristics of hospitalized coronavirus disease 2019 (COVID‐19) patients at Dhaka Medical College and Hospital (DMCH).

Methods

This retrospective study was conducted in COVID‐19 dedicated wards at DMCH from June to August 2020. Demographic, clinical, and laboratory data were collected from patient treatment sheets. Two groups of COVID‐19 patients were retrospectively screened on the basis of plasma sodium level at admission: hyponatremic (sodium < 135 mM, n = 84) or normonatremic (sodium ≥ 135 mM, n = 48) patients. Severity was assessed using World Health Organization classification for COVID‐19 disease severity. To compare the two groups, Pearson's χ² (qualitative variables) and Student's T tests (quantitative variables) were applied. The link between patients' clinical data and outcomes was investigated using logistic regression model.

Results

A total of 132 patients were included in the study, with a mean age of 51.41 (±14.13) years. Hyponatremia was found in 84 patients (63.6%) and the remaining 48 patients (36.4%) had normal plasma Na⁺ values. Among them, 74 (56.06%) presented with severe disease and 53 (40.15%) with moderate disease. At presentation, patients with moderate COVID‐19 disease had 2.15 (1.04–4.5) times higher odds of suffering from hyponatremia. Besides, hyponatremia was independently associated with on admission SpO₂ (p = 0.038), hemoglobin (p = 0.004), and C‐reactive protein (p = 0.001).

Conclusions

The authors suggest that patients' serum electrolytes be measured during initial hospital admission and then monitored throughout the hospital stay to predict the probability for referral for invasive ventilation and for better management.

Activation of fibroblast growth factor-inducible 14 in the early phase of childhood IgA nephropathy

IgA nephropathy (IgAN) is the most common form of glomerulonephritis worldwide. Pediatric patients in Japan are diagnosed with IgAN at an early stage of the disease through annual urinary examinations. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and fibroblast growth factor-inducible 14 (Fn14) have various roles, including proinflammatory effects, and modulation of several kidney diseases; however, no reports have described their roles in pediatric IgAN. In this study, we performed pathological and immunohistochemical analyses of samples from 14 pediatric IgAN patients. Additionally, gene expression arrays of glomeruli by laser-captured microdissection were performed in hemi-nephrectomized high serum IgA (HIGA) mice, a model of IgA nephropathy, to determine the role of Fn14. Glomeruli with intense Fn14 deposition were observed in 80% of mild IgAN cases; however, most severe cases showed glomeruli with little or no Fn14 deposition. Fn14 deposition was not observed in obvious mesangial proliferation or the crescent region of glomeruli, but was detected strongly in the glomerular tuft, with an intact appearance. In HIGA mice, Fn14 deposition was observed mildly beginning at 11 weeks of age, and stronger Fn14 deposition was detected at 14 weeks of age. Expression array analysis indicated that Fn14 expression was higher in HIGA mice at 6 weeks of age, increased slightly at 11 weeks, and then decreased at 26 weeks when compared with controls at equivalent ages. These findings suggest that Fn14 signaling affects early lesions but not advanced lesions in patients with IgAN. Further study of the TWEAK/Fn14 pathway will contribute to our understanding of the progression of IgAN.

Diagnostic value of TWEAK for predicting active lupus nephritis in patients with systemic lupus erythematosus: a systematic review and meta-analysis

Purpose

Accumulative studies showed that tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) was up-regulated in the blood and urine from patients diagnosed with lupus nephritis (LN) and that it might be used as a novel biomarker for active LN. This meta-analysis aimed to determine the diagnostic value of TWEAK in active LN.

Methods

We searched the Cochrane Library, Embase, PubMed, Springer, Wanfang and CNKI databases for articles published up to 20 August 2020. The diagnostic capacity of TWEAK for active LN was assessed using pooled sensitivity and specificity, positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), and area under the receiver operating characteristic curve (AUC). Quality assessment and publication bias were also evaluated. STATA 11.0 and Meta-Disc 1.4 were used to perform these analyses.

Results

Nine cross-sectional studies were included in this meta-analysis. The overall pooled sensitivity of TWEAK for the diagnosis of active LN was 0.69 (95% CI, 0.63–0.75), and specificity was 0.77 (95% CI, 0.71–0.82). The overall pooled PLR and NLR were 3.31 (95% CI, 2.05–5.35) and 0.38 (95% CI, 0.26–0.55), respectively, with a DOR of 10.89 (95% CI, 6.73–17.63) and AUC (SE) of 0.8276 (0.0289). Deeks’ funnel plot revealed that the publication bias was insignificant in the study (p = .32).

Conclusions

Our results suggest that TWEAK might be a potential biomarker for patients with active LN. Future cross-sectional and longitudinal studies are needed to confirm its diagnostic value, as well as to establish more definite cutoff for active LN.

TWEAK Signaling Pathway Blockade Slows Cyst Growth and Disease Progression in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

In autosomal dominant polycystic kidney disease (ADPKD), cyst development and enlargement lead to ESKD. Macrophage recruitment and interstitial inflammation promote cyst growth. TWEAK is a TNF superfamily (TNFSF) cytokine that regulates inflammatory responses, cell proliferation, and cell death, and its receptor Fn14 (TNFRSF12a) is expressed in macrophage and nephron epithelia.

METHODS

To evaluate the role of the TWEAK signaling pathway in cystic disease, we evaluated Fn14 expression in human and in an orthologous murine model of ADPKD. We also explored the cystic response to TWEAK signaling pathway activation and inhibition by peritoneal injection.

RESULTS

Meta-analysis of published animal-model data of cystic disease reveals mRNA upregulation of several components of the TWEAK signaling pathway. We also observed that TWEAK and Fn14 were overexpressed in mouse ADPKD kidney cysts, and TWEAK was significantly high in urine and cystic fluid from patients with ADPKD. TWEAK administration induced cystogenesis and increased cystic growth, worsening the phenotype in a murine ADPKD model. Anti-TWEAK antibodies significantly slowed the progression of ADPKD, preserved renal function, and improved survival. Furthermore, the anti-TWEAK cystogenesis reduction is related to decreased cell proliferation-related MAPK signaling, decreased NF-κB pathway activation, a slight reduction of fibrosis and apoptosis, and an indirect decrease in macrophage recruitment.

CONCLUSIONS

This study identifies the TWEAK signaling pathway as a new disease mechanism involved in cystogenesis and cystic growth and may lead to a new therapeutic approach in ADPKD.

Cytokines: From Clinical Significance to Quantification

Cytokines are critical mediators that oversee and regulate immune and inflammatory responses via complex networks and serve as biomarkers for many diseases. Quantification of cytokines has significant value in both clinical medicine and biology as the levels provide insights into physiological and pathological processes and can be used to aid diagnosis and treatment. Cytokines and their clinical significance are introduced from the perspective of their pro- and anti-inflammatory effects. Factors affecting cytokines quantification in biological fluids, native levels in different body fluids, sample processing and storage conditions, sensitivity to freeze-thaw, and soluble cytokine receptors are discussed. In addition, recent advances in in vitro and in vivo assays, biosensors based on different signal outputs and intracellular to extracellular protein expression are summarized. Various quantification platforms for high-sensitivity and reliable measurement of cytokines in different scenarios are discussed, and commercially available cytokine assays are compared. A discussion of challenges in the development and advancement of technologies for cytokine quantification that aim to achieve real-time multiplex cytokine analysis for point-of-care situations applicable for both biomedical research and clinical practice are discussed.

Ferroptosis and Necroptosis in the Kidney

In the last decade, the role of apoptosis in the pathophysiology of acute kidney injury (AKI) and AKI to chronic kidney disease (CKD) progression has been revisited as our understanding of ferroptosis and necroptosis has emerged. A growing body of evidence, reviewed here, ascribes a central pathophysiological role for ferroptosis and necroptosis to AKI, nephron loss, and acute tubular necrosis. We will introduce concepts to the non-cell-autonomous manner of kidney tubular injury during ferroptosis, a phenomenon that we refer to as a "wave of death." We hypothesize that necroptosis might initiate cell death propagation through ferroptosis. The remaining necrotic debris requires effective removal processes to prevent a secondary inflammatory response, referred to as necroinflammation. Open questions include the differences in the immunogenicity of ferroptosis and necroptosis, and the specificity of necrostatins and ferrostatins to therapeutically target these processes to prevent AKI-to-CKD progression and end-stage renal disease.

Inhibition of fibroblast growth factor-inducible 14 attenuates experimental tubulointerstitial fibrosis and profibrotic factor expression of proximal tubular epithelial cells

BACKGROUND AND AIM

As a proinflammatory cytokine, tumor necrosis factor-like weak inducer of apoptosis (TWEAK) participates in the progression of renal fibrosis by binding to its receptor, fibroblast growth factor-inducible 14 (Fn14). However, the effect of Fn14 inhibition on tubular epithelial cell-mediated tubulointerstitial fibrosis remains unclear. This study aimed to elucidate the role of TWEAK/Fn14 interaction in the development of experimental tubulointerstitial fibrosis as well as the protective effect of Fn14 knockdown on proximal tubular epithelial cells.

METHODS

A murine model of unilateral ureteral obstruction was constructed in both wild-type and Fn14-deficient BALB/c mice, followed by observation of the tubulointerstitial pathologies.

RESULTS

Fn14 deficiency ameliorated the pathological changes, including inflammatory cell infiltration and cell proliferation, accompanied by reduced production of profibrotic factors and extracellular matrix deposition. In vitro experiments showed that TWEAK dose-dependently enhanced the expression of collagen I, fibronectin, and α-smooth muscle actin in proximal tubular epithelial cells. Interestingly, TWEAK also upregulated the expression levels of Notch1/Jagged1. Fn14 knockdown and Notch1/Jagged1 inhibition also mitigated the effect of TWEAK on these cells.

CONCLUSIONS

In conclusion, TWEAK/Fn14 signals contributed to tubulointerstitial fibrosis by acting on proximal tubular epithelial cells. Fn14 inhibition might be a therapeutic strategy for protecting against renal interstitial fibrosis.

TWEAK-Fn14 as a common pathway in the heart and the kidneys in cardiorenal syndrome

There is a complex relationship between cardiac and renal disease, often referred to as the cardiorenal syndrome. Heart failure adversely affects kidney function, and both acute and chronic kidney disease are associated with structural and functional changes to the myocardium. The pathological mechanisms and contributing interactions that surround this relationship remain poorly understood, limiting the opportunities for therapeutic intervention. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed in injured kidneys and heart. The TWEAK-Fn14 axis promotes responses that drive tissue injury such as inflammation, proliferation, fibrosis, and apoptosis, while restraining the expression of tissue protective factors such as the anti-aging factor Klotho and the master regulator of mitochondrial biogenesis peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). High levels of TWEAK induce cardiac remodeling, and promote inflammation, tubular and podocyte injury and death, fibroblast proliferation, and, ultimately, renal fibrosis. Accordingly, targeting the TWEAK-Fn14 axis is protective in experimental kidney and heart disease. TWEAK has also emerged as a biomarker of kidney damage and cardiovascular outcomes and has been successfully targeted in clinical trials. In this review, we update our current knowledge of the roles of the TWEAK-Fn14 axis in cardiovascular and kidney disease and its potential contribution to the cardiorenal syndrome. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Is There a Relationship between COVID-19 and Hyponatremia?

Nowadays, humanity faces one of the most serious health crises, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The severity of coronavirus disease 2019 (COVID-19) pandemic is related to the high rate of interhuman transmission of the virus, variability of clinical presentation, and the absence of specific therapeutic methods. COVID-19 can manifest with non-specific symptoms and signs, especially among the elderly. In some cases, the clinical manifestations of hyponatremia may be the first to appear. The pathophysiological mechanisms of hyponatremia among patients with COVID-19 are diverse, including syndrome of inappropriate antidiuretic hormone secretion (SIADH), digestive loss of sodium ions, reduced sodium ion intake or use of diuretic therapy. Hyponatremia may also be considered a negative prognostic factor in patients diagnosed with COVID-19. We need further studies to evaluate the etiology and therapeutic management of hyponatremia in patients with COVID-19.

TWEAK/Fn14 axis is an important player in fibrosis

Fibrosis is a common pathological condition associated with abnormal repair after tissue injury. However, the etiology and molecular mechanisms of fibrosis are still not well-understood. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) belongs to the TNF superfamily and acts by binding to its receptor, fibroblast growth factor-inducible 14 (Fn14), thereby activating a variety of intracellular signal transduction pathways in various types of cells. Besides promoting the expression of growth factors, activation of TWEAK/Fn14 signaling after tissue injury can promote the expression of pro-inflammatory cytokines, which trigger the immune response, thereby exacerbating the injury. Severe or repetitive injury leads to a dysregulated tissue repair process, in which the TWEAK/Fn14 axis promotes the activation and proliferation of myofibroblasts, induces the secretion of the extracellular matrix, and regulates profibrotic mediators to further perpetuate and sustain the fibrotic process. In this review, we summarize the available experimental evidence on the underlying molecular mechanisms by which the TWEAK/Fn14 pathway mediates the development and progression of fibrosis. In addition, we discuss the therapeutic potential of the TWEAK/Fn14 pathway in fibrosis-associated diseases based on evidence derived from multiple models and cells from injured tissue and fibrotic tissue.

Microparticles expressing myeloperoxidase as potential biomarkers in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV)

Abstract

To investigate presence of circulating myeloperoxidase-positive microparticles (MPO⁺MPs) in relation to disease activity in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Forty-six patients with AAV and 23 age- and sex-matched healthy controls were included. Vasculitis disease activity was assessed using the Birmingham Vasculitis Activity Score (BVAS). MPs were analyzed in citrate plasma by flow cytometry and phenotyped based on MPO expression and co-expression of pentraxin-3 (PTX3), high mobility group box 1 protein (HMGB1), and tumor necrosis factor-like weak inducer of apoptosis (TWEAK). Serum levels of PTX3, sTWEAK, and HMGB1 were also determined. Twenty-three patients had active vasculitis (BVAS ≥ 1). Concentrations of MPO⁺MPs expressing PTX3, HMGB1, and TWEAK were significantly higher in patients compared to healthy controls (p < 0.001, p < 0.01, p < 0.001, respectively), while concentrations of PTX3⁺ and HMGB1⁺MPO⁺MPs were significantly higher in active AAV compared to patients in remission. MPO⁺MPs expressing either PTX3 or HMGB1 were associated with BVAS (r = 0.5, p < 0.001; r = 0.3, p = 0.04, respectively). Significantly higher serum PTX3 levels were found in active- than in inactive AAV (p < 0.001), correlating strongly with BVAS (r = 0.7, p < 0.001). Serum levels of sTWEAK and HMGB1 did not differ between patients and controls. Concentration of MPO⁺MPs is increased in plasma from AAV patients compared to healthy individuals. PTX3 in serum as well as PTX3 and HMGB1 expressed on MPO⁺MPs were associated with disease activity in the investigated patients.

Key messages

Myeloperoxidase-positive microparticles (MPO⁺MPs) are increased in plasma from patients with ANCA-associated vasculitis.

Concentrations of MPO⁺MPs expressing PTX3, HMGB1, and TWEAK were significantly higher in patients compared to healthy controls.

MPO⁺MPs expressing PTX3 and HMGB1 are associated with disease activity in ANCA-associated vasculitis.

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01955-2) contains supplementary material, which is available to authorized users.

Parthenolide ameliorates tweak-induced podocytes injury

Parthenolide (PTL) is a natural product from the shoots of Tanacetum parthenium, which has immunomodulatory effects in multiply type of diseases. This study aimed to explore the effect and the underlying mechanism of PTL on the anti-apoptotic and anti- inflammatory ability of tweak-induced podocytes. Conditionally immortalized mouse podocytes were incubated with Tumor necrosis factor-like weak inducer of apoptosis (Tweak, 100 ng/ml), PTL(10 µM) or Tweak + PTL for 12 h, 24 and 48 h, respectively. Podocytes viability was detected by CCK-8 assay. Tweak and Cxcl16 expression were evaluated by western blot and immunofluorescence assay. Dil-oxLDL stain was detected by immunofluorescence analysis. Intracellular Total Cholesterol (TC) content was measured through TC detection Kit. These results demonstrated that the podocytes cells viability was gradually decreased after treatment with different concentrations of Tweak (0, 50, 100, 150). Tweak and Cxcl16 protein expression in mouse podocytes treated with tweak were remarkably elevated and were found to have higher intracellular lipid accumulation compared with the control group, whereas co-administration with PTL, tweak and Cxcl16 expression as well as the intracellular lipid accumulation were notablely decreased in tweak-induced podocytes. Therefore, our conclusion was that tweak and Cxcl16 were involved in the regulation of tweak-induced podocytes injury. Meanwhile, the anti-apoptotic and anti-inflammatory effect of PTL may be correlated with the tweak and Cxcl16 expression decreased.

TWEAK/Fn14 axis in respiratory diseases

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a well known multifunctional cytokine extensively distributed in cell types and tissues. Accumulating evidence has shown that TWEAK binding to the receptor factor-inducible 14 (Fn14) participates in diverse pathologic processes including cell proliferation and death, angiogenesis, carcinogenesis and inflammation. Interestingly, alterations of intracellular signaling cascades are correlated to the development of respiratory disease. Recently, a several lines of evidence suggests that TWEAK in lung tissues are closely associated with these signaling pathways. In this review, we explore if TWEAK could provide a novel therapeutic strategy for managing respiratory disease in general and pulmonary arterial hypertension (PAH), obstructive sleep apnea syndrome (OSAS), asthma, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and non-small cell lung cancer (NSCLC), specifically.

Kidney disease and electrolytes in COVID-19: more than meets the eye

COVID-19 is a global pandemic fuelled in some countries by government actions. The current issue of Clinical Kidney Journal presents 15 articles on COVID-19 and kidney disease from three continents, providing a global perspective of the impact of severe acute respiratory syndrome coronavirus 2 on electrolytes and different kidney compartments (glomeruli, tubules and vascular compartments) and presenting clinically as a syndrome of inappropriate antidiuretic hormone secretion, acute kidney injury, acute kidney disease, collapsing glomerulopathy and thrombotic microangiopathy, among others, in the context of a brand-new cardiorenal syndrome. Kidney injury may need acute dialysis that may overwhelm haemodialysis (HD) and haemofiltration capabilities. In this regard, acute peritoneal dialysis (PD) may be lifesaving. Additionally, pre-existent chronic kidney disease increases the risk of more severe COVID-19 complications. The impact of COVID-19 on PD and HD patients is also discussed, with emphasis on preventive measures. Finally, current therapeutic approaches and potential future therapeutic approaches undergoing clinical trials, such as complement targeting by eculizumab, are also presented.

FN14 Signaling Plays a Pathogenic Role in a Mouse Model of Experimental Autoimmune Myocarditis

BACKGROUND

The pathogenesis of inflammatory cardiomyopathy is affected by the activation of autoimmune-mediated cascades. To study these cascades, we developed an experimental model of troponin I (TnI)-induced autoimmune myocarditis (EAM). One factor playing a pivotal role in the context of autoimmune disorders is the receptor fibroblast growth factor-inducible 14 (FN14). Thus, the impact of FN14 in the development of autoimmune myocarditis was investigated.

METHODS AND RESULTS

TnI-immunization led to a significantly increased myocardial FN14 mRNA and protein expression in wild-type (wt) mice. To investigate the precise role of FN14 in EAM, FN14 knockout (ko) and wt littermates were immunized with TnI or control buffer. The animals were evaluated for cardiac parameters and indicators of myocardial injury. FN14 deficiency resulted in better cardiac performance, less myocardial inflammation, fibrosis, and cardiac damage. A lower myocardial mRNA expression of inflammatory cytokines and chemokines as well as their receptors could be demonstrated in TnI-immunized FN14ko compared to wt mice also immunized with TnI. Western blot analysis revealed a contribution of nuclear factor kappa-light-chain-enhancer of activated B cells to FN14-induced signaling cascades.

CONCLUSIONS

In the pathogenesis of autoimmune myocarditis, the inflammatory response to cardiac injury is attenuated in FN14ko mice. Thus, inhibition of FN14 in patients might represent a novel therapeutic strategy in the treatment of inflammatory cardiomyopathy.

TRAIL, OPG, and TWEAK in kidney disease: biomarkers or therapeutic targets?

Ligands and receptors of the tumor necrosis factor (TNF) superfamily regulate immune responses and homeostatic functions with potential diagnostic and therapeutic implications. Kidney disease represents a global public health problem, whose prevalence is rising worldwide, due to the aging of the population and the increasing prevalence of diabetes, hypertension, obesity, and immune disorders. In addition, chronic kidney disease is an independent risk factor for the development of cardiovascular disease, which further increases kidney-related morbidity and mortality. Recently, it has been shown that some TNF superfamily members are actively implicated in renal pathophysiology. These members include TNF-related apoptosis-inducing ligand (TRAIL), its decoy receptor osteoprotegerin (OPG), and TNF-like weaker inducer of apoptosis (TWEAK). All of them have shown the ability to activate crucial pathways involved in kidney disease development and progression (e.g. canonical and non-canonical pathways of the transcription factor nuclear factor-kappa B), as well as the ability to regulate cell proliferation, differentiation, apoptosis, necrosis, inflammation, angiogenesis, and fibrosis with double-edged effects depending on the type and stage of kidney injury. Here we will review the actions of TRAIL, OPG, and TWEAK on diabetic and non-diabetic kidney disease, in order to provide insights into their full clinical potential as biomarkers and/or therapeutic options against kidney disease.

Serum soluble TWEAK levels in severe traumatic brain injury and its prognostic significance

BACKGROUND

Severe traumatic brain injury (sTBI) is characterized by a high mortality. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) participates in inflammation. We determined serum soluble TWEAK (sTWEAK) levels with respect to its prognostic ability.

METHODS

This was a single-center prospective, observational study that was performed from December 2014 to December 2017. A total of 114 sTBI patients who met the inclusion criteria and 114 randomly selected healthy controls were included in the study. Serum sTWEAK levels were gauged. Patients were followed-up until death or completion of 6 months. Poor outcome was referred to as Glasgow outcome scale score of 1-3.

RESULTS

In comparison with controls, patients displayed predominantly higher serum sTWEAK levels. Serum sTWEAK levels were strongly correlated with Glasgow coma scale scores and serum C-reactive protein levels. 32 patients (28.1%) died and 60 patients (52.6%) suffered from a poor outcome. Receiver operating characteristic curve analysis clearly showed that serum sTWEAK levels had substantially high predictive performance for 6-month mortality and poor outcome. Serum sTWEAK emerged as an independent predictor for 6-month mortality, overall survival and poor outcome.

CONCLUSIONS

Raised serum sTWEAK levels are closely related to increasing inflammatory response, elevated trauma severity and worse clinical outcome after sTBI.

Serum sTWEAK levels in chronic periodontitis and type 2 diabetes mellitus

AIM

The two-way relationship between diabetes mellitus and periodontitis has been extensively studied with various interconnected biomarkers sharing a link. Soluble Tumour Necrosis Factor-like Weak inducer of apoptosis (sTWEAK) is gaining attention as an important mediator in chronic inflammatory diseases. Thus, the aim of this study was to detect, estimate and compare the levels of sTWEAK in the serum of health, chronic periodontitis (CP), and CP with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

Forty-five participants between 18 and 65 years were divided into groups of 15 each as Group 1: healthy, Group 2: CP, and Group 3: CP + T2DM. Clinical periodontal parameters and glycemic status were assessed. sTWEAK in serum was estimated using a commercially available ELISA kit. The data was statistically analyzed.

RESULTS

sTWEAK was detected in all participants. Significant differences were observed between the groups for sTWEAK; highest in health, lower in CP and lowest in CP + T2DM. In the diseased groups, the clinical and glycemic parameters correlated positively with each other, whereas sTWEAK correlated negatively with each of the parameters.

CONCLUSION

The literature reports lower concentrations of systemic sTWEAK in T2DM which may be comparable to our observations in CP + T2DM when compared to health and its negative correlation with all the parameters suggesting an association with both clinical periodontal parameters and glycemic levels. However, serum sTWEAK levels may not be necessarily elevated in periodontitis as previously reported, and hence has the potential to be studied extensively for clarification with its association with T2DM.

How Acute Kidney Injury Contributes to Renal Fibrosis

Acute kidney injury (AKI) is a widespread clinical syndrome directly associated with patient short-term and long-term morbidity and mortality. During the last decade, the incidence rate of AKI has been increasing, the repeated and severe episodes of AKI have been recognized as a major risk factor chronic kidney diseases (CKD) and end-stage kidney disease (ESRD) leading to global disease burden. Proposed pathological processes and risk factors that add to the transition of AKI to CKD and ESRD include severity and frequency of kidney injury, older age, gender, genetics and chronic health conditions like diabetes, hypertension, and obesity. Therefore, there is a great interest in learning about the mechanism of AKI leading to renal fibrosis, the ultimate renal lesions of CKD. Over the last several years, a significant attention has been given to the field of renal fibrosis with impressive progression in knowing the mechanism of renal fibrosis to detailed cellular characterization and molecular pathways implicated in tubulointerstitial fibrosis. Research and clinical trial are underway for emerging biomarkers detecting early kidney injury, predicting kidney disease progression and developing strategies to efficiently treat AKI and to minimize AKI progression to CKD and ESRD. Specific interventions to prevent renal fibrosis are still experimental. Potential therapeutic advances based on those molecular mechanisms will hopefully offer promising insights into the development of new therapeutic interventions for patients in the near future.

TWEAK increases CD74 expression and sensitizes to DDT proinflammatory actions in tubular cells

CD74 is a multifunctional protein and a receptor for Macrophage Migration Inhibitory Factor (MIF) and MIF-2 / D-dopachrome tautomerase (DDT) cytokines, upregulated in diabetic kidney disease. However, the drivers of CD74 expression and DDT function in kidney cells are poorly characterized. TWEAK is a proinflammatory cytokine that promotes kidney injury. We have now identified CD74 gene expression as upregulated in the kidneys in response to systemic TWEAK administration in mice, and have characterized the in vivo CD74 expression and the functional consequences in cultured cells. TWEAK administration to mice resulted in a progressive time-dependent (up to 24h) upregulation of kidney CD74 mRNA (RT-PCR) and protein (Western blot). Furthermore, the CD74 ligands MIF and DDT were also upregulated at the protein level 24h after TWEAK administration. Immunohistochemistry localized the increased CD74, MIF and DDT expression to tubular cells. In cultured tubular cells, TWEAK increased CD74 mRNA and protein expression dose-dependently, with a temporal pattern similar to in vivo. TWEAK-induced CD74 localized to the cell membrane, where it can function as a cytokine receptor. For the first time, we explored the actions of DDT in tubular cells and found that DDT amplified the increase in MCP-1 and RANTES expression in response to TWEAK. By contrast, DDT did not significantly modify TWEAK-induced Klotho downregulation. In conclusion, TWEAK upregulates CD74 and its ligands MIF and DDT in renal tubular cells. This may have functional consequences for kidney injury since DDT amplified the inflammatory response to TWEAK.

Tnfrsf12a-Mediated Atherosclerosis Signaling and Inflammatory Response as a Common Protection Mechanism of Shuxuening Injection Against Both Myocardial and Cerebral Ischemia-Reperfusion Injuries

Shuxuening injection (SXNI) is a widely prescribed herbal medicine of Ginkgo biloba extract (EGB) for cerebral and cardiovascular diseases in China. However, its curative effects on ischemic stroke and heart diseases and the underlying mechanisms remain unknown. Taking an integrated approach of RNA-seq and network pharmacology analysis, we compared transcriptome profiles of brain and heart ischemia reperfusion injury in C57BL/6J mice to identify common and differential target genes by SXNI. Models for myocardial ischemia reperfusion injury (MIRI) by ligating left anterior descending coronary artery (LAD) for 30 min ischemia and 24 h reperfusion and cerebral ischemia reperfusion injury (CIRI) by middle cerebral artery occlusion (MCAO) for 90 min ischemia and 24 h reperfusion were employed to identify the common mechanisms of SXNI on both cerebral and myocardial ischemia reperfusion. In the CIRI model, ischemic infarct volume was markedly decreased after pre-treatment with SXNI at 0.5, 2.5, and 12.5 mL/kg. In the MIRI model, pre-treatment with SXNI at 2.5 and 12.5 mL/kg improved cardiac function and coronary blood flow and decreased myocardial infarction area. Besides, SXNI at 2.5 mL/kg also markedly reduced the levels of LDH, AST, CK-MB, and CK in serum. RNA-seq analysis identified 329 differentially expressed genes (DEGs) in brain and 94 DEGs in heart after SXNI treatment in CIRI or MIRI models, respectively. Core analysis by Ingenuity Pathway Analysis (IPA) revealed that atherosclerosis signaling and inflammatory response were top-ranked in the target profiles for both CIRI and MIRI after pre-treatment with SXNI. Specifically, Tnfrsf12a was recognized as an important common target, and was regulated by SXNI in CIRI and MIRI. In conclusion, our study showed that SXNI effectively protects brain and heart from I/R injuries via a common Tnfrsf12a-mediated pathway involving atherosclerosis signaling and inflammatory response. It provides a novel knowledge of active ingredients of Ginkgo biloba on cardio-cerebral vascular diseases in future clinical application.

NF-κB inducing kinase is a therapeutic target for systemic lupus erythematosus

NF-κB-inducing kinase (NIK) mediates non-canonical NF-κB signaling downstream of multiple TNF family members, including BAFF, TWEAK, CD40, and OX40, which are implicated in the pathogenesis of systemic lupus erythematosus (SLE). Here, we show that experimental lupus in NZB/W F1 mice can be treated with a highly selective and potent NIK small molecule inhibitor. Both in vitro as well as in vivo, NIK inhibition recapitulates the pharmacological effects of BAFF blockade, which is clinically efficacious in SLE. Furthermore, NIK inhibition also affects T cell parameters in the spleen and proinflammatory gene expression in the kidney, which may be attributable to inhibition of OX40 and TWEAK signaling, respectively. As a consequence, NIK inhibition results in improved survival, reduced renal pathology, and lower proteinuria scores. Collectively, our data suggest that NIK inhibition is a potential therapeutic approach for SLE.

Targeting Cell Death Pathways for Therapeutic Intervention in Kidney Diseases

Precise regulation of cell death and survival is essential for proper maintenance of organismal homeostasis, development, and the immune system. Deregulated cell death can lead to developmental defects, neuropathies, infections, and cancer. Kidney diseases, especially acute pathologies linked to ischemia-reperfusion injury, are among illnesses that profoundly are affected by improper regulation or execution of cell death pathways. Attempts to develop medicines for kidney diseases have been impacted by the complexity of these pathologies given the heterogeneous patient population and diverse etiologies. By analyzing cell death pathways activated in kidney diseases, we attempt to differentiate their importance for these pathologies with a goal of identifying those that have more profound impact and the best therapeutic potential. Although classic apoptosis still might be important, regulated necrosis pathways including necroptosis, ferroptosis, parthanatos, and mitochondrial permeability transition-associated cell death play a significantly role in kidney diseases, especially in acute kidney pathologies. Although targeting receptor-interacting protein 1 kinase appears to be the best therapeutic strategy, combination with inhibitors of other cell death pathways is likely to bring superior benefit and possible cure to patients suffering from kidney diseases.

An Overview of Pathways of Regulated Necrosis in Acute Kidney Injury

Necrosis is the predominant form of regulated cell death in acute kidney injury (AKI) and represents results in the formation of casts that appear in the urine sedimentation, referred to as muddy brown casts, which are part of the diagnosis of AKI. Pathologists referred to this typical feature as acute tubular necrosis. We are only beginning to understand the dynamics and the molecular pathways that underlie such typical necrotic morphology. In this review, we provide an overview of candidate pathways and summarize the emerging evidence for the relative contribution of these pathways of regulated necrosis, such as necroptosis, ferroptosis, mitochondrial permeability transition-mediated regulated necrosis, parthanatos, and pyroptosis. Inhibitors of each of these pathways are available, and clinical trials may be started after the detection of the most promising drug targets, which will be discussed here. With the global burden of AKI in mind, inhibitiors of regulated necrosis represent promising means to prevent this disease.

Biomeasures and mechanistic modeling highlight PK/PD risks for a monoclonal antibody targeting Fn14 in kidney disease

Discovery of the upregulation of fibroblast growth factor-inducible-14 (Fn14) receptor following tissue injury has prompted investigation into biotherapeutic targeting of the Fn14 receptor for the treatment of conditions such as chronic kidney diseases. In the development of monoclonal antibody (mAb) therapeutics, there is an increasing trend to use biomeasures combined with mechanistic pharmacokinetic/pharmacodynamic (PK/PD) modeling to enable decision making in early discovery. With the aim of guiding preclinical efforts on designing an antibody with optimized properties, we developed a mechanistic site-of-action (SoA) PK/PD model for human application. This model incorporates experimental biomeasures, including concentration of soluble Fn14 (sFn14) in human plasma and membrane Fn14 (mFn14) in human kidney tissue, and turnover rate of human sFn14. Pulse-chase studies using stable isotope-labeled amino acids and mass spectrometry indicated the sFn14 half-life to be approximately 5 hours in healthy volunteers. The biomeasures (concentration, turnover) of sFn14 in plasma reveals a significant hurdle in designing an antibody against Fn14 with desired characteristics. The projected dose (>1 mg/kg/wk for 90% target coverage) derived from the human PK/PD model revealed potential high and frequent dosing requirements under certain conditions. The PK/PD model suggested a unique bell-shaped relationship between target coverage and antibody affinity for anti-Fn14 mAb, which could be applied to direct the antibody engineering towards an optimized affinity. This investigation highlighted potential applications, including assessment of PK/PD risks during early target validation, human dose prediction and drug candidate optimization.

miR-200bc/429 cluster alleviates inflammation in IgA nephropathy by targeting TWEAK/Fn14

Immunoglobulin A nephropathy (IgAN) is one of the most common glomerular diseases worldwide. Various studies have identified a host of microRNAs (miRNAs) abnormally expressed in IgAN and might affect the pathogenesis and progression of IgAN. However, miR-200bc/429 cluster in the pathopoiesis of IgAN remains poorly understood. For this study, we found that miR-200bc/429 cluster is downregulated in IgAN tissues and IgAN podocytes and HK2 cells compared with their matched controls respectively. In addition, overexpression of miR-200bc/429 cluster in IgAN podocytes and HK2 cells could attenuate the release of inflammatory cytokines MCP-1, IL-6 and RANTES. Moreover, the 3' untranslated region (UTR) of TNF-like weak inducer of apoptosis (TWEAK) was identified to be a direct target of miR-200bc/429 cluster. Furthermore, our results showed that miR-200bc/429 cluster can inhibit TWEAK mediated NF-κB pathway activation in IgAN. Overall, our findings revealed that miR-200bc/429 cluster alleviates inflammation in IgAN through TWEAK/Fn14 system and might serve as a biomarker as well as a promising therapeutic target for IgAN.

AKI on CKD: heightened injury, suppressed repair, and the underlying mechanisms

Acute kidney injury (AKI) and chronic kidney disease (CKD) are interconnected. Although AKI-to-CKD transition has been intensively studied, the information of AKI on CKD is very limited. Nonetheless, AKI, when occurring in patients with CKD, is known to be more severe and difficult to recover. CKD is associated with significant changes in cell signaling in kidney tissues, including the activation of transforming growth factor-β, p53, hypoxia-inducible factor, and major developmental pathways. At the cellular level, CKD is characterized by mitochondrial dysfunction, oxidative stress, and aberrant autophagy. At the tissue level, CKD is characterized by chronic inflammation and vascular dysfunction. These pathologic changes may contribute to the heightened sensitivity of, and nonrecovery from, AKI in patients with CKD.