TWEAK levels in psoriatic patients treated with narrowband ultraviolet B and methotrexate

BACKGROUND

Psoriasis is an autoimmune disease which has an effect on the joints and skin. Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK) is a multi-functional cytokine which regulates the cellular processes and has been related to a variation of conditions.

OBJECTIVES

To measure the level of serum TWEAK in psoriatic diseased persons and its relationship to the PASI score pre- and post-therapy with narrowband ultraviolet B phototherapy (NB-UVB) and methotrexate (MTX).

METHODS

This randomized controlled trial was conducted on 40 patients and 20 healthy persons as controls. Patient Group was randomly subdivided to two groups. The 1st group consisted of 20 patients who received NB-UVB treatment. The 2nd group included 20 MTX-treated candidates. Blood samples were drawn from patients in order to detect serum TWEAK levels using ELISA. The research was registered on Clinical Trials Registration: RCT approval numbers: NCT0481191.

RESULTS

The mean PASI score percent improvement after 12 weeks of treatment was higher in the MTX group (90%) than NB-UVB group (60%). The serum TWEAK level at baseline was 60.47 ± 12.6 pg/mL in NB-UVB group and 54.69 ± 21.7 pg/mL in MTX group which reduced to 24.93 ± 17.6 pg/mL and 32.13 ± 23.6 pg/mL, respectively (p < 0.001), after 12 weeks of treatment. There was a positive correlation between the serum levels of TWEAK and severity of PASI score (r = 0.399, p = 0.014).

CONCLUSION

TWEAK grades in psoriasis are substantially higher than in controls. TWEAK levels were dramatically reduced during NB-UVB and MTX treatment. TWEAK may have a potential sign for psoriasis diagnosis and prognosis.

The crosstalk between macrophages and cancer cells potentiates pancreatic cancer cachexia

With limited treatment options, cachexia remains a major challenge for patients with cancer. Characterizing the interplay between tumor cells and the immune microenvironment may help identify potential therapeutic targets for cancer cachexia. Herein, we investigate the critical role of macrophages in potentiating pancreatic cancer induced muscle wasting via promoting TWEAK (TNF-like weak inducer of apoptosis) secretion from the tumor. Specifically, depletion of macrophages reverses muscle degradation induced by tumor cells. Macrophages induce non-autonomous secretion of TWEAK through CCL5/TRAF6/NF-κB pathway. TWEAK promotes muscle atrophy by activating MuRF1 initiated muscle remodeling. Notably, tumor cells recruit and reprogram macrophages via the CCL2/CCR2 axis and disrupting the interplay between macrophages and tumor cells attenuates muscle wasting. Collectively, this study identifies a feedforward loop between pancreatic cancer cells and macrophages, underlying the non-autonomous activation of TWEAK secretion from tumor cells thereby providing promising therapeutic targets for pancreatic cancer cachexia.

CD163 protein inhibits lipopolysaccharide-induced macrophage transformation from M2 to M1 involved in disruption of the TWEAK-Fn14 interaction

Macrophages play a crucial role in regulating inflammation and innate immune responses, and their polarization into distinct phenotypes, such as M1 and M2, is involved in various diseases. However, the specific role of CD163, a scavenger receptor expressed by macrophages, in the transformation of M2 to M1 macrophages remains unclear. Here, dexamethasone-induced M2 macrophages were treated with lipopolysaccharide (LPS) to induce the transformation of M2 to M1 macrophages. We found that treatment with lipopolysaccharide (LPS) induced the transformation of M2-like macrophages to an M1-like phenotype, as evidenced by increased mRNA levels of Il1b and Tnf, decreased mRNA levels of Cd206 and Il10, and increased TNF-α secretion. Knockdown of CD163 enhanced the phenotypic features of M1 macrophages, while treatment with recombinant CD163 protein (rmCD163) inhibited the LPS-induced M2-to-M1 transformation. Furthermore, LPS stimulation resulted in the activation of P38, ERK, JNK, and NF-κB P65 signaling pathways, and this activation was increased after CD163 knockdown and suppressed after rmCD163 treatment during macrophage transformation. Additionally, we observed that LPS treatment reduced the expression of CD163 in dexamethasone-induced M2 macrophages, leading to a decrease in the CD163-TWEAK complex and an increase in the interaction between TWEAK and Fn14. Overall, our findings suggest that rmCD163 can inhibit the LPS-induced transformation of M2 macrophages to M1 by disrupting the TWEAK-Fn14 interaction and modulating the MAPK-NF-κB pathway.

TNF-like weak inducer of apoptosis inhibition is comparable to IL-13 blockade in ameliorating atopic dermatitis inflammation

BACKGROUND

Targeting IL-13 is highly efficacious in patients with Th2-biased atopic dermatitis (AD), but inhibition of other inflammatory molecules might also limit disease. We investigated the importance of the TNF family cytokine TNF-like weak inducer of apoptosis (TWEAK; TNFSF12) to keratinocyte dysregulation and the pathogenesis of AD in mice and also tested if blocking TWEAK has a similar therapeutic effect as targeting IL-13.

METHODS

Conditional knockout mice lacking Fn14 (TNFRSF12A), the receptor for TWEAK, only in keratinocytes, were repetitively sensitized with house dust mite allergen and analyzed for AD-like skin inflammation. To determine the translational potential, wild-type mice with AD were therapeutically treated with anti-TWEAK and/or anti-IL-13 antibodies, and skin inflammation was assessed.

RESULTS

Mice deficient in Fn14 in keratinocytes were resistant to developing maximal clinical features of AD, exhibiting reduced epidermal hyperplasia and dermal thickening, less skin infiltration of immune cells, and downregulated inflammatory gene expression. Moreover, therapeutic neutralization of TWEAK in wild-type mice with AD reduced all of the pathological features to a comparable extent as blocking IL-13.

CONCLUSIONS

The activity of TWEAK in keratinocytes contributes to AD development, and neutralizing TWEAK represents a future potential therapeutic option in human AD similar to targeting IL-13.

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.

Erratum: Antibody-based soluble and membrane-bound TWEAK mimicking agonists with FcγR-independent activity

[This corrects the article DOI: 10.3389/fimmu.2023.1194610.].

TWEAK promotes inflammatory response in liver fibrosis

This study aimed to investigate the role and mechanism of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in liver fibrosis. The liver Kupffer cells (KCs) and mononuclear macrophages (J774A.1) were used as the objects of study to induce M1 polarization with LPS/IFN-γ. After TWEAK intervention, the M1 cell proportion and marker cytokine levels were detected. Thereafter, CD266 expression was silenced, and NLRP3 expression was inhibited by the NLRP3 inhibitor, so as to investigate the impact of TWEAK on M1 polarization of KCs. In addition, the mouse model of liver fibrosis was constructed to observe the influence of TWEAK on mouse liver fibrosis. According to our results, TWEAK promoted M1 polarization of liver KCs and J774A.1 cells, and silencing CD266 expression or treatment with the NLRP3 inhibitor suppressed the effect of TWEAK. In the mouse experiment, it was discovered that after knocking down NLRP3 expression or using NLRP3 inhibitor to antagonize the effect of TWEAK, the mouse liver function and M1 cell level in liver tissues were improved.

MAP3K19 Affects TWEAK-Induced Response in Cultured Bronchial Epithelial Cells and Regulates Allergic Airway Inflammation in an Asthma Murine Model

The mitogen-activated protein kinase (MAPK) signaling pathway is involved in the epithelial-mesenchymal transition (EMT) and asthma; however, the role of mitogen-activated protein kinase kinase kinase 19 (MAP3K19) remains uncertain. Therefore, we investigated the involvement of MAP3K19 in in vitro EMT and ovalbumin (OVA)-induced asthma murine models. The involvement of MAP3K19 in the EMT and the production of cytokines and chemokines were analyzed using a cultured bronchial epithelial cell line, BEAS-2B, in which MAP3K19 was knocked down using small interfering RNA. We also evaluated the involvement of MAP3K19 in the OVA-induced asthma murine model using Map3k19-deficient (MAP3K19-/-) mice. Transforming growth factor beta 1 (TGF-β1) and tumor necrosis factor-like weak inducer of apoptosis (TWEAK) induced the MAP3K19 messenger RNA (mRNA) expression in the BEAS-2B cells. The knockdown of MAP3K19 enhanced the reduction in E-cadherin mRNA and the production of regulated upon activation normal T cell express sequence (RANTES) via stimulation with TWEAK alone or with the combination of TGF-β1 and TWEAK. Furthermore, the expression of MAP3K19 mRNA was upregulated in both the lungs and tracheas of the mice in the OVA-induced asthma murine model. The MAP3K19-/- mice exhibited worsened eosinophilic inflammation and an increased production of RANTES in the airway epithelium compared with the wild-type mice. These findings indicate that MAP3K19 suppressed the TWEAK-stimulated airway epithelial response, including adhesion factor attenuation and RANTES production, and suppressed allergic airway inflammation in an asthma mouse model, suggesting that MAP3K19 regulates allergic airway inflammation in patients with asthma.

Fn14 and TNFR2 as regulators of cytotoxic TNFR1 signaling

Tumor necrosis factor (TNF) receptor 1 (TNFR1), TNFR2 and fibroblast growth factor-inducible 14 (Fn14) belong to the TNF receptor superfamily (TNFRSF). From a structural point of view, TNFR1 is a prototypic death domain (DD)-containing receptor. In contrast to other prominent death receptors, such as CD95/Fas and the two TRAIL death receptors DR4 and DR5, however, liganded TNFR1 does not instruct the formation of a plasma membrane-associated death inducing signaling complex converting procaspase-8 into highly active mature heterotetrameric caspase-8 molecules. Instead, liganded TNFR1 recruits the DD-containing cytoplasmic signaling proteins TRADD and RIPK1 and empowers these proteins to trigger cell death signaling by cytosolic complexes after their release from the TNFR1 signaling complex. The activity and quality (apoptosis versus necroptosis) of TNF-induced cell death signaling is controlled by caspase-8, the caspase-8 regulatory FLIP proteins, TRAF2, RIPK1 and the RIPK1-ubiquitinating E3 ligases cIAP1 and cIAP2. TNFR2 and Fn14 efficiently recruit TRAF2 along with the TRAF2 binding partners cIAP1 and cIAP2 and can thereby limit the availability of these molecules for other TRAF2/cIAP1/2-utilizing proteins including TNFR1. Accordingly, at the cellular level engagement of TNFR2 or Fn14 inhibits TNFR1-induced RIPK1-mediated effects reaching from activation of the classical NFκB pathway to induction of apoptosis and necroptosis. In this review, we summarize the effects of TNFR2- and Fn14-mediated depletion of TRAF2 and the cIAP1/2 on TNFR1 signaling at the molecular level and discuss the consequences this has in vivo.

TWEAK and Fn14 are overexpressed in immune-mediated necrotizing myopathy: implications for muscle damage and repair

OBJECTIVES

TNF-like weak inducer of apoptosis (TWEAK) and its sole receptor fibroblast growth factor-inducible 14 (Fn14) are involved in various inflammatory conditions. This study was performed to investigate the potential role of TWEAK/Fn14 in immune-mediated necrotizing myopathy (IMNM).

METHODS

Muscle biopsies from patients with IMNM (n = 37) and controls (n = 11) were collected. Human muscle cells were treated with TWEAK in vitro. Muscle biopsies and cultured muscle cells were analysed by immunostaining and quantitative PCR. Serum levels of TWEAK and Fn14 were detected by ELISA.

RESULTS

TWEAK and Fn14 were overexpressed in IMNM muscle biopsies. The percentage of Fn14-positive myofibers correlated with disease severity, myonecrosis, regeneration and inflammation infiltrates. Fn14-positive myofibers tended to be surrounded or invaded by CD68+ macrophages. TWEAK treatment had a harmful effect on cultured muscle cells by inducing the production of multiple chemokines and pro-inflammatory cytokines. Serum Fn14 levels were increased in patients with IMNM and correlated with muscle weakness.

CONCLUSIONS

TWEAK/Fn14 signalling was activated in IMNM, most likely aggravating muscle damage via amplifying inflammatory response and macrophages chemotaxis. Fn14 seems to be a biomarker for assessing disease severity in IMNM. In addition, Fn14 may also contribute to muscle injury repair.

STING1 deficiency ameliorates immune-mediated crescentic glomerulonephritis in mice

Rapidly progressive/crescentic glomerulonephritis (RPGN/CGN) involves the formation of glomerular crescents by maladaptive differentiation of parietal epithelial cells that leads to rapid loss of renal function. The molecular mechanisms of crescent formation are poorly understood. Therefore, new insights into molecular mechanisms could identify alternative therapeutic targets for RPGN/CGN. Analysis of kidney biopsies from patients with RPGN revealed increased interstitial, glomerular, and tubular expression of STING1, an accessory protein of the c-GAS-dependent DNA-sensing pathway, which was also observed in murine nephrotoxic nephritis induced by an anti-GBM antibody. STING1 was expressed by key cell types involved in RPGN and crescent formation such as glomerular parietal epithelial cells, and tubular cells as well as by inflammation accessory cells. In functional in vivo studies, Sting1-/- mice with nephrotoxic nephritis had lower kidney cytokine expression, milder kidney infiltration by innate and adaptive immune cells, and decreased disease severity. Pharmacological STING1 inhibition mirrored these findings. Direct STING1 agonism in parietal and tubular cells activated the NF-κB-dependent cytokine response and the interferon-induced genes (ISGs) program. These responses were also triggered in a STING1-dependent manner by the pro-inflammatory cytokine TWEAK. These results identify STING1 activation as a pathological mechanism in RPGN/CGN and TWEAK as an activator of STING1. Pharmacological strategies targeting STING1, or upstream regulators may therefore be potential alternatives to treat RPGN. © 2023 The Pathological Society of Great Britain and Ireland.

TWEAK Knockdown Alleviates Post-Cardiac Arrest Brain Injury via the p38 MAPK/NF-κB Pathway

BACKGROUND

Cardiac arrest (CA) and subsequent cardiopulmonary resuscitation (CPR) can cause brain injury, which is one of the factors affecting the recovery of brain function in CA patients. There is increasing evidence that tumor necrosis factor-like weak apoptosis-inducing factor (TWEAK) is associated with the brain injury diseases. This study was aimed to investigate the modulation mechanism of TWEAK involved in brain injury after cardiac arrest/subsequent cardiopulmonary resuscitation (CA/CPR).

MATERIALS AND METHODS

For in vivo experiments, healthy male Sprague-Dawley (SD) rats were applied to establish CA/CPR model, and oxygen-glucose deprivation/reoxygenation (OGD/R)-stimulated neurons model was established in vitro. TWEAK short hairpin RNAs (shRNAs) were injected into the lateral ventricle of CA/CPR rats or transfected into OGD/R cell culture to analyze the consequent alteration in neurological scores, behavioral tests, cell proliferation, cell apoptosis, and neuroinflammation through immunofluorescence staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and enzyme linked immunosorbent assay (ELISA).

RESULTS

There were high expressions of TWEAK and fibroblast growth factor-inducible 14 (Fn14) in the cerebral cortex of CA/CPR rats and OGD/R-stimulated neuronal cells. TWEAK knockdown attenuated cell apoptosis, inflammation and showed better behavioral tests in CA/CPR rats. Furthermore, TWEAK shRNAs obviously facilitated cell proliferation, suppressed apoptosis and inflammation after OGD/R injury. Western blotting results stated that TWEAK silencing promoted phosphorylated p38 (p-p38) and phosphorylated p65 (p-p65) expressions.

CONCLUSIONS

TWEAK might be involved in the pathogenesis of CA/CPR through inhibiting p38 MAPK/NF-κB pathway.

Antibody-based soluble and membrane-bound TWEAK mimicking agonists with FcγR-independent activity

Fibroblast growth factor (FGF)-inducible 14 (Fn14) activates the classical and alternative NFκB (nuclear factor 'kappa-light-chain-enhancer' of activated B-cells) signaling pathway but also enhances tumor necrosis factor (TNF)-induced cell death. Fn14 expression is upregulated in non-hematopoietic cells during tissue injury and is also often highly expressed in solid cancers. In view of the latter, there were and are considerable preclinical efforts to target Fn14 for tumor therapy, either by exploiting Fn14 as a target for antibodies with cytotoxic activity (e.g. antibody-dependent cellular cytotoxicity (ADCC)-inducing IgG variants, antibody drug conjugates) or by blocking antibodies with the aim to interfere with protumoral Fn14 activities. Noteworthy, there are yet no attempts to target Fn14 with agonistic Fc effector function silenced antibodies to unleash the proinflammatory and cell death-enhancing activities of this receptor for tumor therapy. This is certainly not at least due to the fact that anti-Fn14 antibodies only act as effective agonists when they are presented bound to Fcγ receptors (FcγR). Thus, there are so far no antibodies that robustly and selectively engage Fn14 signaling without triggering unwanted FcγR-mediated activities. In this study, we investigated a panel of variants of the anti-Fn14 antibody 18D1 of different valencies and domain architectures with respect to their inherent FcγR-independent ability to trigger Fn14-associated signaling pathways. In contrast to conventional 18D1, the majority of 18D1 antibody variants with four or more Fn14 binding sites displayed a strong ability to trigger the alternative NFκB pathway and to enhance TNF-induced cell death and therefore resemble in their activity soluble (TNF)-like weak inducer of apoptosis (TWEAK), one form of the natural occurring ligand of Fn14. Noteworthy, activation of the classical NFκB pathway, which naturally is predominately triggered by membrane-bound TWEAK but not soluble TWEAK, was preferentially observed with a subset of constructs containing Fn14 binding sites at opposing sites of the IgG scaffold, e.g. IgG1-scFv fusion proteins. A superior ability of IgG1-scFv fusion proteins to trigger classical NFκB signaling was also observed with the anti-Fn14 antibody PDL192 suggesting that we identified generic structures for Fn14 antibody variants mimicking soluble and membrane-bound TWEAK.

TWEAK Progress in Dermatology: A Review

Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a member of the TNF superfamily (TNFSF). It acts through its receptor fibroblast growth factor-inducible 14 (Fn14). Studies have indicated that TWEAK/Fn14 pathway activation controls multiple cellular responses, including proliferation, angiogenesis and induction of inflammatory cytokines. TWEAK/Fn14 is manifested in many tissues of our body and most importantly in the skin causing inflammation and many autoimmune and neoplastic cutaneous disorders. Evidence suggests that the TWEAK/Fn14 axis, the downstream signalling pathway and its inflammatory molecular expressions are involved in the pathogenesis of many cutaneous disorders such as psoriasis, atopic dermatitis (AD) vitiligo and melanoma. So, this literature review describes a brief introduction of TWEAK and TWEAK/Fn14 pathway and summarises the case-series and open-label studies performed in the field of dermatology and its potential therapeutic benefit.

Protein therapy of skeletal muscle atrophy and mechanism by angiogenic factor AGGF1

BACKGROUND

Skeletal muscle atrophy is a common condition without a pharmacologic therapy. AGGF1 encodes an angiogenic factor that regulates cell differentiation, proliferation, migration, apoptosis, autophagy and endoplasmic reticulum stress, promotes vasculogenesis and angiogenesis and successfully treats cardiovascular diseases. Here, we report the important role of AGGF1 in the pathogenesis of skeletal muscle atrophy and attenuation of muscle atrophy by AGGF1.

METHODS

In vivo studies were carried out in impaired leg muscles from patients with lumbar disc herniation, two mouse models for skeletal muscle atrophy (denervation and cancer cachexia) and heterozygous Aggf1^+/- mice. Mouse muscle atrophy phenotypes were characterized by body weight and myotube cross-sectional areas (CSA) using H&E staining and immunostaining for dystrophin. Molecular mechanistic studies include co-immunoprecipitation (Co-IP), western blotting, quantitative real-time PCR analysis and immunostaining analysis.

RESULTS

Heterozygous Aggf1^+/- mice showed exacerbated phenotypes of reduced muscle mass, myotube CSA, MyHC (myosin heavy chain) and α-actin, increased inflammation (macrophage infiltration), apoptosis and fibrosis after denervation and cachexia. Intramuscular and intraperitoneal injection of recombinant AGGF1 protein attenuates atrophy phenotypes in mice with denervation (gastrocnemius weight 81.3 ± 5.7 mg vs. 67.3 ± 5.1 mg for AGGF1 vs. buffer; P < 0.05) and cachexia (133.7 ± 4.7 vs. 124.3 ± 3.2; P < 0.05). AGGF1 expression undergoes remodelling and is up-regulated in gastrocnemius and soleus muscles from atrophy mice and impaired leg muscles from patients with lumbar disc herniation by 50-60% (P < 0.01). Mechanistically, AGGF1 interacts with TWEAK (tumour necrosis factor-like weak inducer of apoptosis), which reduces interaction between TWEAK and its receptor Fn14 (fibroblast growth factor-inducing protein 14). This leads to inhibition of Fn14-induced NF-kappa B (NF-κB) p65 phosphorylation, which reduces expression of muscle-specific E3 ubiquitin ligase MuRF1 (muscle RING finger 1), resulting in increased MyHC and α-actin and partial reversal of atrophy phenotypes. Autophagy is reduced in Aggf1^+/- mice due to inhibition of JNK (c-Jun N-terminal kinase) activation in denervated and cachectic muscles, and AGGF1 treatment enhances autophagy in two atrophy models by activating JNK. In impaired leg muscles of patients with lumbar disc herniation, MuRF1 is up-regulated and MyHC and α-actin are down-regulated; these effects are reversed by AGGF1 by 50% (P < 0.01).

CONCLUSIONS

These results indicate that AGGF1 is a novel regulator for the pathogenesis of skeletal muscle atrophy and attenuates skeletal muscle atrophy by promoting autophagy and inhibiting MuRF1 expression through a molecular signalling pathway of AGGF1-TWEAK/Fn14-NF-κB. More importantly, the results indicate that AGGF1 protein therapy may be a novel approach to treat patients with skeletal muscle atrophy.

TWEAK/Fn14 signaling may function as a reactive compensatory mechanism against extracellular matrix accumulation in keloid fibroblasts

Overabundance of the extracellular matrix resulting from hyperproliferation of keloid fibroblasts (KFs) and dysregulation of apoptosis represents the main pathophysiology underlying keloids. TWEAK is a weak apoptosis inducer, and it plays a critical role in pathological tissue remodeling via its receptor, Fn14. However, the role of TWEAK/Fn14 signaling in the pathogenesis of keloids has not been investigated. In this study, we confirmed the overexpression levels of TWEAK and Fn14 in clinical keloid tissue specimens and primary KFs. The extracellular matrix (ECM)-related genes were also evaluated between primary KFs and their normal counterparts to determine the factors leading to the formation or development of keloids. Unexpectedly, exogenous TWEAK significantly reduced the levels of collagen I and collagen III, as well as alpha-smooth muscle actin (α-SMA). Additionally, TWEAK promoted MMPs expression and apoptosis activity of KFs. Furthermore, we verified that the inhibitory effect of TWEAK on KFs is through down-regulation of Polo-like kinase 5, which modulates cell differentiation and apoptosis. The TWEAK-Fn14 axis seems to be a secondary, although less effective, compensatory mechanism to increase the catabolic functions of fibroblasts in an attempt to further decrease the accumulation of collagen. DATA AVAILABILITY: All data generated or analyzed during this study are included in this published article (and its Supporting Information files).

TYROBP-positive endothelial cell-derived TWEAK as a promoter of osteosarcoma progression: insights from single-cell omics

Background

Endothelial cells (ECs) play a vital role in promoting the progression of malignant cells, and they exhibit heterogeneity in their phenotypic characteristics. We aimed to explore the initiating cells of ECs in osteosarcoma (OS) and investigate their potential interaction with malignant cells.

Method

We obtained scRNA-seq data from 6 OS patients, and datasets were batch-corrected to minimize variations among samples. Pseudotime analysis was performed to investigate the origin of differentiation of ECs. CellChat was employed to examine the potential communication between endothelial cells and malignant cells, and gene regulatory network analysis was performed to identify transcription factor activity changes during the conversion process. Importantly, we generated TYROBP-positive ECs in vitro and investigated its role in OS cell lines. Finally, we explored the prognosis of specific ECs cluster and their impact on the tumor microenvironment (TME) at the bulk transcriptome level.

Results

The results showed that TYROBP-positive ECs may play a crucial role in initiating the differentiation of ECs. TYROBOP-positive endothelial cells (ECs) exhibited the strongest crosstalk with malignant cells, likely mediated by TWEAK, a multifunctional cytokine. TYROBP-positive ECs exhibited significant expression of TME-related genes, unique metabolic and immunological profiles. Importantly, OS patients with low enrichment of TYROBP-positive ECs had better prognoses and a lower risk of metastasis. Finally, vitro assays confirmed that TWEAK was significantly increased in ECs-conditioned medium (ECs-CM) when TYROBP was over-expressed in EC cells, and could promote the proliferation and migration of OS cells.

Conclusion

We concluded that TYROBP-positive ECs may be the initiating cells and play a crucial role in the promotion of malignant cell progression. TYROBP-positive ECs have a unique metabolic and immunological profile and may interact with malignant cells through the secretion of TWEAK.

Evaluation of serum TWEAK, TRAIL, and oxidative stress markers in rosacea patients

BACKGROUND

Rosacea is a chronic inflammatory skin disease of unknown pathogenesis. TWEAK and TRAIL are two cytokines thought to have a role in the pathogenesis of some inflammatory and autoimmune diseases.

AIMS

The purpose of this study was to examine TWEAK and TRAIL serum levels and oxidative stress markers in patients with rosacea.

MATERIAL AND METHOD

Forty rosacea patients and 40 sex- and age-matched healthy controls were involved in the study. Serum TWEAK and TRAIL levels were evaluated with ELISA kits. Serum total antioxidant status, total oxidant status, total thiol, native thiol, disulfide levels were evaluated, and oxidative stress index was computed.

RESULTS

Serum levels of TWEAK, TRAIL, and oxidative stress markers did not differ statistically in the patients and controls. Both TWEAK and TRAIL levels in the patients were detected to be statistically higher in male than in female.

CONCLUSION

TWEAK and TRAIL may not have a systemic effect in rosacea, unlike other inflammatory diseases. More studies are needed to investigate the role of TWEAK and TRAIL in rosacea.

TWEAK and TNFα, Both TNF Ligand Family Members and Multiple Sclerosis-Related Cytokines, Induce Distinct Gene Response in Human Brain Microvascular Endothelial Cells

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the TNF ligand family involved in various diseases including brain inflammatory pathologies such as multiple sclerosis. It has been demonstrated that TWEAK can induce cerebrovascular permeability in an in vitro model of the blood-brain barrier. The molecular mechanisms playing a role in TWEAK versus TNFα signaling on cerebral microvascular endothelial cells are not well defined. Therefore, we aimed to identify gene expression changes in cultures of human brain microvascular endothelial cells (hCMEC/D3) to address changes initiated by TWEAK exposure. Taken together, our studies highlighted that gene involved in leukocyte extravasation, notably claudin-5, were differentially modulated by TWEAK and TNFα. We identified differential gene expression of hCMEC/D3 cells at three timepoints following TWEAK versus TNFα stimulation and also found distinct modulations of several canonical pathways including the actin cytoskeleton, vascular endothelial growth factor (VEGF), Rho family GTPases, and phosphatase and tensin homolog (PTEN) pathways. To our knowledge, this is the first study to interrogate and compare the effects of TWEAK versus TNFα on gene expression in brain microvascular endothelial cells.

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.

Methotrexate Mechanism of Action in Plaque Psoriasis: Something New in the Old View

BACKGROUND

Despite the era of biologic therapy in the management of psoriasis, methotrexate, the traditional backbone of psoriasis treatment, does not stop surprising us with what it can offer.

OBJECTIVE

In this study, we aimed to evaluate the peripheral expression and the serum levels of TWEAK in patients with psoriasis vulgaris before and after receiving methotrexate treatment.

METHODS

The study included 58 patients with moderate to severe psoriasis vulgaris, and 90 apparently healthy individuals as a control group. Before starting the treatment course, all patients were evaluated clinically using Psoriasis Area Severity Index (PASI) score and were subjected to TWEAK serum levels and peripheral expression measurement using ELISA and qRT-PCR techniques, respectively. After 12 weeks of treatment with methotrexate (intramuscular methotrexate; up to 30mg per week) the patients were re-evaluated both clinically and in the laboratory.

RESULTS

The baseline serum TWEAK levels and its peripheral mRNA expression in the patients group were significantly lower than those in the control group. After 12 weeks of treatment with methotrexate, the PASI scores were reduced significantly while the serum TWEAK levels and its peripheral expression were significantly elevated.

CONCLUSION

Enhancing TWEAK expression and elevating its serum levels in psoriasis patients seems to be a newly observed mechanism of action of methotrexate.

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.

3β-Hydroxy-5β-hydroxy-B-norcholestane-6β-carboxaldehyde (SEC-B) Induces Proinflammatory Activation of Human Endothelial Cells Associated with Nitric Oxide Production and Endothelial Nitric Oxide Synthase/Caveolin-1 Dysregulation

Oxysterols are a family of 27-carbon cholesterol oxidation derivatives found in low-density lipoproteins (LDLs) and atherosclerotic plaques where they trigger several biological responses involved in the initiation and progression of atherosclerosis. Several pieces of evidence suggest that oxysterols contribute to endothelial dysfunction (ED) due to their ability to alter membrane fluidity and cell permeability leading to inflammation, oxidative stress and apoptosis. The present study aimed to investigate the molecular events occurring in human microvascular endothelial cells (HMEC-1) in response to autoxidation-generated 3β-hydroxy-5β-hydroxy-B-norcholestane-6β-carboxaldehyde (SEC-B) exposure. Our results highlight that SEC-B rapidly activates HMEC-1 by inducing oxidative stress, nitric oxide (NO) production and pro-inflammatory cytokine release. Exposure to SEC-B up to 24 h results in persistent accumulation of the vasodilator NO paralleled by an upregulation of the endothelial nitric oxide synthase (eNOS) enzyme and downregulation of Caveolin-1 (Cav-1) protein levels. Moreover, reduced expression and extracellular release of the vasoconstrictor factor endothelin-1 (ET-1) are observed. Furthermore, SEC-B stimulates the expression of the cytokines interleukin-6 (IL-6) and tumor necrosis factor-like weak inducer of apoptosis (TWEAK). This proinflammatory state leads to increased monocyte recruitment on activated HMEC-1 cells. Our findings add new knowledge on the role of SEC-B in ED and further support its potential implication in atherosclerosis.

The TWEAK/Fn14/CD163 axis-implications for metabolic disease

TWEAK (tumor necrosis factor-like weak inducer of apoptosis) is a member of the TNF superfamily that controls a multitude of cellular events including proliferation, migration, differentiation, apoptosis, angiogenesis, and inflammation. TWEAK control of these events is via an expanding list of intracellular signalling pathways which include NF-κB, ERK/MAPK, Notch, EGFR and AP-1. Two receptors have been identified for TWEAK - Fn14, which targets the membrane bound form of TWEAK, and CD163, which scavenges the soluble form of TWEAK. TWEAK appears to elicit specific events based on the receptor to which it binds, tissue type in which it is expressed, specific extrinsic conditions, and the presence of other cytokines. TWEAK signalling is protective in healthy tissues, but in chronic inflammatory states become detrimental to the tissue. Consistent data show a role for the TWEAK/FN14/CD163 axis in metabolic disease, chronic autoimmune diseases, and acute ischaemic stroke. Low circulating concentrations of soluble TWEAK are predictive of poor cardiovascular outcomes in those with and without diabetes. This review details the current understanding of the TWEAK/Fn14/CD163 axis as one of the chief regulators of immune signalling and its cell-specific role in metabolic disease development and progression.

TNF-like weak inducer of apoptosis / nuclear factor κB axis feedback loop promotes spinal cord injury by inducing astrocyte activation

Non-canonical signaling pathways have been proved to act as potent sites of astrocytes osmotic expanding or proliferation, which promotes the regeneration of axons in areas with non-neural spinal cord injury (SCI). However, the relevant signal pathway that induces autophagic cell death in astrocytes and its function relative to the TNF-like weak inducer of apoptosis/nuclear factor κB (TWEAK/NF-κB) axis remains elusive. The SCI model was established by vertically striking the spinal cord according to Allen’s model. Astrocytes and neuronal cells were prepared from spinal cells extracted from spinal cord tissues of SCI or normal C57BL/6 newborn mice. After co-culturing astrocytes and neurons, cell viability and autophagy were determined by CCK-8, transmission electron microscopy (TEM), and western blot. The expression of TWEAK, NF-κB and inflammatory cytokines was confirmed by qRT-PCR, western blot, Immunofluorescence and ELISA assay. Chromatin immunoprecipitation (CHIP) was used to evaluate the interaction between TWEAK and NF-κB. Our results demonstrated that knockdown of TWEAK and NF-κB inhibited secretion of high levels of TNF-α/IL-1β, partially counteracted by adding Rap. TWEAK/NF-κB was the positive correlation feedback loop regulating the proliferation and autophagy of astrocytes involved in SCI. Moreover, restraining the excess growth of astrocytes was beneficial to the growth of neurons. Collectively, our findings illustrated that the TWEAK/NF-κB pathway might act as a positive modulator of SCI by inducing astrocyte activation, shedding new insights for SCI treatment.

Growth differentiation factor-15 preserves Klotho expression in acute kidney injury and kidney fibrosis

Growth differentiation factor-15 (GDF15) is a member of the GDF subfamily with potential kidney protective functions. Here, we explored the impact of GDF15 on the expression of the kidney protective factor Klotho in models of acute kidney injury and kidney fibrosis in mice. GDF15 was the most upregulated GDF family gene in experimental toxic acute kidney injury and in kidney fibrosis transcriptomics. GDF15 function was explored in toxic acute kidney injury in genetically modified mice and following treatment with GDF15. Gdf15-deficient mice developed more severe toxic acute kidney injury (folic acid or cisplatin) while GDF15 overexpression or GDF15 administration were protective. Kidney expression of Klotho was more severely depressed in Gdf15-deficient mice and was preserved by GDF15 overexpression or GDF15 treatment. Moreover, increased plasma calcitriol levels inversely correlated with kidney Klotho across models with diverse levels of GDF15 availability. Kidney fibrosis induced by unilateral ureteral obstruction was more severe in Gdf15-deficient mice while GDF15 overexpression decreased kidney injury and preserved Klotho expression. GDF15 increased Klotho expression in vivo in healthy mice, in cultured tubular cells, and prevented Klotho downregulation by inflammatory factors in tubular cells by preventing transcription factor NF-ĸB activation. Thus, spontaneous increased kidney expression of endogenous GDF15 is not enough to prevent kidney injury, but further increments in GDF15 are kidney protecting and preserve expression of the kidney protective factor Klotho within the kidney in acute and chronic settings.

Bone Marrow-Derived RIPK3 Mediates Kidney Inflammation in Acute Kidney Injury

BACKGROUND

Receptor-interacting protein kinase 3 (RIPK3), a component of necroptosis pathways, may have an independent role in inflammation. It has been unclear which RIPK3-expressing cells are responsible for the anti-inflammatory effect of overall Ripk3 deficiency and whether Ripk3 deficiency protects against kidney inflammation occurring in the absence of tubular cell death.

METHODS

We used chimeric mice with bone marrow from wild-type and Ripk3-knockout mice to explore RIPK3's contribution to kidney inflammation in the presence of folic acid-induced acute kidney injury AKI (FA-AKI) or absence of AKI and kidney cell death (as seen in systemic administration of the cytokine TNF-like weak inducer of apoptosis [TWEAK]).

RESULTS

Tubular and interstitial cell RIPK3 expressions were increased in murine AKI. Ripk3 deficiency decreased NF-κB activation and kidney inflammation in FA-AKI but did not prevent kidney failure. In the chimeric mice, RIPK3-expressing bone marrow-derived cells were required for early inflammation in FA-AKI. The NLRP3 inflammasome was not involved in RIPK3's proinflammatory effect. Systemic TWEAK administration induced kidney inflammation in wild-type but not Ripk3-deficient mice. In cell cultures, TWEAK increased RIPK3 expression in bone marrow-derived macrophages and tubular cells. RIPK3 mediated TWEAK-induced NF-κB activation and inflammatory responses in bone marrow-derived macrophages and dendritic cells and in Jurkat T cells; however, in tubular cells, RIPK3 mediated only TWEAK-induced Il-6 expression. Furthermore, conditioned media from TWEAK-exposed wild-type macrophages, but not from Ripk3-deficient macrophages, promoted proinflammatory responses in cultured tubular cells.

CONCLUSIONS

RIPK3 mediates kidney inflammation independently from tubular cell death. Specific targeting of bone marrow-derived RIPK3 may limit kidney inflammation without the potential adverse effects of systemic RIPK3 targeting.

New Insights in Cytokines in Childhood Obesity: Changes in TWEAK and CD163 After a 2-Year Intervention Program in Prepubertal Children With Obesity

OBJECTIVE

Obesity is characterized by a low-grade inflammatory state in adipose tissue. Tumor Necrosis Factor Weak Inducer of Apoptosis (TWEAK) and Cluster of Differentiation 163 (CD163) are cytokines potentially involved in the pathogenesis of obesity. Little is known about them in children. The aim of this study was to observe serum levels of TWEAK and CD163 in prepubertal children with obesity compared to lean, and to evaluate its changes after a 2-year intervention program in children with obesity.

METHODS

Case-control study with a prospective follow-up of cases for 2 years in a referral pediatric endocrine outpatient centre. Seventy-three prepubertal children with obesity, and forty-seven age- and gender-matched lean controls were studied. Sixty-two cases finished the program. Anthropometric parameters, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), lipid profile, and concentrations of TWEAK and CD163 were determined. Children with obesity were re-evaluated after a 2-year intervention program consisting of diet and exercise. Weight loss was considered if z-score Body Mass Index (BMI) decreased at least 0.5 Standard Deviations (SD).

RESULTS

We observed higher CD163 levels in children with obesity compared to controls. No significant differences were observed in TWEAK and CD163/TWEAK ratio at baseline. After the 2-year intervention program, TWEAK levels were higher and CD163/TWEAK ratio was lower in children with weight loss than those without weight loss. CD163 decreased in both groups.

CONCLUSION

TWEAK and CD163 seem to have a role in the pathogenesis of obesity in prepubertal children.

Emerging role of TWEAK-Fn14 axis in lupus, a disease related to autoimmunity and fibrosis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder. Lupus nephritis (LN) is one of the severe clinical implications in SLE, and this was relates to fibrosis in the kidney. As an important marker in the tumor necrosis factor (TNF) superfamily, TNF-like weak inducer of apoptosis (TWEAK) has been given much attention with respect to its role in regulating pro-inflammatory immune response. Fibroblast growth factor-inducible 14 (Fn14), the sole receptor for TWEAK, has been found expressed in different immune and non-immune cells. TWEAK binds to Fn14, and then regulates inflammatory components production via downstream signaling pathways. To date, dysregulated expression of TWEAK, Fn14 has been reported in SLE, LN patients, and in vivo, in vitro studies have discussed the significant role of TWEAK-Fn14 axis in SLE, LN pathogenesis, partly through mediating the fibrosis process. In this review, we will discuss the association of TWEAK-Fn14 axis in lupus. Understanding the relationship will better realize the potential for making TWEAK-Fn14 as a marker for the diseases, and will help to give many clues for targeting them in treatment of lupus in the future.

Serum Levels of the Cytokine TWEAK Are Associated with Metabolic Status in Patients with Prostate Cancer and Modulate Cancer Cell Lipid Metabolism In Vitro

Simple Summary

TWEAK is an inflammatory cytokine related to prostate cancer (PCa) progression that exerts its effects by engaging its cognate receptor Fn14. A soluble form of TWEAK (sTWEAK) has been detected in the PCa microenvironment. Altered levels of circulating sTWEAK are associated with aberrant glucose metabolism. We show that reduced serum levels of sTWEAK are associated with the metabolic status in patients with PCa and that the treatment of PC-3 cells with sTWEAK enhances the expression of genes related to lipid, but not to glucose, metabolism. sTWEAK also increases the lipid uptake and lipid accumulation in PC-3 cells. We corroborated that the observed effects were due to TWEAK/Fn14 engagement by silencing Fn14 expression, which attenuated the aberrant gene and protein expression. Additionally, we observed that the phosphorylation of ERK1/2 and AKT (ser473) were required for TWEAK/Fn14 actions. Thus, the contribution of the sTWEAK/Fn14 axis on PCa metabolism supports its potential as a therapeutic target for PCa.

Abstract

Soluble TWEAK (sTWEAK) has been proposed as a prognostic biomarker of prostate cancer (PCa). We found that reduced serum levels of sTWEAK, together with higher levels of prostate-specific antigen and a higher HOMA-IR index, are independent predictors of PCa. We also showed that sTWEAK stimulus failed to alter the expression of glucose transporter genes (SLC2A4 and SLC2A1), but significantly reduced the expression of glucose metabolism-related genes (PFK, HK1 and PDK4) in PCa cells. The sTWEAK stimulation of PC-3 cells significantly increased the expression of the genes related to lipogenesis (ACACA and FASN), lipolysis (CPT1A and PNPLA2), lipid transport (FABP4 and CD36) and lipid regulation (SREBP-1 and PPARG) and increased the lipid uptake. Silencing the TWEAK receptor (Fn14) in PC-3 cells confirmed the observed lipid metabolic effects, as shown by the downregulation of ACACA, FASN, CPT1A, PNPLA2, FABP4, CD36, SREBP-1 and PPARG expression, which was paralleled by a reduction of FASN, CPT1A and FABP4 protein expression. Specific-signaling inhibitor assays show that ERK1/2 and AKT (ser473) phosphorylation can regulate lipid metabolism-related genes in PCa cells, pointing to the AKT locus as a possible target for PCa. Overall, our data support sTWEAK/Fn14 axis as a potential therapeutic target for PCa.

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.

Furin is involved in uterine activation for labor

The uterus undergoes distinct molecular and functional changes during pregnancy and parturition. These processes are associated with the dramatic changes in various proteins. Given that the maturation and activation of many proteins require proteolytic processing by proprotein convertases (PCs), we sought to explore the role of PCs in uterine activation for labor. First, we found that furin was the most dramatically increased PC member in myometrial tissues from the pregnant women after onset of labor at term. Using the model of cultured human myometrial smooth muscle cells (HMSMCs), we showed that furin inhibitor CMK, D6R treatment and furin siRNA transfection suppressed contractility. Inhibition of furin activity or interfering furin expression decreased connexin 43 (CX43), prostaglandin (PG) endoperoxide synthase-2 (COX-2) and PGF2α receptor (FP) expression and NF-κB activation. In mouse model, administration of furin inhibitors prolonged gestational length. However, D6R treatment did not affect RU38486- and lipopolysaccharides (LPS)-induced preterm birth. Furthermore, D6R and furin siRNA treatment reduced the release of soluble form of tumor necrosis factor (TNF)-related weak inducer of apoptosis (TWEAK), while furin overexpression led to an increase in soluble TWEAK release in cultured HMSMCs. D6R treatment decreased TWEAK level in blood of pregnant mice. TWEAK treatment promoted contractility and NF-κB activation, while TWEAK receptor fibroblast growth factor-inducible 14 (FN14) antagonist treatment inhibited contractility and NF-κB activation in HMSMCs. In pregnant mice, administration of FN14 antagonist prolonged gestational length. Our data suggest that furin can act as a stimulator for uterine activation for labor at term. TWEAK is one of the potential substrates which mediate furin regulation of parturition initiation.

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 signalling promotes cholangiocarcinoma niche formation and progression

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a cancer of the hepatic bile ducts that is rarely resectable and is associated with poor prognosis. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is known to signal via its receptor fibroblast growth factor-inducible 14 (Fn14) and induce cholangiocyte and myofibroblast proliferation in liver injury. We aimed to characterise its role in CCA.

METHODS

The expression of the TWEAK ligand and Fn14 receptor was assessed immunohistochemically and by bulk RNA and single cell transcriptomics of human liver tissue. Spatiotemporal dynamics of pathway regulation were comprehensively analysed in rat and mouse models of thioacetamide (TAA)-mediated CCA. Flow cytometry, qPCR and proteomic analyses of CCA cell lines and conditioned medium experiments with primary macrophages were performed to evaluate the downstream functions of TWEAK/Fn14. In vivo pathway manipulation was assessed via TWEAK overexpression in NICD/AKT-induced CCA or genetic Fn14 knockout during TAA-mediated carcinogenesis.

RESULTS

Our data reveal TWEAK and Fn14 overexpression in multiple human CCA cohorts, and Fn14 upregulation in early TAA-induced carcinogenesis. TWEAK regulated the secretion of factors from CC-SW-1 and SNU-1079 CCA cells, inducing polarisation of proinflammatory CD206+ macrophages. Pharmacological blocking of the TWEAK downstream target chemokine monocyte chemoattractant protein 1 (MCP-1 or CCL2) significantly reduced CCA xenograft growth, while TWEAK overexpression drove cancer-associated fibroblast proliferation and collagen deposition in the tumour niche. Genetic Fn14 ablation significantly reduced inflammatory, fibrogenic and ductular responses during carcinogenic TAA-mediated injury.

CONCLUSION

These novel data provide evidence for the action of TWEAK/Fn14 on macrophage recruitment and phenotype, and cancer-associated fibroblast proliferation in CCA. Targeting TWEAK/Fn14 and its downstream signals may provide a means to inhibit CCA niche development and tumour growth.

LAY SUMMARY

Cholangiocarcinoma is an aggressive, chemotherapy-resistant liver cancer. Interactions between tumour cells and cells that form a supportive environment for the tumour to grow are a source of this aggressiveness and resistance to chemotherapy. Herein, we describe interactions between tumour cells and their supportive environment via a chemical messenger, TWEAK and its receptor Fn14. TWEAK/Fn14 alters the recruitment and type of immune cells in tumours, increases the growth of cancer-associated fibroblasts in the tumour environment, and is a potential target to reduce tumour formation.

Anti-TWEAK Antibody Alleviates Renal Interstitial Fibrosis by Increasing PGC-1α Expression in Lupus Nephritis

Purpose

Current studies on the mechanism of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in lupus nephritis (LN) mainly focus on the inflammatory pathway. Herein, we aimed to determine whether TWEAK could promote the progression of renal interstitial fibrosis by regulating peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) expression and intervening in lipid metabolism in LN.

Materials and Methods

MRL/lpr mice, an animal model of lupus, were treated with the anti-TWEAK antibody or co-treated with adeno-associated virus-mediated PGC-1α short hairpin RNA (shRNA). In addition, human proximal tubular epithelial cells (HK2 cells) were treated with recombinant human TWEAK (rhTWEAK) or ammonium pyrrolidine dithiocarbamate (PDTC) in vitro.

Results

The renal contents of free fatty acids and triglycerides were higher in MRL/lpr mice than in MRL/MpJ mice; however, these contents were decreased by treatment with the anti-TWEAK antibody. Based on immunofluorescence staining, the expression of PGC-1α was markedly more in the renal tubules of MRL/MpJ mice than in the glomeruli. However, treatment with anti-TWEAK antibody increased the levels of PGC-1α and its downstream target genes, which were remarkably lower in MRL/lpr mice than in MRL/MpJ mice. Anti-TWEAK antibody effectively eased renal interstitial fibrosis, which manifested as a decrease in the deposition of collagen fibers and the inhibition of type I collagen and fibronectin expression. However, the therapeutic effects of the anti-TWEAK antibody were abolished by PGC-1α shRNA. Treatment with rhTWEAK decreased PGC-1α expression in both dose- and time-dependent manners in HK2 cells in vitro. PDTC, an inhibitor of IκBα phosphorylation, suppressed the decrease in the PGC-1α protein level induced by rhTWEAK treatment.

Conclusion

Our results suggest that TWEAK prevents renal tubular PGC-1α expression by promoting NF-κB activation, resulting in a deficiency in lipid metabolism and the progress of renal interstitial fibrosis. The upregulation of renal tubular PGC-1α expression to improve lipid metabolism is one of the mechanisms employed by the anti-TWEAK antibody to treat renal interstitial fibrosis.

Tumor necrosis factor superfamily molecules are increased in behavioral variant frontotemporal dementia and correlate with cortical atrophy: An exploratory investigation

Frontotemporal dementia (FTD) is the second most frequent cause of young-onset dementia. Even though immune-mediated and neuroinflammatory factors have been recognized as potential pathophysiological mechanisms, the role of specific immune molecules, such as the tumor necrosis factor (TNF) superfamily, remains elusive. The aim of this study was to investigate TNF Superfamily Molecules (TNF, TNF-related weak inducer of apoptosis [TWEAK], soluble TNF receptor type 1 [sTNFRI] and soluble TNF receptor type 2 [sTNFRII]) in patients with behavioral variant FTD (bvFTD) and controls, and to explore potential associations with clinical parameters and brain atrophy. This study included two groups of participants matched for age, sex and schooling years: patients with probable bvFTD (n = 17, mean age = 64.9 years, 6 women/11 men) and healthy controls (HC, n = 17; mean age = 63.9 years, 10 women/7 men). All participants underwent comprehensive cognitive assessment and structural brain imaging with 3 T magnetic resonance imaging. Plasma levels of TNF, TWEAK, sTNFRI and sTNFRII were determined by ELISA. We conducted voxel-based morphometry analyses to investigate correlations between grey matter (GM) atrophy and plasma levels of TNF, TWEAK, sTNFRI and sTNFRII within bvFTD group. Compared to HC, bvFTD patients had lower cognitive scores and marked frontotemporal atrophy. Patients with bvFTD had significantly higher plasma levels of TNF (p < 0.0001), sTNFRI (p < 0.001), and sTNFRII (p < 0.0001), and similar levels of TWEAK in comparison with controls. The levels of sTNFRII were positively correlated with GM atrophy involving temporal poles, precuneus and cerebellum in bvFTD patients, while the levels of TWEAK positively correlated with right superior temporal gyrus. Our results implicate TNF superfamily in the pathophysiology of FTD.

Remodeling of Neurotransmission, Chemokine, and PI3K-AKT Signaling Genomic Fabrics in Neuropsychiatric Systemic Lupus Erythematosus

Cognitive dysfunction and mood changes are prevalent and especially taxing issues for patients with systemic lupus erythematosus (SLE). Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its cognate receptor Fn14 have been shown to play an important role in neurocognitive dysfunction in murine lupus. We profiled and compared gene expression in the cortices of MRL/+, MRL/lpr (that manifest lupus-like phenotype) and MRL/lpr-Fn14 knockout (Fn14ko) adult female mice to determine the transcriptomic impact of TWEAK/Fn14 on cortical gene expression in lupus. We found that the TWEAK/Fn14 pathway strongly affects the expression level, variability and coordination of the genomic fabrics responsible for neurotransmission and chemokine signaling. Dysregulation of the Phosphoinositide 3-kinase (PI3K)-AKT pathway in the MRL/lpr lupus strain compared with the MRL/+ control and Fn14ko mice was particularly prominent and, therefore, promising as a potential therapeutic target, although the complexity of the transcriptomic fabric highlights important considerations in in vivo experimental models.

Developmental synaptic regulator, TWEAK/Fn14 signaling, is a determinant of synaptic function in models of stroke and neurodegeneration

Identifying molecular mediators of neural circuit development and/or function that contribute to circuit dysfunction when aberrantly reengaged in neurological disorders is of high importance. The role of the TWEAK/Fn14 pathway, which was recently reported to be a microglial/neuronal axis mediating synaptic refinement in experience-dependent visual development, has not been explored in synaptic function within the mature central nervous system. By combining electrophysiological and phosphoproteomic approaches, we show that TWEAK acutely dampens basal synaptic transmission and plasticity through neuronal Fn14 and impacts the phosphorylation state of pre- and postsynaptic proteins in adult mouse hippocampal slices. Importantly, this is relevant in two models featuring synaptic deficits. Blocking TWEAK/Fn14 signaling augments synaptic function in hippocampal slices from amyloid-beta-overexpressing mice. After stroke, genetic or pharmacological inhibition of TWEAK/Fn14 signaling augments basal synaptic transmission and normalizes plasticity. Our data support a glial/neuronal axis that critically modifies synaptic physiology and pathophysiology in different contexts in the mature brain and may be a therapeutic target for improving neurophysiological outcomes.

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.

Evaluation of Computationally Designed Peptides against TWEAK, a Cytokine of the Tumour Necrosis Factor Ligand Family

The tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumour necrosis factor ligand family and has been shown to be overexpressed in tumoral cells together with the fibroblast growth factor–inducible 14 (Fn14) receptor. TWEAK-Fn14 interaction triggers a set of intracellular pathways responsible for tumour cell invasion and migration, as well as proliferation and angiogenesis. Hence, modulation of the TWEAK-Fn14 interaction is an important therapeutic goal. The targeting of protein-protein interactions by external agents, e.g., drugs, remains a substantial challenge. Given their intrinsic features, as well as recent advances that improve their pharmacological profiles, peptides have arisen as promising agents in this regard. Here, we report, by in silico structural design validated by cell-based and in vitro assays, the discovery of four peptides able to target TWEAK. Our results show that, when added to TWEAK-dependent cellular cultures, peptides cause a down-regulation of genes that are part of TWEAK-Fn14 signalling pathway. The direct, physical interaction between the peptides and TWEAK was further elucidated in an in vitro assay which confirmed that the bioactivity shown in cell-based assays was due to the targeting of TWEAK. The results presented here are framed within early pre-clinical drug development and therefore these peptide hits represent a starting point for the development of novel therapeutic agents. Our approach exemplifies the powerful combination of in silico and experimental efforts to quickly identify peptides with desirable traits.

Urinary MCP-1 and TWEAK as non-invasive markers of disease activity and treatment response in patients with lupus nephritis in South Africa

BACKGROUND

Treatment of patients with lupus nephritis (LN) requires judicious use of immunosuppression. Novel biomarkers may be useful for monitoring disease activity and treatment response. We assessed the utility of urinary monocyte chemoattractant protein-1 (uMCP-1) and urinary tumour necrosis factor-like weak inducer of apoptosis (uTWEAK) for disease activity and treatment response monitoring in South Africans with LN.

METHODS

We recruited consenting patients with active LN confirmed on kidney biopsy. Urinary levels of MCP-1 and TWEAK were assayed at baseline and after completion of induction therapy using ELISA methods. We also collected relevant demographic, clinical and biochemical data for patients included in this study.

RESULTS

The mean age of patients in this study was 29.8 ± 10.7 years, 60% were patients of mixed ancestry, 70% had proliferative LN and mean spot urine proteinuria at baseline was 0.37 (0.18-0.59) g/mmolCr. At completion of induction therapy, the level of uMCP-1 had reduced to 314.5 (IQR: 197.0-622) pg/mgCr from a baseline of 1092.7 (IQR 578.6-1848) pg/mgCr (P = 0.06) while uTWEAK had reduced to 36.0 (IQR 17.0-88.0) pg/mgCr from 159.0 (IQR: 88.5-295.5) pg/mgCr (P = 0.03). For patients reaching early complete or partial remission (n = 17), both biomarkers had significantly declined in their urine: uMCP-1 (P = 0.018) and uTWEAK (P = 0.015). There was no reduction of both biomarkers in patients not achieving remission and no association between uMCP-1 or uTWEAK with renal histological features.

CONCLUSION

Our study shows that uMCP-1 and uTWEAK are elevated in patients with active LN, correlated with the remission status (response to treatment) at the end of induction therapy and can, therefore, be useful for monitoring disease activity and treatment response.

Liquid Biopsy-Based Exo-oncomiRNAs Can Predict Prostate Cancer Aggressiveness

Liquid biopsy-based biomarkers, including microRNAs packaged within extracellular vesicles, are promising tools for patient management. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is related to PCa progression and is found in the semen of patients with PCa. TWEAK can induce the transfer of exo-oncomiRNAs from tumor cells to body fluids, and this process might have utility in non-invasive PCa prognosis. We investigated TWEAK-regulated exo-microRNAs in semen and in post-digital rectal examination urine from patients with different degrees of PCa aggressiveness. We first identified 14 exo-oncomiRNAs regulated by TWEAK in PCa cells in vitro, and subsequently validated those using liquid biopsies from 97 patients with PCa. Exo-oncomiR-221-3p, -222-3p and -31-5p were significantly higher in the semen of high-risk patients than in low-risk peers, whereas exo-oncomiR-193-3p and -423-5p were significantly lower in paired samples of post-digital rectal examination urine. A panel of semen biomarkers comprising exo-oncomiR-221-3p, -222-3p and TWEAK was designed that could correctly classify 87.5% of patients with aggressive PCa, with 85.7% specificity and 76.9% sensitivity with an area under the curve of 0.857. We additionally found that TWEAK modulated two exo-oncomiR-221-3p targets, TCF12 and NLK. Overall, we show that liquid biopsy detection of TWEAK-regulated exo-oncomiRNAs can improve PCa prognosis prediction.

The assessment of the serum levels of TWEAK and prostaglandin F2α in COVID – 19

Background/aim

It is claimed that aberrant immune response has a more important role than the cytopathic effect of the virus in the morbidity and mortality of the coronavirus disease 2019 (COVID-19). We aimed to investigate the possible roles of tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 pathway and leukotrienes (LT) in uncontrolled immune response that occurs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Materials and methods

This study included 25 asymptomatic patients and 35 patients with lung involvement who were diagnosed with COVID-19 as well as 22 healthy volunteers. Lung involvement was determined using computed-tomography. Serum TWEAK, LTE4, and prostaglandin F2α (PGF2α) levels were determined.

Results

Compared with the healthy control group, TWEAK, LTE4, and PGF2α levels were higher in the group of SARS-CoV-2 infection without lung involvement. In the group of SARS-CoV-2 infection with lung involvement, age, fibrinogen, sedimentation, C-reactive protein and ferritin, TWEAK, LTE4, and PGF2α levels were higher, and lymphocyte levels were lower compared with the asymptomatic group.

Conclusions

In the study, TWEAK and LTE4 levels increased in cases with COVID-19. These results support that TWEAK/Fn14 pathway and LT may involved in the pathology of aberrant immune response against SARS-CoV-2. Inhibition of each of these pathways may be a potential target in the treatment of COVID-19.

Involvement of the cytokine TWEAK in the pathogenesis of psoriasis vulgaris, pustular psoriasis, and erythrodermic psoriasis

Psoriasis is a common chronic inflammatory dermatitis in which various cytokines play a detrimental role. The cytokine tumor necrosis factor-related weak inducer of apoptosis (TWEAK) is involved in the pathogenesis of multiple inflammatory disorders. However, the potential role of TWEAK in various subtypes of psoriasis has not been studied in depth. To investigate whether the levels of TWEAK are associated with clinical traits and the levels of some known psoriasis-related cytokines, such as interleukin (IL)-17A, IL-22, interferon (IFN)-γ, and IL-36γ, 20 patients with psoriasis vulgaris (PV), 8 patients with pustular psoriasis (PP), 8 patients with erythrodermic psoriasis (EP), and 20 healthy controls (HCs) were recruited into this study. The levels of serum cytokines were detected by commercial enzyme-linked immunosorbent assay kits. The average levels of TWEAK, IL-17A, IL-22, IFN-γ, and IL-36γ were significantly higher in the psoriasis groups than in the HC group. Furthermore, there was a statistically significant correlation between TWEAK and IL-17A/IFN-γ in PV and IL-36γ in EP, but there was no correlation between TWEAK and IL-22 in any subtype of psoriasis. This study suggests that TWEAK may have a role in the pathogenesis of PV, PP, and EP via synergy with IL-17A, IFN-γ, or IL-36γ, but not with IL-22.

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.

Norcantharidin protects against renal interstitial fibrosis by suppressing TWEAK-mediated Smad3 phosphorylation

AIMS

This study investigated the role and mechanism of action of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in the pathogenesis of renal interstitial fibrosis (RIF), and its involvement in the anti-RIF effect of norcantharidin (NCTD).

MAIN METHODS

Mice with unilateral ureteral obstruction and BUMPT mouse proximal tubular cells exposed to transforming growth factor (TGF)-β1 were used as in vivo and in vitro models of RIF, respectively. NCTD was administered to mice by intraperitoneal injection (0.075 mg kg^-1·day^-1). Hematoxylin-eosin and Masson's trichrome staining were performed to assess pathologic changes in the kidney. Immunohistochemistry, western blotting, and real-time PCR were performed to evaluate the expression of TWEAK and the fibrotic factors fibronectin (FN) and collagen type I (Col-I). The role of TWEAK in RIF and in the anti-RIF effect of NCTD was evaluated by TWEAK overexpression and neutralization with a specific antibody, and specific inhibitor of Mothers against decapentaplegic homolog (Smad)3 (SIS3) was used to examine the involvement of TGF-β1/Smad3 signaling.

KEY FINDINGS

TWEAK was mainly expressed in renal tubules in mice; the level was markedly elevated in both in vivo and in vitro RIF models. TWEAK overexpression in BUMPT cells increased the levels of phosphorylated Smad3, FN, and Col-I, which were reduced by treatment with SIS3. NCTD suppressed FN and Col-I expression by blocking TWEAK-mediated Smad3 phosphorylation.

SIGNIFICANCE

Upregulation of TWEAK contributes to RIF by promoting Smad3 phosphorylation, while NCTD inhibits this process.

CD163 deficiency increases foam cell formation and plaque progression in atherosclerotic mice

Atherosclerosis is an inflammatory disease characterized by the accumulation of macrophages in the vessel wall. Macrophages depend on their polarization to exert either pro-inflammatory or anti-inflammatory effects. Macrophages of the anti-inflammatory phenotype express high levels of CD163, a scavenger receptor for the hemoglobin-haptoglobin complex. CD163 can also bind to the pro-inflammatory cytokine TWEAK. Using ApoE-deficient or ApoE/CD163 double-deficient mice we aim to investigate the involvement of CD163 in atherosclerosis development and its capacity to neutralize the TWEAK actions. ApoE/CD163 double-deficient mice displayed a more unstable plaque phenotype characterized by an increased lipid and macrophage content, plaque size, and pro-inflammatory cytokine expression. In vitro experiments demonstrated that the absence of CD163 in M2-type macrophages-induced foam cell formation through upregulation of CD36 expression. Moreover, exogenous TWEAK administration increased atherosclerotic lesion size, lipids, and macrophages content in ApoE^-/- /CD163^-/- compared with ApoE^-/- /CD163^+/+ mice. Treatment with recombinant CD163 was able to neutralize the proatherogenic effects of TWEAK in ApoE/CD163 double-deficient mice. Recombinant CD163 abolished the pro-inflammatory actions of TWEAK on vascular smooth muscle cells, decreasing NF-kB activation, cytokines and metalloproteinases expression, and macrophages migration. In conclusion, CD163-expressing macrophages serve as a protective mechanism to prevent the deleterious effects of TWEAK on atherosclerotic plaque development and progression.

B Cell Disorders in Children: Part II

PURPOSE OF REVIEW

B cell disorders result in decreased levels or function of immunoglobulins in an individual. Genetic mutations have been reported in a variety of B cell disorders. This review, in follow-up to a previous review, describes some rare B cell disorders as well as their known underlying genetic etiologies.

RECENT FINDINGS

Genetic studies identify and permit precise classification of an increasing number of B cell disorders, leading to a greater understanding of B cell development and function. The B cell disorders are rare diseases. While clinicians are most familiar with X-linked agammaglobulinemia and so-called common variable immunodeficiency (CVID), there are many causes of hypogammaglobulinemia. Genetic testing provides a specific diagnosis, offers useful information for genetic counseling, and can identify previously unrecognized B cell disorders.