Nuclear factor-κB Activation Research Articles

RANK and RANKL Expression in Tumors of Patients with Early Breast Cancer

AbstractThe receptor activator of nuclear factor-κB (RANK) pathway was associated with the pathogenesis of breast cancer. Several studies attempted to link the RANK/RANKL pathway to prognosis; however, with inconsistent outcomes. We aimed to further contribute to the knowledge about RANK/RANKL as prognostic factors in breast cancer. Within this study, protein expression of RANK and its ligand, RANKL, in the tumor tissue was analyzed in association with disease-free survival (DFS) and overall survival (OS) in a study cohort of patients with early breast cancer.607 samples of female primary and early breast cancer patients from the Bavarian Breast Cancer Cases and Controls Study were analyzed to correlate the RANK and RANKL expression with DFS and OS. Therefore, expression was quantified using immunohistochemical staining of a tissue microarray. H-scores were determined with the cut-off value of 8.5 for RANK and 0 for RANKL expression, respectively.RANK and RANKL immunohistochemistry were assessed by H-score. Both biomarkers did not correlate (ρ = −0.04). According to molecular subtypes, triple-negative tumors and HER2-positive tumors showed a higher number of RANK-positive tumors (H-score ≥ 8.5), however, no subtype-specific expression of RANKL could be detected. Higher RANKL expression tended to correlate with a better prognosis. However, RANK and RANKL expression could not be identified as statistically significant prognostic factors within the study cohort.Tumor-specific RANK and RANKL expressions are not applicable as prognostic factors for DFS and OS, but might be associated with subtype-specific breast cancer progression.

CFLIPL acts as a suppressor of TRAIL- and Fas-initiated inflammation by inhibiting assembly of caspase-8/FADD/RIPK1 NF-κB-activating complexes

TRAIL and FasL are potent inducers of apoptosis but can also promote inflammation through assembly of cytoplasmic caspase-8/FADD/RIPK1 (FADDosome) complexes, wherein caspase-8 acts as a scaffold to drive FADD/RIPK1-mediated nuclear factor κB (NF-κB) activation. cFLIP is also recruited to FADDosomes and restricts caspase-8 activity and apoptosis, but whether cFLIP also regulates death receptor-initiated inflammation is unclear. Here, we show that silencing or deletion of cFLIP leads to robustly enhanced Fas-, TRAIL-, or TLR3-induced inflammatory cytokine production, which can be uncoupled from the effects of cFLIP on caspase-8 activation and apoptosis. Mechanistically, cFLIPL suppresses Fas- or TRAIL-initiated NF-κB activation through inhibiting the assembly of caspase-8/FADD/RIPK1 FADDosome complexes, due to the low affinity of cFLIPL for FADD. Consequently, increased cFLIPL occupancy of FADDosomes diminishes recruitment of FADD/RIPK1 to caspase-8, thereby suppressing NF-κB activation and inflammatory cytokine production downstream. Thus, cFLIP acts as a dual suppressor of apoptosis and inflammation via distinct modes of action.

Diethyl phthalate, a plasticizer, induces adipocyte inflammation and apoptosis in mice after long-term dietary administration.

The incidence of metabolic diseases is increasing alarmingly in recent times. Parallel to nutritional excess and sedentary lifestyle, the random usage of several endocrine disrupting chemicals including plasticizers is reported to be closely associated with metabolic diseases. Diethyl phthalate (DEP) is a widely used plasticizer in a host of consumer and daily care products. Adipose tissue plays a central role in energy storage and whole-body metabolism. The impairment of adipose function is critically implicated in the pathogenesis of insulin resistance, diabetes, and related metabolic diseases. Recently, exposure to certain phthalate esters has been linked to the development of obesity and diabetes, although there are contradictions and the mechanisms are not clearly understood. In an effort to ascertain the metabolic consequences of chronic phthalate exposure and the underlying mechanism, the present study was designed to examine the effects of long-term dietary consumption of DEP in adipocytes. DEP-treated mice were hyperglycemic but nonobese; their body weight initially increased which subsequently was reduced compared to control. DEP exposure at lower levels impaired adipogenesis by downregulating the key transcription factor, peroxisome proliferator-activated receptor γ and its downstream insulin-sensitizing adipokine, adiponectin, thereby severely compromising adipocyte function. The activation of master regulator nuclear factor κB led to rise in proinflammatory cytokines. We found that DEP triggered intrinsic apoptotic pathways through activated cytochrome c-Apaf1-caspase 9-caspase 3 axis in adipocytes. Taken together, our data revealed that chronic administration of dietary DEP could unleash adverse metabolic outcomes by initiating oxidative stress, inflammation, and apoptosis in the adipocytes, thus leading to adipose tissue dysfunction.

Swimming training and caffeine supplementation protects against metabolic syndrome–induced nuclear factor–κB activation and cognitive deficits in rats

Metabolic syndrome (MS) is a disorder that increasingly affects the world population, mainly because of changes in lifestyle and dietary habits. In this regard, both physical exercise and caffeine are low-cost and easily accessible therapies that separately have shown positive effects against metabolic disorders. Therefore, we hypothesized that physical exercise combined with caffeine could have a synergistic effect in the treatment of MS, risk factors, and cognitive deficits. Animals were divided into 8 groups and received fructose (15% w/v) or vehicle for 10 weeks. Swimming training and caffeine (6 mg/kg) started 4 weeks after fructose administration. Trained animals presented decreased body weight and visceral fat mass and increased soleus weight compared with untrained fructose-treated animals. Caffeine supplementation also prevented the gain of visceral fat mass induced by fructose. Furthermore, both treatments reversed fructose-induced decrease in glucose clearance over time and fructose-induced increase in 4-hydroxynonenal and nuclear factor-κB immunoreactivity. Physical training also improved the lipidic profile in fructose-treated animals (high-density lipoprotein, low-density lipoprotein, and triglycerides), improved short-term, long-term, and localization memory, and reversed the fructose-induced deficit in short-term memory. Physical training also increased nuclear factor erythroid 2-related factor 2 immunoreactivity per se. Considering that physical training and caffeine reversed some of the damages induced by fructose it is plausible to consider these treatments as alternative, nonpharmacological, and low-cost therapies to help reduce MS-associated risk factors; however, combined treatments did not show additive effects as hypothesized.

Natural drug asiaticoside inhibits osteoclast differentiation and promotes repair of steroid-induced osteonecrosis of femoral head via RANKL pathway

Asiaticoside is one of the most classic traditional Chinese medicines. The interaction between Receptor activator of nuclear factor κB (RANK) and Receptor Activator of Nuclear Factor-κ B Ligand (RANKL) activates a series of intracellular signaling pathways. Our research explored the mechanism of asiaticoside inhibiting osteoclast differentiation and repair of steroid-induced osteonecrosis of femoral head (SIONFH) through RANKL pathway. Asiaticoside’s effect on osteoclasts was determined by Microneedle Therapy System (MTS) method, and the number of Tartrate resistant acid phosphatase (TRAcP) multinucleated cells (3 nuclei) was quantitatively analyzed. Under different dose treatments, the changes of bone function were detected by eroded area and TRAcP staining on hydroxyapatite-coated plate, and the expression of different osteocyte formation and osteogenic differentiation were detected. Asiaticoside weakened the osteoclast function induced by RANKL. When the concentration of asiaticoside was 10 μmol/L, osteoclast formation regulatory genes (NFATc1 and Acp5) and osteoclast cell function-related genes (AP-1 and P65) were significantly downregulated in the presence of RANKL. Asiaticoside (10 μmol/L) significantly decreased calcium oscillations induced by RANKL via preventing RANKL-mediated NF-κB activation and Ca2+ oscillation.

Disturbance of sleep maintenance, but not sleep duration, activates nuclear factor-κB and signal transducer and activator of transcription (STAT) family proteins in older adults: Sex differences

Disturbance of sleep maintenance, but not sleep duration, activates nuclear factor-κB and signal transducer and activator of transcription (STAT) family proteins in older adults: Sex differences

5′-Methylthioadenosine strongly suppresses RANKL-induced osteoclast differentiation and function via inhibition of RANK-NFATc1 signalling pathways

Excessive osteoclast-mediated bone resorption is a critical cause of osteoporosis affecting many aging people worldwide. 5′-Methylthioadenosine (MTA) is a natural sulfur-containing nucleoside normally produced in prokaryotes, plants, yeast, and higher eukaryotes via polyamine metabolism. MTA affects various physiological responses particularly the inflammatory pathway in both normal and cancerous cells and modulates the activation of nuclear factor-κB involved in the osteoclastogenesis signalling process. While several studies have reported that natural products possess anti-osteoclastogenesis phenolics and flavonoids, the effect of nucleoside derivatives on osteoclastogenesis remains limited. Therefore, this study aimed to explore the molecular mechanisms by which MTA affects pre-osteoclastic RAW 264.7 cells as a potential alleviation compound for inflammation-mediated bone loss. Osteoclasts were established by incubating RAW264.7 macrophage cells with receptor activator of nuclear factor kappa B ligand (RANKL) and macrophage colony-stimulating factor, the vital cytokines for activation of osteoclast differentiation. Cell viability was measured using MTT assays at 24, 48, and 72 h. The suppressive effect of MTA on RANKL-induced osteoclast differentiation and function was assessed using tartrate-resistant acid phosphatase (TRAP) analysis, qRT-PCR, and pit formation, Western blot, and immunofluorescence assays. MTA showed dose-dependent anti-osteoclastogenic activity by inhibiting TRAP-positive cell and pit formation and reducing essential digestive enzymes, including TRAP, cathepsin K, and matrix metallopeptidase 9. MTA was observed to suppress the osteoclast transduction pathway through (RANKL)-induced nuclear factor kappa-light-chain-enhancer of activated B cells (NFƘB); it attenuated NFƘB-P65 expression and down-regulated cFos proto-oncogene and nuclear factor of activated T cell c1 (NFATc1), the main regulators of osteoclasts. Moreover, the suppression of RANK (the initial receptor triggering several osteoclastogenic transduction pathways) was observed. Thus, this study highlights the potential of MTA as an effective therapeutic compound for restoring bone metabolic disease by inhibiting the RANK-NFATc1 signal pathway.

Regulation of anti-inflammatory and antioxidant responses by methanol extract of Mikania cordata (Burm. f.) B. L. Rob. leaves via the inactivation of NF-κB and MAPK signaling pathways and activation of Nrf2 in LPS-induced RAW 264.7 macrophages

Mikania cordata (Burm. f.) B.L. Rob. has been traditionally used in tropical countries throughout Asia and Africa to treat gastric ulcers, dyspepsia, and dysentery. However, the mechanisms responsible for its anti-inflammatory and antioxidant activities are not fully understood. Therefore, this study sought to investigate the anti-inflammatory and antioxidant effects of methanol extracts of M. cordata (MMC) on inflammation and oxidative stress in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages and elucidate its underlying regulatory mechanism. MMC significantly suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated RAW 264.7 macrophages by downregulating the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the mRNA and protein levels. Moreover, MMC effectively reduced the mRNA expression levels and production of pro-inflammatory cytokines, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α). These suppressive effects of MMC on pro-inflammatory mediators and cytokines were mediated through the inhibition of transforming growth factor beta-activated kinase 1 (TAK1), which subsequently blocked the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). MMC also upregulated the nuclear factor erythroid-2-related factor 2 (Nrf2) by inducing the degradation of Kelch-like ECH-related protein 1 (Keap1), an Nrf2-specific E3 ligase. Accordingly, MMC enhanced Nrf2 target gene expression of anti-oxidative regulators such as heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1). However, it had minimal effect on the DPPH radical scavenging capacity in vitro. Collectively, these findings demonstrate that MMC holds promise as a potential therapeutic agent for alleviating inflammation-related diseases and oxidative stress.

Ramelteon attenuates hippocampal neuronal loss and memory impairment following kainate-induced seizures.

Evidence suggests that the neuroprotective effects of melatonin involve both receptor-dependent and -independent actions. However, little is known about the effects of melatonin receptor activation on the kainate (KA)neurotoxicity. This study examined the effects of repeated post-KAtreatment with ramelteon, a selective agonist of melatonin receptors, on neuronal loss, cognitive impairment, and depression-like behaviors following KA-induced seizures. The expression of melatonin receptors decreased in neurons, whereas it was induced in astrocytes 3 and 7 days after seizures elicited by KA (0.12 μg/μL) in the hippocampus of mice. Ramelteon (3 or 10 mg/kg, i.p.) and melatonin (10 mg/kg, i.p.) mitigated KA-induced oxidative stress and impairment of glutathione homeostasis and promoted the nuclear translocation and DNA binding activity of Nrf2 in the hippocampus after KA treatment. Ramelteon and melatonin also attenuated microglial activation but did not significantly affect astroglial activation induced by KA, despite the astroglial induction of melatonin receptors after KA treatment. However, ramelteon attenuated KA-induced proinflammatory phenotypic changes in astrocytes. Considering the reciprocal regulation of astroglial and microglial activation, these results suggest ramelteon inhibits microglial activation by regulating astrocyte phenotypic changes. These effects were accompanied by the attenuation of the nuclear translocation and DNA binding activity of nuclear factor κB (NFκB) induced by KA. Consequently, ramelteon attenuated the KA-induced hippocampal neuronal loss, memory impairment, and depression-like behaviors; the effects were comparable to those of melatonin. These results suggest that ramelteon-mediated activation of melatonin receptors provides neuroprotection against KA-induced neurotoxicity in the mouse hippocampus by activating Nrf2 signaling to attenuate oxidative stress and restore glutathione homeostasis and by inhibiting NFκB signaling to attenuate neuroinflammatory changes.

Sargachromenol Attenuates Inflammatory Responses by Regulating NF-κB and Nrf2 Pathways in RAW 264.7 Cells and LPS-treated Mice.

This study aims to explore the anti-inflammatory mechanisms of sargachromenol in both RAW 264.7 cells and lipopolysaccharide (LPS)-treated mice, as previous reports have suggested that sargachromenol possesses anti-aging, anti-inflammatory, antioxidant, and neuroprotective properties. Although the precise mechanism behind its anti-inflammatory activity remains unclear, pretreatment with sargachromenol effectively reduced the production of nitric oxide, prostaglandin E2, and interleukin (IL)-1β in LPS-stimulated RAW 264.7 cells by inhibiting cyclooxygenase-2. Moreover, sargachromenol inhibited the activation of nuclear factor-κB (NF-κB) by preventing the degradation of the inhibitor of κB-α (IκB-α) and inhibiting protein kinase B (Akt) phosphorylation in LPS-stimulated cells. We also found that sargachromenol induced the production of heme oxygenase-1 (HO-1) by activating the nuclear transcription factor erythroid-2-related factor 2 (Nrf2). In LPS-treated mice, oral administration of sargachromenol effectively reduced the levels of IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) in the serum, suggesting its ability to suppress the production of inflammatory mediators by inhibiting the Akt/NF-κB pathway and upregulating the Nrf2/HO-1 pathway.

Conditional knockout of PDK1 in osteoclasts suppressed osteoclastogenesis and ameliorated prostate cancer-induced osteolysis in murine model

BackgroundThe development and maintenance of normal bone tissue is maintained by balanced communication between osteoblasts and osteoclasts. The invasion of cancer cells disrupts this balance, leading to osteolysis. As the only bone resorbing cells in vivo, osteoclasts play important roles in cancer-induced osteolysis. However, the role of 3-phosphoinositide-dependent protein kinase-1 (PDK1) in osteoclast resorption remains unclear.MethodsIn our study, we used a receptor activator of nuclear factor-kappa B (RANK) promoter‐driven Cre‐LoxP system to conditionally delete the PDK1 gene in osteoclasts in mice. We observed the effect of osteoclast‐specific knockout of PDK1 on prostate cancer-induced osteolysis. Bone marrow-derived macrophage cells (BMMs) were extracted and induced to differentiate osteoclasts in vitro to explore the role of PDK1 in osteoclasts.ResultsIn this study, we found that PDK1 conditional knockout (cKO) mice exhibited smaller body sizes when compared to the wild-type (WT) mice. Moreover, deletion of PDK1 in osteoclasts ameliorated osteolysis and rPDK1educed bone resorption markers in the murine model of prostate cancer-induced osteolysis. In vivo, we discovered that osteoclast‐specific knockout of suppressed RANKL-induced osteoclastogenesis, bone resorption function, and osteoclast-specific gene expression (Ctsk, TRAP, MMP-9, NFATc1). Western blot analyses of RANKL-induced signaling pathways showed that conditional knockout of PDK1 in osteoclasts inhibited the early nuclear factor κB (NF-κB) activation, which consequently suppressed the downstream induction of NFATc1.ConclusionThese findings demonstrated that PDK1 performs an important role in osteoclastogenesis and prostate cancer-induced osteolysis by modulating the PDK1/AKT/NF-κB signaling pathway.

Complement receptor 3-mediated neurotoxic glial activation contributes to rotenone-induced cognitive decline in mice

Microglia-mediated chronic neuroinflammation has been associated with cognitive decline induced by rotenone, a well-known neurotoxic pesticide used in agriculture. However, the mechanisms remain unclear. This work aimed to elucidate the role of complement receptor 3 (CR3), a highly expressed receptor in microglia, in cognitive deficits induced by rotenone. Rotenone up-regulated the expression of CR3 in the hippocampus and cortex area of mice. CR3 deficiency markedly ameliorated rotenone-induced cognitive impairments, neurodegeneration and phosphorylation (Ser129) of α-synuclein in mice. CR3 deficiency also attenuated rotenone-stimulated microglial M1 activation. In microglial cells, siRNA-mediated knockdown of CR3 impeded, while CR3 activation induced by LL-37 exacerbated, rotenone-induced microglial M1 activation. Mechanistically, CR3 deficiency blocked rotenone-induced activation of nuclear factor κB (NF-κB), signal transducer and activator of transcription 1 (STAT1) and STAT3 signaling pathways. Pharmacological inhibition of NF-κB or STAT3 but not STAT1 was confirmed to suppress microglial M1 activation elicited by rotenone. Further study revealed that CR3 deficiency or knockdown also reduced rotenone-induced expression of C3, an A1 astrocyte marker, and production of microglial C1q, TNFα and IL-1α, a cocktail for activated microglia to induce neurotoxic A1 astrocytes, via NF-κB and STAT3 pathways. Finally, a small molecule modulator of CR3 efficiently mitigated rotenone-elicited cognitive deficits in mice even administered after the establishment of cognitive dysfunction. Taken together, our findings demonstrated that CR3 is a key factor in mediating neurotoxic glial activation and subsequent cognitive impairments in rotenone-treated mice, giving novel insights into the immunopathogenesis of cognitive impairments in pesticide-related Parkinsonism.

Electroacupuncture stimulating Zusanli (ST36), Sanyinjiao (SP6) in mice with collagen-induced arthritis leads to adenosine A2A receptor-mediated alteration of p38α mitogen-activated protein kinase signaling and inhibition of osteoclastogenesis.

To observe the effect of electroacupuncture (EA) stimulating Zusanli (ST36), Sanyinjiao (SP6) on inhibition of osteoclastogenesis and the role of the adenosine A2A receptor (A2AR) and the p38α Mitogen-Activated Protein Kinase (MAPK) signaling pathway in mediating this effect. Mice with collagen induced arthritis (CIA) received different treatments. Immunohistochemistry and western blotting were used to determine the levels of multiple signaling molecules in these joints [receptor activator of nuclear transcription factor-κB (NF-κB) ligand (RANKL), receptor activator of NF-κB (RANK), tumor necrosis factor receptor associated factor 6 (TRAF6), p38α, NF-κB, and nuclear factor of activated T cells C1 (NFATc1)]. Osteoclasts were identified using tartrate-resistant acid phosphatase (TRAP) staining. The immunohistochemistry results indicated upregulation of p38α, NF-κB, and NFATc1 in the CIA-control and CIA-EA-SCH58261 groups, but reduced levels in the CIA-EA group. Western blotting indicated upregulation of RANKL, RANK, TRAF6, p38α, NF-κB, and NFATc1 in the CIA-control and CIA-EA-SCH58261 groups, but reduced expression in the CIA-EA group. Osteoclasts were more abundant in the CIA-control and CIA-EA-SCH58261 groups than in the CIA-EA group. EA treatment enhanced the A2AR activity and inhibited osteoclast formation by inhibition of RANKL, RANK, TRAF6, p38α, NF-κB, and NFATc1. SCH58261 reversed the effect of EA. These results suggest that EA regulated p38α-MAPK signaling by increasing A2AR activity, which inhibited osteoclastogenesis.

RANK ligand converts the NCoR/HDAC3 co-repressor to a PGC1β- and RNA-dependent co-activator of osteoclast gene expression

The nuclear receptor co-repressor (NCoR) complex mediates transcriptional repression dependent on histone deacetylation by histone deacetylase 3 (HDAC3) as a component of the complex. Unexpectedly, we found that signaling by the receptor activator of nuclear factor κB (RANK) converts the NCoR/HDAC3 co-repressor complex to a co-activator of AP-1 and NF-κB target genes that are required for mouse osteoclast differentiation. Accordingly, the dominant function of NCoR/HDAC3 complexes in response to RANK signaling is to activate, rather than repress, gene expression. Mechanistically, RANK signaling promotes RNA-dependent interaction of the transcriptional co-activator PGC1β with the NCoR/HDAC3 complex, resulting in the activation of PGC1β and inhibition of HDAC3 activity for acetylated histone H3. Non-coding RNAs Dancr and Rnu12, which are associated with altered human bone homeostasis, promote NCoR/HDAC3 complex assembly and are necessary for RANKL-induced osteoclast differentiation invitro. These findings may be prototypic for signal-dependent functions of NCoR in other biological contexts.

Therapeutic approaches for cholestatic liver diseases: the role of nitric oxide pathway.

Cholestasis describes bile secretion or flow impairment, which is clinically manifested with fatigue, pruritus, and jaundice. Neutrophils play a crucial role in many diseases such as cholestasis liver diseases through mediating several oxidative and inflammatory pathways. Data have been collected from clinical, in vitro, and in vivo studies published between 2000 and December 2021 in English and obtained from the PubMed, Google Scholar, Scopus, and Cochrane libraries. Although nitric oxide plays an important role in the pathogenesis of cholestatic liver diseases, excessive levels of NO in serum and affected tissues, mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme, can exacerbate inflammation. NO induces the inflammatory and oxidative processes, which finally leads to cell damage. We found that natural products such as baicalin, curcumin, resveratrol, and lycopene, as well as chemical likes ursodeoxycholic acid, dexamethasone, rosuvastatin, melatonin, and sildenafil, are able to markedly attenuate the NO production and iNOS expression, mainly through inducing the nuclear factor κB (NF-κB), Janus kinase and signal transducer and activator of transcription (JAK/STAT), and toll like receptor-4 (TLR4) signaling pathways. This study summarizes the latest scientific data about the bile acid signaling pathway, the neutrophil chemotaxis recruitment process during cholestasis, and the role of NO in cholestasis liver diseases. Literature review directed us to propose that suppression of NO and its related pathways could be a therapeutic option for preventing or treating cholestatic liver diseases.

NLRP2 in health and disease.

NLR family pyrin domain containing 2 (NLRP2) is a novel member of the Nod-like receptor (NLR) family. However, our understanding of NLRP2 has long been ambiguous. NLRP2 may have a role in the innate immune response, but its 'specific' functions remain controversial. Although NLRP2 can initiate inflammasome and promote inflammation, it can also downregulate inflammatory signals. Additionally, NLRP2 has been reported to function in the reproductive system and shows high expression in the placenta. However, the exact role of NLRP2 in the reproductive system is unclear. Here, we highlight the most current progress on NLRP2 in inflammasome activation, effector function and regulation of nuclear factor-κB. And we discuss functions of NLRP2 in inflammatory diseases, reproductive disorders and the potential implication of NLRP2 in human diseases.

CXCL1 enhances COX-II expression in rheumatoid arthritis synovial fibroblasts by CXCR2, PLC, PKC, and NF-κB signal pathway

Rheumatoid arthritis (RA) is the most common autoimmune disease, affecting the joints of the hands and feet. Several chemokines and their receptors are crucial in RA pathogenesis through immune cell recruitment. C-X-C Motif Chemokine Ligand 1 (CXCL1), a chemokine for the recruitment of various immune cells, can be upregulated in patients with RA. However, the discussion on the role of CXCL1 in RA pathogenesis is insufficient. Here, we found that CXCL1 promoted cyclooxygenase-2 (COX-II) expression in a dose- and time-dependent manner in rheumatoid arthritis synovial fibroblasts (RASFs). CXCL1 overexpression in RASFs led to a significant increase in COX-II expression, while the transfection of RASFs with the shRNA plasmid resulted in a noticeable decrease in COX-II expression. Next, we delineated the molecular mechanism underlying CXCL1-promoted COX-II expression and noted that CXC chemokine receptor 2 (CXCR2), phospholipase C (PLC), and protein kinase C (PKC) signal transduction were responsible for COX-II expression after CXCL1 incubation for RASFs. Finally, we confirmed the transcriptional activation of nuclear factor κB (NF-κB) in RASFs after incubation with CXCL1. In conclusion, the current study provided a novel insight into the role of CXCL1 in RA pathogenesis.

P7C3 Ameliorates Bone Loss by Inhibiting Osteoclast Differentiation and Promoting Osteogenesis.

Bone homeostasis, the equilibrium between bone resorption and formation, is essential for maintaining healthy bone tissue in adult humans. Disruptions of this process can lead to pathological conditions such as osteoporosis. Dual-targeted agents, capable of inhibiting excessive bone resorption and stimulating bone formation, are being explored as a promising strategy for developing new treatments to address osteoporosis. In this study, we investigated the effects of P7C3 on bone remodeling and its potential therapeutic role in osteoporosis treatment in mice. Specifically, P7C3 can remarkably suppress receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages via the Akt-NF-κB-NFATc1 signaling pathway. Additionally, RNA sequencing (RNAseq) analysis revealed that P7C3 promoted osteoblast differentiation and function through the Wnt/β-catenin signaling pathway, thereby enhancing bone formation. Furthermore, μCT analysis and histological examination of bone tissues from P7C3-treated mice showed attenuation of both Ti-induced bone erosion and ovariectomy (OVX)-induced bone loss. These findings suggest that P7C3 may have a novel function in bone remodeling and may be a promising therapeutic agent for the treatment of osteoporosis. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Genomic DNA Extracted from Lactiplantibacillus plantarum Attenuates Porphyromonas gingivalis Lipopolysaccharide (LPS)-Induced Inflammatory Responses via Suppression of Toll-Like Receptor (TLR)-Mediated Mitogen-Activated Protein Kinase (MAPK) and Nuclear Factor-κB (NF-κB) Signaling Pathways.

In the present study, we aimed to examine the inhibition of genomic DNA from Lactiplantibacillus plantarum (LpDNA) on Porphyromonas gingivalis lipopolysaccharide (PgLPS)-induced inflammatory responses in RAW264.7 cells. Pretreatment with LpDNA for 15 h significantly inhibited PgLPS-induced mRNA expression and protein secretion of interleukin (IL)-1β, IL-6, and monocyte chemoattractant protein-1. LpDNA pretreatment also reduced the mRNA expression of Toll-like receptor (TLR)2 and TLR4. Furthermore, LpDNA inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) and the activation of nuclear factor-κB (NF-κB) induced by PgLPS. Taken together, these findings demonstrate that LpDNA attenuates PgLPS-induced inflammatory responses by regulating MAPKs and NF-κB signaling pathways through the suppression of TLR2 and TLR4 expression.

Intracellular replication of Pseudomonas aeruginosa in epithelial cells requires suppression of the caspase-4 inflammasome.

Pathogenesis of Pseudomonas aeruginosa infections can include bacterial survival inside epithelial cells. Previously, we showed that this involves multiple roles played by the type three secretion system (T3SS), and specifically the effector ExoS. This includes ExoS-dependent inhibition of a lytic host cell response that subsequently enables intracellular replication. Here, we studied the underlying cell death response to intracellular P. aeruginosa, comparing wild-type to T3SS mutants varying in capacity to induce cell death and that localize to different intracellular compartments. Results showed that corneal epithelial cell death induced by intracellular P. aeruginosa lacking the T3SS, which remains in vacuoles, correlated with the activation of nuclear factor-κB as measured by p65 relocalization and tumor necrosis factor alpha transcription and secretion. Deletion of caspase-4 through CRISPR-Cas9 mutagenesis delayed cell death caused by these intracellular T3SS mutants. Caspase-4 deletion also countered more rapid cell death caused by T3SS effector-null mutants still expressing the T3SS apparatus that traffic to the host cell cytoplasm, and in doing so rescued intracellular replication normally dependent on ExoS. While HeLa cells lacked a lytic death response to T3SS mutants, it was found to be enabled by interferon gamma treatment. Together, these results show that epithelial cells can activate the noncanonical inflammasome pathway to limit proliferation of intracellular P. aeruginosa, not fully dependent on bacterially driven vacuole escape. Since ExoS inhibits the lytic response, the data implicate targeting of caspase-4, an intracellular pattern recognition receptor, as another contributor to the role of ExoS in the intracellular lifestyle of P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa can exhibit an intracellular lifestyle within epithelial cells in vivo and in vitro. The type three secretion system (T3SS) effector ExoS contributes via multiple mechanisms, including extending the life of invaded host cells. Here, we aimed to understand the underlying cell death inhibited by ExoS when P. aeruginosa is intracellular. Results showed that intracellular P. aeruginosa lacking T3SS effectors could elicit rapid cell lysis via the noncanonical inflammasome pathway. Caspase-4 contributed to cell lysis even when the intracellular bacteria lacked the entire T33S and were consequently unable to escape vacuoles, representing a naturally occurring subpopulation during wild-type infection. Together, the data show the caspase-4 inflammasome as an epithelial cell defense against intracellular P. aeruginosa, and implicate its targeting as another mechanism by which ExoS preserves the host cell replicative niche.