Effects of chronic low-level lead (Pb) exposure on cognitive function and hippocampal neuronal ferroptosis: An integrative approach using bioinformatics analysis, machine learning, and experimental validation

Lead (Pb), a pervasive and ancient toxic heavy metal, continues to pose significant neurological health risks, particularly in regions such as Southeast Asia. While previous research has primarily focused on the adverse effects of acute, high-level lead exposure on neurological systems, studies on the impacts of chronic, low-level exposure are less extensive, especially regarding the precise mechanisms linking ferroptosis - a novel type of neuron cell death - with cognitive impairment. This study aims to explore the potential effects of chronic low-level lead exposure on cognitive function and hippocampal neuronal ferroptosis. This research represents the first comprehensive investigation into the impact of chronic low-level lead exposure on hippocampal neuronal ferroptosis, spanning clinical settings, bioinformatic analyses, and experimental validation. Our findings reveal significant alterations in the expression of genes associated with iron metabolism and Nrf2-dependent ferroptosis following lead exposure, as evidenced by comparing gene expression in the peripheral blood of lead-acid battery workers and workers without lead exposure. Furthermore, our in vitro and in vivo experimental results strongly suggest that lead exposure may precipitate cognitive dysfunction and induce hippocampal neuronal ferroptosis. In conclusion, our study indicates that chronic low-level lead exposure may activate microglia, leading to the promotion of ferroptosis in hippocampal neurons.

RTKN2 Inhibits the Growth, Migration, Invasion and Glycolysis of Lung Adenocarcinoma Cells by Inactivating the NF-κB Signalling Pathway

BACKGROUND

Lung adenocarcinoma (LUAD) is a malignant tumour that seriously threatens the life and health of people worldwide. This research was carried out to investigate the role of Rhotekin 2 (RTKN2) in LUAD progression.

METHODS AND RESULTS

The GEPIA online database was used to analyse abnormally expressed genes in lung adenocarcinoma and RTKN2 expression in various cancers. Cell proliferation was detected with CCK-8 and colony formation assays. Transwell assays were carried out to assess cell migration and invasion. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were evaluated by a Seahorse XFe96 analyser. The interaction between RTKN2 and p65 was confirmed using a coimmunoprecipitation assay. RTKN2 expression was detected with qPCR, immunohistochemistry, and western blot assays. The p65 levels in the cytoplasm and nucleus were determined by western blot assays. RTKN2 levels were prominently decreased in LUAD tissues and cell lines. RTKN2 overexpression suppressed LUAD cell growth, invasion, migration, and glycolysis, while RTKN2 knockdown showed the opposite effects. Additionally, p65 could be negatively regulated by RTKN2. RTKN2 overexpression increased p65 levels in the cytoplasm but decreased p65 levels in the nucleus. Furthermore, blocking the NF-κB signalling pathway neutralized the effect of RTKN2 silencing in LUAD cells.

CONCLUSION

RTKN2 inhibited the malignant behaviour and glycolysis of LUAD cells by blocking the NF-κB signalling pathway, implying that RTKN2 could be a cancer suppressor in LUAD progression.

Cannabidiol attenuates periodontal inflammation through inhibiting TLR4/NF-κB pathway

BACKGROUND AND OBJECTIVE

Periodontitis is a chronic inflammatory disease involving soft and hard tissue destruction in the periodontal region. Cannabidiol (CBD) is a natural compound isolated from cannabis, which has the effect of inhibiting inflammation. However, the role of CBD in periodontitis remains unclear. The aim of this study was to investigate the anti-inflammatory effects and osteoprotective actions of CBD in periodontitis and its molecular mechanisms.

MATERIALS AND METHODS

After establishing the rat periodontitis model by ligatures, the specimens were processed for morphometric analysis by Micro-CT. The gingival tissues were collected, and the levels of TNF-α, IL-1β, and TLR4 were measured by enzyme-linked immunosorbent assay. LPS was used to induce the inflammatory response of human periodontal ligament cells (hPDLCs) in vitro. QPCR and western blot were carried out to detect the expression of related inflammatory cytokines and signaling pathways.

RESULTS

Cannabidiol significantly inhibits bone loss in experimental rat periodontitis models. CBD downregulated the pro-inflammatory mediator TNF-α, related to the decrease of TLR4 protein expression. Overexpression of TNF-α and TLR4 caused by LPS in hPDLCs. CBD inactivated the TLR4/NF-κB signaling pathway by inhibiting TLR-4 expression and p65 NF-κB phosphorylation. CBD can be considered as a therapeutic agent for periodontitis.

CONCLUSION

Our study demonstrated that CBD attenuates ligature-induced periodontitis in rats and LPS-induced inflammation in hPDLCs by inhibiting TLR4/NF-κB pathway activation. It indicates that topical CBD application is effective in treating periodontitis.

CD74 regulates cellularity and maturation of medullary thymic epithelial cells partially by activating the canonical NF-κB signaling pathway

Thymic epithelial cells (TECs) are indispensable for T cell development, T cell receptor (TCR) repertoire selection, and specific lineage differentiation. Medullary thymic epithelial cells (mTECs), which account for the majority of TECs in adults, are critical for thymocyte selection and self-tolerance. CD74 is a nonpolymorphic transmembrane glycoprotein of major histocompatibility complex class II (MHCII) that is expressed in TECs. However, the exact role of CD74 in regulating the development of mTEC is poorly defined. In this research, we found that loss of CD74 resulted in a significant diminution in the medulla, a selective reduction in the cell number of mature mTECs expressing CD80 molecules, which eventually led to impaired thymic CD4⁺ T cell development. Moreover, RNA-sequence analysis showed that CD74 deficiency obviously downregulated the canonical nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in mTECs. Our results suggest that CD74 positively controls mTEC cellularity and maturation partially by activating the canonical NF-κB signaling pathway.

NF-κB and NLRP3 gene expression changes during warm hepatic ischemia-reperfusion in rats with and without silibinin

AIM

This research examined silibinin's anti-inflammatory outcomes on the NOD-like receptor protein-3 (NLRP3) and NF-κB gene expression, which plays a notable role in inciting inflammatory pathways.

BACKGROUND

Hepatic ischemia-reperfusion (I/R) is a common phenomenon in many clinical cases, including liver surgery and transplantation. Inflammatory mediators are vital contributors to the expansion of hepatic damage after I/R injury (I/RI), and therefore, targeting inflammation is a considerable candidate for the management of hepatic I/RI and its complications.

METHODS

Thirty-two male Wistar rats were divided equally into four groups: 1) Control (Vehicle) group, in which rats underwent laparotomy and received normal saline; 2) SILI group, in which rats underwent laparotomy, and 30 mg/kg silibinin was injected intraperitoneal (IP); 3) I/R group, in which rats underwent I/R and received normal saline; and 4) I/R + SILI group, who encountered I/R after laparotomy and received silibinin. After one hour of ischemia and three hours of reperfusion, blood and liver tissue samples were assembled for future biochemical, histological, and gene expression studies.

RESULTS

In vivo analysis attested that serum AST and ALT activities were significantly lessened by silibinin in the SILI + I/R group (p <0.001). Silibinin ameliorated inflammatory liver tissue injuries, including neutrophil and macrophage infiltration, hepatocyte degeneration, cytoplasmic vacuolation, vascular endothelial damages, and sinusoid dilation observed in the I/R group. During I/R, NLRP3 and NF-κB gene expression showed a significant increment compared to the control group (p <0.001), which could be alleviated by silibinin (p <0.01).

CONCLUSION

The results evidence that adjusting the expression of NLRP3 and NF-κB genes during I/R is probably one of the mechanisms of the anti-inflammatory effects of silibinin.

Vitexin restores pancreatic β-cell function and insulin signaling through Nrf2 and NF-κB signaling pathways

Chronic hyperglycemia induces pancreatic β-cell dysfunction through several cell signaling pathways. The β-cell loss by apoptosis appears to play a crucial role in the onset and progression of diabetes. This study was aimed to investigate the role of vitexin against high glucose-induced β-cells apoptosis and the underlying mechanisms involved therein. INS-1 cells were pretreated with vitexin (20 and 40 μM) followed by high glucose (33 mM) exposure and the cytotoxicity was assessed by MTT. The effect of vitexin on nuclear factor erythroid 2-related factor 2 (Nrf2) and NF-kB signaling molecules have been studied. Vitexin-mediated stimulation of Nrf2 was assessed. Vitexin protected the cells against high glucose toxicity in a concentration-dependent manner. Vitexin improved insulin signaling as analyzed by the levels of functional proteins in the insulin pathways, viz., insulin receptor (IR), insulin receptor substrate (IRS)-1 and IRS-2, glucose transporter -2, and glucose-stimulated insulin secretion. Vitexin improved the high glucose-induced nuclear transcription factor system by suppressing Rel A, Rel B, P50/p105, and IκB expression resulting in decreased cell apoptosis, further confirmed by the reduction in the percentage of Annexin-V positive cells. Our data suggest that vitexin improves insulin secretion by activating key proteins, including NF-κB and Nrf2 in β-cells regulating apoptosis.

Patriscabrin F from the roots of Patrinia scabra attenuates LPS-induced inflammation by downregulating NF-κB, AP-1, IRF3, and STAT1/3 activation in RAW 264.7 macrophages

BACKGROUND

The roots of Partrinia scabra have been used as a medicinal herb in Asia. We previously reported that the inhibitory effect of patriscabrin F on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was the most potent than that of other isolated iridoids from the roots of P. scabra.

PURPOSE

We investigated the anti-inflammatory activity of patriscabrin F as an active compound of P. scabra and related signaling cascade in LPS-activated macrophages.

METHOD

The anti-inflammatory activities of patriscabrin F were determined according to its inhibitory effects on NO, prostaglandin E₂ (PGE₂), and pro-inflammatory cytokines. The molecular mechanisms were revealed by analyzing nuclear factor-κB (NF-κB), activator protein-1 (AP-1), interferon regulatory factor 3 (IRF3), and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway.

RESULTS

Patriscabrin F inhibited the LPS-induced production of NO, PGE_2, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 in both bone-marrow derived macrophages (BMDMs) and RAW 264.7 macrophages. Patriscabrin F downregulated LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), TNF-α, IL-1β, and IL-6 at the transcriptional level. Patriscabrin F suppressed LPS-induced NF-κB activation by decreasing p65 nuclear translocation, inhibitory κBα (IκBα) phosphorylation, and IκB kinase (IKK)α/β phosphorylation. Patriscabrin F attenuated LPS-induced AP-1 activity by inhibiting c-Fos phosphorylation. Patriscabrin F suppressed the LPS-induced phosphorylation of IRF3, JAK1/JAK2, and STAT1/STAT3.

CONCLUSION

Taken together, our findings suggest patriscabrin F may exhibit anti-inflammatory properties via the inhibition of NF-κB, AP-1, IRF3, and JAK-STAT activation in LPS-induced macrophages.

High Glucose-reduced Apoptosis in Human Breast Cancer Cells Is Mediated by Activation of NF-κB

Tumor cells rely on glycolysis for their energy supply with the production of lactate even in normoxia condition, which is named aerobic glycolysis or Warburg effect. Therefore, high glucose (HG) concentration provides a favorable condition for increasing proliferation, angiogenesis and decreasing apoptosis, but its molecular mechanisms are still unknown. The objective of this study is to investigate HG condition on tumor cells behavior including proliferation, apoptosis, and an angiogenesis mediator. In this study, MCF-7 derived from human breast adenocarcinoma, were cultured in DMEM with two different concentrations of glucose for 48 h (5.5 mM as normal glucose (NG) condition and 25 mM as HG condition). We used Zingiber officinale extraction for the inhibition of NF-κB. Cell proliferation assay was done by direct counting, cell viability by MTT method, bcl-2 by Immunocytochemistry, apoptosis by Hoechst/PI double staining and vascular endothelium growth factor (VEGF) by ELISA. Results showed that HG increased lactate production, significantly. HG increased cell proliferation, cell viability, VEGF secretion, and bcl-2 expression while it decreased apoptosis. However, when HG was combined with Zingiber officinale extraction, cell proliferation, cell viability, VEGF secretion and bcl-2 expression decreased and apoptosis increased significantly due to inhibition of NF-κB. Results revealed that HG increased cell proliferation, angiogenesis and decreased apoptosis due to activation of NF-κB pathway. Moreover, the probable mechanism of the activation of NF-κB in HG is increasing reactive oxygen species (ROS) in this condition that can activate NF-κB directly.

2'-Hydroxy-5'-methoxyacetophenone attenuates the inflammatory response in LPS-induced BV-2 and RAW264.7 cells via NF-κB signaling pathway

Seahorse has been used as a traditional medicine in Southeast Asian countries for a long time. A compound, 2'-Hydroxy-5'-Methoxyacetophenone (2H5M) isolated from seahorse, Hippocampus kuda, was tested for its anti-inflammatory effect in lipopolysaccharides (LPS)-stimulated BV-2 cells and RAW264.7 cells. MTT assay indicated that 2H5M has no cytotoxicity on two kinds of cells. The concentration of nitric oxide (NO) measured by Griess Reaction System showed that 2H5M could significantly inhibit the NO concentration. The ELISA results showed that 2H5M could suppress the secretion of TNF-α in a dose-dependent manner. Moreover, western blot analysis was utilized to measure the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. Electrophoretic mobility shift assay (EMSA) demonstrated that 2H5M reduced NF-κB DNA binding activity. Furthermore, the molecular docking study showed that 2H5M can form active sites with NF-κB. Collectively, these results indicated that 2H5M possesses anti-inflammatory effects and may have a potential application in inflammatory disorders in the future.

Phytochemical naphtho[1,2-b] furan-4,5‑dione induced topoisomerase II-mediated DNA damage response in human non-small-cell lung cancer

BACKGROUND

Phytochemical naphtho[1,2-b] furan-4,5‑dione (NFD) presenting in Avicennia marina exert anti-cancer effects, but little is known regarding about DNA damage-mediated apoptosis in non-small-cell lung carcinoma (NSCLC).

PURPOSE

To examine whether NFD-induced apoptosis of NSCLC cells is correlated with the induction of DNA damage, and to investigate its underlying mechanism.

STUDY DESIGN

The anti-proliferative effects of NFD were assessed by MTS Assay Kit FACS assay, and in vivo nude mice xenograft assay. The DNA damage related proteins, the Bcl-2 family and pro-apoptotic factors were examined by immunofluorescence assay, q-PCR, and western blotting. The activity of NF-κB p65 in nuclear extracts was detected using a colorimetric DNA-binding ELISA assay. The inhibitory activity of topoisomerase II (TOPO II) was evaluated by molecular docking and TOPO II catalytic assay.

RESULTS

NFD exerted selective cytotoxicity against NSCLC H1299, H1437 and A549 cells rather than normal lung-embryonated cells MRC-5. Remarkably, we found that NFD activated the hull marker and modulator of DNA damage repairs such as γ-H2AX, ATM, ATR, CHK1, and CHK2 probably caused by the accumulation of intracellular reactive oxygen species (ROS) and inhibition of TOPO II activity. Furthermore, the suppression of transcription factor NF-κB by NFD resulted in significantly decreased levels of pro-survival proteins including Bcl-2 family Bcl-2, Bcl-xL and Mcl-1 and the endogenous inhibitors of apoptosis XIAP and survivin in H1299 cells. Moreover, the nude mice xenograft assay further validated the suppression of H1299 growth by NFD, which is the first report for evaluating the anti-cancer effect of NFD in vivo.

CONCLUSION

These findings provide a novel mechanism indicating the inhibition of TOPO II activity and NF-κB signaling by NFD, leading to DNA damage and apoptosis of NSCLC tumor cells.

Standardized extract of Zingiber zerumbet suppresses LPS-induced pro-inflammatory responses through NF-κB, MAPK and PI3K-Akt signaling pathways in U937 macrophages

BACKGROUND

Zingiber zerumbet rhizome has been used as spices and in traditional medicine to heal various immune-inflammatory related ailments. Although the plant was reported to have potent anti-inflammatory and immunosuppressive properties by several studies, the molecular mechanisms underlying the effects have not been well justified.

PURPOSE

The study was carried out to investigate the molecular mechanisms underlying the anti-inflammatory properties of the standardized 80% ethanol extract of Z. zerumbet through its effect on mitogen-activated protein kinase (MyD88)-dependent nuclear factor-kappa B (NF-кB), mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/Akt (PI3K-Akt) signaling pathways in lipopolysaccharide (LPS)-induced U937 human macrophages.

METHODS

Standardization of the 80% ethanol extract of Z. zerumbet was performed by using a validated reversed-phase HPLC method, while LC-MS/MS was used to profile the secondary metabolites. The release of pro-inflammatory markers, tumor necrosis factor (TNF)-α, interleukin (IL)-1β and prostaglandin E₂ (PGE₂) was evaluated by enzyme-linked immunosorbent assay (ELISA), while the Western blot technique was executed to elucidate the expression of mediators linked to MyD88-dependent respective signaling pathways. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay was carried out to quantify the relative gene expression of cyclooxygenase (COX)-2 and pro-inflammatory mediators at the transcriptional level.

RESULTS

The quantitative and qualitative analyses of Z. zerumbet extract showed the presence of several compounds including the major chemical marker zerumbone. Z. zerumbet extract suppressed the release of pro-inflammatory mediators, COX-2 protein expression and downregulated the mRNA expression of pro-inflammatory markers. Z. zerumbet-treatment also blocked NF-κB activation by preventing the phosphorylation of IKKα/β and NF-κB (p65) as well as the phosphorylation and degradation of IκBα. Z. zerumbet extract concentration-dependently inhibited the phosphorylation of respective MAPKs (JNK, ERK, and p38) as well as Akt. Correspondingly, Z. zerumbet extract suppressed the upstream signaling adaptor molecules, TLR4 and MyD88 prerequisite for the NF-κB, MAPKs, and PI3K-Akt activation.

CONCLUSION

The findings suggest that Z. zerumbet has impressive role in suppressing inflammation and related immune disorders by inhibition of various pro-inflammatory markers through the imperative MyD88-dependent NF-κB, MAPKs, and PI3K-Akt activation.

Metformin increases the cytotoxicity of oxaliplatin in human DLD-1 colorectal cancer cells through down-regulating HMGB1 expression

Colorectal cancer (CRC) is the fourth most common cause of cancer death worldwide. Chemotherapy has been the major strategy for treating patients with advanced CRC. Oxaliplatin (OXA) is used as both an adjuvant and neoadjuvant anticancer agent available to treat advanced CRC. High-mobility group box 1 protein (HMGB1) is a critical regulator of cell death and survival. HMGB1 overexpression has been shown to be resistant to cytotoxic agents. In addition, Metformin, a widely used drug for diabetes, has emerged as a potential anticancer agent. In this study, we examined whether HMGB1 plays a role in the OXA- and/or metformin-induced cytotoxic effect on CRC cells. The results showed that treatment with OXA increased HMGB1 expression in the ERK1/2- and Akt-dependent manners in DLD-1 cells. HMGB1 gene knockdown enhanced the cytotoxicity and cell growth inhibition of OXA. Moreover, OXA-increased HMGB1 expression was by inducing NF-κB-DNA-binding activity to in DLD-1 cells. Compared to a single agent, OXA combined with metformin administration resulted in cytotoxicity and cell growth inhibition synergistically, accompanied with reduced HMGB1 level. These findings may have implications for the rational design of future drug regimens incorporating OXA and metformin for the treatment of CRC.

BG-4, a novel bioactive peptide from momordica charantia, inhibits lipopolysaccharide-induced inflammation in THP-1 human macrophages

BACKGROUND

Bitter melon (Momordica charantia) is a commonly used food crop for management of a variety of diseases most notably for control of diabetes, a disease associated with aberrant inflammation.

PURPOSE

To evaluate the anti-inflammatory property of BG-4, a novel bioactive peptide isolated from the seed of bitter melon.

METHODS

Differentiated THP-1 human macrophages were pre-treated with BG-4 and stimulated with lipopolysaccharide. Pro-inflammatory cytokines IL-6 and TNF-α were measured by enzyme-linked immunosorbent assay. The mechanism of action involving activation of NF-κB and phosphorylation of ERK and STAT3 was measured by western blot and immunofluorescence. The production of intracellular reactive oxygen species was evaluated by fluorescence microscopy and fluorescence spectrophotometry.

RESULTS

BG-4 dose dependently reduce the production of pro-inflammatory cytokines IL-6 and TNF-α. The ability of BG-4 to reduce production of cytokines are associated with reduced phosphorylation of ERK and STAT3 accompanied by reduced nuclear translocation of p65 NF-κB subunit. The mechanism of action is reduction of LPS-induced production of intracellular reactive oxygen species.

CONCLUSION

Our results demonstrated the ability of BG-4, a novel peptide from the seed of bitter melon, to exert anti-inflammatory action. This could explain the traditional use of bitter melon against diseases associated with aberrant and uncontrolled inflammation.

SIRT6/NF-κB signaling axis in ginsenoside Rg1-delayed hematopoietic stem/progenitor cell senescence

OBJECTIVE

To investigate the role of SIRT6/NF-κB signaling axis in ginsenoside Rg1-delayed hematopoietic stem/progenitor cell senescence and to provide theoretical and experimental evidence for delaying HSC/HPC senescence pathway.

METHODS

After the separation and purification by immunomagnetic sorting, Sca-1+HSC/HPC was divided into: normal control group; aging group; positive control group; Rg1 delaying group and Rg1 treatment group. Senescence-associated β-galactosidase (SA-β-Gal) staining, flow cytometry analysis of cell cycle and hematopoietic progenitor cells mixed colony (CFU-Mix) culture were performed to determine the delaying or curing roles of Rg1 in Sca-1+HSC/HPC senescence. Quantitative PCR and Western blotting were used to detect the mRNA and protein expression of senescence regulatory molecules, such as SIRT6 and NF-κB.

RESULTS

Compared with the aging group, the positive rate of SA-β-gal staining cells and the proportion of cells in G1 phase decreased; the number of CFU-Mix increased; mRNA and protein expression of SIRT6 increased; mRNA and protein expression of NF-κB was down-regulated in Rg1 delaying and treatment groups; the changes of the indicators in Rg1 delaying group were more significant than those in Rg1 treatment group.

CONCLUSION

Rg1 may fight against Sca-1+HSC/HPC senescence induced by t-BHP through regulating SIRT6-NF-κB signaling pathway.