TPL2 kinase action and control of inflammation

Building polarization into protein-inhibitor binding dynamics in rational drug design for rheumatoid arthritis

Standard force field-based simulations to accomplish structure-based evaluations of lead molecules is a powerful tool. Combining protein fragmentation into tractable sub-systems with continuum solvation method is envisaged to enable quantum mechanics-based electronic structure calculations of macromolecules in their realistic environment. This along with incorporation of many-body polarization effect in molecular dynamics simulations may augment an accurate description of electrostatics of protein-inhibitor systems for effective drug design. Rheumatoid arthritis (RA) is a complex autoimmune disorder plagued by the ceiling effect of current targeted therapies, encouraging identification of new druggable targets and corresponding drug design to tackle the refractory form of disease. In this study, polarization-inclusive force field approach has been used to model protein solvation and ligand binding for 'Mitogen-activated protein kinase' (MAP3K8), a regulatory node of notable pharmacological relevance in RA synovial biology. For MAP3K8 inhibitors belonging to different scaffold series, the calculations illustrated differential electrostatic contribution to their relative binding affinities and successfully explained examples from available structure-activity relationship studies. Results from this study exemplified i) the advantage of this approach in reliably ranking inhibitors having close nanomolar range activities for the same target; and ii) its prospective application in lead molecule identification aiding drug discovery efforts in RA.Communicated by Ramaswamy H. Sarma.

Targeting Protein Kinases to Protect Beta-Cell Function and Survival in Diabetes

The prevalence of diabetes is increasing worldwide. Massive death of pancreatic beta-cells causes type 1 diabetes. Progressive loss of beta-cell function and mass characterizes type 2 diabetes. To date, none of the available antidiabetic drugs promotes the maintenance of a functional mass of endogenous beta-cells, revealing an unmet medical need. Dysfunction and apoptotic death of beta-cells occur, in particular, through the activation of intracellular protein kinases. In recent years, protein kinases have become highly studied targets of the pharmaceutical industry for drug development. A number of drugs that inhibit protein kinases have been approved for the treatment of cancers. The question of whether safe drugs that inhibit protein kinase activity can be developed and used to protect the function and survival of beta-cells in diabetes is still unresolved. This review presents arguments suggesting that several protein kinases in beta-cells may represent targets of interest for the development of drugs to treat diabetes.

The EGR1-Artemin Axis in Keratinocytes Enhances the Innervation of Epidermal Sensory Neurons during Skin Inflammation Induced by House Dust Mite Extract from Dermatophagoidesfarinae

Epidermal hyperinnervation is a critical feature of pruritus during skin inflammation. However, the mechanisms underlying epidermal hyperinnervation are unclear. This study investigates the role of the transcription factor EGR1 in epidermal innervation by utilizing wild-type (Egr1+/+) and Egr1-null (Egr1‒/‒) mice topically applied Dermatophagoides farinae extract from dust mite. Our findings revealed that Egr1‒/‒ mice exhibited reduced scratching behaviors and decreased density of epidermal innervation compared with Egr1+/+ mice. Furthermore, we identified artemin, a neurotrophic factor, as an EGR1 target responsible for Dermatophagoides farinae extract-induced hyperinnervation. It has been demonstrated that Dermatophagoides farinae extract stimulates toll-like receptors in keratinocytes. To elucidate the cellular mechanism, we stimulated keratinocytes with Pam3CSK4, a toll-like receptor 1/2 ligand. Pam3CSK4 triggered a toll-like receptor 1/2-mediated signaling cascade involving IRAK4, IκB kinase, MAPKs, ELK1, EGR1, and artemin, leading to increased neurite outgrowth and neuronal migration. In addition, increased expression of EGR1 and artemin was observed in the skin tissues of patients with atopic dermatitis. These findings highlight the significance of the EGR1-artemin axis in keratinocytes, promoting the process of epidermal innervation and suggesting it as a potential therapeutic target for alleviating itch and pain associated with house dust mite-induced skin inflammation.

Leishmania surface molecule lipophosphoglycan-TLR2 interaction moderates TPL2-mediated TLR2 signalling for parasite survival

Leishmania donovani, a protozoan parasite, resides and replicates in macrophages and inflicts the potentially fatal disease visceral leishmaniasis (VL). The parasite-expressed surface lipophosphoglycan (LPG) was implicated in binding TLR2 on NK cells, but the modus operandi of its disease-promoting influence remained unknown. As TPL2, a member of the MAPK module in mammalian macrophages, was implicated in the anti-inflammatory immune response and promoting pathogen survival, we investigated the possibility of TPL2-directed LPG-TLR2 signalling in Leishmania infection. We observed that TLR2 or TPL2 blockade differentially influenced the TLR2 ligand proteoglycan (PGN)-induced p38MAPK and ERK-1/2 activation. TLR2 blockade abrogated the PGN-induced TPL2 activation. L. donovani infection impaired the Akt activation whereas, upon TPL2 inhibition, the infection fails to control Akt phosphorylation. In L. donovani-infected macrophages, TLR2 blocking negatively affected p38, Akt and TPL2 phosphorylation while ERK1/2 phosphorylation increased relative to the infection alone. TPL2 blockade reduced TGF-β, but increased TNF-α expression and diminished amastigote count in macrophages. While exploring stimulation patterns of TLR2 ligands, LPG, unlike PGN, selectively increased TLR2 expression in macrophages. LPG blockade increased p38MAPK and AKT, but slightly affected ERK-1/2 and significantly reduced TPL2 phosphorylation from L. donovani-infected macrophages. Molecular docking and molecular dynamics analysis drew a parallel between LPG's glycan chain lengths with the frequency of interaction with TLR2 which might impact TLR2 signalling. Therefore, the parasite regulates the TLR2 signalling via TPL2 when elicited by LPG-TLR2 interaction for pathogenesis.

Functions of MAP3Ks in antiviral immunity

Immune signal transduction is crucial to the body's defense against viral infection. Recognition of pathogen-associated molecular patterns by pattern recognition receptors (PRRs) activates the transcription of interferon regulators and nuclear factor-κB (NF-κB); this promotes the release of interferons and inflammatory factors. Efficient regulation of type I interferon and NF-κB signaling by members of the mitogen-activated protein (MAP) kinase kinase kinase (MAP3K) family plays an important role in antiviral immunity. Elucidating the specific roles of MAP3K activation during viral infection is essential to develop effective antiviral therapies. In this review, we outline the specific regulatory mechanisms of MAP3Ks in antiviral immunity and discuss the feasibility of targeting MAP3Ks for the treatment of virus-induced diseases.

Imperatorin inhibits LPS-induced bone marrow-derived macrophages activation by decreased NF-κB p65 phosphorylation

BACKGROUND

Imperatorin (IMP) is a secondary metabolite of plants and is the most abundant in Angelica dahurica. Previous studies showed that IMP exhibited anti-inflammatory activity in RAW264.7 cell line. Here, we aim to investigate the roles and mechanisms of IMP in bone marrow-derived macrophages (BMDMs), in view of the difference between primary macrophages and cell lines.

METHODS

BMDMs were stimulated with LPS for the inflammation model. Flow cytometry was performed with BMDMs treated with different doses of IMP (0-20mg/L) within staining Annexin V-APC for 5 min. The cytokines and inflammatory mediators were detected by RT-PCR or ELISA. RNA-seq was performed in IMP-treated BMDMs or control, stimulated with LPS for 6h. Western blotting is carried out to determine the phosphorylation of p65, ERK1/2, JNK1, p38, and Akt.

RESULTS

Our results showed that IMP inhibited IL-12p40, IL-6, TNF-α and IL-1β in LPS-stimulated BMDMs. RNA-seq analysis suggested that IMP inhibits Toll-like receptor signaling pathway (KEGG), TNF signaling pathway (KEGG), NF-κB signaling pathway (KEGG), Inflammatory Response (GO). In addition, IMP inhibited myd88, tpl2, cxcl1, ptgs2(COX-2) expression in mRNA level. Finally, we found decreased phosphorylation of NF-κB p65 in IMP-treated BMDMs, after stimulated with LPS.

CONCLUSION

IMP inhibits IL-12p40, IL-6, TNF-α, and IL-1β expression in LPS-stimulated BMDMs. IMP inhibits macrophage activation, which maybe resulted in decreased phosphorylation of NF-κB p65. Furthermore, IMP may protect against the progress of inflammatory-related diseases.

Interplay of Chemokines Receptors, Toll-like Receptors, and Host Immunological Pathways

A comprehensive framework has been established for understanding immunological pathways, which can be categorized into eradicated and tolerable immune responses. Toll-like receptors (TLRs) are associated with specific immune responses. TH1 immunity is related to TLR7, TLR8, and TLR9, while TH2 immunity is associated with TLR1, TLR2, and TLR6. TH22 immunity is linked to TLR2, TLR4, and TLR5, and THαβ (Tr1) immunity is related to TLR3, TLR7, and TLR9. The chemokine receptor CXCR5 is a marker of follicular helper T cells, and other chemokine receptors can also be classified within a framework based on host immunological pathways. On the basis of a literature review on chemokines and immunological pathways, the following associations were identified: CCR5 with TH1 responses, CCR1 with TH1-like responses, CCR4 (basophils) and CCR3 (eosinophils) with TH2 and TH9 responses, CCR10 with TH22 responses, CCR6 with TH17 responses, CXCR3 with THαβ responses, CCR8 with regulatory T cells (Treg), and CCR2 with TH3 responses. These findings contribute to the identification of biomarkers for immune cells and provide insights into host immunological pathways. Understanding the chemokine and Toll-like receptor system is crucial for comprehending the function of the innate immune system, as well as adaptive immune responses.

TPL2 kinase activity regulates microglial inflammatory responses and promotes neurodegeneration in tauopathy mice

Tumor progression locus 2 (TPL2) (MAP3K8) is a central signaling node in the inflammatory response of peripheral immune cells. We find that TPL2 kinase activity modulates microglial cytokine release and is required for microglia-mediated neuron death in vitro. In acute in vivo neuroinflammation settings, TPL2 kinase activity regulates microglia activation states and brain cytokine levels. In a tauopathy model of chronic neurodegeneration, loss of TPL2 kinase activity reduces neuroinflammation and rescues synapse loss, brain volume loss, and behavioral deficits. Single-cell RNA sequencing analysis indicates that protection in the tauopathy model was associated with reductions in activated microglia subpopulations as well as infiltrating peripheral immune cells. Overall, using various models, we find that TPL2 kinase activity can promote multiple harmful consequences of microglial activation in the brain including cytokine release, iNOS (inducible nitric oxide synthase) induction, astrocyte activation, and immune cell infiltration. Consequently, inhibiting TPL2 kinase activity could represent a potential therapeutic strategy in neurodegenerative conditions.

Tumor progression locus 2 (TPL2): A Cot-plicated progression from inflammation to chronic liver disease

The cytoplasmic protein tumor progression locus 2 (TPL2), also known as cancer Osaka thyroid (Cot), or MAP3K8, is thought to have a significant role in a variety of cancers and illnesses and it is a key component in the activation pathway for the expression of inflammatory mediators. Despite the tight connection between inflammation and TPL2, its function has not been extensively studied in chronic liver disease (CLD), a major cause of morbidity and mortality worldwide. Here, we analyze more in detail the significance of TPL2 in CLD to shed light on the pathological and molecular transduction pattern of TPL2 during the progression of CLD. This might result in important advancements and enable progress in the diagnosis and treatment of CLD.

The Tpl2-MEK pathway plays a critical role in spheroid-cultured endometriotic stromal cells

PROBLEM

Endometriosis is a proliferative disease characterized by cytokine-induced inflammation. The objective of this study was to assess cell growth and PGE₂ production induced by TNF-α in endometriotic stromal cells (ESCs) in spheroid cell culture and to identify the signaling pathway involved with a view to finding new therapeutic targets for endometriosis.

METHOD OF STUDY

Tissue samples were collected from patients with and without endometriosis. ESCs were isolated from ovarian endometrioma (OE). Gene expression was evaluated by real-time PCR and DNA microarray analysis, the proliferative effect on ESCs by WST-8 assay, and PGE₂ production by ELISA. Protein phosphorylation was detected using western blotting.

RESULTS

COX-2, aromatase and VEGFA mRNA expression and PGE₂ production were significantly elevated in spheroid cell cultures compared to monolayer cell cultures. TNF-α receptor (TNFR) 1 and TNFR2 mRNA was also significantly increased. TNF-α promoted the proliferation and PGE₂ production of ESCs in spheroid cell cultures significantly more than in monolayer cell cultures. TNF-α increased the expression of several genes related to the pathophysiology of endometriosis in spheroid ESCs. DNA microarray analysis revealed that the Tpl2 gene, which codes for a MAPK upstream of MEK, was upregulated in OE and endometrium with endometriosis compared to normal endometrium. TNF-α increased the phosphorylation and expression of Tpl2 and MEK, and Tpl2 and MEK inhibitors inhibited TNF-α-induced proliferation and PGE₂ production in spheroid ESCs.

CONCLUSION

The Tpl2-MEK signaling pathway may play a critical role in the cell growth and PGE₂ production induced by TNF-α in spheroid ESCs.

NONO regulates multiple cytokine production in sepsis via the ERK1/2 signaling pathway

The massive release of pro-inflammatory cytokines is a crucial step in triggering the inflammatory cascade in sepsis. Exploring the key molecules regulating the expression and release of multiple cytokines has important value for revealing the mechanism of the cytokine storm in sepsis. This study aimed to investigate the role of multifunctional nuclear protein non-POU domain containing octamer-binding protein (NONO) in the sepsis cytokine storm and to elucidate the underlying mechanism. We found that NONO expression in tissues and cells of sepsis mice was significantly upregulated. Downregulation of NONO expression inhibited the mRNA expression of multiple cytokines, including IL-6, IL-1β, MCP-1, MIP-1α, and MIP-1β in inflammatory cells from mice and human leukemic monocyte-THP1 cells challenged with lipopolysaccharide (LPS), and significantly decreased the level of these cytokines and TNF-α in the supernatant of THP1 cells challenged by LPS. Nono knockout also reduced the levels of TNF-α, IL-6, MIP-1α, and MIP-1β in serum, alleviated hepatocyte edema, and improved the survival rate of sepsis mice. Reduced NONO expression decreased the phospho-ERK1/2 level in inflammatory cells from sepsis mice or THP1 cells challenged by LPS. Phospho-ERK1/2 inhibitor decreased the mRNA expression and concentration of cytokines in the culture supernatant of LPS-induced THP1 cells, similar to the effect of NONO knockdown. After LPS challenge, the levels of phospho-ERK1/2 and NONO were increased, with obvious colocalization in the nucleus and vesicular-like organelles in macrophages. NONO knockdown decreased nuclear translocation of phospho-ERK1/2 in LPS-challenged THP1 cells. These results suggest that NONO is a potentially critical molecule involved in multiple cytokine production in sepsis. Upregulated NONO in sepsis may promote the expression and release of multiple cytokines to participate in a sepsis cytokine storm by promoting ERK1/2 phosphorylation.

Enhanced expression of miR-26a ameliorates lipopolysaccharide-induced endometritis by targeting MAP3K8 to inactivate MAPK signaling pathway

Endometritis is a severe postpartum inflammatory disease that puts cows' reproductive health at risk and causes the dairy industry to suffer significant financial losses. The present study aimed to investigate the regulatory role of miR‑26a in LPS‑induced bovine endometrial epithelial cells (bEECs) and the implication for endometritis. Here, we found inflammatory cell infiltration and destruction of endometrial structure in cow uterus, and dramatic increase in myeloperoxidase (MPO) activity and upregulation of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) in endometritis. Meanwhile, miR-26a was down-regulated, but MAP3K8 was increased in the uterine tissue of endometritis. Similarly, the expression of miR-26a was significantly decreased in LPS-stimulated bEECs, while MAP3K8 was risen. In addition, we further verified that MAP3K8 was a target of miR-26a by dual-luciferase reporter assay. Under LPS stress, over-expressing miR-26a markedly decreased MAP3K8 expression levels, along with the reduced expression of inflammatory factors, such as IL-1β, TNF-α and IL-6, whereas this effect was countered by the inhibition of miR-26a. Furthermore, we demonstrated that miR-26a overexpression prevented the MAPK pathway from being activated by targeting MAP3K8. Then we carried out experiments in LPS-stimulated mice uterus to expound that MAP3K8 was essential in endometritis development, which further confirmed the reliability of the above results. In conclusion, overexpression of miR-26a effectively inhibited the expression of MAP3K8 in LPS-induced bEECs and thereby partially suppressed the activation of MAPK signaling pathway. miR-26a and MAP3K8 may be a promising biomarker and therapeutic target for dairy cow endometritis.

Establishment and characterization of a new activated B-cell-like DLBCL cell line, TMD12

We report the establishment of a novel activated B-cell-like (ABC) diffuse large B-cell lymphoma (DLBCL) cell line, designated as TMD12, from a patient with highly refractory DLBCL. ABC-DLBCL is a subtype with a relatively unfavorable prognosis that was originally categorized using gene expression profiling according to its cell of origin. TMD12 cells were isolated from the pleural effusion of the patient at relapse and passaged continuously in vitro for >4 years. The cells displayed cluster of differentiation (CD)19, CD20, CD22, CD38, human leukocyte antigen-DR isotype, and κ positivity and CD5, CD10, CD23, and λ negativity, as detected using flow cytometric analysis. The chromosomal karyotypic analysis, including the spectral karyotyping method, confirmed t(1;19)(q21:q13.1), del(6q23), gain of chromosome 18, and other abnormalities. Mutation analyses, including whole-exome sequencing, revealed that TMD12 cells harbored mutations in MYD88 and CD79B, indicating an ABC subtype. TMD12 cells exhibited chronic active B-cell receptor signaling and constitutive activation of the nuclear factor κB pathway, which is typically associated with sensitivity to a specific Bruton tyrosine kinase inhibitor, ibrutinib. Intriguingly, TMD12 cells displayed moderate resistance to ibrutinib and lacked activation of Janus kinase/signal transducers and activators of transcription 3 signaling, another hallmark of this DLBCL subtype. Treatment with an inhibitor against tumor progression locus 2 (TPL2), a multifunctional intracellular kinase that is activated particularly downstream of Toll-like receptors or MYD88 and IκB kinase α/β (IKKα/β), suppressed the proliferation of TMD12 cells, implying the possible involvement of the TPL2-p105 pathway in the tumorigenesis of ABC-DLBCL. Because only a limited number of ABC-DLBCL cell lines are currently available, TMD12 cells might provide a useful tool in the search for novel druggable targets for this intractable lymphoma.

Neoplasia-associated Chromosome Translocations Resulting in Gene Truncation

Chromosomal translocations in cancer as well as benign neoplasias typically lead to the formation of fusion genes. Such genes may encode chimeric proteins when two protein-coding regions fuse in-frame, or they may result in deregulation of genes via promoter swapping or translocation of the gene into the vicinity of a highly active regulatory element. A less studied consequence of chromosomal translocations is the fusion of two breakpoint genes resulting in an out-of-frame chimera. The breaks then occur in one or both protein-coding regions forming a stop codon in the chimeric transcript shortly after the fusion point. Though the latter genetic events and mechanisms at first awoke little research interest, careful investigations have established them as neither rare nor inconsequential. In the present work, we review and discuss the truncation of genes in neoplastic cells resulting from chromosomal rearrangements, especially from seemingly balanced translocations.

ERK1/2 in immune signalling

Extracellular signal-related kinases 1 and 2 (ERK1/2) are the final components of the mitogen-activated protein kinase (MAPK) phosphorylation cascade, an integral module in a diverse array of signalling pathways for shaping cell behaviour and fate. More recently, studies have shown that ERK1/2 plays an essential role downstream of immune receptors to elicit inflammatory gene expression in response to infection and cell or tissue damage. Much of this work has studied ERK1/2 activation in Toll-like receptor (TLR) pathways, providing mechanistic insights into its recruitment, compartmentalisation and activation in cells of the innate immune system. In this review, we summarise the typical activation of ERK1/2 in growth factor receptor pathways before discussing its known roles in immune cell signalling with a focus downstream of TLRs. We examine emerging research uncovering evidence of dysfunctional ERK1/2 signalling in inflammatory diseases and discuss the potential therapeutic benefit of targeting ERK1/2 pathways in inflammation.

Tumor Progression Locus 2 Protects against Acute Respiratory Distress Syndrome in Influenza A Virus-Infected Mice

Excessive inflammation in patients with severe influenza disease may lead to acute lung injury that results in acute respiratory distress syndrome (ARDS). ARDS is associated with alveolar damage and pulmonary edema that severely impair gas exchange, leading to hypoxia. With no existing FDA-approved treatment for ARDS, it is important to understand the factors that lead to virus-induced ARDS development to improve prevention, diagnosis, and treatment. We have previously shown that mice deficient in the serine-threonine mitogen-activated protein kinase, Tpl2 (MAP3K8 or COT), succumb to infection with a typically low-pathogenicity strain of influenza A virus (IAV; HKX31, H3N2 [x31]). The goal of the current study was to evaluate influenza A virus-infected Tpl2-/- mice clinically and histopathologically to gain insight into the disease mechanism. We hypothesized that Tpl2-/- mice succumb to IAV infection due to development of ARDS-like disease and pulmonary dysfunction. We observed prominent signs of alveolar septal necrosis, hyaline membranes, pleuritis, edema, and higher lactate dehydrogenase (LDH) levels in the lungs of IAV-infected Tpl2-/- mice compared to wild-type (WT) mice from 7 to 9 days postinfection (dpi). Notably, WT mice showed signs of regenerating epithelium, indicative of repair and recovery, that were reduced in Tpl2-/- mice. Furthermore, biomarkers associated with human ARDS cases were upregulated in Tpl2-/- mice at 7 dpi, demonstrating an ARDS-like phenotype in Tpl2-/- mice in response to IAV infection. IMPORTANCE This study demonstrates the protective role of the serine-threonine mitogen-activated protein kinase, Tpl2, in influenza virus pathogenesis and reveals that host Tpl2 deficiency is sufficient to convert a low-pathogenicity influenza A virus infection into severe influenza disease that resembles ARDS, both histopathologically and transcriptionally. The IAV-infected Tpl2-/- mouse thereby represents a novel murine model for studying ARDS-like disease that could improve our understanding of this aggressive disease and assist in the design of better diagnostics and treatments.

Switch-associated protein 70 protects against nonalcoholic fatty liver disease through suppression of TAK1

BACKGROUND AND AIMS

NAFLD is a progressive disease without known effective drug treatments. Switch-associated protein 70 (SWAP70) is a guanine nucleotide exchange factor that participates in the regulation of many cellular processes. However, the role of SWAP70 in NAFLD remains unclear. This study aimed to identify the function and mechanism of SWAP70 in NAFLD.

APPROACH AND RESULTS

The results showed that the expression of SWAP70 was significantly increased in mice and hepatocytes after metabolic stimulation. Overexpression of SWAP70 in hepatocytes suppressed lipid deposition and inflammation, and SWAP70 knockdown created the inverse effect. Using hepatocyte-specific Swap70 knockout and overexpression mice fed a high-fat, high-cholesterol diet, we demonstrated that SWAP70 suppressed the progression of nonalcoholic steatohepatitis by inhibiting lipid accumulation, inflammatory response, and fibrosis. Mechanically, RNA sequencing analysis and immunoprecipitation assays revealed that SWAP70 inhibited the interaction between transforming growth factor β-activated kinase 1 (TAK1) binding protein 1 and TAK1 and sequentially suppressed the phosphorylation of TAK1 and subsequent c-Jun N-terminal kinase/P38 signaling. Inhibition of TAK1 activation blocked hepatocyte lipid deposition and inflammation caused by SWAP70 knockdown.

CONCLUSIONS

SWAP70 is a protective molecule that can suppress the progression of NAFLD by inhibiting hepatic steatosis and inflammation. SWAP70 may be important for mitigating the progression of NAFLD.

Cellular mechanism underlying the facilitation of contractile response induced by IL-25 in mouse tracheal smooth muscle

Asthma is a common heterogeneous respiratory disease characterized by airway inflammation and airway hyperresponsiveness (AHR) which is associated with abnormality in smooth muscle contractility. The epithelial cell-derived cytokine IL-25 is implicated in type 2 immune pathology including asthma, whereas the underlying mechanisms have not been fully elucidated. This study aims to investigate the effects of IL-25 on mouse tracheal smooth muscle contractility and elucidate the cellular mechanisms. Incubation with IL-25 augmented the contraction of mouse tracheal smooth muscles, which could be suppressed by the L-type voltage-dependent Ca²⁺ channel (L-VDCC) blocker nifedipine. Furthermore, IL-25 enhanced the cytosolic Ca²⁺ signals and triggered up-regulation of α1C L-VDCC (Ca_V1.2) in primary cultured mouse tracheal smooth muscle cells. Knocking down IL-17RA/IL-17RB receptors or inhibiting the transforming growth factor-β-activated kinase 1 (TAK1)-tumor progression locus 2 (TPL2)-MAPK kinase 1/2 (MEK1/2)-ERK1/2-activating protein-1 (AP-1) signaling pathways suppressed the IL-25-elicited up-regulation of Ca_V1.2 and hyperreactivity in tracheal smooth muscles. Moreover, inhibition of TPL2, ERK1/2 or L-VDCC alleviated the AHR symptom induced by IL-25 in a murine model. This study revealed that IL-25 potentiated the contraction of tracheal smooth muscle and evoked AHR via activation of TPL2-ERK1/2-Ca_V1.2 signaling, providing novel targets for the treatment of asthma with a high-IL-25 phenotype.

Immunotherapeutic HCW9218 augments anti-tumor activity of chemotherapy via NK cell-mediated reduction of therapy-induced senescent cells

Therapy induced senescence (TIS) in tumors and TIS cancer cells secrete proinflammatory senescence-associated secretory phenotype (SASP) factors. SASP factors promote TIS cancer cells to re-enter the growth cycle with stemness characteristics, resulting in chemo-resistance and disease relapse. Herein, we show that the immunotherapeutic HCW9218, comprising transforming growth factor-β (TGF-β) receptor II and interleukin (IL)-15/IL-15 receptor α domains, enhances metabolic and cytotoxic activities of immune cells and reduces TIS tumor cells in vivo to improve the efficacy of docetaxel and gemcitabine plus nab-paclitaxel against B16F10 melanoma and SW1990 pancreatic tumors, respectively. Mechanistically, HCW9218 treatment reduces the immunosuppressive tumor microenvironment and enhances immune cell infiltration and cytotoxicity in the tumors to eliminate TIS cancer cells. Immuno-depletion analysis suggests that HCW9218-activated natural killer cells play a pivotal role in TIS cancer cell removal. HCW9218 treatment following docetaxel chemotherapy further enhances efficacy of tumor antigen-specific and anti-programmed death-ligand 1 (PD-L1) antibodies in B16F10 tumor-bearing mice. We also show that HCW9218 treatment decreases TIS cells and lowers SASP factors in off-target tissues caused by chemotherapy of tumor-bearing mice. Collectively, HCW9218 has the potential to significantly enhance anti-tumor efficacy of chemotherapy, therapeutic antibodies, and checkpoint blockade by eliminating TIS cancer cells while reducing TIS-mediated proinflammatory side effects in normal tissues.

Regulatory spine RS3 residue of protein kinases: a lipophilic bystander or a decisive element in the small-molecule kinase inhibitor binding?

In recent years, protein kinases have been one of the most pursued drug targets. These determined efforts have resulted in ever increasing numbers of small-molecule kinase inhibitors reaching to the market, offering novel treatment options for patients with distinct diseases. One essential component related to the activation and normal functionality of a protein kinase is the regulatory spine (R-spine). The R-spine is formed of four conserved residues named as RS1–RS4. One of these residues, RS3, located in the C-terminal part of αC-helix, is usually accessible for the inhibitors from the ATP-binding cavity as its side chain is lining the hydrophobic back pocket in many protein kinases. Although the role of RS3 has been well acknowledged in protein kinase function, this residue has not been actively considered in inhibitor design, even though many small-molecule kinase inhibitors display interactions to this residue. In this minireview, we will cover the current knowledge of RS3, its relationship with the gatekeeper, and the role of RS3 in kinase inhibitor interactions. Finally, we comment on the future perspectives how this residue could be utilized in the kinase inhibitor design.

New Druggable Targets for Rheumatoid Arthritis Based on Insights From Synovial Biology

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease characterized by chronic inflammation and destruction of multiple small joints which may lead to systemic complications. Altered immunity via pathogenic autoantibodies pre-date clinical symptom development by several years. Incompletely understood range of mechanisms trigger joint-homing, leading to clinically evident articular disease. Advances in therapeutic approaches and understanding pathogenesis have improved prognosis and likely remission. However, partial/non-response to conventional and biologic therapies witnessed in a subset of patients highlights the need for new therapeutics. It is now evident that joint disease chronicity stems from recalcitrant inflammatory synovial environment, majorly maintained by epigenetically and metabolically reprogrammed synoviocytes. Therefore, interference with effector functions of activated cell types seems a rational strategy to reinstate synovial homeostasis and complement existing anti-inflammatory interventions to mitigate chronic RA. Presenting this newer aspect of fibroblast-like synoviocytes and myeloid cells underlying the altered synovial biology in RA and its potential for identification of new druggable targets is attempted in this review. Major leads from i) molecular insights of pathogenic cell types from hypothesis free OMICS approaches; ii) hierarchy of their dysregulated signaling pathways; and iii) knowledge of druggability of molecular nodes in these pathways are highlighted. Development of such synovial biology-directed therapeutics hold promise for an enriched drug repertoire for RA.

IKBKE-driven TPL2 and MEK1 phosphorylations sustain constitutive ERK1/2 activation in tumor cells

IKBKE have been associated with numerous cancers. As a result, IKBKE have emerged as potential target for cancer therapy. Accumulating evidence support that IKBKE orchestrate tumor cell survival in cancers. Here we evaluated the possible link between IKBKE and ERK phosphorylation. The effects of IKBKE silencing on MAPK activation in tumor vs. normal cells were evaluated via WB and RT-PCR. Ectopically expressed IKBKE, TPL2 or MEK1 constructs were used to examine the possible interactions among them via co-IP. In vitro kinase assays were performed to understand nature of the observed interactions. In tumors, IKBKE regulates MEK/ERK constitutive activations in vitro and in vivo. IKBKE and TPL2 physically interact and this interaction leads to TPL2 phosphorylation. We describe here a novel regulatory link between IKBKE and constitutive ERK1/2 activation in tumor cells. This new circuitry may be relevant for tumor cell survival in various malignancies.

MAP3K8 Is a Prognostic Biomarker and Correlated With Immune Response in Glioma

MAP3K8 is a serine/threonine kinase that is widely expressed in immune cells, non-immune cells, and many tumor types. The expression, clinical significance, biological role, and the underlying molecular mechanisms of MAP3K8 in glioma have not been investigated yet. Here, we discovered that MAP3K8 was aberrantly overexpressed in glioma and correlated with poor clinicopathological features of glioma by analysis on different datasets and immunohistochemistry staining. MAP3K8 is an independent prognostic indicator and significantly correlates with the progression of glioma. We also performed the function and pathway enrichment analysis of MAP3K8 in glioma to explore its biological functions and underlying molecular mechanisms in glioma. MAP3K8 co-expressed genes were mainly enriched in immune-related biological processes such as neutrophil activation, leukocyte migration, neutrophil-mediated immunity, lymphocyte-mediated immunity, T-cell activation, leukocyte cell–cell adhesion, regulation of leukocyte cell–cell adhesion, B-cell-mediated immunity, myeloid cell differentiation, and regulation of cell–cell adhesion. Single-cell RNA sequencing data and immunohistochemistry analysis demonstrated that MAP3K8 is expressed in malignant and immune cells and mainly enriched in the microglia/macrophage cells of glioma. The expression of MAP3K8 was positively correlated with immune infiltration, including effector memory CD4⁺ T cells, plasmacytoid dendritic cells, neutrophils, myeloid dendritic cells, mast cells, and macrophage in glioma. Further correlation analysis demonstrated that a series of inhibitory immune checkpoint molecules, chemokines, and chemokine receptors was positively correlated with the expression of MAP3K8. MAP3K8 might play an essential role in tumor immunity, and inhibition of MPA3K8 is a plausible strategy for glioma immunotherapy.

Early Transcriptional Changes in Rabies Virus-Infected Neurons and Their Impact on Neuronal Functions

Rabies is a zoonotic disease caused by rabies virus (RABV). As rabies advances, patients develop a variety of severe neurological symptoms that inevitably lead to coma and death. Unlike other neurotropic viruses that can induce symptoms of a similar range, RABV-infected post-mortem brains do not show significant signs of inflammation nor the structural damages on neurons. This suggests that the observed neurological symptoms possibly originate from dysfunctions of neurons. However, many aspects of neuronal dysfunctions in the context of RABV infection are only partially understood, and therefore require further investigation. In this study, we used differentiated neurons to characterize the RABV-induced transcriptomic changes at the early time-points of infection. We found that the genes modulated in response to the infection are particularly involved in cell cycle, gene expression, immune response, and neuronal function-associated processes. Comparing a wild-type RABV to a mutant virus harboring altered matrix proteins, we found that the RABV matrix protein plays an important role in the early down-regulation of host genes, of which a significant number is involved in neuronal functions. The kinetics of differentially expressed genes (DEGs) are also different between the wild type and mutant virus datasets. The number of modulated genes remained constant upon wild-type RABV infection up to 24 h post-infection, but dramatically increased in the mutant condition. This result suggests that the intact viral matrix protein is important to control the size of host gene modulation. We then examined the signaling pathways previously studied in relation to the innate immune responses against RABV, and found that these pathways contribute to the changes in neuronal function-associated processes. We further examined a set of regulated genes that could impact neuronal functions collectively, and demonstrated in calcium imaging that indeed the spontaneous activity of neurons is influenced by RABV infection. Overall, our findings suggest that neuronal function-associated genes are modulated by RABV early on, potentially through the viral matrix protein-interacting signaling molecules and their downstream pathways.

Tpl2 contributes to IL-1β-induced IL-8 expression via ERK1/2 activation in canine dermal fibroblasts

In autoimmune diseases, fibroblasts produce and secrete various cytokines and act as sentinel immune cells during inflammatory states. However, the contribution of sentinel immune cells (i.e. dermal fibroblasts) in autoimmune diseases of the skin, such as atopic dermatitis, has been obscure. The pro-inflammatory cytokine interleukin 1β (IL-1β) induces the expression of chemokines, such as interleukin 8 (IL-8), in autoimmune diseases of the skin. IL-8 induces the activation and recruitment of innate immune cells such as neutrophils to the site of inflammation. IL-1β-mediated induction of IL-8 expression is important for the pathogenesis of autoimmune diseases; however, the intracellular singling remains to be understood. To elucidate the mechanism of the onset of autoimmune diseases, we established a model for IL-1β-induced dermatitis and investigated MAPK signaling pathways in IL-1β-induced IL-8 expression. We also identified that a MAP3K Tpl2 acts as an upstream modulator of IL-1β-induced ERK1/2 activation in dermal fibroblasts. We observed an increase in the expression of IL-8 mRNA and protein in cells treated with IL-1β. ERK1/2 inhibitors significantly reduced IL-1β-induced IL-8 expression, whereas the inhibitor for p38 MAPK or JNK had no effect. IL-1β induced ERK1/2 phosphorylation, which was attenuated in the presence of an ERK1/2 inhibitor. IL-1β failed to induce IL-8 expression in cells transfected with siRNA for ERK1, or ERK2. Notably, a Tpl2 inhibitor reduced IL-1β-induced IL-8 expression and ERK1/2 phosphorylation. We confirmed that the silencing of Tpl2 in siRNA-transfected fibroblasts prevented both in IL-1β-induced IL-8 expression and ERK1/2 phosphorylation. Taken together, our data indicate the importance of Tpl2 in the modulation of ERK1/2 signaling involved in the IL-1β-induced development of autoimmune diseases affecting the dermal tissue, such as atopic dermatitis.

Aplysia Neurons as a Model of Alzheimer's Disease: Shared Genes and Differential Expression

Although Alzheimer’s disease (AD) is the most common form of dementia in the United States, development of therapeutics has proven difficult. Invertebrate alternatives to current mammalian AD models have been successfully employed to study the etiology of the molecular hallmarks of AD. The marine snail Aplysia californica offers a unique and underutilized system in which to study the physiological, behavioral, and molecular impacts of AD. Mapping of the Aplysia proteome to humans and cross-referencing with two databases of genes of interest in AD research identified 898 potential orthologs of interest in Aplysia. Included among these orthologs were alpha, beta and gamma secretases, amyloid-beta, and tau. Comparison of age-associated differential expression in Aplysia sensory neurons with that of late-onset AD in the frontal lobe identified 59 ortholog with concordant differential expression across data sets. The 21 concordantly upregulated genes suggested increased cellular stress and protein dyshomeostasis. The 47 concordantly downregulated genes included important components of diverse neuronal processes, including energy metabolism, mitochondrial homeostasis, synaptic signaling, Ca⁺⁺ regulation, and cellular cargo transport. Compromised functions in these processes are known hallmarks of both human aging and AD, the ramifications of which are suggested to underpin cognitive declines in aging and neurodegenerative disease.

The anti-cancer drug dabrafenib is not cardiotoxic and inhibits cardiac remodelling and fibrosis in a murine model of hypertension

Raf kinases signal via extracellular signal-regulated kinases 1/2 (ERK1/2) to drive cell division. Since activating mutations in BRAF (B-Raf proto-oncogene, serine/threonine kinase) are highly oncogenic, BRAF inhibitors including dabrafenib have been developed for cancer. Inhibitors of ERK1/2 signalling used for cancer are cardiotoxic in some patients, raising the question of whether dabrafenib is cardiotoxic. In the heart, ERK1/2 signalling promotes not only cardiomyocyte hypertrophy and is cardioprotective but also promotes fibrosis. Our hypothesis is that ERK1/2 signalling is not required in a non-stressed heart but is required for cardiac remodelling. Thus, dabrafenib may affect the heart in the context of, for example, hypertension. In experiments with cardiomyocytes, cardiac fibroblasts and perfused rat hearts, dabrafenib inhibited ERK1/2 signalling. We assessed the effects of dabrafenib (3 mg/kg/d) on male C57BL/6J mouse hearts in vivo. Dabrafenib alone had no overt effects on cardiac function/dimensions (assessed by echocardiography) or cardiac architecture. In mice treated with 0.8 mg/kg/d angiotensin II (AngII) to induce hypertension, dabrafenib inhibited ERK1/2 signalling and suppressed cardiac hypertrophy in both acute (up to 7 d) and chronic (28 d) settings, preserving ejection fraction. At the cellular level, dabrafenib inhibited AngII-induced cardiomyocyte hypertrophy, reduced expression of hypertrophic gene markers and almost completely eliminated the increase in cardiac fibrosis both in interstitial and perivascular regions. Dabrafenib is not overtly cardiotoxic. Moreover, it inhibits maladaptive hypertrophy resulting from AngII-induced hypertension. Thus, Raf is a potential therapeutic target for hypertensive heart disease and drugs such as dabrafenib, developed for cancer, may be used for this purpose.

Tpl2 kinase regulates inflammation but not tumorigenesis in mice

Tumor progression locus 2 (Tpl2, gene name MAP3K8), a mitogen-activated protein kinase, is widely expressed in immune and non-immune cells to integrate tumor necrosis factor (TNF), toll-like receptors (TLRs), and interleukin-1 (IL1) receptor signaling to regulate inflammatory response. Given its central role in inflammatory response, Tpl2 is an attractive small molecule drug target. However, the role of Tpl2 as an oncogene or tumor suppressor gene remains controversial, and its function outside immune cells is not understood. We therefore utilized a Tpl2 kinase dead (Tpl2-KD) mouse model in an 18-month aging study to further elucidate Tpl2 effects on lifespan and chronic disease. Histopathological studies revealed the incidence and severity of spontaneous tumors and non-neoplastic lesions were comparable between wild type and Tpl2-KD mice. The only finding was that male Tpl2-KD mice had higher bodyweight and an increased incidence of liver steatosis, suggesting a sex-specific role for Tpl2 in hepatic lipid metabolism. In conclusion, loss of Tpl2 kinase activity did not lead to increased tumorigenesis over aging in mice but affected likely alterations in lipid metabolism in male animals.

Endothelial Tpl2 regulates vascular barrier function via JNK-mediated degradation of claudin-5 promoting neuroinflammation or tumor metastasis

Increased vascular permeability and leakage are hallmarks of several pathologies and determine disease progression and severity by facilitating inflammatory/metastatic cell infiltration. Using tissue-specific genetic ablation in endothelial cells, we have investigated in vivo the role of Tumor progression locus 2 (Tpl2), a mitogen-activated protein kinase kinase kinase (MAP3K) member with pleiotropic effects in inflammation and cancer. In response to proinflammatory stimuli, endothelial Tpl2 deletion alters tight junction claudin-5 protein expression through inhibition of JNK signaling and lysosomal degradation activation, resulting in reduced vascular permeability and immune cell infiltration. This results in significantly attenuated disease scores in experimental autoimmune encephalomyelitis and fewer tumor nodules in a hematogenic lung cancer metastasis model. Accordingly, pharmacologic inhibition of Tpl2 or small interfering RNA (siRNA)-mediated Tpl2 knockdown recapitulates our findings and reduces lung metastatic tumor invasions. These results establish an endothelial-specific role for Tpl2 and highlight the therapeutic potential of blocking the endothelial-specific Tpl2 pathway in chronic inflammatory and metastatic diseases.

Bioinformatics-Based Analysis of the lncRNA-miRNA-mRNA Network and TF Regulatory Network to Explore the Regulation Mechanism in Spinal Cord Ischemia/Reperfusion Injury

Background

Spinal cord ischemia/reperfusion injury (SCII) is a catastrophic complication involved with cardiovascular, spine, and thoracic surgeries and can lead to paraplegia. Nevertheless, the molecular mechanism of SCII remain ill-defined.

Methods

Expression profiling (GSE138966) data were obtained from GEO database. Then, differentially expressed (DE) lncRNAs and DEmRNAs were screened out with p < 0.05, and | fold change| > 1.5. Aberrant miRNAs expression in SCII was obtained from PubMed. Functional enrichment analysis of overlapping DEmRNAs between predicted mRNAs in miRDB database and DEmRNAs obtained from GSE138966 was performed using cluster Profiler R package. The lncRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) network was established in light of ceRNA theory. The key lncRNAs in the ceRNA network were identified by topological analysis. Subsequently, key lncRNAs related ceRNA-pathway network and transcription factors (TFs)-mRNAs network were constructed. Simultaneously, the expression levels of hub genes were measured via qRT-PCR.

Results

The results in this study indicated that 76 miRNAs, 1373 lncRNAs, and 4813 mRNAs were differentially expressed in SCII. A SCII-related ceRNA network was constructed with 154 ncRNAs, 139 mRNAs, and 51 miRNAs. According topological analysis, six lncRNAs (NONRATT019236.2, NONRATT009530.2, NONRATT026999.2, TCONS_00032391, NONRATT023112.2, and NONRATT021956.2) were selected to establish the ceRNA-pathway network, and then two candidate hub lncRNAs (NONRATT009530.2 and NONRATT026999.2) were identified. Subsequently, two lncRNA-miRNA-mRNA regulatory axes were identified. NONRATT026999.2 and NONRATT009530.2 might involve SCII via miR-20b-5p/Map3k8 axis based on the complex ceRNA network. SP1 and Hnf4a acting as important TFs might regulate Map3k8. Furthermore, qRT-PCR results showed that the NONRATT009530.2, NONRATT026999.2, Map3k8, Hfn4a, and SP1 were significantly upregulated in SCII of rats, while the miR-20b-5p was downregulated.

Conclusion

Our results offer a new insight to understand the ceRNA regulation mechanism in SCII and identify highlighted lncRNA-miRNA-mRNA axes and two key TFs as potential targets for prevention and treatment of SCII.

TPL-2 kinase induces phagosome acidification to promote macrophage killing of bacteria

Tumour progression locus 2 (TPL‐2) kinase mediates Toll‐like receptor (TLR) activation of ERK1/2 and p38α MAP kinases in myeloid cells to modulate expression of key cytokines in innate immunity. This study identified a novel MAP kinase‐independent regulatory function for TPL‐2 in phagosome maturation, an essential process for killing of phagocytosed microbes. TPL‐2 catalytic activity was demonstrated to induce phagosome acidification and proteolysis in primary mouse and human macrophages following uptake of latex beads. Quantitative proteomics revealed that blocking TPL‐2 catalytic activity significantly altered the protein composition of phagosomes, particularly reducing the abundance of V‐ATPase proton pump subunits. Furthermore, TPL‐2 stimulated the phosphorylation of DMXL1, a regulator of V‐ATPases, to induce V‐ATPase assembly and phagosome acidification. Consistent with these results, TPL‐2 catalytic activity was required for phagosome acidification and the efficient killing of Staphylococcus aureus and Citrobacter rodentium following phagocytic uptake by macrophages. TPL‐2 therefore controls innate immune responses of macrophages to bacteria via V‐ATPase induction of phagosome maturation.

Foot-and-Mouth Disease Virus Structural Protein VP1 Destroys the Stability of TPL2 Trimer by Degradation TPL2 to Evade Host Antiviral Immunity

Tumor progression locus 2 (TPL2) is a serine/threonine kinase that belongs to the mitogen-activated protein 3 kinase (MAP3K) family, and it plays an important role in pathogen infection. The trimer complex of TPL2, p105, and ABIN2 is essential for maintenance of TPL2 steady-state levels and host cell response to pathogens. Foot-and-mouth disease virus (FMDV) is a positive-strand RNA virus of the family Picornaviridae that encodes proteins capable of antagonizing host immune responses to achieve infection. The VP1 protein of FMDV is a multifunctional protein that can bind host cells and induce an immune response as well as cell apoptosis. However, the role and mechanisms of TPL2 in FMDV infection remain unknown. Here, we determined that FMDV infection could inhibit TPL2, p105, and ABIN2 at the transcription and protein levels, while VP1 could only inhibit TPL2, p105 and ABIN2 at protein level. TPL2 inhibited the replication of FMDV in vivo and in vitro, the 268 to 283 amino-acid region in the TPL2 kinase domain was essential for interaction with VP1. Moreover, VP1 promoted K48-linked polyubiquitination of TPL2 and degraded TPL2 by the proteasome pathway. However, VP1-induced degradation of p105 and ABIN2 was independent of proteasome, autophagy, lysosome, and caspase-dependent pathways. Further studies showed that VP1 destroyed the stability of the TPL2-p105-ABIN2 complex. Taken together, these results revealed that VP1 antagonized TPL2-meditated antivirus activity by degrading TPL2 and destroying its complex. These findings may contribute to understand FMDV-host interactions and improve development of a novel vaccine to prevent FMDV infection.Importance Virus-host interactions are critical for virus infection. This study was the first to demonstrate the antiviral effect of host TPL2 during FMDV replication by increasing production of interferons and antiviral cytokines. Both FMDV and VP1 protein can reduce host TPL2, ABIN2 and p105 to destroy TPL2-p105-ABIN2 trimer complex. VP1 interacted with TPL2 and degrade TPL2 via proteasome pathway to repress TPL2-mediated antivirus activity. This study provided new insights into FMDV immune evasion mechanisms, elucidating new informations regarding FMDV counteraction of host antivirus activity.

Oxidative DNA Damage, Inflammatory Signature, and Altered Erythrocytes Properties in Diamond-Blackfan Anemia

Molecular pathophysiology of Diamond-Blackfan anemia (DBA) involves disrupted erythroid-lineage proliferation, differentiation and apoptosis; with the activation of p53 considered as a key component. Recently, oxidative stress was proposed to play an important role in DBA pathophysiology as well. CRISPR/Cas9-created Rpl5- and Rps19-deficient murine erythroleukemia (MEL) cells and DBA patients' samples were used to evaluate proinflammatory cytokines, oxidative stress, DNA damage and DNA damage response. We demonstrated that the antioxidant defense capacity of Rp-mutant cells is insufficient to meet the greater reactive oxygen species (ROS) production which leads to oxidative DNA damage, cellular senescence and activation of DNA damage response signaling in the developing erythroblasts and altered characteristics of mature erythrocytes. We also showed that the disturbed balance between ROS formation and antioxidant defense is accompanied by the upregulation of proinflammatory cytokines. Finally, the alterations detected in the membrane of DBA erythrocytes may cause their enhanced recognition and destruction by reticuloendothelial macrophages, especially during infections. We propose that the extent of oxidative stress and the ability to activate antioxidant defense systems may contribute to high heterogeneity of clinical symptoms and response to therapy observed in DBA patients.

Toll-Like Receptor 2-Tpl2-Dependent ERK Signaling Drives Inverse Interleukin 12 Regulation in Dendritic Cells and Macrophages

This study investigated responses to Toll-like receptor 2 (TLR2)-driven extracellular signal-related kinase (ERK) signaling in dendritic cells (DCs) versus macrophages. TLR2 signaling was induced with Pam₃Cys-Ser-Lys₄, and the role of ERK signaling was interrogated pharmacologically with MEK1/2 inhibitor U0126 or genetically with bone marrow-derived macrophages or DCs from Tpl2^-/- mice. We assessed cytokine production via enzyme-linked immunosorbent assay (ELISA) or V-Plex, and mRNA levels were assessed via reverse transcriptase quantitative PCR (qRT-PCR). In macrophages, blockade of ERK signaling by pharmacologic or genetic approaches inhibited interleukin 10 (IL-10) expression and increased expression of the p40 subunit shared by IL-12 and IL-23 (IL-12/23p40). In DCs, blockade of ERK signaling similarly inhibited IL-10 expression but decreased IL-12/23p40 expression, which is opposite to the effect of ERK signaling blockade on IL-12/23p40 in macrophages. This difference in IL-12/23p40 regulation correlated with the differential expression of transcription factors cFos and IRF1, which are known to regulate IL-12 family members, including IL-12 and IL-23. Thus, the impact of ERK signaling in response to TLR2 stimulation differs between macrophages and DCs, potentially regulating their distinctive functions in the immune system. ERK-mediated suppression of IL-12/23p40 in macrophages may prevent excessive inflammation and associated tissue damage following TLR2-stimulation, while ERK-mediated induction of IL-12/23p40 in DCs may promote priming of T helper 1 (Th1) responses. A greater understanding of the role that ERK signaling plays in different immune cell types may inform the development of host-directed therapy and optimal adjuvanticity for a number of infectious pathogens.

Activation of c-Jun N-Terminal Kinase, a Potential Therapeutic Target in Autoimmune Arthritis

The c-Jun-N-terminal kinase (JNK) is a critical mediator involved in various physiological processes, such as immune responses, and the pathogenesis of various diseases, including autoimmune disorders. JNK is one of the crucial downstream signaling molecules of various immune triggers, mainly proinflammatory cytokines, in autoimmune arthritic conditions, mainly including rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis. The activation of JNK is regulated in a complex manner by upstream kinases and phosphatases. Noticeably, different subtypes of JNKs behave differentially in immune responses. Furthermore, aside from biologics targeting proinflammatory cytokines, small-molecule inhibitors targeting signaling molecules such as Janus kinases can act as very powerful therapeutics in autoimmune arthritis patients unresponsiveness to conventional synthetic antirheumatic drugs. Nevertheless, despite these encouraging therapies, a population of patients with an inadequate therapeutic response to all currently available medications still remains. These findings identify the critical signaling molecule JNK as an attractive target for investigation of the immunopathogenesis of autoimmune disorders and for consideration as a potential therapeutic target for patients with autoimmune arthritis to achieve better disease control. This review provides a useful overview of the roles of JNK, how JNK is regulated in immunopathogenic responses, and the potential of therapeutically targeting JNK in patients with autoimmune arthritis.

Kinase inhibition in autoimmunity and inflammation

Despite recent advances in the treatment of autoimmune and inflammatory diseases, unmet medical needs in some areas still exist. One of the main therapeutic approaches to alleviate dysregulated inflammation has been to target the activity of kinases that regulate production of inflammatory mediators. Small-molecule kinase inhibitors have the potential for broad efficacy, convenience and tissue penetrance, and thus often offer important advantages over biologics. However, designing kinase inhibitors with target selectivity and minimal off-target effects can be challenging. Nevertheless, immense progress has been made in advancing kinase inhibitors with desirable drug-like properties into the clinic, including inhibitors of JAKs, IRAK4, RIPKs, BTK, SYK and TPL2. This Review will address the latest discoveries around kinase inhibitors with an emphasis on clinically validated autoimmunity and inflammatory pathways.

Unmet medical needs in the treatment of autoimmune and inflammatory diseases still exist. This Review discusses the activity of kinases that regulate production of inflammatory mediators and the recent advances in developing inhibitors to target such kinases.

Apolipoprotein E Signals via TLR4 to Induce CXCL5 Secretion by Asthmatic Airway Epithelial Cells

The primary function of APOE (apolipoprotein E) is to mediate the transport of cholesterol- and lipid-containing lipoprotein particles into cells by receptor-mediated endocytosis. APOE also has pro- and antiinflammatory effects, which are both context and concentration dependent. For example, Apoe^-/- mice exhibit enhanced airway remodeling and hyperreactivity in experimental asthma, whereas increased APOE levels in lung epithelial lining fluid induce IL-1β secretion from human asthmatic alveolar macrophages. However, APOE-mediated airway epithelial cell inflammatory responses and signaling pathways have not been defined. Here, RNA sequencing of human asthmatic bronchial brushing cells stimulated with APOE identified increased expression of mRNA transcripts encoding multiple proinflammatory genes, including CXCL5 (C-X-C motif chemokine ligand 5), an epithelial-derived chemokine that promotes neutrophil activation and chemotaxis. We subsequently characterized the APOE signaling pathway that induces CXCL5 secretion by human asthmatic small airway epithelial cells (SAECs). Neutralizing antibodies directed against TLR4 (Toll-like receptor 4), but not TLR2, attenuated APOE-mediated CXCL5 secretion by human asthmatic SAECs. Inhibition of TAK1 (transforming growth factor-β-activated kinase 1), IκKβ (inhibitor of nuclear factor κ B kinase subunit β), TPL2 (tumor progression locus 2), and JNK (c-Jun N-terminal kinase), but not p38 MAPK (mitogen-activated protein kinase) or MEK1/2 (MAPK kinase 1/2), attenuated APOE-mediated CXCL5 secretion. The roles of TAK1, IκKβ, TPL2, and JNK in APOE-mediated CXCL5 secretion were verified by RNA interference. Furthermore, RNA interference showed that after APOE stimulation, both NF-κB p65 and TPL2 were downstream of TAK1 and IκKβ, whereas JNK was downstream of TPL2. In summary, elevated levels of APOE in the airway may activate a TLR4/TAK1/IκKβ/NF-κB/TPL2/JNK signaling pathway that induces CXCL5 secretion by human asthmatic SAECs. These findings identify new roles for TLR4 and TPL2 in APOE-mediated proinflammatory responses in asthma.

Ubiquitin Ligases cIAP1 and cIAP2 Limit Cell Death to Prevent Inflammation

Cellular inhibitor of apoptosis proteins cIAP1 and cIAP2 ubiquitinate nuclear factor κB (NF-κB)-inducing kinase (NIK) to suppress non-canonical NF-κB signaling and substrates such as receptor interacting protein kinase 1 (RIPK1) to promote cell survival. We investigate how these functions contribute to homeostasis by eliminating cIap2 from adult cIap1-deficient mice. cIAP1 and cIAP2 (cIAP1/2) deficiency causes rapid weight loss and inflammation, with aberrant cell death, indicated by cleaved caspases-3 and -8, prevalent in intestine and liver. Deletion of Casp8 and Ripk3 prevents this aberrant cell death, reduces the inflammation, and prolongs mouse survival, whereas Ripk3 loss alone offers little benefit. Residual inflammation in mice lacking cIap1/2, Casp8, and Ripk3 is reduced by inhibition of NIK. Loss of Casp8 and Mlkl (mixed lineage kinase domain-like), but not Mlkl loss alone, also prevents cIAP1/2-deficient mice from dying around embryonic day 11. Therefore, a major function of cIAP1/2 in vivo is to suppress caspase-8-dependent cell death.

Tumor progression locus 2 (TPL2) in tumor-promoting Inflammation, Tumorigenesis and Tumor Immunity

Over the years, tumor progression locus 2 (TPL2) has been identified as an essential modulator of immune responses that conveys inflammatory signals to downstream effectors, subsequently modulating the generation and function of inflammatory cells. TPL2 is also differentially expressed and activated in several cancers, where it is associated with increased inflammation, malignant transformation, angiogenesis, metastasis, poor prognosis and therapy resistance. However, the relationship between TPL2-driven inflammation, tumorigenesis and tumor immunity has not been addressed. Here, we reconcile the function of TPL2-driven inflammation to oncogenic functions such as inflammation, proliferation, apoptosis resistance, angiogenesis, metastasis, immunosuppression and immune evasion. We also address the controversies reported on TPL2 function in tumor-promoting inflammation and tumorigenesis, and highlight the potential role of the TPL2 adaptor function in regulating the mechanisms leading to pro-tumorigenic inflammation and tumor progression. We discuss the therapeutic implications and limitations of targeting TPL2 for cancer treatment. The ideas presented here provide some new insight into cancer pathophysiology that might contribute to the development of more integrative and specific anti-inflammatory and anti-cancer therapeutics.

Effect of Acupuncture on the p38 Signaling Pathway in Several Nervous System Diseases: A Systematic Review

Acupuncture is clinically used to treat various diseases and exerts positive local and systemic effects in several nervous system diseases. Advanced molecular and clinical studies have continually attempted to decipher the mechanisms underlying these effects of acupuncture. While a growing understanding of the pathophysiology underlying several nervous system diseases shows it to be related to inflammation and impair cell regeneration after ischemic events, the relationship between the therapeutic mechanism of acupuncture and the p38 MAPK signal pathway has yet to be elucidated. This review discusses the latest advancements in the identification of the effect of acupuncture on the p38 signaling pathway in several nervous system diseases. We electronically searched databases including PubMed, Embase, and the Cochrane Library from their inception to April 2020, using the following keywords alone or in various combinations: "acupuncture", "p38 MAPK pathway", "signaling", "stress response", "inflammation", "immune", "pain", "analgesic", "cerebral ischemic injury", "epilepsy", "Alzheimer's disease", "Parkinson's disease", "dementia", "degenerative", and "homeostasis". Manual acupuncture and electroacupuncture confer positive therapeutic effects by regulating proinflammatory cytokines, ion channels, scaffold proteins, and transcription factors including TRPV1/4, Nav, BDNF, and NADMR1; consequently, p38 regulates various phenomena including cell communication, remodeling, regeneration, and gene expression. In this review article, we found the most common acupoints for the relief of nervous system disorders including GV20, GV14, ST36, ST37, and LI4. Acupuncture exhibits dual regulatory functions of activating or inhibiting different p38 MAPK pathways, contributing to an overall improvement of clinical symptoms and function in several nervous system diseases.

microRNA-381-3p Confers Protection Against Ischemic Stroke Through Promoting Angiogenesis and Inhibiting Inflammation by Suppressing Cebpb and Map3k8

Ischemic stroke is a serious disease with limited prevention methods, and various genes and microRNAs (miRNAs) have been found to be dysregulated in the pathogenesis of this disease. This study aims to explore the potential role of miR-381-3p in ischemic stroke, along with its underlying mechanism. A mouse model of ischemic stroke was developed using middle cerebral artery occlusion. Next, the expression of mitogen-activated protein kinase kinase kinase 8 (Map3k8) and CCAAT enhancer binding protein beta (Cebpb) was determined by RT-qPCR. Gain- and loss-of-function approaches were applied to analyze the effects of miR-381-3p, Cebpb and Map3k8 on the biological functions of endothelial progenitor cells (EPCs) with the involvement of the tumor necrosis factor-α (TNF-α) signaling pathway. In addition, dual luciferase reporter gene assay was performed for the analysis of the relationship among miR-381-3p, Map3k8 and Cebpb. Further, rescue experiment was performed with the help of JNK/p38 specific agonist, Anisomycin. Map3k8 and Cebpb were highly expressed in ischemic stroke. Loss-of-function of Map3k8 or Cebpb in EPCs contributed to accelerated proliferation, migration and angiogenesis of EPCs. Next, miR-381-3p downregulated the expression of its two target genes, Map3k8 and Cebpb. miR-381-3p overexpression promoted angiogenesis of EPCs, and inhibited inflammation, which could be reversed by restoration of Map3k8 or Cebpb. Additionally, silencing Map3k8 or Cebpb inhibited the activation of TNF-α signaling pathway. Furthermore, Anisomycin treatment could enhance inflammation and inhibit angiogenesis. Taken together, miR-381-3p downregulates Map3k8 and Cebpb to protect against ischemic stroke, broadening our understanding of the pathogenesis of ischemic stroke.

Involvement of exchange protein directly activated by cAMP and tumor progression locus 2 in IL-1β production in microglial cells following activation of β-adrenergic receptors

Endogenous noradrenaline (NA) has multiple bioactive functions and, in the central nervous system (CNS), has been implicated in modulating neuroinflammation via β-adrenergic receptors (β-ARs). Microglia, resident macrophages in the CNS, have a central role in the brain immune system and have been reported to be activated by NA. However, intracellular signaling mechanisms of the AR-mediated proinflammatory responses of microglia are not fully understood. Using a rapid and stable in vitro reporter assay system to evaluate IL-1β production in microglial BV2 cells, we found that NA and the β-AR agonist isoproterenol upregulated the IL-1β reporter activity. This effect was suppressed by β-AR antagonists. We further examined the involvement of EPAC (exchange protein directly activated by cAMP) and TPL2 (tumor progression locus 2, MAP3K8) and found that inhibitors for EPAC and TPL2 reduced AR agonist-induced IL-1β reporter activity. These inhibitors also suppressed NA-induced endogenous Il1b mRNA expression and IL-1β protein production. Our results suggest that EPAC and TPL2 are involved in β-AR-mediated IL-1β production in microglial cells, and extend our understanding of its intracellular signaling mechanism.

Identification of key genes associated with multiple sclerosis based on gene expression data from peripheral blood mononuclear cells

The aim of this study was to identify the potential key candidate genes of multiple sclerosis (MS) and uncover mechanisms in MS. We combined data from the microarray expression profile of three MS stages and performed bioinformatics analysis. Differentially expressed genes (DEGs) were identified among the distinct stages of MS and healthy controls, and a total of 349 shared DEGs were identified. Gene ontology (GO) and pathway enrichment analyses showed that the DEGs were significantly enriched in the biological processes (BPs) of purine-related metabolic processes and signaling, especially the common DEGs, which were enriched in some immunological processes. Most of the DEGs were enriched in signaling pathways associated with the immune system, some immune diseases and infectious disease pathways. Through a protein-protein interaction (PPI) network analysis and a gene expression regulatory network constructed with MS-related miRNAs, we confirmed FOS, TP53, VEGFA, JUN, HIF1A, RB1, PTGS2, CXCL8, OAS2, NFKBIA and OAS1 as candidate genes of MS. Furthermore , we explored the potential SNPs associated with MS by database mining. In conclusion, this study provides the identified genes, SNPs, biological processes, and cellular pathways associated with MS. The uncovered candidate genes may be potential biomarkers involved in the diagnosis and therapy of MS.

ATF-2 and Tpl2 regulation of endothelial cell cycle progression and apoptosis

Cells respond to soluble and membrane-bound factors to activate signalling cascades that control cell proliferation and cell death. Vascular endothelial growth factor A (VEGF-A) is a soluble ligand that modulates a variety of cellular responses including cell proliferation and apoptosis. It is not well understood how VEGF-A signalling pathways regulate cell proliferation and cell death. To address this, we examined VEGF-A-regulated signalling pathways in the cytosol and nucleus and functional requirement for such cellular responses. The VEGF-A-regulated transcription factor, ATF-2, is required for cell cycle proteins such as p53, p21 and Cyclin D1. A cytosolic serine/threonine protein kinase (Tpl2) modulates ATF-2-regulated effects on the endothelial cell cycle. Such regulatory effects impact on endothelial cell proliferation, cell viability and apoptosis. These cellular effects influence complex cell-based organisation such as endothelial tubulogenesis. Our study now provides a framework for incorporating VEGF-A-stimulated signalling events from the cytosol to the nucleus which helps to understand how cell proliferation and apoptosis are controlled.

ABIN-2, of the TPL-2 Signaling Complex, Modulates Mammalian Inflammation

Mammalian TPL-2 kinase (MAP3K8) mediates Toll-like receptor activation of ERK1/2 and p38α MAP kinases and is critical for regulating immune responses to pathogens. TPL-2 also has an important adaptor function, maintaining stability of associated ABIN-2 ubiquitin-binding protein. Consequently, phenotypes detected in Map3k8^-/- mice can be caused by lack of TPL-2, ABIN-2, or both proteins. Recent studies show that increased inflammation of Map3k8^-/- mice in allergic airway inflammation and colitis results from reduced ABIN-2 signaling, rather than blocked TPL-2 signaling. However, Map3k8^-/- mice have been employed extensively to evaluate the potential of TPL-2 as an anti-inflammatory drug target. We posit that Map3k8^D270A/D270A mice, expressing catalytically inactive TPL-2 and physiologic ABIN-2, should be used to evaluate the potential effects of TPL-2 inhibitors in disease.

Extracellular Signal-Regulated Kinase: A Regulator of Cell Growth, Inflammation, Chondrocyte and Bone Cell Receptor-Mediated Gene Expression

Extracellular signal-regulated kinase (ERK) is a member of the mitogen-activated protein kinase family of signaling molecules. ERK is predominantly found in two forms, ERK1 (p44) and ERK2 (p42), respectively. There are also several atypical forms of ERK, including ERK3, ERK4, ERK5 and ERK7. The ERK1/2 signaling pathway has been implicated in many and diverse cellular events, including proliferation, growth, differentiation, cell migration, cell survival, metabolism and transcription. ERK1/2 is activated (i.e., phosphorylated) in the cytosol and subsequently translocated to the nucleus, where it activates transcription factors including, but not limited to, ETS, c-Jun, and Fos. It is not surprising that the ERK1/2 signaling cascade has been implicated in many pathological conditions, namely, cancer, arthritis, chronic inflammation, and osteoporosis. This narrative review examines many of the cellular events in which the ERK1/2 signaling cascade plays a critical role. It is anticipated that agents designed to inhibit ERK1/2 activation or p-ERK1/2 activity will be developed for the treatment of those diseases characterized by dysregulated gene expression through ERK1/2 activation.

Mitogen-activated protein kinase kinase kinase 8 (MAP3K8) mediates the LH-induced stimulation of progesterone synthesis in the porcine corpus luteum

Progesterone (P4) synthesized by the corpus luteum (CL) plays a key role in the establishment and maintenance of pregnancy. The LH signal is important for luteinisation and P4 synthesis in pigs. In a previous study, we demonstrated that mitogen-activated protein kinase kinase kinase 8 (MAP3K8) regulates P4 synthesis in mouse CL, but whether the function and mechanism of MAP3K8 in the pig is similar to that in the mouse is not known. Thus, in the present study we investigated the effects of MAP3K8 on porcine CL. Abundant expression of MAP3K8 was detected in porcine CL, and, in pigs, MAP3K8 expression was higher in mature CLs (or those of the mid-luteal phase) than in regressing CLs (late luteal phase). Further functional studies in cultured porcine luteal cells showed that P4 synthesis and the expression of genes encoding the key enzymes in P4 synthesis are significantly reduced when MAP3K8 is inhibited with the MAP3K8 inhibitor Tpl2 kinase inhibitor (MAP3K8i, 10μM). After 12-24h treatment of luteal cells with 100ngmL-1 LH, MAP3K8 expression and P4 secretion were significantly upregulated. In addition, the 10μM MAP3K8 inhibitor blocked the stimulatory effect of LH on P4 synthesis and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in porcine luteal cells. The LH-induced increases in MAP3K8 phosphorylation and expression, ERK1/2 phosphorylation and P4 synthesis were all blocked when protein kinase A was inhibited by its inhibitor H89 (20 μM) in porcine luteal cells. In conclusion, MAP3K8 mediates the LH-induced stimulation of P4 synthesis through the PKA/mitogen-activated protein kinase signalling pathway in porcine CL.

TPL2 Is a Key Regulator of Intestinal Inflammation in Clostridium difficile Infection

Tumor progression locus 2 (TPL2), a serine/threonine protein kinase, is a major inflammatory mediator in immune cells. The predominant inflammatory actions of TPL2 depend on the activation of mitogen-activated protein kinases (MAPK) and the upregulated production of the cytokines tumor necrosis factor alpha (TNF-α) and interleukin 1β (IL-1β) in macrophages and dendritic cells in response to lipopolysaccharide (LPS). Significant increases in TNF-α, IL-6, IL-β, and IL-8 levels in patients with Clostridium difficile infection (CDI) have been reported. Both TNF-α and IL-6 have been postulated to play key roles in the systemic inflammatory response in CDI, and IL-8 is essential for the development of local intestinal inflammatory responses in CDI. The objective of this study was to elucidate the role of TPL2 in the pathogenesis of CDI. We found that TPL2 was significantly activated in human and mouse intestinal tissues upon C. difficile toxin exposure or CDI. We further demonstrated that TPL2 knockout (TPL2-KO) mice were significantly more resistant to CDI than wild-type mice, with significantly reduced production of TNF-α, IL-6, IL-1β, KC (a mouse homologue of IL-8), and myeloperoxidase (MPO) in the ceca and colons of TPL2-KO mice. Finally, we found that TPL2 inhibition by a specific inhibitor or TPL2 gene ablation significantly reduced TcdB-induced production of TNF-α, IL-6, IL-β, and KC by inhibiting the activation of p38, extracellular signal-regulated kinase (ERK), and c-Jun NH₂-terminal kinase (JNK). Taken together, our data suggest that TPL2 represents a potential therapeutic target for CDI treatment.