Regulation Of Innate Immunity Research Articles

IFIH1 loss of function predisposes to inflammatory and SARS-CoV-2-related infectious diseases.

The IFIH1 gene, encoding melanoma differentiation-associated protein 5 (MDA5), is an indispensable innate immune regulator involved in the early detection of viral infections. Previous studies described MDA5 dysregulation in weakened immunological responses, and increased susceptibility to microbial infections and autoimmune disorders. Monoallelic gain-of-function of the IFIH1 gene has been associated with multisystem disorders, namely Aicardi-Goutieres and Singleton-Merten syndromes, while biallelic loss causes immunodeficiency. In this study, nine patients suffering from recurrent infections, inflammatory diseases, severe COVID-19 or multisystem inflammatory syndrome in children (MIS-C) were identified with putative loss-of-function IFIH1 variants by whole-exome sequencing. All patients revealed signs of lymphopaenia and an increase in inflammatory markers, including CRP, amyloid A, ferritin and IL-6. One patient with a pathogenic homozygous variant c.2807+1G>A was the most severe case showing immunodeficiency and glomerulonephritis. The c.1641+1G>C variant was identified in the heterozygous state in patients suffering from periodic fever, COVID-19 or MIS-C, while the c.2016delA variant was identified in two patients with inflammatory bowel disease or MIS-C. There was a significant association between IFIH1 monoallelic loss of function and susceptibility to infections in males. Expression analysis showed that PBMCs of one patient with a c.2016delA variant had a significant decrease in ISG15, IFNA and IFNG transcript levels, compared to normal PBMCs, upon stimulation with Poly(I:C), suggesting that MDA5 receptor truncation disrupts the immune response. Our findings accentuate the implication of rare monogenic IFIH1 loss-of-function variants in altering the immune response, and severely predisposing patients to inflammatory and infectious diseases, including SARS-CoV-2-related disorders.

Neutrophil extracellular traps modulate chemotherapy efficacy and its adverse side effects.

Neutrophils, major regulator of innate immunity have recently emerged as key components of the tumor microenvironment. The role of neutrophils in cancer has been linked to their ability to form neutrophil extracellular traps (NETs), structures composed of decondensed DNA decorated with enzymes that are released into the extracellular space. Here, we discuss the pivotal roles of NETs, in influencing responses to chemotherapy and its severe adverse effect. Highlighting recent insights, we discuss the dual nature of NETs in the context of chemotherapy treatment, examining their potential to either counteract or enhance treatment outcomes. Strategic targeting of NETs emerges as a promising avenue for determining combination therapies that could help counteracting resistance or enhancing chemotherapy efficacy as well as limiting complications due to this type of treatment.

The role of γδT lymphocytes in atherosclerosis

Atherosclerosis poses a significant threat to human health, impacting overall well-being and imposing substantial financial burdens. Current treatment strategies mainly focus on managing low-density lipids (LDL) and optimizing liver functions. However, it’s crucial to recognize that Atherosclerosis involves more than just lipid accumulation; it entails a complex interplay of immune responses. Research highlights the pivotal role of lipid-laden macrophages in the formation of atherosclerotic plaques. These macrophages attract lymphocytes like CD4 and CD8 to the inflamed site, potentially intensifying the inflammatory response. γδ T lymphocytes, with their diverse functions in innate and adaptive immune responses, pathogen defense, antigen presentation, and inflammation regulation, have been implicated in the early stages of Atherosclerosis. However, our understanding of the roles of γδ T cells in Atherosclerosis remains limited. This mini-review aims to shed light on the characteristics and functions of γδ T cells in Atherosclerosis. By gaining insights into the roles of γδ T cells, we may uncover a promising strategy to mitigate plaque buildup and dampen the inflammatory response, thereby opening new avenues for effectively managing this condition.

An effector SsCVNH promotes the virulence of Sclerotinia sclerotiorum through targeting class III peroxidase AtPRX71.

Many plant pathogens secrete effector proteins into the host plant to suppress host immunity and facilitate pathogen colonization. The necrotrophic pathogen Sclerotinia sclerotiorum causes severe plant diseases and results in enormous economic losses, in which secreted proteins play a crucial role. SsCVNH was previously reported as a secreted protein, and its expression is significantly upregulated at 3 h after inoculation on the host plant. Here, we further demonstrated that deletion of SsCVNH leads to attenuated virulence. Heterologous expression of SsCVNH in Arabidopsis enhanced pathogen infection, inhibited the host PAMP-triggered immunity (PTI) response and increased plant susceptibility to S. sclerotiorum. SsCVNH interacted with class III peroxidase AtPRX71, a positive regulator of innate immunity against plant pathogens. SsCVNH could also interact with other class III peroxidases, thus reducing peroxidase activity and suppressing plant immunity. Our results reveal a new infection strategy employed by S. sclerotiorum in which the fungus suppresses the function of class III peroxidases, the major component of PTI to promote its own infection.

Rational design of monomeric IL37 variants guided by stability and dynamical analyses of IL37 dimers

IL37 plays important roles in the regulation of innate immunity and its oligomeric status is critical to these roles. In its monomeric state, IL37 can effectively inhibit the inflammatory response of IL18 by binding to IL18Rα, a capacity lost in its dimeric form, underlining the pivotal role of the oligomeric status of IL37 in its anti-inflammatory action. Until now, two IL37 dimer structures have been deposited in PDB, reflecting a substantial difference in their dimer interfaces. Given this discrepancy, we analyzed the PDB structures of the IL37 dimer (PDB IDs: 6ncu, 5hn1) along with a AF2-multimer prediction by molecular dynamics (MD) simulations. Results showed that the 5hn1 and AF2-predicted dimers have the same interface and stably maintained their conformations throughout simulations, while the recent IL37 dimer (PDB ID: 6ncu) with a different interface did not, proposing a possible issue with the recent IL37 dimer structure (6ncu). Next, focusing on the stable dimer structures, we have identified five critical positions of V71/Y85/I86/E89/S114, three new positions compared to the literature, that would reduce dimer stability without affecting the monomer structure. Two quintuple mutants were tested by MD simulations and showed partial or complete dissociation of the dimer. Overall, the insights gained from this study reinforce the validity of the 5hn1 and AF2 multimer structures, while also advancing our understanding of the IL37 dimer interface through the generation of monomer-locked IL37 variants.

Rare association between spinocerebellar ataxia and amyotrophic lateral sclerosis: a case series.

In this work, we describe a new case of association between SCA2 and MND. A 58-year-old man who was diagnosed with spinocerebellar ataxia type 2 presented dysphagia and a significant decline in his ability to walk, with a reduction in autonomy and the need to use a wheelchair. We performed electromyography and electroneurography of the four limbs and of the cranial district and motor-evoked potentials to study upper and lower motor neurons. Referring to the revised El Escorial criteria of 2015, ALS diagnosis was made. Considering different cases described in literature over the years, SCA2 could represent an important risk factor for developing ALS. In particular, the presence of alleles of ATXN2 with 27 and 28 CAG repeats seems to slightly decrease the risk of developing the disease, which would instead be progressively increased by the presence of alleles with 29, 30, 31, 32, and 33 repeats. The exact physiopathological mechanism by which the mutation increases the risk of developing the disease is currently unknown. Transcriptomic studies on mouse models have demonstrated the involvement of several pathways, including the innate immunity regulation by STING and the biosynthesis of fatty acid and cholesterol by SREBP. CAG repeat expansions in the ATXN2 gene have been associated with variable neurological presentations, which include SCA2, ALS, Parkinsonism, or a combination of them. Further research is needed to understand the relationship between SCA2 and ALS better and explore molecular underlying mechanisms.

Ovalbumin promotes innate immune response of Caenorhabditis elegans through DAF-16 and SKN-1 pathways in insulin/IGF-1 signaling.

Ovalbumin (OVA) is a major allergen in eggs and could induce severe allergic reactions in sensitive individuals, where the innate immune system works as a regulator. The mechanism of how innate immunity adjusts to food allergy is relatively well-studied, however, the effects of allergen uptake on the innate immune system remain unclear. Therefore, the Caenorhabditis elegans (C. elegans) model was utilized to assess the effects of OVA on its innate immune system. OVA enhanced the immune response of C. elegans with higher survival rates under Pseudomonas aeruginosa infection. Moreover, sustaining OVA treatment improved the health states that were reflected in the prolonged lifespan, alleviated oxidative stress, accelerated growth, and promoted motility. RNA-sequencing analysis and the slow-killing assays in the mutants of insulin/IGF-1 signaling (IIS)-related genes confirmed that IIS was necessary for OVA to regulate innate immunity. Besides, OVA activated SKN-1 temporarily and facilitated the nuclear localization of DAF-16 for improving immunity and health status in C. elegans. Together, OVA could enhance the innate immune responses via DAF-16 and SKN-1 pathways in the IIS of C. elegans, and this work will provide novel insights into the regulation of innate immunity by OVA in higher organisms.

Dual modifying of MAVS at lysine 7 by SIRT3-catalyzed deacetylation and SIRT5-catalyzed desuccinylation orchestrates antiviral innate immunity

To effectively protect the host from viral infection while avoiding excessive immunopathology, the innate immune response must be tightly controlled. However, the precise regulation of antiviral innate immunity and the underlying mechanisms remain unclear. Here, we find that sirtuin3 (SIRT3) interacts with mitochondrial antiviral signaling protein (MAVS) to catalyze MAVS deacetylation at lysine residue 7 (K7), which promotes MAVS aggregation, as well as TANK-binding kinase I and IRF3 phosphorylation, resulting in increased MAVS activation and enhanced type I interferon signaling. Consistent with these findings, loss of Sirt3 in mice and zebrafish renders them more susceptible to viral infection compared to their wild-type (WT) siblings. However, Sirt3 and Sirt5 double-deficient mice exhibit the same viral susceptibility as their WT littermates, suggesting that loss of Sirt5 in Sirt3-deficient mice may counteract the increased viral susceptibility displayed in Sirt3-deficient mice. Thus, we not only demonstrate that SIRT3 positively regulates antiviral immunity in vitro and in vivo, likely via MAVS, but also uncover a previously unrecognized mechanism by which SIRT3 acts as an accelerator and SIRT5 as a brake to orchestrate antiviral innate immunity.

M6A Methylation in Regulation of Antiviral Innate Immunity.

The epitranscriptomic modification m6A is a prevalent RNA modification that plays a crucial role in the regulation of various aspects of RNA metabolism. It has been found to be involved in a wide range of physiological processes and disease states. Of particular interest is the role of m6A machinery and modifications in viral infections, serving as an evolutionary marker for distinguishing between self and non-self entities. In this review article, we present a comprehensive overview of the epitranscriptomic modification m6A and its implications for the interplay between viruses and their host, focusing on immune responses and viral replication. We outline future research directions that highlight the role of m6A in viral nucleic acid recognition, initiation of antiviral immune responses, and modulation of antiviral signaling pathways. Additionally, we discuss the potential of m6A as a prognostic biomarker and a target for therapeutic interventions in viral infections.

Lipopolysaccharide Regulates the Macrophage RNA-Binding Proteome.

RNA-protein interactions within cellular signaling pathways have significant modulatory effects on RNA binding proteins' (RBPs') effector functions. During the innate immune response, specific RNA-protein interactions have been reported as a regulatory layer of post-transcriptional control. We investigated changes in the RNA-bound proteome of immortalized mouse macrophages (IMM) following treatment with lipopolysaccharide (LPS). Stable isotope labeling by amino acids in cell culture (SILAC) of cells followed by unbiased purification of RNP complexes at two time points after LPS stimulation and bottom-up proteomic analysis by LC-MS/MS resulted in a set of significantly affected RBPs. Global RNA sequencing and LFQ proteomics were used to characterize the correlation of transcript and protein abundance changes in response to LPS at different time points with changes in protein-RNA binding. Il1α, MARCKS, and ACOD1 were noted as RBP candidates involved in innate immune signaling. The binding sites of the RBP and RNA conjugates at amino acid resolution were investigated by digesting the cross-linked oligonucleotide from peptides remaining after elution using Nuclease P1. The combined data sets provide directions for further studies of innate immune signaling regulation by RBP interactions with different classes of RNA.

CSF1R inhibitor PLX3397 depletes microglia in Mongolian gerbil Meriones unguiculatus, but not in syrian hamster Mesocricetus auratus

Microglia are the residential immune cells in the central nervous system. Their roles as innate immune cells and regulators of synaptic remodeling are critical to the development and the maintenance of the brain. Numerous studies have depleted microglia to elucidate their involvement in healthy and pathological conditions. PLX3397, a blocker of colony stimulating factor 1 receptor (CSF1R), is widely used to deplete mouse microglia due to its non-invasiveness and convenience. Recently, other small rodents, including Syrian hamsters (Mesocricetus auratus) and Mongolian gerbils (Meriones unguiculatus), have been recognized as valuable animal models for studying brain functions and diseases. However, whether microglia depletion via PLX3397 is feasible in these species remains unclear. Here, we administered PLX3397 orally via food pellets to hamsters and gerbils. PLX3397 successfully depleted gerbil microglia but had no effect on microglial density in hamsters. Comparative analysis of the CSF1R amino acid sequence in different species hints that amino acid substitutions in the juxtamembrane domain may potentially contribute to the inefficacy of PLX3397 in hamsters.

Abstract 2691: Mapping the landscape of innate immune pattern recognition receptors in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) accounts for 90% of all pancreatic cancer cases, and is among the most aggressive and lethal malignancies worldwide. PDAC is driven by genetic alterations in the pancreatic epithelium (e.g. KRAS, TRP53) coupled with a dysregulated innate immune response, the latter leading to an inflammatory tumor microenvironment enriched in innate immune cells (e.g. macrophages). However, immune-based treatment regimens for PDAC patients have primarily focused on immunotherapy with adaptive immune checkpoint inhibitors (e.g. PD-1) which disappointingly have yielded minimal clinical benefit. Thus, there is an unmet clinical need to identity disease-associated innate immune regulators as therapeutic targets in PDAC. Innate immune responses depend on a series of cell surface, endosomal and cytosolic pattern recognition receptors (PRRs) that are expressed in immune and non-immune cells. PRRs are classified into several structurally and functionally conserved subfamilies, including Toll-like receptors (TLRs), Absent in melanoma 2 (AIM2)-like receptors (ALRs), and Nod-like receptors (NLRs). A subset of NLRs and AIM2 are also well documented for their formation of multiprotein complexes called ‘inflammasomes’ - comprising the adaptor ASC and Caspase-1 - which direct the maturation and release of bioactive pro-inflammatory cytokines, IL-18 and IL-1β. However, the role of these critical innate immune regulators in PDAC has been underexplored, and is virtually unknown. By coupling endoscopic ultrasound-guided fine needle aspiration (EUS FNA) to capture tumor biopsies from all stages of PDAC, with whole transcriptome profiling of PDAC patient primary tumors, we reveal specific enrichment of the innate immune TLR2 and ASC inflammasome molecular pathways. Augmented TLR2 and ASC expression was prognostic for low survival, and a “TLR2 activation” signature was also predictive for chemoresistance. Antibody-mediated anti-TLR2 therapy suppressed tumor growth in human PDAC tumor xenografts (patient and cell line) in both immunocompromised and ‘humanized’ mice. With respect to ASC, using the genetically engineered KPC PDAC mouse model, we show that Caspase-1 activation, a read-out for inflammasome activation, is upregulated in pancreatic tumors. Moreover, genetic ablation of ASC in KPC mice markedly suppressed the development of pancreatic tumors, which was associated with significant reductions in levels of both Caspase-1 activation and inflammation. Transcriptome profiling further identified unique downstream molecular networks associated with a range of oncogenic cellular processes. Taken together, our results support innate immune TLR2- and ASC inflammasome-based therapeutic targeting in PDAC, with further clinical utility that ASC inflammasome and TLR2 activation is prognostic, with TLR2 also predictive for chemoresponsiveness. Citation Format: Bassam Kashgari, Louise McLeod, Linden J. Gearing, Daniel Croagh, Brendan J. Jenkins. Mapping the landscape of innate immune pattern recognition receptors in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2691.

Abstract 4711: Evaluation of effect of autophagy inhibition by SAR405, a selective Vps34 inhibitor, on proliferation of pleural mesothelioma cells

Abstract Pleural mesothelioma is a poor prognostic malignancy because the efficacy of therapies remains limited; thus, there is an urgent need to elucidate the pathophysiology leading to newer treatment modalities. Macroautophagy (hereafter referred to as autophagy) is an intracellular degradation system in which cytoplasmic components are degraded by the lysosome. Autophagy plays pivotal roles in various physiological processes, including adaptation to starvation, preimplantation embryonic development, elimination of intracellular pathogens, and regulation of innate and adaptive immunity. In cancer cells, autophagy may have the potential to function protectively for the cells and, alternatively, to work suppressively. It can promote tumor growth in established cancers through autophagy-mediated intracellular recycling, providing substrates for metabolism and maintain that the functional pool of mitochondria. On the other hand, it may lead to a cytotoxic effect called autophagy-dependent cell death. Several reports have demonstrated that autophagy has cytoprotective effects on pleural mesothelioma cell lines. In this study, we assessed effects of inhibition of autophagy using SAR405, which specifically inhibits Vps34 in an early step of autophagy, on pleural mesothelioma cells. Additionally, we investigated whether SAR405 could enhance the growth suppression induced by cisplatin in these cells. Mesothelioma cell lines, including NCI-H28 (H28), NCI-H2452 (H2452), and MSTO-211H (211H), were cultured with 0.1-50 μM SAR405 or 1.0-5.0 μM cisplatin for cell viability analysis using water-soluble tetrazolium salt-8, and cell cycle analysis. For the assessment of autophagy, a plasmid, pMRX-IP-GFP-LC3-RFP-LC3ΔG, was stably transfected into mesothelioma cells. Transfected cells generate GFP-LC3-RFP-LC3ΔG, and it is cleaved into GFP-LC3 and RFP-LC3ΔG by inherent ATG4. GFP-LC3 levels are decreased by autophagy activation, while RFP-LC3ΔG serves as an internal control. SAR405 dose-dependently suppressed cell viability, accompanied by a significantly increase in the proportions of cells in the G2/M phase. The IC50 of SAR405 at 72 hours was 11.5 μM for H28, 16.7 μM for H2452, and 14.9 μM for 211H. SAR405 inhibited autophagy 24 hours after treatment at 2.5 μM for H28 and 211H, and at 5.0 μM for H2452. Furthermore, cisplatin induced autophagy at 5.0 μM for H28, 0.5 μM for H2452, 1.0 μM for 211H. The combination of 2.5-10 µM SAR405 and 0.5-5.0 µM cisplatin exhibited additive or synergistic effects on cell growth inhibition in all plural mesothelioma cell lines. In conclusion, Vps34 inhibition by SAR405 suppressed cell growth in pleural mesothelioma cells, accompanied by autophagy inhibition. The combination of SAR405 and cisplatin resulted in a synergistic inhibition of cell proliferation. Citation Format: Yoshiki Kuwabara, Kosuke Sakai, Shigeru Ishi, Shin Yokosuka, Masatoshi Abe, Tomoyuki Takahashi, Yuichiro Kawano, Hiroaki Nishimura, Maiko Toda-Sasaki, Yumiko Kobayashi-Ogawa, Satoshi Kikuchi, Yusuke Hirata, Hiroyuki Kyoyama, Gaku Moriyama, Nobuyuki Koyama, Kazutsugu Uematsu. Evaluation of effect of autophagy inhibition by SAR405, a selective Vps34 inhibitor, on proliferation of pleural mesothelioma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4711.

Abstract 4189: BALB/c-hIL12RB1/hIL12RB2: A robust model for preclinical research in human IL-12 therapy

Abstract Interleukin-12 (IL-12) is a multifaceted cytokine primarily produced by antigen-activated dendritic cells, macrophages, and neutrophils. Its receptor is a composite of IL12RB1 and IL12RB2, and the union of these two subunits forms a high-affinity receptor complex proficient in mediating IL-12 signaling. As a pivotal regulator of innate and adaptive immunity, IL-12 plays a crucial role in steering the differentiation of naïve T cells into Th1 cells. It is renowned as a T cell stimulatory factor, fostering T cell proliferation. Furthermore, IL-12 has the capacity to augment the activation of cytotoxic lymphocytes and natural killer cells (NK), thereby enhancing interferon (IFN-γ) production. Empirical evidence consistently demonstrates that IL-12 synergistically exerts anti-tumor effects in conjunction with various immune cells, such as T cells and NK cells. Its effectiveness in preclinical studies has solidified IL-12 as an appealing drug target, leading to the development of activating antibodies, therapeutic IL-12 proteins, and tumor vaccines as potential treatments. To delve deeper into the functionality and therapeutic potential of IL-12, we have engineered a humanized mouse model, known as BALB/c-hIL12RB1/hIL12RB2. Notably, this model fully preserves the intracellular domains of mouse IL12RB1 and IL12RB2 proteins, ensuring the normal propagation of intracellular signaling. It also effectively expresses human IL12RB1 and IL12RB2. In vitro functional validation experiments have verified that BALB/c-hIL12RB1/hIL12RB2 mice can proficiently generate IFN-γ when induced by human IL-12. Furthermore, in vivo efficacy experiments have yielded compelling results. Intratumoral administration of human IL-12 mRNA in BALB/c-hIL12RB1/hIL12RB2 mice led to a significant suppression in the growth of CT26 tumors, culminating in complete tumor regression. Subsequent rechallenge experiments conducted after the discontinuation of treatment revealed no tumor recurrence, signifying the enduring inhibitory effect of hIL12 mRNA on mouse tumors. In conclusion, the development of BALB/c-hIL12RB1/hIL12RB2 mice stands as a robust model for advancing preclinical research in the realm of human IL-12 therapy. Citation Format: Yuan Fang, Huiyi Wang, Jun Xing, Lu Yang, Jing Zhao, Xiang Gao, Cunxiang Ju. BALB/c-hIL12RB1/hIL12RB2: A robust model for preclinical research in human IL-12 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4189.

Prognostic value of inflammation and immune-related gene NOD2 in clear cell renal cell carcinoma.

Inflammation and immune responses play important roles in cancer development and prognosis. We identified 59 upregulated inflammation- and immune-related genes (IIRGs) in clear cell renal cell carcinoma (ccRCC) from The Cancer Genome Atlas database. Among the upregulated IIRGs, nucleotide binding oligomerization domain 2 (NOD2), PYD and CARD domain (PYCARD) were also confirmed to be upregulated in the Oncomine database and in three independent GEO data sets. Tumor immune infiltration resource database analysis revealed that NOD2 and PYCARD levels were significantly positively correlated with infiltration levels of B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages and dendritic cells. Multivariate Cox hazards regression analysis indicated that based on clinical variables (age, gender, tumor grade, pathological TNM stage), NOD2, but not PYCARD, was an independent, unfavorable ccRCC prognostic biomarker. Functional enrichment analyses (GSEA) showed that NOD2 was involved in innate immune responses, inflammatory responses, and regulation of cytokine secretion. Meanwhile, mRNA and protein levels of NOD2 were elevated in four ccRCC cell lines (786-O, ACHN, A498 and Caki-1), and its knockdown significantly inhibited IL-8 secretion, thereby inhibiting ccRCC cell proliferation and invasion. Furthermore, results showed that miR-20b-5p targeted NOD2 to alleviate NOD2-mediated IL-8 secretion. In conclusion, NOD2 is a potential prognostic biomarker for ccRCC and the miR-20b-5p/NOD2/IL-8 axis may regulate inflammation- and immune-mediated tumorigenesis in ccRCC.

Circadian disruption dysregulates lung gene expression associated with inflammatory lung injury.

Circadian systems drive the expression of multiple genes in nearly all cells and coordinate cellular-, tissue-, and system-level processes that are critical to innate immunity regulation. We examined the effects of circadian rhythm disorganization, produced by light shift exposure, on innate immunity-mediated inflammatory lung responses including vascular permeability and gene expression in a C57BL/6J murine model of inflammatory lung injury. A total of 32 C57BL/6J mice were assigned to circadian phase shifting (CPS) with intratracheal phosphate-buffered saline (PBS), CPS with intratracheal lipopolysaccharide (LPS), control (normal lighting) condition with intratracheal PBS, and control condition with intratracheal LPS. Bronchoalveolar lavage (BAL) protein, cell counts, tissue immunostaining, and differentially expressed genes (DEGs) were measured in lung tissues at 2 and 10 weeks. In mice exposed to both CPS and intratracheal LPS, both BAL protein and cell counts were increased at both 2 and 10 weeks compared to mice exposed to LPS alone. Multiple DEGs were identified in CPS-LPS-exposed lung tissues compared to LPS alone and were involved in transcriptional pathways associated with circadian rhythm disruption, regulation of lung permeability, inflammation with Rap1 signaling, and regulation of actin cytoskeleton. The most dysregulated pathways included myosin light chain kinase, MAP kinase, profilin 2, fibroblast growth factor receptor, integrin b4, and p21-activated kinase. Circadian rhythm disruption results in exacerbated immune response and dysregulated expression of cytoskeletal genes involved in the regulation of epithelial and vascular barrier integrity-the mechanistic underpinnings of acute lung injury. Further studies need to explore circadian disorganization as a druggable target.

Brucella infection and Toll-like receptors.

Brucella consists of gram-negative bacteria that have the ability to invade and replicate in professional and non-professional phagocytes, and its prolonged persistence in the host leads to brucellosis, a serious zoonosis. Toll-like receptors (TLRs) are the best-known sensors of microorganisms implicated in the regulation of innate and adaptive immunity. In particular, TLRs are transmembrane proteins with a typical structure of an extracellular leucine-rich repeat (LRR) region and an intracellular Toll/interleukin-1 receptor (TIR) domain. In this review, we discuss Brucella infection and the aspects of host immune responses induced by pathogens. Furthermore, we summarize the roles of TLRs in Brucella infection, with substantial emphasis on the molecular insights into its mechanisms of action.

RHBDL4-triggered downregulation of COPII adaptor protein TMED7 suppresses TLR4-mediated inflammatory signaling

The toll-like receptor 4 (TLR4) is a central regulator of innate immunity that primarily recognizes bacterial lipopolysaccharide cell wall constituents to trigger cytokine secretion. We identify the intramembrane protease RHBDL4 as a negative regulator of TLR4 signaling. We show that RHBDL4 triggers degradation of TLR4’s trafficking factor TMED7. This counteracts TLR4 transport to the cell surface. Notably, TLR4 activation mediates transcriptional upregulation of RHBDL4 thereby inducing a negative feedback loop to reduce TLR4 trafficking to the plasma membrane. This secretory cargo tuning mechanism prevents the over-activation of TLR4-dependent signaling in an in vitro Mycobacterium tuberculosis macrophage infection model and consequently alleviates septic shock in a mouse model. A hypomorphic RHBDL4 mutation linked to Kawasaki syndrome, an ill-defined inflammatory disorder in children, further supports the pathophysiological relevance of our findings. In this work, we identify an RHBDL4-mediated axis that acts as a rheostat to prevent over-activation of the TLR4 pathway.

IDI1 inhibits the cGAS-Sting signaling pathway in hepatocellular carcinoma

Metabolic reprogramming is one of the prominent features that distinguishes tumor cells from normal cells. The role of metabolic abnormalities in regulating innate immunity is poorly understood. In this study, we found that IDI1 is significantly upregulated in liver cancer. IDI1 has no significant effect on the growth or invasion of liver cancer cells but significantly promotes liver cancer development in mice. Through molecular mechanism studies, we found that IDI1 interacts with the important regulator of innate immunity cGAS and recruits the E3 ligase TRIM41 to promote cGAS ubiquitination and degradation, inhibiting the cGAS-Sting signaling pathway. IDI1 inhibits the phosphorylation of TBK1 and the downstream factor IRF3 as well as the expression of CCL5 and CXCL10. In summary, this study revealed the important role of the metabolic enzyme IDI1 in the regulation of innate immunity, suggesting that it may be a potential target for liver cancer treatment.

Abstract 1728 Alternative Splicing of the Innate Immune Regulator IRF7 Across Cell Types and in Response to Immune stimuli

Abstract 1728 Alternative Splicing of the Innate Immune Regulator IRF7 Across Cell Types and in Response to Immune stimuli