Induction Of Innate Immune Responses Research Articles

HIV-1 capsid stability and reverse transcription are finely balanced to minimize sensing of reverse transcription products via the cGAS-STING pathway.

In HIV-1 particles, the dimeric RNA genome and associated viral proteins and enzymes are encased in a proteinaceous lattice composed of the viral capsid protein. Herein, we assessed how altering the stability of this capsid lattice through orthogonal genetic and chemical approaches impacts the induction of innate immune responses. Specifically, we found that decreasing capsid lattice stability results in more potent sensing of viral reverse transcription products, but not the genomic RNA, in a cGAS-STING-dependent manner. The recently developed capsid inhibitors lenacapavir and GS-CA1 enhanced the innate immune sensing of HIV-1. Unexpectedly, due to increased levels of reverse transcription and cytosolic accumulation of the resulting viral cDNA, capsid mutants with hyperstable cores also resulted in the potent induction of type I interferon-mediated innate immunity. Our findings suggest that HIV-1 capsid lattice stability and reverse transcription are finely balanced to minimize exposure of reverse transcription products in the cytosol of host cells.

Alphavirus-based replicons demonstrate different interactions with host cells and can be optimized to increase protein expression.

Alphavirus replicons are being developed as self-amplifying RNAs aimed at improving the efficacy of mRNA vaccines. These replicons are convenient for genetic manipulations and can express heterologous genetic information more efficiently and for a longer time than standard mRNAs. However, replicons mimic many aspects of viral replication in terms of induction of innate immune response, modification of cellular transcription and translation, and expression of nonstructural viral genes. Moreover, all replicons used in this study demonstrated expression of heterologous genes in cell- and replicon's origin-specific modes. Thus, many aspects of the interactions between replicons and the host remain insufficiently investigated, and further studies are needed to understand the biology of the replicons and their applicability for designing a new generation of mRNA vaccines. On the other hand, our data show that replicons are very flexible expression systems, and additional modifications may have strong positive impacts on protein expression.

Molecular cloning and functional characterization of duck MRE11

The human meiotic recombination 11 (MRE11) protein has been recognized as a cytosolic double-stranded DNA sensor that plays a critical role in the induction of type I interferon (IFN). However, the properties and functions of avian MRE11 in the innate immune response are not well understood. In this study, we cloned and characterized the full-length sequence of duck MRE11 (duMRE11) from duck embryo fibroblasts (DEFs) for the first time. The duMRE11 gene encoded a protein of 703 amino acid residues and showed the highest sequence similarity to goose MRE11. Quantitative real-time PCR analysis showed that duMRE11 was ubiquitously expressed in all tissues examined, with particularly high expression levels in the bursa of Fabricius, thymus and spleen. Overexpression of duMRE11 in DEFs led to the activation of IRF1 and NF-κB and the production of IFN-β. Furthermore, knockdown of duMRE11 significantly reduced the activity of the IFN-β promoter in poly(dA:dT)-stimulated or duck enteritis virus (DEV)-infected DEFs. Antiviral analysis showed that duMRE11 effectively suppressed the replication of DEV at different time points after infection. These results indicate that duMRE11 plays an important role in the induction of innate immune responses in ducks.

HIV protease inhibitor saquinavir inhibits toll-like receptor 4 activation by targeting receptor dimerization

ObjectiveToll-like receptor 4 (TLR4) is crucial in induction of innate immune response through recognition of invading pathogens or endogenous alarming molecules. Ligand-triggered dimerization of TLR4 is essential for the activation of NF-κB and IRF3 through MyD88- or TRIF-dependent pathways. Saquinavir (SQV), an FDA-approved HIV protease inhibitor, has been shown to attenuate the activation of NF-κB induced by HMGB1 by blocking TLR4-MyD88 association in proteasome independent pathway. This study aims to define whether SQV is an HMGB1-specific and MyD88-dependent TLR4 signaling inhibitor and which precise signaling element of TLR4 is targeted by SQV.Materials and methodsPMA differentiated human THP-1 macrophages or reconstituted HEK293 cells were pretreated with SQV before stimulated by different TLR agonists. TNF-α level was evaluated through ELISA assay. NF-κB activation was analyzed using NF-κB SEAP reporting system. The levels of MyD88/TRIF pathways-related factors were examined by immunoblot. TLR4 endocytosis was assessed by immunocytochemistry. TLR4 dimerization was determined using immunoprecipitation between different tagged TLR4 and an in silico molecular docking experiment was performed to explore the possible binding site of SQV on its target.ResultsOur data showed that SQV suppresses both MyD88- and TRIF-dependent pathways in response to lipopolysaccharide (LPS), a critical sepsis inducer and TLR4 agonist, leading to downregulation of NF-κB and IRF3. SQV did not suppress MyD88-dependent pathway triggered by TLR1/2 agonist Pam3csk4. In the only TRIF-dependent pathway, SQV did not alleviate IRF3 phosphorylation induced by TLR3 agonist Poly(I:C). Furthermore, dimerization of TLR4 following LPS or HMGB1 stimulation was decreased by SQV.ConclusionWe concluded that TLR4 receptor complex is one of the mammalian targets of SQV, and TLR4-mediated immune responses and consequent risk for uncontrolled inflammation could be modulated by FDA-approved drug SQV.

Crosstalk of Inflammation and Coagulation in Bothrops Snakebite Envenoming: Endogenous Signaling Pathways and Pathophysiology.

Snakebite envenoming represents a major health problem in tropical and subtropical countries. Considering the elevated number of accidents and high morbidity and mortality rates, the World Health Organization reclassified this disease to category A of neglected diseases. In Latin America, Bothrops genus snakes are mainly responsible for snakebites in humans, whose pathophysiology is characterized by local and systemic inflammatory and degradative processes, triggering prothrombotic and hemorrhagic events, which lead to various complications, organ damage, tissue loss, amputations, and death. The activation of the multicellular blood system, hemostatic alterations, and activation of the inflammatory response are all well-documented in Bothrops envenomings. However, the interface between inflammation and coagulation is still a neglected issue in the toxinology field. Thromboinflammatory pathways can play a significant role in some of the major complications of snakebite envenoming, such as stroke, venous thromboembolism, and acute kidney injury. In addition to exacerbating inflammation and cell interactions that trigger vaso-occlusion, ischemia-reperfusion processes, and, eventually, organic damage and necrosis. In this review, we discuss the role of inflammatory pathways in modulating coagulation and inducing platelet and leukocyte activation, as well as the inflammatory production mediators and induction of innate immune responses, among other mechanisms that are altered by Bothrops venoms.

High mobility group box 1 and a network of other biomolecules influence fatigue in patients with Crohn’s disease

BackgroundFatigue is common in patients with chronic inflammatory and autoimmune diseases, often with a severe impact on the patient’s daily life. From a biological point of view, fatigue can be regarded as an element of the sickness behavior response, a coordinated set of responses induced by pathogens to enhance survival during an infection and immunological danger. The mechanisms are not fully understood but involve activation of the innate immune system, with pro-inflammatory cytokines, in particular interleukin (IL)-1β, acting on cerebral neurons. These mechanisms are also active during chronic inflammatory conditions. High mobility group box 1 (HMGB1) protein has interleukin-1 like properties and is a strong inducer of innate immune responses. Its role in generation of fatigue is not clarified. Emerging evidence indicates that also other biomolecules may influence sickness behavior. We aimed to elucidate how HMGB1 influences fatigue in patients with Crohn’s disease, and how the protein interacts with other candidate biomarkers of fatigue.MethodsIn 56 patients with newly diagnosed Crohn’s disease, fatigue was evaluated using three different fatigue instruments: the fatigue visual analog scale (fVAS), Fatigue Severity Scale (FSS), and the vitality subscale of Medical Outcomes Study Short-Form Health Survey (SF-36vs). The biochemical markers IL-1 receptor antagonist (RA), soluble IL-1 receptor type 2 (sIL-RII), heat shock protein 90 alpha (HSP90α), HMGB1, anti-fully reduced (fr)HMGB1 antibodies (abs), hemopexin (HPX), and pigment epithelium-derived factor (PEDF) were measured in plasma. Multivariable regression and principal component analyses (PCA) were applied.ResultsMultivariable regression analyses revealed significant contributions to fatigue severity for HMGB1 in the FSS model, HSP90α in the fVAS model and IL-1RA in the SF-36vs model. Depression and pain scores contributed to all three models. In PCA, two components described 53.3% of the variation. The “inflammation and cellular stress dimension” was dominated by IL-1RA, sIL-1RII, HSP90α, HPX, and PEDF scores, where the “HMGB1 dimension” was dominated by HMGB1, anti-frHMGB1 abs, and fVAS scores.ConclusionThis study supports the hypothesis that HMGB1 and a network of other biomolecules influence fatigue severity in chronic inflammatory conditions. The well-known association with depression and pain is also acknowledged.

TLR3 recognition of viral double-stranded RNA in human dental pulp cells is important for the innate immunity

Dental caries or trauma can expose human dental pulp cells (DPCs) to various oral microorganisms, which play an important role in the development of an innate immune response. In the present study, we examined the expression of Toll-like receptors (TLRs) for sensing microbe-associated molecular patterns in human DPCs. Interestingly, real-time PCR analysis demonstrated that TLR3 is the most highly expressed among 10 different TLRs in human DPCs. Poly(I:C), a representative TLR3 ligand mimicking viral double-stranded RNA, potently induced IL-8 expression in a time- and dose-dependent manner. Concordantly, poly(I:C) treatment substantially increased the expression of pro-inflammatory cytokines and chemokines such as IL-6, CCL2, and CXCL10. Human DPCs transfected with TLR3 siRNA exhibited decreased IL-8 production compared with non-targeting siRNA-transfected cells, suggesting that the expression of poly(I:C)-induced inflammatory cytokines is dependent on TLR3. IL-8 secretion induced by poly(I:C) was down-regulated by MAP kinase inhibitors, indicating that the MAP kinase pathway contributes to IL-8 production. Furthermore, C/EBPβ and NF-κB were essential transcriptional factors for poly(I:C)-induced IL-8 expression, as demonstrated by the transient transfection and reporter gene assay. Since lipoproteins are known as major immunostimulatory components of bacteria, human DPCs were treated with poly(I:C) together with Pam2CSK4, a synthetic lipopeptide mimicking bacterial lipoproteins. Pam2CSK4 and poly(I:C) co-treatment synergistically increased IL-8 production in comparison to Pam2CSK4 or poly(I:C) alone, implying that co-infection of viruses and bacteria can synergistically induce inflammatory responses in the dental pulp. Taken together, these results suggest that human DPCs potentially sense and respond to viral double-stranded RNAs, leading to effective induction of innate immune responses.

Evaluation of Immune Nanoparticles for Rapid and Non-Specific Activation of Antiviral and Antibacterial Immune Responses in Cattle, Swine, and Poultry.

Given the rapid potential spread of agricultural pathogens, and the lack of vaccines for many, there is an important unmet need for strategies to induce rapid and non-specific immunity against these viral and bacterial threats. One approach to the problem is to generate non-specific immune responses at mucosal surfaces to rapidly protect from entry and replication of both viral and bacterial pathogens. Using complexes of charged nanoparticle liposomes with both antiviral and antibacterial toll-like receptor (TLR) nucleic acid ligands (termed liposome-TLR complexes or LTC), we have previously demonstrated considerable induction of innate immune responses in nasal and oropharyngeal tissues and protection from viral and bacterial pathogens in mixed challenge studies in rodents, cattle, and companion animals. Therefore, in the present study, we used in vitro assays to evaluate the ability of the LTC immune stimulant to activate key innate immune pathways, particularly interferon pathways, in cattle, swine, and poultry. We found that LTC complexes induced strong production of type I interferons (IFNα and IFNβ) in both macrophages and leukocyte cultures from all three species. In addition, the LTC complexes induced the production of additional key protective cytokines (IL-6, IFNγ, and TNFα) in macrophages and leukocytes in cattle and poultry. These findings indicate that the LTC mucosal immunotherapeutic has the capability to activate key innate immune defenses in three major agricultural species and potentially induce broad protective immunity against both viral and bacterial pathogens. Additional animal challenge studies are warranted to evaluate the protective potential of LTC immunotherapy in cattle, swine, and poultry.

Interferon alpha inducible protein 6 is a negative regulator of innate immune responses by modulating RIG-I activation.

Interferons (IFNs), IFN-stimulated genes (ISGs), and inflammatory cytokines mediate innate immune responses, and are essential to establish an antiviral response. Within the innate immune responses, retinoic acid-inducible gene I (RIG-I) is a key sensor of virus infections, mediating the transcriptional induction of IFNs and inflammatory proteins. Nevertheless, since excessive responses could be detrimental to the host, these responses need to be tightly regulated. In this work, we describe, for the first time, how knocking-down or knocking-out the expression of IFN alpha-inducible protein 6 (IFI6) increases IFN, ISG, and pro-inflammatory cytokine expression after the infections with Influenza A Virus (IAV), Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and Sendai Virus (SeV), or poly(I:C) transfection. We also show how overexpression of IFI6 produces the opposite effect, in vitro and in vivo, indicating that IFI6 negatively modulates the induction of innate immune responses. Knocking-out or knocking-down the expression of IFI6 diminishes the production of infectious IAV and SARS-CoV-2, most likely because of its effect on antiviral responses. Importantly, we report a novel interaction of IFI6 with RIG-I, most likely mediated through binding to RNA, that affects RIG-I activation, providing a molecular mechanism for the effect of IFI6 on negatively regulating innate immunity. Remarkably, these new functions of IFI6 could be targeted to treat diseases associated with an exacerbated induction of innate immune responses and to combat viral infections, such as IAV and SARS-CoV-2.

Role of NLRP3 inflammasome in diabetic neuropathy and prevention and treatment with traditional Chinese medicine

As one of the most frequent complications of diabetes, diabetic neuropathy often involves peripheral and central nervous systems. Neuroinflammation is the key pathogenic factor of secondary nerve injury in diabetes. NOD-like receptor pyrin domain-containing 3(NLRP3) inflammasome is a group of subcellular multiprotein complexes, including NLRP3, apoptosis associated speck-like protein(ASC), and pro-cysteinyl aspartate specific proteinase 1(pro-caspase-1). NLRP3 inflammasome is an inducer of innate immune responses. Its activation stimulates the inflammatory cascade reaction, promotes the release of inflammatory mediators, triggers cell death and uncontrolled autophagy, activates glial cells, facilitates peripheral immune cell infiltration, and initiates amyoid β(Aβ)-tau cascade reactions. As a result, it contributes to the central nerve, somatic nerve, autonomic nerve, and retinal nerve cell damage secondary to diabetes. Therefore, due to its key role in the neuroinflammation responses of the body, NLRP3 inflammasome may provide new targets for the treatment of diabetic neuropathy. With multi-target and low-toxicity advantages, traditional Chinese medicine plays a vital role in the treatment of diabetic neuropathy. Accumulating evidence has shown that traditional Chinese medicine exerts curative effects on diabetic neuropathy possibly through regulating NLRP3 inflammasome. Although the role of NLRP3 inflammasome in diabetes and related complications has been investigated in the literature, systematical studies on drugs and mechanism analysis for secondary neuropathy are still lacking. In this article, the role of NLRP3 inflammasome in diabetic neuropathy was explored, and the research progress on traditional Chinese medicine in the treatment of diabetic neuropathy through NLRP3 inflammasome was reviewed.

Armored modified vaccinia Ankara in cancer immunotherapy.

Cancer immunotherapy relies on unleashing the patient´s immune system against tumor cells. Cancer vaccines aim to stimulate both the innate and adaptive arms of immunity to achieve durable clinical responses. Some roadblocks for a successful cancer vaccine in the clinic include the tumor antigen of choice, the adjuvants employed to strengthen antitumor-specific immune responses, and the risks associated with enhancing immune-related adverse effects in patients. Modified vaccinia Ankara (MVA) belongs to the family of poxviruses and is a versatile vaccine platform that combines several attributes crucial for cancer therapy. First, MVA is an excellent inducer of innate immune responses leading to type I interferon secretion and induction of T helper cell type 1 (Th1) immune responses. Second, it elicits robust and durable humoral and cellular immunity against vector-encoded heterologous antigens. Third, MVA has enormous genomic flexibility, which allows for the expression of multiple antigenic and costimulatory entities. And fourth, its replication deficit in human cells ensures a excellent safety profile. In this review, we summarize the current understanding of how MVA induces innate and adaptive immune responses. Furthermore, we will give an overview of the tumor-associated antigens and immunomodulatory molecules that have been used to armor MVA and describe their clinical use. Finally, the route of MVA immunization and its impact on therapeutic efficacy depending on the immunomodulatory molecules expressed will be discussed.

Analogous comparison unravels heightened antiviral defense and boosted viral infection upon immunosuppression in bat organoids

Horseshoe bats host numerous SARS-related coronaviruses without overt disease signs. Bat intestinal organoids, a unique model of bat intestinal epithelium, allow direct comparison with human intestinal organoids. We sought to unravel the cellular mechanism(s) underlying bat tolerance of coronaviruses by comparing the innate immunity in bat and human organoids. We optimized the culture medium, which enabled a consecutive passage of bat intestinal organoids for over one year. Basal expression levels of IFNs and IFN-stimulated genes were higher in bat organoids than in their human counterparts. Notably, bat organoids mounted a more rapid, robust and prolonged antiviral defense than human organoids upon Poly(I:C) stimulation. TLR3 and RLR might be the conserved pathways mediating antiviral response in bat and human intestinal organoids. The susceptibility of bat organoids to a bat coronavirus CoV-HKU4, but resistance to EV-71, an enterovirus of exclusive human origin, indicated that bat organoids adequately recapitulated the authentic susceptibility of bats to certain viruses. Importantly, TLR3/RLR inhibition in bat organoids significantly boosted viral growth in the early phase after SARS-CoV-2 or CoV-HKU4 infection. Collectively, the higher basal expression of antiviral genes, especially more rapid and robust induction of innate immune response, empowered bat cells to curtail virus propagation in the early phase of infection.

Porcine Endogenous Retrovirus Induces CXCL10 in Human Monocytes and Monocyte-Derived Primary Cells

Introduction: Pigs are suitable donor species for xenotransplantation and biological materials from these animals are used for this purpose for many years. A major risk of xenotransplantation is a zoonosis by transspecies transmission of animal viruses. In this regard, porcine endogenous retroviruses (PERVs) are of paramount importance because some of them are able to infect human cells and could induce innate immune responses. Methods: Using a replication-competent polytropic PERV-A/C strain, we have analysed the induction of innate immune responses by this virus in human monocytes, monocyte-derived macrophages, and monocyte-derived dendritic cells. Results: PERV-A/C elevates the expression of the C-X-C motif chemokine 10 (CXCL10) up to 1,000-fold in human monocytes and monocyte-derived primary cells. In comparison to CXCL10, the levels of interferon-β (IFN-β) and interferon-stimulated gene 54 (ISG54) were almost unchanged. Heat-inactivated virus did not induce CXCL10 expression. Neither treatment with the reverse transcriptase inhibitors azidothymidine (AZT) and stavudine (d4T) nor treatment with the integrase inhibitor raltegravir (RAL) reduced the activation levels. Furthermore, depletion of SAM domain and HD domain-containing protein 1 (SAMHD1), a restriction factor that blocks PERV-A/C infection at the level of reverse transcription in these myeloid cells, had no significant effect on the CXCL10 induction level. These results imply that innate immune sensing leading to the strong CXCL10 response occurs at an early step of the replication process and does not require products of reverse transcription. Inhibition of Janus kinases (JAKs) by AT9283 prevented the observed CXCL10 induction by the virus, providing evidence that the JAK-STAT signalling pathway is involved in the CXCL10 response in theses myeloid cells. Conclusion: Our findings highlight PERVs as inducers of the pro-inflammatory chemokine CXCL10 and other innate immune responses in human monocytes and derived cells with potential implications in the context of xenotransplantation.

Abstract C024: CD206 small molecule activation recruits TLR1/2 to enhance cancer cell phagocytosis in reprogrammed tumor-associated macrophages and improves tumor control

Abstract Introduction: Targeting innate immune checkpoints on tumor-associated macrophages (TAMs) like CD40 activation or CD47 blockade is currently tested as a promising new therapeutic strategy in pancreas cancer. The mannose receptor CD206 is expressed on M2-like TAM populations and activation of CD206 can recalibrate these immune suppressive cells towards an anti-tumor M1-like phenotype to elicit effective innate immune responses and tumor control. The lack of a detailed understanding of the molecular mechanisms of CD206-mediated macrophage reprogramming, however, is an impediment for the design of novel, effective combination studies or the development of accurate biomarkers. Methods: Single-cell RNA-Seq analysis of TAM populations of autochthonous KP16 and KPC tumors treated with a CD206 checkpoint modulator was used to classify CD206 positive M2-like TAMs into responsive vs non-responsive to CD206 modulation. Candidates of differentially expressed innate immune regulators were evaluated for their role in CD206 activation in macrophages derived from transgenic knockout mouse models deficient for different innate immune regulators. The induction of CD206 protein-protein interactions with other innate immune regulators was examined via proximal ligation assays (PLA) or co-immunoprecipitation, as well as a series of CD206 mutants expressed in different reporter assays. CCR2-RFP transgenic mice were used to study cancer cell phagocytosis in vitro and in vivo. Results: CD206 activation via small molecule candidate NCGC00413972 induces a conformational change in CD206 which induces the formation of a TLR1/2-CD206 trimeric complex, activates SYK kinase, recruits MyD88, and activates NF-κB and type I interferon signaling. Carbohydrate recognition domain 3 (CRD3) of the non-activated CD206 receptor negatively regulates CD206-TLR1/2 interaction. CD206 small molecule ligation, or the deletion of the N-terminal CRDs of CD206, leads to the formation of active TLR1/2-CD206 complexes, NF-κB activation, and TAM reprogramming. Loss of SYK kinase binding sites in the cytoplasmatic domain of CD206 or inhibition of SYK abrogates NF-κB activation and reduces cell death of M2-like macrophages but does not affect interferon signaling or cancer cell phagocytosis. The combination of an FDA-approved SYK inhibitor with a CD206 small molecule activator increased the fraction of M2-to-M1 reprogrammed TAMs and cancer cell phagocytosis in the tumoral stroma of KPC mice. CD206 and TLR2 activators also cooperated in the reprogramming of TAMs, resulting in a recalibration of the immune landscape towards an anti-tumor phenotype and enhanced tumor control. Conclusions: Deconvolution of the mechanism of action of CD206 small molecule activation identifies toll-like receptor signaling as an essential co-regulator for the induction of innate immune responses. Co-stimulation of CD206 and TLR2 demonstrates therapeutic potential as an effective immunotherapy in a recalcitrant disease, as it cooperatively increases NF-κB signaling, cancer cell phagocytosis, and recalibrates myeloid cells. Citation Format: Sitanshu Sekhar Singh, Rushikesh V. Sable, Anju Kumari, Xin Hu, Abhijeet Kapoor, Raul Calvo, Emily Major, Taivan Odzorig, Laura Bassel, Serguei Kozolov, Mark Henderson, Juan Marugan, Udo Rudloff. CD206 small molecule activation recruits TLR1/2 to enhance cancer cell phagocytosis in reprogrammed tumor-associated macrophages and improves tumor control [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C024.

Early Events in Reovirus Infection Influence Induction of Innate Immune Response.

Mammalian orthoreovirus (reovirus) is a double-stranded RNA (dsRNA) virus which encapsidates its 10 genome segments within a double-layered viral particle. Reovirus infection triggers an antiviral response in host cells which serves to limit viral replication. This antiviral response is initiated by recognition of the incoming viral genome by host sensors present in the cytoplasm. However, how host sensors gain access to the reovirus genome is unclear, as this dsRNA is protected by the viral particle proteins throughout infection. To initiate infection, reovirus particles are endocytosed and the outer viral particle layer is disassembled through the action of host proteases. This disassembly event is required for viral escape into the cytoplasm to begin replication. We show that endosomal proteases are required even late in infection, when disassembly is complete, to induce an immune response to reovirus. Additionally, counter to dogma, our data demonstrate that at least some viral dsRNA genome is exposed and detectable during entry. We hypothesize that some proportion of reovirus particles remain trapped within endosomes, allowing for the breakdown of these particles and release of their genome. We show that rapidly uncoating mutants escape the endosome more rapidly and induce a diminished immune response. Further, we show that particles entering through dynamin-independent pathways evade detection by host sensors. Overall, our data provide new insight into how genomes from entering reovirus particles are detected by host cells. IMPORTANCE Viruses must infect host cells to replicate, often killing the host cell in the process. However, hosts can activate defenses to limit viral replication and protect the organism. To trigger these host defenses to viral infections, host cells must first recognize that they are infected. Mammalian orthoreovirus (reovirus) is a model system used to study host-virus interactions. This study identifies aspects of host and virus biology which determine the capacity of host cells to detect infection. Notably, entry of reovirus into host cells plays a critical role in determining the magnitude of immune response triggered during infection. Mutants of reovirus which can enter cells more rapidly are better at avoiding detection by the host. Additionally, reovirus can enter cells through multiple routes. Entry through some of these routes also helps reovirus evade detection.

Mitotic SENP3 activation couples with cGAS signaling in tumor cells to stimulate anti-tumor immunity

Our previous studies show that the mitotic phosphorylation of SUMO-specific protease 3 (SENP3) can inhibit its de-SUMOylation activity in G2/M phase of the cell cycle. Inhibition of SENP3 plays a critical role in the correct separation of sister chromatids in mitosis. The mutation of mitotic SENP3 phosphorylation causes chromosome instability and promotes tumorigenesis. In this study, we find that the mutation of mitotic SENP3 phosphorylation in tumor cells can suppress tumor growth in immune-competent mouse model. We further detect an increase of CD8+ T cell infiltration in the tumors, which is essential for the anti-tumor effect in immune-competent mouse model. Moreover, we find that mitotic SENP3 activation increases micronuclei formation, which can activate cGAS signaling-dependent innate immune response. We confirmed that cGAS signaling mediates the mitotic SENP3 activation-induced anti-tumor immunity. We further show that p53 responding to DNA damage activates mitotic SENP3 by inhibiting phosphorylation, and further increases cellular senescence as well as the related innate immune response in tumor cells. Furthermore, TCGA database demonstrates that the SENP3 expression positively correlates with the induction of innate immune response as well as the survival of the p53 mutant pancreatic cancer patients. Together, these data reveal that mitotic SENP3 activation in tumor cells can promote host anti-tumor immune response by coupling with cGAS signaling.

Men With Chronic Orchialgia Exhibit Differential Neuroinflammatory Gene Expression Relative to Asymptomatic Controls

ObjectiveTo identify differences in neuroinflammatory gene expression in individuals with chronic orchialgia (CO) compared to asymptomatic controls. MethodsVas deferens, spermatic cord fascia, blood, and urine were collected from 9 men with CO at time of microscopic spermatic cord denervation and 7 asymptomatic controls at time of vasectomy. RNA was isolated and analyzed with the NanoString Human Neuroinflammation panel. Data were normalized, gene expression fold changes and enriched pathways relative to asymptomatic controls were determined. Gene expression was considered significantly different if there was a >2-fold change and P-value <.05 relative to controls. ResultsMean patient age was 51 years and median symptom duration 12 months. There were 26 genes with significantly differential expression in vas deferens. cFos, a marker of nociceptive pain, had the greatest difference (30.2-fold change, P <.000001). Enriched pathways in vas deferens included nerve function, matrix remodeling, and innate immune responses. In fascia, cFos also had the greatest differential expression (38-fold, P = .000002), followed by S100A12 (11-fold, inducer of innate immune response). Enriched pathways in fascia included nerve function and inflammation. In blood, there were no differentially expressed genes, and in urine there were 95 differentially expressed genes. ConclusionMen with CO have a diverse set of neuroinflammatory genes with differential expression in tissue and urine relative to healthy controls. These findings confirm pathologic changes in tissue targeted by denervation surgery, and suggest molecular changes in neuropathic pain that could lead to biomarker identification and novel treatment.

Toll-Like Receptor Signaling and Its Role in Cell-Mediated Immunity.

Innate immunity is the first defense system against invading pathogens. Toll-like receptors (TLRs) are well-defined pattern recognition receptors responsible for pathogen recognition and induction of innate immune responses. Since their discovery, TLRs have revolutionized the field of immunology by filling the gap between the initial recognition of pathogens by innate immune cells and the activation of the adaptive immune response. TLRs critically link innate immunity to adaptive immunity by regulating the activation of antigen-presenting cells and key cytokines. Furthermore, recent studies also have shown that TLR signaling can directly regulate the T cell activation, growth, differentiation, development, and function under diverse physiological conditions. This review provides an overview of TLR signaling pathways and their regulators and discusses how TLR signaling, directly and indirectly, regulates cell-mediated immunity. In addition, we also discuss how TLR signaling is critically important in the host’s defense against infectious diseases, autoimmune diseases, and cancer.

Effect of Corticosteroids on Peptide Transporter 2 Function and Induction of Innate Immune Response by Bacterial Peptides in Alveolar Epithelial Cells

In the lung alveolar region, the innate immune system serves as an important host defense system. We recently reported that peptide transporter 2 (PEPT2) has an essential role in the uptake of bacterial peptides and induction of innate immune response in alveolar epithelial cells. In this study, we aimed to clarify the effects of corticosteroids on PEPT2 function and PEPT2-dependent innate immune response. NCI-H441 (H441) cells were used as an in vitro model of human alveolar type II epithelial cells, and the effects of dexamethasone (DEX) and budesonide (BUD) on the transport function of PEPT2 and the innate immune response induced by bacterial peptides were examined. PEPT2 function, estimated by measuring β-alanyl-Nε-(7-amino-4-methyl-2-oxo-2H-1-benzopyran-3-acetyl)-L-lysine (β-Ala-Lys-AMCA) uptake in H441 cells, was suppressed by treatment with DEX and BUD in a concentration- and time-dependent manner. The suppression of PEPT2 function was partially recovered by a glucocorticoid receptor antagonist. The expression of PEPT2 and nucleotide-binding oligomerization domain 1 (NOD1) mRNAs was suppressed by treatment with DEX and BUD, while PEPT2 protein level was not changed by these treatment conditions. Additionally, the increased mRNA expression of interleukin (IL)-8 and the increased secretion of IL-8 into the culture medium induced by bacterial peptides were also suppressed by treatment with these corticosteroids. Taken together, these results clearly suggest that corticosteroids suppress PEPT2 function and bacterial peptide-induced innate immune response in alveolar epithelial cells. Therefore, PEPT2- and NOD1-dependent innate immune response induced by bacterial peptides in the lung alveolar region may be suppressed during the inhaled corticosteroid therapy.

Induction of Innate Immune Response by TLR3 Agonist Protects Mice against SARS-CoV-2 Infection.

SARS-CoV-2, a member of the coronavirus family, is the causative agent of the COVID-19 pandemic. Currently, there is still an urgent need in developing an efficient therapeutic intervention. In this study, we aimed at evaluating the therapeutic effect of a single intranasal treatment of the TLR3/MDA5 synthetic agonist Poly(I:C) against a lethal dose of SARS-CoV-2 in K18-hACE2 transgenic mice. We demonstrate here that early Poly(I:C) treatment acts synergistically with SARS-CoV-2 to induce an intense, immediate and transient upregulation of innate immunity-related genes in lungs. This effect is accompanied by viral load reduction, lung and brain cytokine storms prevention and increased levels of macrophages and NK cells, resulting in 83% mice survival, concomitantly with long-term immunization. Thus, priming the lung innate immunity by Poly(I:C) or alike may provide an immediate, efficient and safe protective measure against SARS-CoV-2 infection.