Intestinal IL-17R Signaling Controls Secretory IgA and Oxidase Balance in Citrobacter rodentium Infection.

Type 17 cytokines have been strongly implicated in mucosal immunity, in part by regulating the production of antimicrobial peptides. Using a mouse model of Citrobacter rodentium infection, which causes colitis, we found that intestinal IL-17RA and IL-17RC were partially required for control of infection in the colon and IL-17 regulates the production of luminal hydrogen peroxide as well as expression of Tnsf13 Reduced Tnfsf13 expression was associated with a profound defect in generating C. rodentium-specific IgA+ Ab-secreting cells. Taken together, intestinal IL-17R signaling plays key roles in controlling invading pathogens, in part by regulating luminal hydrogen peroxide as well as regulating the generation of pathogen-specific IgA+ Ab-secreting cells.

Planarian gamma-interferon-inducible lysosomal thiol reductase (GILT) is required for gram-negative bacterial clearance.

The powerful regenerative ability of planarians has long been a concern of scientists, but recently, their efficient immune system has attracted more and more attention from researchers. Gamma-interferon-inducible lysosomal thiol reductase (GILT) is related not only to antigen presentation but also to bacteria invasions. But the systematic studies are not yet to be conducted on the relationship between bacterial infection. Our study reveals for the first time that GILT of planarian (DjGILT) plays an essential role in the clearance of Gram-negative bacteria by conducting H2O2 concentration in planarians. In animals that DjGILT was silenced, it persisted for up to 9 days before all bacteria were cleared, compared with 6 days of the control group. When infected with E. coli and V. anguillarum, the level of H2O2 was significantly increased in DjGILT-silenced planarians, and concomitantly, mRNA level of C-type lectin DjCTL, which modulates agglutination and clearance efficiency of invading bacteria, was decreased. Further study showed that the decrease of H2O2 level led to a significant increase in DjCTL transcripts. Collectively, we proposed a mechanism model for the involvement of GILT gene in bacterial elimination. We have for the first time revealed the specific mechanism of GILT in innate immune response against bacterial infection.

Efficacy of two adjuvants administrated with a novel hydrogen peroxide-inactivated vaccine against Streptococcus agalactiae in Nile tilapia fingerlings.

Streptococcus agalactiae is considered the main bacterial pathogen in cultured Nile tilapia. Formaldehyde-inactivated vaccines are the most accepted method for prevention and control of the disease. However, alternative inactivation methods for S. agalactiae vaccines have not been fully explored. Recently, we developed a hydrogen peroxide-inactivated vaccine against S. agalactiae with moderate efficacy, with the possibility to improve vaccine efficacy by adding adjuvants. The current study compared the efficacy of aluminum hydroxide and Freund's incomplete adjuvant (FIA) incorporated into a novel hydrogen peroxide-inactivated intraperitoneal vaccine against S. agalactiae for Nile tilapia fingerlings. The relative percentage survival (RPS) for aluminum hydroxide-adjuvanted vaccine (59.3%), and FIA-adjuvanted vaccine (77.8%) were higher than the vaccine without adjuvant (40.7%). In addition, fish immunized with aluminum hydroxide-adjuvanted vaccine had significantly higher levels of specific antibodies than control fish at 4 weeks post vaccination (wpv). Blood lymphocytes counts showed a decrease in vaccinated groups when compared to control fish, suggesting white cells migration to the tissues where antigen presentation is ongoing. Fish that received FIA-adjuvanted vaccine exhibited persistence of adjuvant deposits on intraperitoneal surfaces for at least 4 wpv that may be related to its superior performance compared to aluminum hydroxide adjuvanted vaccine, which did not evidence any type of deposit at any sampling times. The results observed in this study demonstrate that hydrogen peroxide-inactivated vaccine administered with either aluminum hydroxide or FIA induce optimal levels of protection, with a superior performance for FIA vaccine, which could be a good alternative to conventional formaldehyde-inactivated vaccines against S. agalactiae, due to its shorter manufacture time, and less toxicity.

A novel condition of mild electrical stimulation exerts immunosuppression via hydrogen peroxide production that controls multiple signaling pathway.

Different modes of exogenous electrical stimulation at physiological strength has been applied to various diseases. Previously, we extensively demonstrated the usability of mild electrical stimulation (MES) with low frequency pulse current at 55 pulses per second (MES55) for several disease conditions. Here we found that MES with high frequency pulse-current (5500 pulse per second; MES5500) suppressed the overproduction of pro-inflammatory cytokines induced by phorbol myristate acetate/ionomycin in Jurkat T cells and primary splenocytes. MES5500 also suppressed the overproduction of inflammatory cytokines, improved liver damage and reduced mouse spleen enlargement in concanavalin-A-treated BALB/c mice. The molecular mechanism underlying these effects included the ability of MES5500 to induce modest amount of hydrogen peroxide and control multiple signaling pathways important for immune regulation, such as NF-κB, NFAT and NRF2. In the treatment of various inflammatory and immune-related diseases, suppression of excessive inflammatory cytokines is key, but because immunosuppressive drugs used in the clinical setting have serious side effects, development of safer methods of inhibiting cytokines is required. Our finding provides evidence that physical medicine in the form of MES5500 may be considered as a novel therapeutic tool or as adjunctive therapy for inflammatory and immune-related diseases.

Methyl jasmonate induces the resistance of postharvest blueberry to gray mold caused by Botrytis cinerea.

BACKGROUND: The effects of postharvest methyl jasmonate (MeJA) treatment (50 µmol L-1 ) on the control of gray mold caused by Botrytis cinerea in blueberry fruit were evaluated by analyzing (i) the levels of disease resistance signals; (ii) the activity of enzymes involved in antioxidant system, disease resistance and phenylpropanoid pathway, and (iii) the secondary metabolite content. RESULTS: The results indicated that MeJA treatment significantly restrained the development of gray mold decay in blueberries. The treatment induced a nitric oxide (NO) burst and increased the endogenous hydrogen peroxide (H2 O2 ) content in the earlier period of storage. The enhanced NO and H2 O2 generation by MeJA treatment might serve as a signal to induce resistance against B. cinerea infection. Furthermore, in inoculated fruit, MeJA treatment significantly promoted antioxidant enzymes and defense-related enzyme activity, which included superoxide dismutase, catalase, ascorbate peroxidase, chitinase, and ß-1,3-glucanase, and the degree of membrane lipid peroxidation was reduced. The MeJA treatment enhanced the phenylpropanoid pathway by provoking phenylalanine ammonialyase, cinnamate 4-hydroxylase, and 4-coumarate CoA ligase activity, which was accompanied by elevated levels of phenolics and flavonoids in blueberry fruit. CONCLUSION: These results suggested that MeJA could induce the disease resistance of blueberries against B. cinerea by regulating the antioxidant enzymes, defense-related enzymes, and the phenylpropanoid pathway through the activation of signaling molecules.

Neutrophils suppress mucosal-associated invariant T cells in humans.

Mucosal-associated invariant T (MAIT) cells are innate-like T lymphocytes that are abundant in mucosal tissues and the liver where they can respond rapidly to a broad range of riboflavin producing bacterial and fungal pathogens. Neutrophils, which are recruited early to sites of infection, play a nonredundant role in pathogen clearance and are crucial for controlling infection. The interaction of these two cell types is poorly studied. Here, we investigated both the effect of neutrophils on MAIT cell activation and the effect of activated MAIT cells on neutrophils. We show that neutrophils suppress the activation of MAIT cells by a cell-contact and hydrogen peroxide dependent mechanism. Moreover, highly activated MAIT cells were able to produce high levels of TNF-α that induced neutrophil death. We therefore provide evidence for a negative regulatory feedback mechanism in which neutrophils prevent overactivation of MAIT cells and, in turn, MAIT cells limit neutrophil survival.

Defense of Scots pine against sawfly eggs (Diprion pini) is primed by exposure to sawfly sex pheromones.

Plants respond to insect infestation with defenses targeting insect eggs on their leaves and the feeding insects. Upon perceiving cues indicating imminent herbivory, such as damage-induced leaf odors emitted by neighboring plants, they are able to prime their defenses against feeding insects. Yet it remains unknown whether plants can amplify their defenses against insect eggs by responding to cues indicating imminent egg deposition. Here, we tested the hypothesis that a plant strengthens its defenses against insect eggs by responding to insect sex pheromones. Our study shows that preexposure of Pinus sylvestris to pine sawfly sex pheromones reduces the survival rate of subsequently laid sawfly eggs. Exposure to pheromones does not significantly affect the pine needle water content, but results in increased needle hydrogen peroxide concentrations and increased expression of defense-related pine genes such as SOD (superoxide dismutase), LOX (lipoxygenase), PAL (phenylalanine ammonia lyase), and PR-1 (pathogenesis related protein 1) after egg deposition. These results support our hypothesis that plant responses to sex pheromones emitted by an herbivorous insect can boost plant defensive responses to insect egg deposition, thus highlighting the ability of a plant to mobilize its defenses very early against an initial phase of insect attack, the egg deposition.

Quality by Design-Driven Process Development of Severe Fever With Thrombocytopenia Syndrome Vaccine.

Owing to the biological activity of the vaccine, the complicated production process, sterility, and uniformity of the product, the producing process of the vaccine is complicated and the product quality hard to control. In recent years, with the development of basic science such as cell biology, molecular biology, and metabolic engineering, bioprocess engineering research has developed rapidly. Therefore, U.S. Food and Drug Administration and European Medicines Agency conduct stringent control over the development of biomedical process engineering and product quality. This case study describes an example of Quality by Design-driven process development for manufacturing a human vaccine produced with Vero cells. Cell density in harvest fermentation broth and antigenic titer were chosen as 2 critical quality attributes. The study through 3 rounds design of experiment revealed that H2O2 and cell boost 4 had a significant effect on antigenic titer. Ethanolamine had significant improvement in the final concentration of cells. Through the Monte Carlo simulation, the design spaces and control space of process parameters were determined. A successful validation in a bioreactor was executed to verify the results of a spinner flask. Our investigation presents a successful case of Quality by Design principle, which encourages other researchers to combine the methodology into other biopharmaceutical manufacturing process.

Hydrogen peroxide release by bacteria suppresses inflammasome-dependent innate immunity.

Hydrogen peroxide (H2O2) has a major function in host-microbial interactions. Although most studies have focused on the endogenous H2O2 produced by immune cells to kill microbes, bacteria can also produce H2O2. How microbial H2O2 influences the dynamics of host-microbial interactions is unclear. Here we show that H2O2 released by Streptococcus pneumoniae inhibits inflammasomes, key components of the innate immune system, contributing to the pathogen colonization of the host. We also show that the oral commensal H2O2-producing bacteria Streptococcus oralis can block inflammasome activation. This study uncovers an unexpected role of H2O2 in immune suppression and demonstrates how, through this mechanism, bacteria might restrain the immune system to co-exist with the host.

Real-time bacterial detection with an intracellular ROS sensing platform.

Reactive oxygen species are highly reactive molecules that as well as being ubiquitously expressed throughout the body, are also known to be involved in many diseases and disorders including bacterial infection. Current technology has limited success in the accurate detection and identification of specific reactive oxygen species. To combat this, we have developed an electrochemical biosensor that is constructed from single walled carbon nanotubes that have been immobilised on an indium tin oxide surface functionalised with osmium-based compound. This sensor was integrated within mouse macrophage cells (RAW 264.7) with multiple serotypes of bacteria used to initiate an immune response. Intracellular hydrogen peroxide was then measured in response to the interaction of the lipopolysaccharides, present on the outer wall of Gram-negative bacteria, with the Toll-like Receptor 4. Additional controls of n-acetylcysteine and sodium pyruvate were implemented to prove the specificity of the sensor towards hydrogen peroxide. The sensors were found to have a lower limit of detection of 368 nM hydrogen peroxide. An increase in intracellular hydrogen peroxide was detected within 3 seconds of interaction of the bacteria with the macrophage cells. This low limit of detection combined with the rapid response of the sensor resulted in the unprecedented detection of hydrogen peroxide on a temporal level not previously seen in response to a bacterial threat. From the three serotypes of Gram-negative bacteria that were tested, there were distinct differences in hydrogen peroxide production. This proves that the innate immune system has the ability to respond dynamically and rapidly, after infection prior to the activation of the adaptive immune system.

Melatonin Induces Disease Resistance to Botrytis cinerea in Tomato Fruit by Activating Jasmonic Acid Signaling Pathway.

Melatonin acts as a crucial signaling molecule with multiple physiological functions in plant response to abiotic and biotic stresses. However, the impact and regulatory mechanism of melatonin on attenuating tomato fruit fungal decay are unclear. In this study, we investigated the potential roles of melatonin in modulating fruit resistance to Botrytis cinerea and explored related physiological and molecular mechanisms. The results revealed that disease resistance was strongly enhanced by melatonin treatment, and 50 µM was confirmed as the best concentration. Melatonin treatment increased the activities of defense-related enzymes and decreased hydrogen peroxide (H2O2) content with enhanced antioxidant enzyme activities. Moreover, we found that melatonin treatment increased methyl jasmonate (MeJA) content; up-regulated the expressions of SlLoxD, SlAOC, and SlPI II; and reduced the expressions of SlMYC2 and SlJAZ1. We postulated that melatonin played a positive role in tomato fruit resistance to Botrytis cinerea through regulating H2O2 level and JA signaling pathway.

Sensitization potential and potency of terpene hydroperoxides in the cocultured activation test method.

BACKGROUND: Positive patch test reactions to mixtures of oxidized terpenes containing allergenic hydroperoxides are frequently reported. However, human sensitization data for these hydroperoxides are not available. OBJECTIVES: To analyse and evaluate the human sensitization potential and potency of hydroperoxides in vitro by using human cells. MATERIALS/METHODS: Limonene-1-hydroperoxide, limonene-2-hydroperoxide, citronellol-7-hydroperoxide, cumene hydroperoxide, 1-(1-hydroperoxy-1-methylethyl)cyclohexene and mixtures of citronellol hydroperoxides (isomers at positions 6 and 7) and linalool hydroperoxides (isomers at positions 6 and 7) were studied. All compounds were synthesized except for cumene hydroperoxide, which was commercially available. Their potential and potency to activate dendritic cells (DCs) was evaluated by measuring the upregulation of CD86 and CD54 on THP-1 cells upon exposure in the cocultured activation test (COCAT) consisting of HaCaT cells (human keratinocyte cell line) and THP-1 monocytes (as a surrogate for DCs). RESULTS: Hydroperoxides upregulated CD86 and/or CD54 on cocultured THP-1 cells in a concentration-dependent manner. The results are comparable with their sensitization potency ranking in predictive animal models. CONCLUSIONS: For the first time, the human sensitization potential and potency of several hydroperoxides were determined by the use of human cells and the COCAT method.

Pyridinecarboxylic Acid Derivative Stimulates Pro-Angiogenic Mediators by PI3K/AKT/mTOR and Inhibits Reactive Nitrogen and Oxygen Species and NF-κB Activation Through a PPARγ-Dependent Pathway in T. cruzi-Infected Macrophages.

Chagas disease is caused by Trypanosoma cruzi infection and represents an important public health concern in Latin America. Macrophages are one of the main infiltrating leukocytes in response to infection. Parasite persistence could trigger a sustained activation of these cells, contributing to the damage observed in this pathology, particularly in the heart. HP24, a pyridinecarboxylic acid derivative, is a new PPARγ ligand that exerts anti-inflammatory and pro-angiogenic effects. The aim of this work was to deepen the study of the mechanisms involved in the pro-angiogenic and anti-inflammatory effects of HP24 in T. cruzi-infected macrophages, which have not yet been elucidated. We show for the first time that HP24 increases expression of VEGF-A and eNOS through PI3K/AKT/mTOR and PPARγ pathways and that HP24 inhibits iNOS expression and NO release, a pro-inflammatory mediator, through PPARγ-dependent mechanisms. Furthermore, this study shows that HP24 modulates H2O2 production in a PPARγ-dependent manner. It is also demonstrated that this new PPARγ ligand inhibits the NF-κB pathway. HP24 inhibits IKK phosphorylation and IκB-α degradation, as well as p65 translocation to the nucleus in a PPARγ-dependent manner. In Chagas disease, both the sustained increment in pro-inflammatory mediators and microvascular abnormalities are crucial aspects for the generation of cardiac damage. Elucidating the mechanism of action of new PPARγ ligands is highly attractive, given the fact that it can be used as an adjuvant therapy, particularly in the case of Chagas disease in which inflammation and tissue remodeling play an important role in the pathophysiology of this disease.

Integrated Proteome and Cytokine Profiles Reveal Ceruloplasmin Eliciting Liver Allograft Tolerance via Antioxidant Cascades.

Acute rejection (AR) and spontaneous tolerance may occur after allograft orthotopic liver transplants (OLT) performed in certain combinations of donor and recipient rat strains, yet the underlying molecular cascades involved in these conditions remain poorly understood. Comprehensive analysis with proteomic tools revealed that ceruloplasmin was highly expressed during the tolerant period on day 63 post-OLT (POD 63) compared to the rejected samples on POD 14. Meanwhile, cytokine expression profiles implied that the inflammation was significantly stimulated in the AR subjects. Again, protein carbonylation was dramatically upregulated in the rejected subject within the tolerant group. Knockdown of ceruloplasmin would elicit more severe ROS damage, leading to cell death in the presence of H2O2, which induced Nrf2 cascade and the recovery of ceruloplasmin to mediate spontaneous tolerance. In summary, ceruloplasmin may contribute to amending the oxidative stress that eventually causes cell apoptosis and to maintaining the survival of hepatocytes in a drug-free tolerance OLT model.

Prophylactic Treatment With Simvastatin Modulates the Immune Response and Increases Animal Survival Following Lethal Sepsis Infection.

Chronic use of statins may have anti-inflammatory action, promoting immunomodulation and survival in patients with sepsis. This study aimed to analyze the effects of pretreatment with simvastatin in lethal sepsis induced by cecal ligation and puncture (CLP). Male Swiss mice received prophylactic treatment with simvastatin or pyrogen-free water orally in a single daily dose for 30 days. After this period, the CLP was performed. Naïve and Sham groups were performed as non-infected controls. Animal survival was monitored for 60 h after the CLP. Half of mice were euthanized after 12 h to analyze colony-forming units (CFUs); hematological parameters; production of IL-10, IL-12, IL-6, TNF-α, IFN-γ, and MCP-1; cell counts on peritoneum, bronchoalveolar lavage (BAL), bone marrow, spleen, and mesenteric lymph node; immunephenotyping of T cells and antigen presenting cells and production of hydrogen peroxide (H2O2). Simvastatin induced an increase in survival and a decrease in the CFU count on peritoneum and on BAL cells number, especially lymphocytes. There was an increase in the platelets and lymphocytes number in the Simvastatin group when compared to the CLP group. Simvastatin induced a greater activation and proliferation of CD4+ T cells, as well as an increase in IL-6 and MCP-1 production, in chemotaxis to the peritoneum and in H2O2 secretion at this site. These data suggest that simvastatin has an impact on the survival of animals, as well as immunomodulatory effects in sepsis induced by CLP in mice.

Peroxidase-immobilized porous silica particles for in situ formation of peroxidase-free hydrogels with attenuated immune responses.

Enzymatic crosslinking chemistry using horseradish peroxidase (HRP) has been widely utilized as an effective approach to fabricating injectable hydrogels with high efficiency under mild reaction conditions. However, their clinical applications are limited by the immunogenicity of the plant-derived enzyme. Herein we report the design, synthesis and characterization of HRP-immobilized porous silica particles (HRP-particles) and their use for in situ formation of HRP-free hydrogels. HRP was immobilized on aminopropyl-modified porous silica particles of 70-140 µm in diameter via poly(ethylene glycol) spacers of different molecular weights by reductive amination reaction. Two different HRP-free hydrogels based on dextran-tyramine and gelatin-hydroxyphenylpropionic acid (GHPA) conjugates were produced by passing a solution containing the conjugates and H2O2 through a syringe packed with HRP-particles. The storage modulus and gelation rate of both hydrogels were tunable by varying the contact time between the polymer solution and HRP-particles. Our in vitro study revealed that HRP-free GHPA hydrogel was less stimulatory to activated mouse macrophages than HRP-containing GHPA hydrogel with the same stiffness. Furthermore, HRP-free GHPA hydrogel exhibited remarkably lower levels of local and systemic inflammation than HRP-containing one upon subcutaneous injection in immunocompetent C57BL/6J mice. The attenuated immunogenicity of HRP-free GHPA hydrogels makes them an attractive platform for tissue engineering applications. STATEMENT OF SIGNIFICANCE: The immunogenicity of HRP is a significant issue for clinical application of HRP-catalyzed in situ forming hydrogels. HRP-particles are developed to overcome the safety concerns by fabricating HRP-free hydrogels. The porosity of silica particles and molecular weight of poly(ethylene glycol) spacers are discovered as important factors determining the catalytic ability of HRP-particles to induce the in situ crosslinking of polymer-phenol conjugates. Although several articles speculate the potential of HRP to trigger immune responses when administered as a part of hydrogel formulation, no literature has attempted to investigate the immunogenicity of HRP-containing hydrogels in comparison with HRP-free hydrogels. Our findings suggest that the immunogenicity issue should be carefully considered before clinical translation of HRP-containing hydrogels.

Self-Supplied Tumor Oxygenation through Separated Liposomal Delivery of H2O2 and Catalase for Enhanced Radio-Immunotherapy of Cancer.

The recent years have witnessed the blooming of cancer immunotherapy, as well as their combinational use together with other existing cancer treatment techniques including radiotherapy. However, hypoxia is one of several causes of the immunosuppressive tumor microenvironment (TME). Herein, we develop an innovative strategy to relieve tumor hypoxia by delivering exogenous H2O2 into tumors and the subsequent catalase-triggered H2O2 decomposition. In our experiment, H2O2 and catalase are separately loaded within stealthy liposomes. After intravenous (iv) preinjection of CAT@liposome, another dose of H2O2@liposome is injected 4 h later. The sustainably released H2O2 could be decomposed by CAT@liposome, resulting in a long lasting effect in tumor oxygenation enhancement. As the result, the combination treatment by CAT@liposome plus H2O2@liposome offers remarkably enhanced therapeutic effects in cancer radiotherapy as observed in a mouse tumor model as well as a more clinically relevant patient-derived xenograft tumor model. Moreover, the relieved tumor hypoxia would reverse the immunosuppressive TME to favor antitumor immunities, further enhancing the combined radio-immunotherapy with cytotoxic T lymphocyte-associated antigen 4 (CTLA4) blockade. This work presents a simple yet effective strategy to promote tumor oxygenation via sequential delivering catalase and exogenous H2O2 into tumors using well-established liposomal carriers, showing great potential for clinical translation in radio-immunotherapy of cancer.

Antiviral innate immune response in non-myeloid cells is augmented by chloride ions via an increase in intracellular hypochlorous acid levels.

Phagocytes destroy ingested microbes by producing hypochlorous acid (HOCl) from chloride ions (Cl-) and hydrogen peroxide within phagolysosomes, using the enzyme myeloperoxidase. HOCl, the active ingredient in bleach, has antibacterial/antiviral properties. As myeloperoxidase is needed for HOCl production, non-myeloid cells are considered incapable of producing HOCl. Here, we show that epithelial, fibroblast and hepatic cells have enhanced antiviral activity in the presence of increasing concentrations of sodium chloride (NaCl). Replication of enveloped/non-enveloped, DNA (herpes simplex virus-1, murine gammaherpesvirus 68) and RNA (respiratory syncytial virus, influenza A virus, human coronavirus 229E, coxsackievirus B3) viruses are inhibited in a dose-dependent manner. Whilst treatment with sodium channel inhibitors did not prevent NaCl-mediated virus inhibition, a chloride channel inhibitor reversed inhibition by NaCl, suggesting intracellular chloride is required for antiviral activity. Inhibition is also reversed in the presence of 4-aminobenzoic hydrazide, a myeloperoxidase inhibitor, suggesting epithelial cells have a peroxidase to convert Cl- to HOCl. A significant increase in intracellular HOCl production is seen early in infection. These data suggest that non-myeloid cells possess an innate antiviral mechanism dependent on the availability of Cl- to produce HOCl. Antiviral activity against a broad range of viral infections can be augmented by increasing availability of NaCl.

Slc11a1 (Nramp-1) gene modulates immune-inflammation genes in macrophages during pristane-induced arthritis in mice.

OBJECTIVE AND DESIGN: Pristane-induced arthritis (PIA) in AIRmax mice homozygous for Slc11a1 R and S alleles was used to characterize the influence of Slc11a1 gene polymorphism on immune responses during disease manifestation. Previous reports demonstrated that the presence of the Slc11a1 S allele increased the incidence and severity of PIA in AIRmax SS , suggesting that this gene could interact with inflammatory loci to modulate PIA. We investigated the effects of Slc11a1 alleles on the activation of phagocytes during PIA. TREATMENT: Mice were injected intraperitoneally with two doses of 0.5 mL of mineral oil pristane at 60-day intervals. Arthritis development was accompanied for 180 days. RESULTS: AIRmax SS mice showed differential peritoneal macrophage gene expression profiles during PIA, with higher expression and production of H2O2, NO, IL-1ß, IL-6, TNF-α, and several chemokines. The presence of the Slc11a1 R allele, on the other hand, diminished the intensity of macrophage activation, restricting arthritis development. CONCLUSION: Our data demonstrated the fine-tuning roles of Slc11a1 alleles modulating macrophage activation, and consequent PIA susceptibility, in those mouse lines.

The receptor-like cytoplasmic kinase BSR1 mediates chitin-induced defense signaling in rice cells.

Broad-Spectrum Resistance 1 (BSR1) encodes a rice receptor-like cytoplasmic kinase, and enhances disease resistance when overexpressed. Rice plants overexpressing BSR1 are highly resistant to diverse pathogens, including rice blast fungus. However, the mechanism responsible for this resistance has not been fully characterized. To analyze the BSR1 function, BSR1-knockout (BSR1-KO) plants were generated using a clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Experiments using suspension-cultured cells revealed that defense responses including H2O2 production (i.e. oxidative burst) and expression of defense-related genes induced by autoclaved conidia of the rice blast fungus significantly decreased in BSR1-KO cells. Furthermore, a treatment with chitin oligomers which function as microbe-associated molecular patterns (MAMPs) of the rice blast fungus resulted in considerably suppressed defense responses in BSR1-KO cells. These results suggest that BSR1 is important for the rice innate immunity triggered by the perception of chitin.