Natural polymorphism of Ym1 regulates pneumonitis through alternative activation of macrophages

Developmental perfluorooctane sulfonic acid exposure exacerbates house dust mite induced allergic responses in adult mice

Perfluorooctane sulfonic acid (PFOS) is a long-chain per- and polyfluoroalkyl substance (PFAS), a persistent organic pollutant, which has been used in aqueous film-forming foams. Emerging epidemiological evidence indicates a significant body burden of PFOS is observed in the lungs. Furthermore, developmental PFOS exposure dysregulates lung development and exacerbates eosinophilic inflammation, which are critical risk factors for asthma. However, it is unknown whether PFOS exerts sex-dependent effects on house dust mite (HDM) induced asthmatic progression and allergic inflammation. In this study, timed pregnant Balb/cJ dams were dosed orally via PFOS (1.0 mg/kg/d) spiked or vehicle control mealworms from gestational day (GD) 0.5 to postnatal day (PND) 21. Subsequently, HDM (30 μg/day) was administered starting at PND 77-82 for 10 days, and the mice were sacrificed 48 h after their final treatment. The serum and lung PFOS concentrations were 3.391 ± 0.189 μg/mL and 3.567 ± 0.1676 μg/g in the offspring, respectively. Male mice exposed to PFOS + HDM showed higher total cell counts in bronchoalveolar lavage fluid (BALF), macrophage counts, and eosinophil counts compared to mice exposed to HDM alone. Female mice exposed to PFOS + HDM had increased BALF eosinophil percentage, mucous production, alternatively activated (M2) macrophage polarization, and M2-associated gene expression compared to female mice exposed to HDM alone. PFOS exposure had no significant effect on HDM-induced IL-4, IL-5, or IL-13, but RANTES was further elevated in female mice. Overall, our data suggest that developmental PFOS exposure increased the risk of exacerbated eosinophilic inflammation and M2 polarization, which were more severe in female mice, suggesting sex-dependent developmental effects of PFOS on allergic airway responses.

Integrin β1-rich extracellular vesicles of kidney recruit Fn1+ macrophages to aggravate ischemia-reperfusion-induced inflammation

Ischemia-reperfusion injury-induced (IRI-induced) acute kidney injury is accompanied by mononuclear phagocyte (MP) invasion and inflammation. However, systematic analysis of extracellular vesicle-carried (EV-carried) proteins mediating intercellular crosstalk in the IRI microenvironment is still lacking. Multiomics analysis combining single-cell RNA-Seq data of kidney and protein profiling of kidney-EV was used to elucidate the intercellular communication between proximal tubular cells (PTs) and MP. Targeted adhesion and migration of various MPs were caused by the secretion of multiple chemokines as well as integrin β1-rich EV by ischemic-damaged PTs after IRI. These recruited MPs, especially Fn1+ macrophagocyte, amplified the surviving PT's inflammatory response by secreting the inflammatory factors TNF-α, MCP-1, and thrombospondin 1 (THBS-1), which could interact with integrin β1 to promote more MP adhesion and interact with surviving PT to further promote the secretion of IL-1β. However, GW4869 reduced MP infiltration and maintained a moderate inflammatory level likely by blocking EV secretion. Our findings establish the molecular bases by which chemokines and kidney-EV mediate PT-MP crosstalk in early IRI and provide insights into systematic intercellular communication.

Fasciola hepatica GST mu-class suppresses the cytokine storm induced by E. coli-lipopolysaccharide, whereas it modulates the dynamic of peritoneal macrophages in a mouse model and suppresses the classical activation of macrophages

IMPORTANCE

Sepsis is the consequence of a systemic bacterial infection that exacerbates the immune cell's activation via bacterial products, resulting in the augmented release of inflammatory mediators. A critical factor in the pathogenesis of sepsis is the primary component of the outer membrane of Gram-negative bacteria known as lipopolysaccharide (LPS), which is sensed by TLR4. For this reason, scientists have aimed to develop antagonists able to block TLR4 and, thereby the cytokine storm. We report here that a mixture of mu-class isoforms from the F. hepatica GST protein family administered intraperitoneally 1 h prior to a lethal LPS injection can modulate the dynamics and abundance of large peritoneal macrophages in the peritoneal cavity of septic mice while significantly suppressing the LPS-induced cytokine storm in a mouse model of septic shock. These results suggest that native F. hepatica glutathione S-transferase is a promising candidate for drug development against endotoxemia and other inflammatory diseases.

Notch Signaling Regulates Immunosuppressive Tumor-Associated Macrophage Function in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) continues to have a dismal prognosis. The poor survival of patients with PDA has been attributed to a high rate of early metastasis and low efficacy of current therapies, which partly result from its complex immunosuppressive tumor microenvironment. Previous studies from our group and others have shown that tumor-associated macrophages (TAM) are instrumental in maintaining immunosuppression in PDA. Here, we explored the role of Notch signaling, a key regulator of immune response, within the PDA microenvironment. We identified Notch pathway components in multiple immune cell types within human and mouse pancreatic cancer. TAMs, the most abundant immune cell population in the tumor microenvironment, expressed high levels of Notch receptors, with cognate ligands such as JAG1 expressed on tumor epithelial cells, endothelial cells, and fibroblasts. TAMs with activated Notch signaling expressed higher levels of immunosuppressive mediators, suggesting that Notch signaling plays a role in macrophage polarization within the PDA microenvironment. Genetic inhibition of Notch in myeloid cells led to reduced tumor size and decreased macrophage infiltration in an orthotopic PDA model. Combination of pharmacologic Notch inhibition with PD-1 blockade resulted in increased cytotoxic T-cell infiltration, tumor cell apoptosis, and smaller tumor size. Our work implicates macrophage Notch signaling in the establishment of immunosuppression and indicates that targeting the Notch pathway may improve the efficacy of immune-based therapies in patients with PDA.

Fasciola hepatica GST mu-class suppresses the cytokine storm induced by E. coli -lipopolysaccharide whereas modulates the dynamic of peritoneal macrophages in a mouse model and suppresses the classical activation of macrophages

The helminth Fasciola hepatica is known as a master of immunomodulation. It suppresses antigen specific Th1 responses in concurrent bacterial infections while promoting the Th2/Treg regulatory responses, thus demonstrating its anti-inflammatory ability in vivo . We have recently demonstrated that a single intraperitoneal injection with native F. hepatica Glutathione S -Transferase (nFhGST), mostly comprised of mu-class isoforms, can suppresses the cytokine storm and increasing the survival rate in a mouse model of septic shock (1). Knowing that the peritoneal macrophages in response to microbial stimuli play essential roles in the defense, tissue repairment, and maintenance of homeostasis, the present study aimed to determine whether nFhGST could modulate the amount and dynamic of these cells concurrently to the suppression of pro-inflammatory cytokines. The remarkable findings described in this article are, (i) nFhGST suppresses serum IL-12, TNF-α, and IFN-γ in BALB/c mice challenged with a lethal dose of LPS, (ii) Although nFhGST does not elicit IL-10, it was able to significantly suppress the high levels of LPS-induced IL-10, which is considered a key cytokine in the pathophysiology of sepsis (2). iii) nFhGST prevent the disappearance of large peritoneal macrophages (LPM) whereas significantly increasing this population in the peritoneal cavity (PerC) of LPS treated animals, (iv) nFhGST promotes the alternative activation of macrophages whereas suppress the classical activation of macrophages in vitro by expressing high levels of Ym-1, a typical M2-type marker, secreting the production of IL-37, and preventing the production of TNF-α, iNOS2 and nitric oxide, which are typical markers of M1-type macrophages, (v) nFhGST suppress the bacterial phagocytosis of macrophages, a role that plays both, M1-and M2-macrophages, thus partially affecting the capacity of macrophages in destroying microbial pathogens. These findings present the first evidence that nFhGST is an excellent modulator of the PerC content in vivo, reinforcing the capacity of nFhGST as an anti-inflammatory drug against sepsis in animal models.

Importance

Sepsis is an infection that can lead to a life-threatening complication. Sepsis is the consequence of a systemic bacterial infection that exacerbates the immune cells' activation by bacterial products, resulting in the augmented release of inflammatory mediators. A critical factor in the pathogenesis of sepsis is the primary component of the outer membrane of Gram-negative bacteria known as lipopolysaccharide (LPS), which is sensed by toll-like receptor 4 (TLR4). For this reason, scientists aimed to develop antagonists able to block the cytokine storm by blocking TLR4. We report here that a mixture of mu-class isoforms from the F. hepatica glutathione S-transferase (nFhGST) protein family administered intraperitoneally 1 h after a lethal LPS injection, is capable of significantly suppressing the LPS-induced cytokine storm in a mouse model of septic shock whereas modulate the dynamic and abundance of large peritoneal macrophages in the peritoneal cavity of septic mice. These results suggest that nFhGST is a prominent candidate for drug development against endotoxemia and other inflammatory diseases.

Chitinase-3-like 1 regulates TH2 cells, TFH cells and IgE responses to helminth infection

Introduction

Data from patient cohorts and mouse models of atopic dermatitis, food allergy and asthma strongly support a role for chitinase-3-like-1 protein (CHI3L1) in allergic disease.

Methods

To address whether Chi3l1 also contributes to TH2 responses following nematode infection, we infected Chi3l1 -/- mice with Heligmosomoides polygyrus (Hp) and analyzed T cell responses.

Results

As anticipated, we observed impaired TH2 responses in Hp-infected Chi3l1 -/- mice. However, we also found that T cell intrinsic expression of Chi3l1 was required for ICOS upregulation following activation of naïve CD4 T cells and was necessary for the development of the IL-4+ TFH subset, which supports germinal center B cell reactions and IgE responses. We also observed roles for Chi3l1 in TFH, germinal center B cell, and IgE responses to alum-adjuvanted vaccination. While Chi3l1 was critical for IgE humoral responses it was not required for vaccine or infection-induced IgG1 responses.

Discussion

These results suggest that Chi3l1 modulates IgE responses, which are known to be highly dependent on IL-4-producing TFH cells.

Protective Role of Phenolic Compounds from Whole Cardamom (Elettaria cardamomum (L.) Maton) against LPS-Induced Inflammation in Colon and Macrophage Cells

The chemical profiling of phenolic and terpenoid compounds in whole cardamom, skin, and seeds (Elettaria cardamomum (L.) Maton) showed 11 phenolics and 16 terpenoids, many of which are reported for the first time. Herein, we report the anti-inflammatory properties of a methanolic extract of whole cardamom in colon and macrophage cells stimulated with an inflammatory bacteria lipopolysaccharide (LPS). The results show that cardamom extracts lowered the expression of pro-inflammatory genes NFkβ, TNFα, IL-6, and COX2 in colon cells by reducing reactive oxygen species (ROS) while not affecting LXRα. In macrophages, cardamom extracts lowered the expression of pro-inflammatory genes NFkβ, TNFα, IL-6, and COX2 and decreased NO levels through a reduction in ROS and enhanced gene expression of nuclear receptors LXRα and PPARγ. The cardamom extracts in a range of 200-800 μg/mL did not show toxicity effects in colon or macrophage cells. The whole-cardamom methanolic extracts contained high levels of phenolics compounds (e.g., protocatechuic acid, caffeic acid, syringic acid, and 5-O-caffeoylquinic acid, among others) and are likely responsible for the anti-inflammatory and multifunctional effects observed in this study. The generated information suggests that cardamom may play a protective role against low-grade inflammation that can be the basis of future in vivo studies using mice models of inflammation and associated chronic diseases.

Soluble epoxide hydrolase inhibition enhances production of specialized pro-resolving lipid mediator and promotes macrophage plasticity

BACKGROUND AND PURPOSE

Epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFA) are lipid mediators that are rapidly inactivated by soluble epoxide hydrolase (sEH). Uncontrolled and chronic inflammatory disorders fail to sufficiently activate endogenous regulatory pathways, including the production of specialized pro-resolving mediators (SPMs). Here, we addressed the relationship between SPMs and the EET/sEH axis and explored the effects of sEH inhibition on resolving macrophage phenotype.

EXPERIMENTAL APPROACH

Mice were treated with a sEH inhibitor, EETs, or sEH inhibitor + EETs (combination) before ligature placement to induce experimental periodontitis. Using RT-qPCR, gingival samples were used to examine SPM receptors and osteolytic and inflammatory biomarkers. Maxillary alveolar bone loss was quantified by micro-CT and methylene blue staining. SPM levels were analysed by salivary metabolo-lipidomics. Gingival macrophage phenotype plasticity was determined by RT-qPCR and flow cytometry. Effects of sEH inhibition on macrophage polarization and SPM production were assessed with bone marrow-derived macrophages (BMDMs).

KEY RESULTS

Pharmacological inhibition of sEH suppressed bone resorption and the inflammatory cytokine storm in experimental periodontitis. Lipidomic analysis revealed that sEH inhibition augmented levels of LXA4, RvE1, RvE2, and 4-HDoHE, concomitant with up-regulation of LTB4R1, CMKLR1/ChemR23, and ALX/FPR2 SPM receptors. Notably, there is an impact on gingival macrophage plasticity was affected suggesting an inflammation resolving phenotype with sEH inhibition. In BMDMs, sEH inhibition reduced inflammatory macrophage activation, and resolving macrophages were triggered to produce SPMs.

CONCLUSION AND IMPLICATIONS

Pharmacological sEH inhibition increased SPM synthesis associated with resolving macrophages, suggesting a potential target to control osteolytic inflammatory disorders.

Chitinases and chitinase-like proteins in asthma

Despite the lack of endogenous chitin synthesis, mammalian genomes encode two enzymatically active true chitinases (chitotriosidase and acidic mammalian chitinase) and a variable number of chitinase-like proteins (CLPs) that have no enzyme activity but bind chitin. Chitinases and CLPs are prominent components of type-2 immune response-mediated respiratory diseases. However, despite extensive research into their role in allergic airway disease, there is still no agreement on whether they are mere biomarkers of disease or actual disease drivers. Functions ascribed to chitinases and CLPs include, but are not limited to host defense against chitin-containing pathogens, directly promoting inflammation, and modulating tissue remodeling and fibrosis. Here, we discuss in detail the chitin-dependent and -independent roles of chitinases and CLPs in the context of allergic airway disease, and recent advances and emerging concepts in the field that might identify opportunities for new therapies.

Irreversible evolutionary loss of chitin-degrading ability in the chitinase-like protein Ym1 under positive selection in rodents

Ym1 (chitinase-like 3, Chil3) expressed in mice is a nonenzymatic chitinase-like protein, which shows 67% identity with mouse acidic chitinase (Chia). Similar to Chia, Ym1 is overexpressed in asthma and parasitic infections in mouse lungs. Due to the lack of chitin-degrading activity, the biomedical role of Ym1 under these pathophysiological conditions remains to be determined. In this study, we investigated what region and amino acid changes in Ym1 resulted in the loss of enzymatic activity. Replacing two amino acids at the catalytic motif to obtain a Chia-like sequence (N136D and Q140E; MT-Ym1) did not activate the protein. We conducted a comparative study of Ym1 and Chia. We found that three protein segments-(i) the catalytic motif residues, (ii) exons 6 and 7, and (iii) exon 10-are responsible for chitinase activity loss in Ym1. We show that replacing each of these three segments in Chia that are also involved in substrate recognition and binding by the Ym1 sequence can fully abolish the enzymatic activity. In addition, we show that there have been extensive gene duplication events at the Ym1 locus specific to the rodent lineages. Consistent with this result, Ym1 orthologs from the rodent genome were under positive selection when analyzed through the CODEML program. These data suggest that numerous amino acid substitutions in the regions involved in the chitin recognition, binding, and degradation ability of the ancestor Ym1 molecule lead to the irreversible inactivation of the protein.

Discovery of 2H-Indazole-3-carboxamide Derivatives as Novel Potent Prostanoid EP4 Receptor Antagonists for Colorectal Cancer Immunotherapy

Nowadays, small-molecule drugs have become an indispensable part of tumor immunotherapy. Accumulating evidence has indicated that specifically blocking PGE₂/EP4 signaling to induce robust antitumor immune response represents an attractive immunotherapy strategy. Herein, a 2H-indazole-3-carboxamide containing compound 1 was identified as a EP4 antagonist hit by screening our in-house small-molecule library. Systematic structure-activity relationship exploration leads to the discovery of compound 14, which displayed single-nanomolar EP4 antagonistic activity in a panel of cell functional assays, high subtype selectivity, and favorable drug-like profiles. Moreover, compound 14 profoundly inhibited the up-regulation of multiple immunosuppression-related genes in macrophages. Oral administration of compound 14, either as monotherapy or in combination with an anti-PD-1 antibody, significantly impaired tumor growth via enhancing cytotoxic CD8⁺ T cell-mediated antitumor immunity in a syngeneic colon cancer model. Thus, these results demonstrate the potential of compound 14 as a candidate for developing novel EP4 antagonists for tumor immunotherapy.

Comparative tissue proteomics reveals unique action mechanisms of vaccine adjuvants

Radiofrequency adjuvant (RFA) was recently developed to boost influenza vaccination without the safety concerns of chemical adjuvants due to their physical nature. Yet, the action mechanisms of RFA remain largely unknown. Omics techniques offer new opportunities to identify molecular mechanisms of RFA. This study utilized comparative tissue proteomics to explore molecular mechanisms of the physical RFA. Comparison of RFA and chemical adjuvant (Alum, AddaVax, MPL, MPL/Alum)-induced tissue proteome changes identified 14 exclusively induced proteins by RFA, among which heat shock protein (HSP) 70 was selected for further analysis due to its known immune-modulating functions. RFA showed much weakened ability to boost ovalbumin and pandemic influenza vaccination in HSP70 knockout than wild-type mice, hinting crucial roles of HSP70 in RFA effects. This study supports comparative tissue proteomics to be an effective tool to study molecular mechanisms of vaccine adjuvants.

Recombinant Expression of Human IL-33 Protein and Its Effect on Skin Wound Healing in Diabetic Mice

Chronic refractory wounds are one of the complications of diabetes mellitus that require effective therapy. The dermal-wound-healing property of IL-33 in diabetics is little understood. Therefore, this study aimed to express recombinant humanized mature IL-33 (rhmatIL-33) in Escherichia coli BL21 (DE3) and demonstrate its efficacy on dermal wounds in streptozotocin (STZ)-induced diabetic and nondiabetic mice by the dorsal incisional skin wound model. Results revealed that the rhmatIL-33 accelerated the scratch-healing of keratinocytes and fibroblasts at the cellular level. The wounds of diabetic mice (DM) showed more severe ulceration and inflammation than wild-type mice (WT), and the exogenous administration of rhmatIL-33 increased wound healing in both diabetic and wild-type mice. Compared with the up-regulation of endogenous IL-33 mRNA after injury in WT mice, the IL-33 mRNA decreased after injury in DM mice. Exogenous IL-33 administration increased the endogenous IL-33 mRNA in the DM group but decreased the IL-33 mRNA expression level of the WT group, indicating that IL-33 plays a balancing role in wound healing. IL-33 administration also elevated ILC2 cells in the wounds of diabetic and non-diabetic mice and improve the transcript levels of YM1, a marker of M2 macrophages. In conclusion, Hyperglycemia in diabetic mice inhibited the expression of IL-33 in the dermal wound. Exogenous addition of recombinant IL-33 promoted wound healing in diabetic mice by effectively increasing the level of IL-33 in wound tissue, increasing ILC2 cells, and accelerating the transformation of macrophage M1 to M2 phenotype.

Microglia in Circumventricular Organs: The Pineal Gland Example

The circumventricular organs (CVOs) are unique areas within the central nervous system. They serve as a portal for the rest of the body and, as such, lack a blood-brain barrier. Microglia are the primary resident immune cells of the brain parenchyma. Within the CVOs, microglial cells find themselves continuously challenged and stimulated by local and systemic stimuli, even under steady-state conditions. Therefore, CVO microglia in their typical state often resemble the activated microglial forms found elsewhere in the brain as they are responding to pathological conditions or other stressors. In this review, I focus on the dynamics of CVO microglia, using the pineal gland as a specific CVO example. Data related to microglia heterogeneity in both homeostatic and unhealthy environments are presented and discussed, including those recently generated by using advanced single-cell and single-nucleus technology. Finally, perspectives in the CVO microglia field are also included.Summary StatementMicroglia in circumventricular organs (CVOs) continuously adapt to react differentially to the diverse challenges they face. Herein, I discuss microglia heterogeneity in CVOs, including pineal gland. Further studies are needed to better understand microglia dynamics in these unique brain areas. .

An update on Ym1 and its immunoregulatory role in diseases

Ym1 is a rodent-specific chitinase-like protein (CLP) lacking catalytic activity, whose cellular origins are mainly macrophages, neutrophils and other cells. Although the detailed function of Ym1 remains poorly understood, Ym1 has been generally recognized as a fundamental feature of alternative activation of macrophages in mice and hence one of the prevalent detecting targets in macrophage phenotype distinguishment. Studies have pointed out that Ym1 may have regulatory effects, which are multifaceted and even contradictory, far more than just a mere marker. Allergic lung inflammation, parasite infection, autoimmune diseases, and central nervous system diseases have been found associations with Ym1 to varying degrees. Thus, insights into Ym1’s role in diseases would help us understand the pathogenesis of different diseases and clarify the genuine roles of CLPs in mammals. This review summarizes the information on Ym1 from the gene to its expression and regulation and focuses on the association between Ym1 and diseases.

Dexmedetomidine Activates Akt, STAT6 and IRF4 Modulating Cytoprotection and Macrophage Anti-Inflammatory Phenotype Against Acute Lung Injury in vivo and in vitro

Purpose

This study aims to investigate the cytoprotective and anti-inflammatory effects of an α₂-adrenoreceptor (α₂-AR) agonist, dexmedetomidine (Dex), on lipopolysaccharides (LPS)-induced acute lung injury and underlying mechanisms with focus on alveolar macrophage polarization modulation.

Methods

C57BL/6 mice were intraperitoneally injected LPS (10 mg/kg) with or without Dex (25 µg/kg) and/or α₂-AR antagonist atipamezole (Atip, 500 µg/kg). Lung tissues were then analysed to determine injuries. In vitro, human pulmonary epithelial cells (A549) and mice alveolar macrophages (MH-S) were exposed to LPS (10 ng/mL) with or without different concentrations of Dex (0.1–100 nM). Alveolar macrophage polarization, NLRP3 inflammasome activation and inflammatory responses were determined. PTEN/Akt signaling and its downstream transcriptional factors as targets for macrophage polarization were assessed.

Results

Dex treatment significantly reduced pro-inflammatory M1 macrophage polarization and NLRP3 inflammasome activation in the lungs relative to the mice treated with LPS. The similar pattern reduction of NLRP3 inflammasome activation by Dex was also found in A549 cells. Atip partly reversed the anti-inflammatory effects of Dex. In cultured alveolar macrophages, Dex reduced LPS-mediated expression of IL-1, −6 and TNF-α receptors while promoting alveolar macrophages differentiation towards a M2 anti-inflammatory phenotype. Additionally, LPS increased Akt signaling activation in a time-dependent manner, which was further activated by Dex via inhibiting phosphatase and tensin homolog (PTEN). The action of Dex on Akt signaling shifted alveolar macrophages from M1 to M2 phenotype through increasing STAT6 and IRF4 transcriptional factors.

Conclusion

Dex protected against LPS-induced lung injury and suppressed LPS-induced pulmonary inflammatory responses by attenuating the NLRP3 inflammasome activation and promoting anti-inflammatory M2 macrophage polarization.

Tryptophan-derived microbial metabolites activate the aryl hydrocarbon receptor in tumor-associated macrophages to suppress anti-tumor immunity

The aryl hydrocarbon receptor (AhR) is a sensor of products of tryptophan metabolism and a potent modulator of immunity. Here, we examined the impact of AhR in tumor-associated macrophage (TAM) function in pancreatic ductal adenocarcinoma (PDAC). TAMs exhibited high AhR activity and Ahr-deficient macrophages developed an inflammatory phenotype. Deletion of Ahr in myeloid cells or pharmacologic inhibition of AhR reduced PDAC growth, improved efficacy of immune checkpoint blockade, and increased intra-tumoral frequencies of IFNγ⁺CD8⁺ T cells. Macrophage tryptophan metabolism was not required for this effect. Rather, macrophage AhR activity was dependent on Lactobacillus metabolization of dietary tryptophan to indoles. Removal of dietary tryptophan reduced TAM AhR activity and promoted intra-tumoral accumulation of TNFα⁺IFNγ⁺CD8⁺ T cells; provision of dietary indoles blocked this effect. In patients with PDAC, high AHR expression associated with rapid disease progression and mortality, as well as with an immune-suppressive TAM phenotype, suggesting conservation of this regulatory axis in human disease.

Ncf1 Governs Immune Niches in the Lung to Mediate Pulmonary Inflammation in Mice

Neutrophil cytosolic factor 1 (Ncf1) is a major genetic factor associated with autoimmune diseases and has been identified as a key player in autoimmune mediated inflammation. We addressed the role of Ncf1 in an antigen-induced pulmonary inflammation model, and found that the Ncf1^m1j mutation, causing a deficient reactive oxygen species response, alleviated disease. The Ncf1^m1j mutation was associated with a reduced inflammatory cell infiltration in airways, but had limited effect on mucus secretion, antibody production and lung fibrosis. The disease remission in the Ncf1 mutated mice was reversed when functional Ncf1 was transgenically expressed in alveolar macrophages, suggesting that the cellular inflammation was depended on functional Ncf1 in alveolar macrophages. By determining cytokine and chemokine profiles in lung and serum, we found that Ncf1 deficiency allowed an increased expression of Th1 cytokines, including TNF-α, IFN-γ and IL-12. Since also epithelial cytokines were found to be regulated by Ncf1, we tested the effect of Ncf1 in IL-33 and IL-25 induced lung inflammation models. Mice with the Ncf1^m1j mutation showed less sensitivity to IL-33, but not IL-25, induced lung inflammation, in a macrophage independent manner. The mice with deficient Ncf1 showed a reduced eosinophil infiltration and group 2 innate lymphoid cell (ILC2) activation. The production of IFN-γ in CD4⁺ T cells was increased, whereas IL-5 and IL-13 in ILC2 were decreased. Importantly, anti-IFN-γ antibody treatment of Ncf1 deficient mice increased eosinophil infiltration and rescued ILC2 activation in the lung. We conclude that Ncf1 deficiency enhances Th1 response, deactivates ILC2, and protects against pulmonitis.

Charcot-Leyden crystals and other protein crystals driving type 2 immunity and allergy

Protein crystals derived from innate immune cells have been synonymous with a Type-2 immune response in both mouse and man for over 150 years. Eosinophilic Galectin-10 (Charcot-Leyden) crystals in humans, and Ym1/Ym2 crystals in mice are frequently found in the context of parasitic infections, but also in diseases such as asthma and chronic rhinosinusitis. Despite their notable presence, these crystals are often overlooked as trivial markers of Type-2 inflammation. Here, we discuss the source, context, and role of protein crystallization. We focus on similarities observed between Galectin-10 and Ym1/2 crystals in driving immune responses; the subsequent benefit to the host during worm infection, and conversely the detrimental exacerbation of inflammation and mucus production during asthma.

Natural Loss-of-Function Mutations in Qa2 and NCF1 Cause the Spread of Mannan-Induced Psoriasis

A basis for the genetic predisposition to psoriasis is a single locus, PSORS1, within the major histocompatibility complex I region. This murine major histocompatibility complex locus encodes nonclassical molecules such as Qa2. We hypothesized that a natural loss-of-function variant of Qa2 gene clusters promotes psoriasis. In this study, we have developed a mannan-induced psoriasis model with the double deficiency of Qa2 and ROS owing to natural mutations of Qa2 gene clusters and the Ncf1 gene in the C57BL/6 background, respectively. We report three key findings in mice with mannan-induced psoriasis. A complete deficiency of Qa2 resulted in the expansion of IL-17‒producing γδ T cells and group 3 innate lymphoid cells in draining lymph nodes, leading to ear psoriasis. A single copy of Qa2-encoding genes was enough to protect against mannan-induced psoriasis, and such a protection was erased by a mutated Ncf1. Double defects with Qa2 and Ncf1 elicited a spread of exaggerated ear psoriasis to the nails, and the deficiency of γδ T cells reduced the severity of nail psoriasis. Collectively, these findings in mice provide evidence for the importance of Ncf1 mutations and Qa2 gene clusters, possibly corresponding to the PSORS1 locus in the spread of psoriasis.