sNASP inhibits TLR signaling to regulate immune response in sepsis

NASP gene contributes to autism by epigenetic dysregulation of neural and immune pathways

BACKGROUND

Epigenetics makes substantial contribution to the aetiology of autism spectrum disorder (ASD) and may harbour a unique opportunity to prevent the development of ASD. We aimed to identify novel epigenetic genes involved in ASD aetiology.

METHODS

Trio-based whole exome sequencing was conducted on ASD families. Genome editing technique was used to knock out the candidate causal gene in a relevant cell line. ATAC-seq, ChIP-seq and RNA-seq were performed to investigate the functional impact of knockout (KO) or mutation in the candidate gene.

RESULTS

We identified a novel candidate gene NASP (nuclear autoantigenic sperm protein) for epigenetic dysregulation in ASD in a Chinese nuclear family including one proband with autism and comorbid atopic disease. The de novo likely gene disruptive variant tNASP(Q289X) subjects the expression of tNASP to nonsense-mediated decay. tNASP KO increases chromatin accessibility, promotes the active promoter state of genes enriched in synaptic signalling and leads to upregulated expression of genes in the neural signalling and immune signalling pathways. Compared with wild-type tNASP, tNASP(Q289X) enhances chromatin accessibility of the genes with enriched expression in the brain. RNA-seq revealed that genes involved in neural and immune signalling are affected by the tNASP mutation, consistent with the phenotypic impact and molecular effects of nasp-1 mutations in Caenorhabditis elegans. Two additional patients with ASD were found carrying deletion or deleterious mutation in the NASP gene.

CONCLUSION

We identified novel epigenetic mechanisms mediated by tNASP which may contribute to the pathogenesis of ASD and its immune comorbidity.

Claudin-2 upregulation enhances intestinal permeability, immune activation, dysbiosis, and mortality in sepsis

Intestinal epithelial expression of the tight junction protein claudin-2, which forms paracellular cation and water channels, is precisely regulated during development and in disease. Here, we show that small intestinal epithelial claudin-2 expression is selectively upregulated in septic patients. Similar changes occurred in septic mice, where claudin-2 upregulation coincided with increased flux across the paracellular pore pathway. In order to define the significance of these changes, sepsis was induced in claudin-2 knockout (KO) and wild-type (WT) mice. Sepsis-induced increases in pore pathway permeability were prevented by claudin-2 KO. Moreover, claudin-2 deletion reduced interleukin-17 production and T cell activation and limited intestinal damage. These effects were associated with reduced numbers of neutrophils, macrophages, dendritic cells, and bacteria within the peritoneal fluid of septic claudin-2 KO mice. Most strikingly, claudin-2 deletion dramatically enhanced survival in sepsis. Finally, the microbial changes induced by sepsis were less pathogenic in claudin-2 KO mice as survival of healthy WT mice injected with cecal slurry collected from WT mice 24 h after sepsis was far worse than that of healthy WT mice injected with cecal slurry collected from claudin-2 KO mice 24 h after sepsis. Claudin-2 upregulation and increased pore pathway permeability are, therefore, key intermediates that contribute to development of dysbiosis, intestinal damage, inflammation, ineffective pathogen control, and increased mortality in sepsis. The striking impact of claudin-2 deletion on progression of the lethal cascade activated during sepsis suggests that claudin-2 may be an attractive therapeutic target in septic patients.

sNASP Mutation Aggravates to the TLR4-Mediated Inflammation in SLE by TAK1 Pathway

Genetic factors play an important role in the pathogenesis of systemic lupus erythematosus (SLE), and abnormal Toll-like receptor (TLR) signaling pathways are closely related to the onset of SLE. In previous studies, we found that the mutant somatic nuclear autoantigenic sperm protein (sNASP) gene in the mouse lupus susceptibility locus Sle2 can promote the development of lupus model mice, but the mechanism is still unclear. Here, we stimulated mouse peritoneal macrophages with different concentrations of lipopolysaccharide. The results showed that sNASP gene mutations can promote the response of the TLR4-TAK1 signaling pathway but have no significant effect on the TLR4-TBK1 signaling pathway. sNASP mutations enhanced TLR4-mediated nuclear factor-κ-gene binding and mitogen-activated protein kinase activation and IL-6, tumor necrosis factor secretion in murine peritoneal macrophages. Collectively, our study revealed the impact of sNASP gene mutation on the sensitivity of TLR4 receptors in mouse peritoneal macrophages and shed light on potential mechanisms underlying inflammation in autoimmune diseases.

Protective effects of S100A8 on sepsis mortality: Links to sepsis risk in obesity and diabetes

Obesity and diabetes are independent risk factors for death during sepsis. S100A8, an alarmin, is related to inflammation, obesity, and diabetes. Here, we examine the role of S100A8 in sepsis of obesity and diabetes models. Injection of S100A8 prolongs the survival of septic mice induced by lethal endotoxemia, Escherichia coli injection, or cecal ligation and puncture. S100A8 decrease the LPS-induced expression of proinflammatory cytokines in peritoneal macrophages by inhibiting TLR4-mediated signals in an autocrine manner. db/db, ob/ob, and western diet-fed mice demonstrate reduced upregulation of S100A8 induced by LPS treatment in both serum and peritoneal cells. These mice also show shorter survival after LPS injection, and S100A8 supplementation prolonged the survival. While myelomonocytic cells-specific S100A8-deficient mice (Lyz2 ^cre :S100A8 ^{floxed/floxed} ) exhibit shorter survival after LPS treatment, S100A8 supplementation prolonged the survival. Thus, myelomonocytic cell-derived S100A8 is crucial for protection from sepsis, and S100A8 supplementation improves sepsis, particularly in mice with obesity and diabetes.

Home Dust Mites Promote MUC5AC Hyper-Expression by Modulating the sNASP/TRAF6 Axis in the Airway Epithelium

House dust mites (HDMs) are a common source of respiratory allergens responsible for allergic asthma and innate immune responses in human diseases. Since HDMs are critical factors in the triggering of allergen-induced airway mucosa from allergic asthma, we aimed to investigate the mechanisms of Toll-like receptors (TLR) in the signaling of the HDM extract that is involved in mucus hypersecretion and airway inflammation through the engagement of innate immunity. Previously, we reported that the somatic nuclear autoantigenic sperm protein (sNASP)/tumor necrosis factor receptor-associated factor 6 (TRAF6) axis controls the initiation of TLRs to maintain the homeostasis of the innate immune response. The present study showed that the HDM extract stimulated the biogenesis of Mucin 5AC (MUC5AC) in bronchial epithelial cells via the TLR2/4 signaling pathway involving MyD88 and TRAF6. Specifically, sNASP binds to TRAF6 in unstimulated bronchial epithelial cells to prevent the activation of TRAF6-depenedent kinases. Upon on HDMs’ stimulation, sNASP is phosphorylated, leading to the activation of TRAF6 downstream of the p38 MAPK and NF-κB signaling pathways. Further, NASP-knockdown enhanced TRAF6 signaling and MUC5AC biogenesis. In the HDM-induced mouse asthma model, we found that the HDM extract promoted airway hyperresponsiveness (AHR), MUC5AC, and allergen-specific IgE production as well as IL-5 and IL-13 for recruiting inflammatory cells. Treatment with the PEP-NASP peptide, a selective TRAF6-blocking peptide, ameliorated HDM-induced asthma in mice. In conclusion, this study indicated that the sNASP/TRAF6 axis plays a regulatory role in asthma by modulating mucus overproduction, and the PEP-NASP peptide might be a potential target for asthma treatment.

PEP-sNASP Peptide Alleviates LPS-Induced Acute Lung Injury Through the TLR4/TRAF6 Axis

Acute lung injury (ALI) is a severe inflammatory lung disease associated with macrophages. Somatic nuclear autoantigenic sperm protein (sNASP) is a negative regulator of Toll-like receptor (TLR) signaling that targets tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) in macrophages, which is required to maintain homeostasis of the innate immune response. In the present study, we generated a cell permeable PEP-sNASP peptide using the sNASP protein N-terminal domain, and examined its potential therapeutic effect in a mouse model of ALI induced by the intranasal administration of lipopolysaccharide (LPS) and elucidated the underlying molecular mechanisms in RAW 264.7 cells. In vivo, PEP-sNASP peptide treatment markedly ameliorated pathological injury, reduced the wet/dry (W/D) weight ratio of the lungs and the production of proinflammatory cytokines (interleukin (IL)-1β, IL-6, and TNF-α). In vitro, we demonstrated that when the PEP-sNASP peptide was transduced into RAW 264.7 cells, it bound to TRAF6, which markedly decreased LPS-induced proinflammatory cytokines by inhibiting TRAF6 autoubiquitination, nuclear factor (NF)-κB activation, reactive oxygen species (ROS) and cellular nitric oxide (NO) levels. Furthermore, the PEP-sNASP peptide also inhibited NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. Our results therefore suggest that the PEP-sNASP may provide a potential protein therapy against oxidative stress and pulmonary inflammation via selective TRAF6 signaling.

Somatic nuclear auto-antigenic sperm protein sensitizes human breast cancer cells to 5-Fluorouracil

PURPOSE

To assess the potential role of nuclear auto-antigenic sperm protein (NASP) in the cellular sensitivity to 5-Fluorouracil (5-FU) in breast cancer cells.

METHODS

The expression of two NASP isotypes, namely somatic NASP (sNASP) and testis NASP (tNASP) in breast cancer lines were detected under 5-FU treatment using real-time polymerase chain reaction and western blot assays. NASP effect on cellular viability and apoptosis under 5-FU treatment were evaluated. The interaction between NASP and its downstream proteins were evaluated using the co-immunoprecipitation (Co-IP) assays.

RESULTS

5-FU significantly decreased the mRNA and protein expression levels of sNASP. Inhibition of sNASP increased cellular viability, colony formation ability, but reduced apoptosis in tested cell lines in response to 5-FU, which were reversed by sNASP over-expression. Further study reveals 5-FU disrupts sNASP/TNF receptor-associated factor 6 (TRAF6) complex, potentiates cellular sensitivity to 5-FU via NK-kB.

CONCLUSION

Our findings suggest sNASP is a novel molecular target having potential to overcome the resistance to 5-FU in breast cancer cells.

Argonaute-2 protects the neurovascular unit from damage caused by systemic inflammation

BACKGROUND

The brain vasculature plays a pivotal role in the inflammatory process by modulating the interaction between blood cells and the neurovascular unit. Argonaute-2 (Ago2) has been suggested as essential for endothelial survival but its role in the brain vasculature or in the endothelial-glial crosstalk has not been addressed. Thus, our aim was to clarify the significance of Ago2 in the inflammatory responses elicited by these cell types.

METHODS

Mouse primary cultures of brain endothelial cells, astrocytes and microglia were used to evaluate cellular responses to the modulation of Ago2. Exposure of microglia to endothelial cell-conditioned media was used to assess the potential for in vivo studies. Adult mice were injected intraperitoneally with lipopolysaccharide (LPS) (2 mg/kg) followed by three daily intraperitoneal injections of Ago2 (0.4 nM) to assess markers of endothelial disruption, glial reactivity and neuronal function.

RESULTS

Herein, we demonstrated that LPS activation disturbed the integrity of adherens junctions and downregulated Ago2 in primary brain endothelial cells. Exogenous treatment recovered intracellular Ago2 above control levels and recuperated vascular endothelial-cadherin expression, while downregulating LPS-induced nitric oxide release. Primary astrocytes did not show a significant change in Ago2 levels or response to the modulation of the Ago2 system, although endogenous Ago2 was shown to be critical in the maintenance of tumor necrosis factor-α basal levels. LPS-activated primary microglia overexpressed Ago2, and Ago2 silencing contained the inflammatory response to some extent, preventing interleukin-6 and nitric oxide release. Moreover, the secretome of Ago2-modulated brain endothelial cells had a protective effect over microglia. The intraperitoneal injection of LPS impaired blood-brain barrier and neuronal function, while triggering inflammation, and the subsequent systemic administration of Ago2 reduced or normalized endothelial, glial and neuronal markers of LPS damage. This outcome likely resulted from the direct action of Ago2 over the brain endothelium, which reestablished glial and neuronal function.

CONCLUSIONS

Ago2 could be regarded as a putative therapeutic agent, or target, in the recuperation of the neurovascular unit in inflammatory conditions.

Regulation of TLR4 signaling through the TRAF6/sNASP axis by reversible phosphorylation mediated by CK2 and PP4

Recognition of invading pathogens by Toll-like receptors (TLRs) activates innate immunity through signaling pathways that involved multiple protein kinases and phosphatases. We previously demonstrated that somatic nuclear autoantigenic sperm protein (sNASP) binds to TNF receptor-associated factor 6 (TRAF6) in the resting state. Upon TLR4 activation, a signaling complex consisting of TRAF6, sNASP, interleukin (IL)-1 receptor-associated kinase 4, and casein kinase 2 (CK2) is formed. CK2 then phosphorylates sNASP to release phospho-sNASP (p-sNASP) from TRAF6, initiating downstream signaling pathways. Here, we showed that protein phosphatase 4 (PP4) is the specific sNASP phosphatase that negatively regulates TLR4-induced TRAF6 activation and its downstream signaling pathway. Mechanistically, PP4 is directly recruited by phosphorylated sNASP to dephosphorylate p-sNASP to terminate TRAF6 activation. Ectopic expression of PP4 specifically inhibited sNASP-dependent proinflammatory cytokine production and downstream signaling following bacterial lipopolysaccharide (LPS) treatment, whereas silencing PP4 had the opposite effect. Primary macrophages and mice infected with recombinant adenovirus carrying a gene encoding PP4 (Ad-PP4) showed significant reduction in IL-6 and TNF-α production. Survival of Ad-PP4-infected mice was markedly increased due to a better ability to clear bacteria in a sepsis model. These results indicate that the serine/threonine phosphatase PP4 functions as a negative regulator of innate immunity by regulating the binding of sNASP to TRAF6.

A Variant of sNASP Exacerbates Lymphocyte Subset Disorder and Nephritis in a Spontaneous Lupus Model Sle1.Yaa Mouse

A variant of somatic nuclear autoantigenic sperm protein (sNASP) was identified from the murine lupus susceptibility locus Sle2c1 by whole exome sequencing (WES). Previous studies have shown that mutant sNASP could synergize with the Fas^lpr mutation in exacerbating autoimmunity and aggravating end-organ inflammation. In the current study, the sNASP mutation was introduced into Sle1.Yaa mice to detect whether it has a synergistic effect with Sle1 or Yaa loci. As expected, compared with Sle1.Yaa mice, Sle1.Yaa.ΔsNASP mice showed enlarged lymph nodes, aggravated renal inflammation, and shortened survival time. The proportions of CD3⁺ T cells, activated CD19⁺CD86⁺ B cells, Th1 cells in the spleen and lymph nodes, and Th17 cells in lymph nodes in Sle1.Yaa.ΔsNASP mice were increased compared to those in Sle1.Yaa mice. The levels of IFN-γ and TNF-α in the serum of Sle1.Yaa.ΔsNASP mice were higher than those of Sle1.Yaa mice. The above results show that mutant sNASP can interact with different lupus susceptibility genes and promote the disease process of systemic lupus erythematosus.

Hydrogen Sulfide Attenuated Sepsis-Induced Myocardial Dysfunction Through TLR4 Pathway and Endoplasmic Reticulum Stress

Aims: We examined the change in endogenous hydrogen sulfide (H₂S) production and its role in sepsis-induced myocardial dysfunction (SIMD). Results: Significant elevations in plasma cardiac troponin I (cTnI), creatine kinase (CK), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were noted in SIMD patients, whereas left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and plasma H₂S were significantly decreased relative to those in the controls. Plasma H₂S was linearly related to LVEF and LVFS. Subsequently, an SIMD model was developed in mice by injecting lipopolysaccharide (LPS), and NaHS, an H₂S donor, was used to elucidate the pathophysiological role of H₂S. The mice showed decreased ventricular function and increased levels of TNF-α, IL-1β, cTnI, and CK after LPS injections. Toll-like receptor (TLR) 4 protein and endoplasmic reticulum stress (ERS) proteins were over expressed in the SIMD mice. All of the parameters above showed more noticeable variations in cystathionine γ-lyase knockout mice relative to those in wild type mice. The administration of NaHS could improve ventricular function and attenuate inflammation and ERS in the heart. Conclusion: Overall, these findings indicated that endogenous H₂S deficiency contributed to SIMD and exogenous H₂S ameliorated sepsis-induced myocardial dysfunction by suppressing inflammation and ERS via inhibition of the TLR4 pathway.

JNK selective inhibitor, IQ-1S, protects the mice against lipopolysaccharides-induced sepsis

Sepsis is a severe systemic inflammatory response induced by infection. Innate immunity recognizes pathogen components such as lipopolysaccharides (LPS), and mediates the polarization of immune cells and the release of cytokines. However, this process is also crucial for triggering sepsis and septic shock. To investigate the potential therapeutic function of 11H-indeno [1,2-b] quinoxalin-11-one oxime (IQ-1S) to sepsis, LPS plus d-galactosamine was used to establish a sepsis mouse model. Flow cytometry was performed to catalyze T cells and macrophages in mouse spleen. ELISA assay and qRT-PCR assay were performed to estimate the expression levels of cytokines and related genes including TNF-α, IL-6, IL-1β, Nos2, Arg and Mrc. The protein levels of NF-κB, AP1, NF-Y, p-JNK2, JNK2, p-p38, p38, p-IκBα, IκBα, p-IKKβ and IKKβ were evaluated by Western blot assay. IQ-1S treatment significantly reduced mortality and lung inflammation in sepsis mice. IQ-1S treatment decreased the levels of inflammatory cytokines in sepsis mice. Polarization of M1 macrophages was suppressed by IQ-1S in vitro. IQ-1S significantly inhibited the activation of the JNK signaling pathway and reduced the phosphorylation level of JNK2 in sepsis mice. IQ-1S protected the mice against LPS-induced sepsis through inhibiting JNK signaling pathway.

Integration Analysis of m6A-SNPs and eQTLs Associated With Sepsis Reveals Platelet Degranulation and Staphylococcus aureus Infection are Mediated by m6A mRNA Methylation

Sepsis is a major threat with high mortality rate for critically ill patients. Response to pathogen infection by the host immune system is a key biological process involved in the onset and development of sepsis. Heterogeneous host genome variation, especially single nucleotide polymorphisms (SNPs), has long been suggested to contribute to differences in disease progression. However, the function of SNPs located in non-coding regions remains to be elucidated. Recently, m⁶A mRNA modification levels were revealed to differ at SNPs. As m⁶A is a crucial regulator of gene expression, these SNPs might control genes by changing the m⁶A level on mRNA. To investigate the potential role of m⁶A SNPs in sepsis, we integrated m⁶A-SNP and expression quantitative trait loci (eQTLs) data. Analysis revealed 15,720 m⁶A-cis-eQTLs and 381 m⁶A-trans-eQTLs associated with sepsis. We identified 1321 genes as locations of m⁶A-cis-eQTLs. These were enriched in platelet degranulation and Staphylococcus aureus infection pathways, which are vital for the pathophysiological process of sepsis. We conclude that m⁶A modification of mRNA plays a very important role in sepsis, with m⁶A-cis-eQTLs potentially having the most effect on individual variation in sepsis progression.

Molecular immune mechanisms of HPV-infected HaCaT cells in vitro based on toll-like receptors signaling pathway

OBJECTIVE

To explore the molecular immune mechanism of HPV-infected HaCaT cells in vitro based on TLRs signaling pathway by analyzing the effects of interfering TLRs on inflammatory and immune factors in the signaling pathway.

METHODS

FCM was used to analyze the proportion of Th1, Th2, Th17, and Treg cells in blood samples. HPV-infected HaCaT cells were divided into five groups: A, B, C, D, and E. Group A added TLR3 antagonist, group B added TLR9 antagonist, group C added equivalent saline, group D added IRF3 agonist, and group E added IRF3 inhibitor. Immunohistochemistry was used to analyze the expression of TLR3 and TLR9 in HaCaT cell model; ELISA was used to analyze the expression of inflammatory factors IL-2, TNF-a, and IFN-beta; WB was used to analyze the expression of TRAF3, IKK epsilon, and TBK1; RT-PCR was used to analyze the expression of IRF3 and IRF7 in each cell model.

RESULTS

The proportion of blood immune cells in patients with HPV infection was Th1, Th17, Th2, and Treg, with statistical significance (P < .05); the expression of TLR3 and TLR9 in HPV-infected cells was higher than that in negative control group, with statistical significance (P < .05); TLR3 was higher than TLR9, with no significant difference (P > .05); the expression of IL-2, TNF-alpha, IFN-beta in each group, TLR3, and TLR9 was higher than that in negative control group (P < .05). The expression of TRAF3, IKK epsilon, and TBK1 in the control group was higher than that in the TLR3 and TLR9 inhibitor groups, and the expression of IRF3 and IRF7 in the TLR9 inhibitor group was higher than that in the TLR3 inhibitor group (P < .05); the expression of IRF3 and IRF7 in the TLR3i and TLR9i inhibitor groups was lower than that in the TLR3 inhibitor group (P < .05). Compared with the control group, IRF3a group was higher than the control group, IRF3i group was lower than the control group, the difference was statistically significant (P < .05).

CONCLUSION

TLR3 and TLR9, the key factors of TLRs, are highly expressed in HaCaT cells infected with HPV. Through TLRs-IKK-e-IRFs-IFN signaling pathway, they can induce high expression of inflammatory factors, IKK-e, IRFs, and IFN, and improve immunity.

Mitigation of acetamiprid - induced renotoxicity by natural antioxidants via the regulation of ICAM, NF-kB and TLR 4 pathways

BACKGROUND

Acetamiprid (ACMP) is a member of the neonicotinoid group of insecticides. It is extensively used worldwide. The misuse of ACMP creates danger hazards to human and animal.

METHODS

ACMP induced renal damage evidenced by an increase in kidney injury biomarkers. So the goal of this work is to clarify the reno protective effect of Quercetin (Qrctn) and/or Nano-glutathione (N-Gluta) solely or in combination to counterbalance the danger effect of ACMP. All treatments with the previous agents were coadministered orally with ACMP for one month.

RESULTS

ACMP ingestion caused a significant rise in serum creatinin, urea, and uric acid, TNF α along with renal cystatin C, lipid peroxidation and nitric oxide with the concomitant decline in the levels of reduced glutathione and IL-10 levels. Protein expression of ICAM was upregulated as well as mRNA expression of NF-κB while mRNA expression of Nrf2 was down-regulated. Immune histochemistry of TLR 4 revealed strong immune reaction. The administration of Qrctn or N-Gluta either individually or together modulated all the preceding aforementioned parameters.

CONCLUSION

Fascinatingly Qrctn and N-Gluta combination was the most powerful regimen to frustrate ACMP reno-toxicity and may be deliberate as a hopeful applicant for renal therapy.

Inhibition of PTP1B Promotes M2 Polarization via MicroRNA-26a/MKP1 Signaling Pathway in Murine Macrophages

Sepsis is a life-threatening condition that often occurs in the intensive care unit. The excessive activation of the host's immune system at early stages contributes to multiple organ damage. Mitogen-activated protein kinase phosphatase-1 (MKP1) exerts an important effect on the inflammatory process. In our recent bioinformatic analysis, we confirmed that the inhibition of protein tyrosine phosphatase-1B (PTP1B) significantly promoted the expression of MKP1 in murine macrophages. However, the underlying mechanism and its effect on macrophage polarization remain unclear. In this study, we show that the suppression of PTP1B induced upregulation of MKP1 in M1 macrophages. A RayBiotech mouse inflammation antibody assay further revealed that MKP1-knockdown promoted pro-inflammatory cytokine (IL-1β, IL12p70, IL-17, IL-21, IL-23, and TNF-α) secretion but suppressed anti-proinflammatory cytokine (IL-10) production in M2 macrophages. Phospho-proteomics analysis further identified ERK1/2 and p38 as downstream molecules of MKP1. Moreover, we found that the inhibition of PTP1B lowered the expression of miR-26a, showing a negative correlation with MKP1 protein expression. Thus, we concluded that the inhibition of PTP1B contributes to M2 macrophage polarization via reducing mir-26a and afterwards enhancing MKP1 expression in murine macrophages.

A Variant of the Histone-Binding Protein sNASP Contributes to Mouse Lupus

The Sle2c1rec1c (rec1c) sublocus is derived from the mouse lupus susceptibility 2 (Sle2) locus identified in the NZM2410 model. Our current study dissected the functional characters and the genetic basis of the rec1c locus relative to lupus when co-expressed with the Fas^lpr mutation, an established inducer of autoimmunity. The rec1c.lpr mice exhibited mild expansion of lymph nodes and had a normal T cell cellularity, but developed significantly kidney and lung inflammation, indicating that the rec1c amplifies lpr-induced autoimmune pathogenesis. A variant of somatic nuclear autoantigenic sperm protein (sNASP) was identified from the rec1c interval as a substitution of two consecutive amino acid residues in the histone-binding domain, resulting in an increased binding affinity to histone H4 and H3.1/H4 tetramer. To determine the role of the sNASP rec1c allele in mouse lupus, a novel strain was generated by introducing the rec1c mutations into the B6 genome. In this transgenic model, the sNASP allele synergized with the lpr mutation leading to moderate autoimmune phenotypes and aggravating inflammatory pathology alterations in kidney and lung that were similar to those observed in the rec1c.lpr mice. These results establish that the sNASP allele is a pathogenic genetic element in the rec1c sublocus, which not only promotes autoimmunity, but also exacerbates the inflammation reaction of end organs in mouse lupus pathogenesis. It also shows the complexity of the Sle2c locus, initially mapped as the major locus associated with B1a cell expansion. In addition to Cdkn2c, which regulates this expansion, we have now identified in the same locus a protective allele of Csf3r, a variant of Skint6 associated with T cell activation, and now a variant of sNASP that amplifies autoimmunity and tissue damage.

Evodiamine Augments NLRP3 Inflammasome Activation and Anti-bacterial Responses Through Inducing α-Tubulin Acetylation

Evodiamine is a major ingredient of the plant Evodia rutaecarpa, which has long been used for treating infection-related diseases including diarrhea, beriberi and oral ulcer, but the underlying mechanism is unclear. Here we aimed to explore whether evodiamine influenced NLRP3 (NLR family, pyrin containing domain 3) inflammasome activation in macrophages, which is a critical mechanism for defending the host against pathogenic infections. We uncovered that evodiamine dose-dependently enhanced NLRP3 inflammasome activation in lipopolysaccharide-primed macrophages, as indicated by increased interleukin (IL)-1β production and caspase-1 cleavage, accompanied by increased ASC speck formation and pyroptosis. Mechanistically, evodiamine induced acetylation of α-tubulin around the microtubule organization center (indicated by γ-tubulin) in lipopolysaccharide-primed macrophages. Such evodiamine-mediated increases in NLRP3 activation and pyroptosis were attenuated by activators of α-tubulin deacetylase, resveratrol and NAD⁺, or dynein-specific inhibitor ciliobrevin A. Small interfering RNA knockdown of αTAT1 (the gene encoding α-tubulin N-acetyltransferase) expression, which reduced α-tubulin acetylation, also diminished evodiamine-mediated augmentation of NLRP3 activation and pyroptosis. Evodiamine also enhanced NLRP3-mediated production of IL-1β and neutrophil recruitment in vivo. Moreover, evodiamine administration evidently improved survival of mice with lethal bacterial infection, accompanied by increased production of IL-1β and interferon-γ, decreased bacterial load, and dampened liver inflammation. Resveratrol treatment reversed evodiamine-induced increases of IL-1β and interferon-γ, and decreased bacterial clearance in mice. Collectively, our results indicated that evodiamine augmented the NLRP3 inflammasome activation through inducing α-tubulin acetylation, thereby conferring intensified innate immunity against bacterial infection.