Circulating extracellular vesicles from patients with valvular heart disease induce neutrophil chemotaxis via FOXO3a and the inhibiting role of dexmedetomidine

We previously demonstrated that circulating extracellular vesicles (EVs) from patients with valvular heart disease (VHD; vEVs) contain inflammatory components and inhibit endothelium-dependent vasodilation. Neutrophil chemotaxis plays a key role in renal dysfunction, and dexmedetomidine (DEX) can reduce renal dysfunction in cardiac surgery. However, the roles of vEVs in neutrophil chemotaxis and effects of DEX on vEVs are unknown. Here, we investigated the impact of vEVs on neutrophil chemotaxis in kidneys and the influence of DEX on vEVs. Circulating EVs were isolated from healthy subjects and patients with VHD. The effects of EVs on chemokine generation, forkhead box protein O3a (FOXO3a) pathway activation and neutrophil chemotaxis on cultured human umbilical vein endothelial cells (HUVECs) and kidneys in mice and the influence of DEX on EVs were detected. vEVs increased FOXO3a expression, decreased phosphorylation of Akt and FOXO3a, promoted FOXO3a nuclear translocation, and activated the FOXO3a signaling pathway in vitro. DEX pretreatment reduced vEV-induced CXCL4 and CCL5 expression and neutrophil chemotaxis in cultured HUVECs via the FOXO3a signaling pathway. vEVs were also found to suppress Akt phosphorylation and activate FOXO3a signaling to increase plasma levels of CXCL4 and CCL5 and neutrophil accumulation in kidney. The overall mechanism was inhibited in vivo with DEX pretreatment. Our data demonstrated that vEVs induced CXCL4-CCL5 to stimulate neutrophil infiltration in kidney, which can be inhibited by DEX via the FOXO3a signaling. Our findings reveal a unique mechanism involving vEVs in inducing neutrophils chemotaxis and may provide a novel basis for using DEX in reducing renal dysfunction in valvular heart surgery.

MiR-222 inhibition alleviates Staphylococcal Enterotoxin B-induced inflammatory acute lung injury by targeting Foxo3

Acute lung injury (ALI) is a common acute and severe disease in clinical practice. Staphylococcal Enterotoxin B (SEB) is a superantigen that can cause inflammatory ALI. MiR-222 has been demonstrated to be upregulated in SEB-induced inflammatory ALI, but its exact roles and functions remain ill-defined. In this study, SEB exposure led to inflammatory ALI and high expression of miR-222 in model mice and lung infiltrating mononuclear cells, but the inflammatory response and high expression of miR-222 were restored in miR-222^-/- mice. Moreover, we investigated the roles of miR-222 in vitro and observed that the concentrations of inflammatory cytokines and the expression of miR-222 were all elevated in SEB-activated splenocytes and miR-222 inhibition reversed the effects. Foxo3 was confirmed as a direct target of miR-222. Interestingly, SEB exposure led to a decrease of Foxo3 expression, and Foxo3 knockdown partially reversed the promotion of Foxo3 and the inhibition of inflammatory cytokines induced by miR-222 inhibitor in SEB-activated splenocytes. Our data indicated that miR-222 inhibition could alleviate SEB-induced inflammatory ALI by directly targeting Foxo3, shedding light on the potential therapeutic of miR-222 for SEB-induced inflammation in the lung.

The role of FOXO3 polymorphisms in susceptibility to tuberculosis in a Chinese population

BACKGROUND

Tuberculosis (TB) is a significant worldwide health problem, and is caused by Mycobacteria tuberculosis. Recent studies have suggested that FOXO3 plays vital roles in the risk of immune-related infectious diseases such as TB.

METHODS AND RESULTS

The present study aimed to evaluate FOXO3 genetic variants and TB risk. We recruited 510 TB patients and 508 healthy controls in this study. All subjects were genotyped with the Agena MassARRAY platform. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression adjusted for age and gender. Our result revealed that rs3800229 T/G and rs4946935 G/A genotypes significantly increased the risk of TB (OR = 1.34, 95% CI = 1.04-1.74, p = 0.026; OR = 1.34, 95% CI = 1.03-1.73, p = 0.029, respectively). In stratified analysis according to gender and age, we observed that rs3800229 T/G and rs4946935 G/A genotypes were associated with an increase the risk of TB among males and age ≤41 years, respectively (OR = 1.47, 95% CI = 1.06-2.04, p = 0.022 and OR = 1.45, 95% CI = 1.05-2.02, p = 0.025).

CONCLUSIONS

Our study showed that rs3800229 and rs4946935 in FOXO3 were associated with a risk of TB in the Chinese population.

Mutations of deubiquitinase OTUD1 are associated with autoimmune disorders

Dysregulation of innate immunity accompanied by excessive interferon production contributes to autoimmune disease. However, the mechanism by which the immune response is modulated in autoimmune disorders is largely unknown. Here we identified loss-of-function mutations of OTUD1 associated with multiple autoimmune diseases. Under inflammatory conditions, inducible OTUD1 acts as an immune checkpoint and blocks RIG-I-like receptors signaling. As a deubiquitinase, OTUD1 directly interacts with transcription factor IRF3 and removes the K63-linked poly-ubiquitin chains on IRF3 Lysine 98, which inhibits IRF3 nuclear translocation and transcriptional activity. In contrast, OTUD1 mutants impair its suppressive effects on IRF3 via attenuating the OTUD1 deubiquinase activity or its association with IRF3. Moreover, we found FOXO3 signaling is required for OTUD1 induction upon antigenic stimulation. Our data demonstrate that OTUD1 is involved in maintaining immune homeostasis and loss-of-function mutations of OTUD1 enhance the immune response and are associated with autoimmunity.

[Preparation and characterization of mouse polyclonal antibody against conserved region of human FOXO3]

Objective To purify the recombinant protein specific to conserved region of forkhead box O3 (FOXO3) and prepare mouse anti-human FOXO3 polyclonal antibody. Methods The DNA fragment (aa290-472) encoding conserved domain of FOXO3 was amplified by PCR, and subsequently cloned into pET28a vector. Following transformation into E.coli BL21, the soluble fusion protein His-FOXO3 was induced by IPTG and purified by Ni-NTA affinity chromatography. The purified protein was used to immunize BALB/c mice to generate polyclonal antibody. The characteristics of the polyclonal antibody were assessed by ELISA, Western blotting and immunoprecipitation assays. Results We successfully prepared the expression vector pET28a-FOXO3 (aa290-472) and expressed the purified fusion protein in a soluble form. By immunizing mice with the fusion protein, we obtained anti-human FOXO3 polyclonal antibody. ELISA and Western blotting showed that the mouse antibody could recognize specifically the endogenous FOXO3 protein. Conclusion The polyclonal antibody against conserved domain of FOXO3 can identify the endogenous FOXO3 protein. It can be used to analyze the endogenous FOXO3 expression level.

CD11b activation suppresses TLR-dependent inflammation and autoimmunity in systemic lupus erythematosus

Genetic variations in the ITGAM gene (encoding CD11b) strongly associate with risk for systemic lupus erythematosus (SLE). Here we have shown that 3 nonsynonymous ITGAM variants that produce defective CD11b associate with elevated levels of type I interferon (IFN-I) in lupus, suggesting a direct link between reduced CD11b activity and the chronically increased inflammatory status in patients. Treatment with the small-molecule CD11b agonist LA1 led to partial integrin activation, reduced IFN-I responses in WT but not CD11b-deficient mice, and protected lupus-prone MRL/Lpr mice from end-organ injury. CD11b activation reduced TLR-dependent proinflammatory signaling in leukocytes and suppressed IFN-I signaling via an AKT/FOXO3/IFN regulatory factor 3/7 pathway. TLR-stimulated macrophages from CD11B SNP carriers showed increased basal expression of IFN regulatory factor 7 (IRF7) and IFN-β, as well as increased nuclear exclusion of FOXO3, which was suppressed by LA1-dependent activation of CD11b. This suggests that pharmacologic activation of CD11b could be a potential mechanism for developing SLE therapeutics.