New strategies in the treatment and prevention of allergic diseases

Radiation-Detoxified Form of Endotoxin Effectively Activates Th1 Responses and Attenuates Ragweed-Induced Th2-Type Airway Inflammation in Mice

Urbanization with reduced microbial exposure is associated with an increased burden of asthma and atopic symptoms. Conversely, environmental exposure to endotoxins in childhood can protect against the development of allergies. Our study aimed to investigate whether the renaturation of the indoor environment with aerosolized radiation-detoxified lipopolysaccharide (RD-LPS) has a preventative effect against the development of ragweed-induced Th2-type airway inflammation. To explore this, cages of six-week-old BALB/c mice were treated daily with aerosolized native LPS (N-LPS) or RD-LPS. After a 10-week treatment period, mice were sensitized and challenged with ragweed pollen extract, and inflammatory cell infiltration into the airways was observed. As dendritic cells (DCs) play a crucial role in the polarization of T-cell responses, in our in vitro experiments, the effects of N-LPS and RD-LPS were compared on human monocyte-derived DCs (moDCs). Mice in RD-LPS-rich milieu developed significantly less allergic airway inflammation than mice in N-LPS-rich or common environments. The results of our in vitro experiments demonstrate that RD-LPS-exposed moDCs have a higher Th1-polarizing capacity than moDCs exposed to N-LPS. Consequently, we suppose that the aerosolized, non-toxic RD-LPS applied in early life for the renaturation of urban indoors may be suitable for the prevention of Th2-mediated allergies in childhood.

Quercetin improves the imbalance of Th1/Th2 cells and Treg/Th17 cells to attenuate allergic rhinitis

Allergic rhinitis (AR) is a common inflammation that affects many people globally. Quercetin has anti-allergic biological activity in AR. Here, we aimed to explore the effects of quercetin on type 1 helper T (Th1)/Th2 and regulatory T cells (Treg)/Th17 balance. We established an ovalbumin (OVA)-induced mouse model and orally administered 20, 35, and 50 mg/kg/day quercetin. The nasal symptoms of mice were observed. The immunoglobulin levels, Treg/Th17-related factors, and pro-inflammatory factors were examined by ELISA. The differentiated inflammation cells were visualized using the diff-quick staining assay. The nasal histopathology was evaluated using H&E, periodic acid Schiff (PAS), and Giemsa staining assay. The results showed that quercetin attenuated OVA-induced rubbing and sneezing. Quercetin reduced IgE, IgG1, histamine, and increased IgG2 in serum. The number of differentiated inflammation cells and goblet cells in tissues that elevated by OVA was reduced by quercetin. Moreover, OVA increased the Treg cell percentage, the levels of IL-17, TGF-β, IL-6, TNF-α, and decreased Th17 cell percentage, IL-10 and FOXP3 levels, while quercetin abrogated their levels induced by OVA. Additionally, quercetin inactivated the NF-κB pathway. Taken together, quercetin attenuated AR symptoms by balancing the Th1/Th2, Treg/Th17 ratios, and inactivating the NF-κB pathway. The results suggested that quercetin may use for AR treatment.

Interleukin-17A up-regulates thymic stromal lymphopoietin production by nasal fibroblasts from patients with allergic rhinitis

PURPOSE

Emerging evidence has shown that interleukin (IL)-17A is implicated in the pathogenesis of allergic rhinitis (AR). Thymic stromal lymphopoietin (TSLP) orchestrates the immune response toward a Th2 phenotype. Although increased TSLP is found in AR, the contribution of IL-17A in TSLP production by nasal fibroblasts is not well understood. We aimed to investigate the effect and mechanism of IL-17A on TSLP production by human nasal fibroblasts (HNFs) from AR patients.

METHODS

HNFs from AR patients were cultured and stimulated with IL-17A in the absence or presence of a Janus kinase (JAK) 2 or JAK1/3 inhibitor. Western blotting was used to assay phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and nuclear factor-kappa B (NF-κB) p65 in HNFs. The TSLP expression in the cells and culture supernatants was evaluated by real-time polymerase chain reaction and enzyme-linked immunoassay.

RESULTS

Stimulation with IL-17A induced STAT3 phosphorylation, which was inhibited by the pretreatment with JAK2 inhibitor AZD1480 or JAK1/3 inhibitor tofacitinib. IL-17A promoted the nuclear translocation of NF-κBp65 protein, leading to increased TSLP production, while the pre-incubation with AZD1480 prior to IL-17A attenuated these effects. However, the pre-incubation with tofacitinib before IL-17A stimulation had no impact on the expression of NF-κBp65 and TSLP.

CONCLUSIONS

IL-17A up-regulated TSLP production by HNFs through JAK2/NF-κB pathway. Although IL-17A induced STAT3 activation through JAK1/2/3, IL-17A-mediated TSLP expression was not dependent on STAT3 signaling. These observations would provide mechanistic insight into therapeutic strategies to improve the immune and inflammation associated with Th17A in the management of AR.

The regulatory network among CircHIPK3, LncGAS5, and miR-495 promotes Th2 differentiation in allergic rhinitis

Allergic rhinitis (AR) is a common allergic disease which is characterized by the promotion of Th2 differentiation of CD4⁺ T cells. However, the mechanisms underlying Th2 differentiation remain unclear. Non-coding RNAs play a critical role in Th2 differentiation, whereas few studies have revealed the interactions among long non-coding RNAs, circular RNAs, and microRNAs. In this study, the differential expressions of several circRNAs and lncRNAs were compared in nasal mucosa samples of AR patients and mice with experimentally induced AR as compared to healthy controls. The results showed that the highly expressed CircHIPK3 and LncGAS5 promoted Th2 differentiation of ovalbumin-induced CD4⁺ T cells and aggravated nasal symptoms of AR mice. We also found that CircHIPK3 and LncGAS5 induced the upregulation of Th2 cell-specific transcript factor GATA-3 via modulating their common target miR-495. Meanwhile, the intranasal administration of CircHIPK3 or LncGAS5 knockdown lentivirus decreased nasal symptoms of AR mice. In conclusion, our findings indicated that the interactions among CircHIPK3, LncGAS5, and miR-495 play a critical role in the regulation of Th2 differentiation in AR.

Exosomal long non-coding RNA GAS5 suppresses Th1 differentiation and promotes Th2 differentiation via downregulating EZH2 and T-bet in allergic rhinitis

The imbalance of helper T cell (Th) 1/Th2 differentiation is involved in the development of allergic rhinitis (AR). Recent studies reveal the regulatory function of exosomes on Th1/Th2 differentiation. However, the key mediator in exosomes that modulate such response remains unclear. In this study, the expression of long-noncoding RNA GAS5 (LncGAS5) was detected in exosomes which were isolated from AR patient nasal mucus (AR-EXO) and ovalbumin (OVA)-stimulated nasal epithelial cells (OVA-EXO). Th1/Th2 differentiation was induced in naïve CD4⁺ T cells, and the percentage of IFN-γ expressing cells (Th1 cells) and IL-4 expressing cells (Th2 cells) was detected using flow cytometry. The result showed that LncGAS5 was upregulated in AR epithelial samples, AR-EXO, and OVA-EXO. The coincubation of AR-EXO and CD4⁺ T cells suppressed Th1 differentiation and promoted Th2 differentiation, which is mediated by LncGAS5 in AR-EXO. The LncGAS5 in AR-EXO inhibited transcription and expression of EZH2, and it also inhibited T-bet expression at mRNA and protein levels. The gain-of-function and loss-of-function experiments suggested that LncGAS5 mediates Th1/Th2 differentiation partly through downregulating T-bet and EZH2. In summary, our findings demonstrated that LncGAS5 in AR epithelium-derived exosomes is the key mediator in Th1/Th2 differentiation, providing a possible therapeutic target of AR.

The mast cell and allergic diseases: role in pathogenesis and implications for therapy

Mast cells have long been recognized for their role in the genesis of allergic inflammation; and more recently for their participation in innate and acquired immune responses. Mast cells reside within tissues including the skin and mucosal membranes, which interface with the external environment; as well as being found within vascularized tissues next to nerves, blood vessels and glandular structures. Mast cells have the capability of reacting both within minutes and over hours to specific stimuli, with local and systemic effects. Mast cells express the high affinity IgE receptor (FcepsilonRI) and upon aggregation of FcepsilonRI by allergen-specific IgE, mast cells release and generate biologically active preformed and newly synthesized mediators which are involved in many aspects of allergic inflammation. While mast cells have been well documented to be essential for acute allergic reactions, more recently the importance of mast cells in reacting through pattern recognition receptors in innate immune responses has become recognized. Moreover, as our molecular understanding of the mast cell has evolved, novel targets for modulation have been identified with promising therapeutic potential.

The promise of siRNAs for the treatment of influenza

Current WHO reports on the Asian avian influenza virus outbreaks are poignant reminders of the potential for the emergence of highly virulent strains of influenza A virus (IAV) and the fact that it remains a scourge on human health. As IAV drifts and shifts its genetic and antigenic composition, it presents an ever-changing challenge for vaccines and antiviral medications. Short-interfering RNAs (siRNAs) are the latest class of potential antiviral therapeutics to be developed. Recent reports using siRNAs in mice suggest that they hold great promise for the prevention and treatment of IAV infections.