IL-33-induced keratoconjunctivitis is mediated by group 2 innate lymphoid cells in mice

Fibroblast growth factor 21 alleviated atopic march by inhibiting the differentiation of type 2 helper T cells

BACKGROUND

The blood FGF21 expression has been previously suggested to increase in patients developing atopic dermatitis (AD) and asthma. However, its impact on atopic march is rarely analyzed. The present work focused on investigating the role of Fibroblast Growth Factor 21(FGF21) in atopic march mice and its underlying mechanisms.

METHODS

The models were induced with Diisononyl phthalate (DINP) and OVA in wild-type C57BL/6 and FGF21-/- mice. RAW264.7 cells were induced by LPS with/without FGF21 or KLB-SiRNA for in vitro analyses.

RESULTS

The data indicated that there were more severe allergic reactions including IgE levels and the proportion of mast cells in the blood of FGF21-/- mice in relative to WT model mice during the progression from AD to asthma. However, exogenous administration of FGF21 inhibited allergies. In this study, we reported that FGF21 mitigated AD-like lesions and Th1/2 or Th17/Treg cell imbalance in AD mice, and significantly decreased TSLP, IL-33, IL-4, IL-5, IL-13 and IL-17A expression on skin. During the asthma phase, FGF21 improved airway remodeling by downgrading inflammatory factors IL-4, IL-5, IL-13 and IL-17A; fibrotic markers α-SMA and Collagen I; and oxidative products MDA and ROS in wild-type model mice. Compared with WT model mice, the adverse consequences were aggravated in FGF21-/- asthmatic mice. From the mechanistic perspective, FGF21 suppressed NF-κB/NLRP3, TGF-β1/Smad3 and JNK signaling pathways and increased Nrf2 expression in vivo and in vitro. In addition, β-Klotho knockdown attenuated the ameliorative impact of FGF21 on cellular damage. Blocking AMPKα in the LPS-treated RAW264.7 cells inhibited the reduction of FGF21 and the phosphorylation of JNK.

CONCLUSIONS

To conclude, FGF21 alleviated atopic march by inhibiting Th2/17 immune response, and reduced airway remodeling by regulating NF-κB/NLRP3, TGF-β1/Smad3 and AMPKα/JNK pathways. Moreover, this study provides a rationale and novel ideas for applying FGF21 in treating AD and asthma.

TRPV1+ sensory nerves suppress conjunctival inflammation via SST-SSTR5 signaling in murine allergic conjunctivitis

Allergic conjunctivitis (AC), an allergen-induced ocular inflammatory disease, primarily involves mast cells (MCs) and eosinophils. The role of neuroimmune mechanisms in AC, however, remains to be elucidated. We investigated the effects of transient receptor potential vanilloid 1 (TRPV1)-positive sensory nerve ablation (using resiniferatoxin) and TRPV1 blockade (using Acetamide, N-[4-[[6-[4-(trifluoromethyl)phenyl]-4-pyrimidinyl]oxy]-2-benzothiazolyl] (AMG-517)) on ovalbumin-induced conjunctival allergic inflammation in mice. The results showed an exacerbation of allergic inflammation as evidenced by increased inflammatory gene expression, MC degranulation, tumor necrosis factor-α production by MCs, eosinophil infiltration and activation, and C-C motif chemokine 11 (CCL11) (eotaxin-1) expression in fibroblasts. Subsequent findings demonstrated that TRPV1+ sensory nerves secrete somatostatin (SST), which binds to SST receptor 5 (SSTR5) on MCs and conjunctival fibroblasts. SST effectively inhibited tumor necrosis factor-α production in MCs and CCL11 expression in fibroblasts, thereby reducing eosinophil infiltration and alleviating AC symptoms, including eyelid swelling, lacrimation, conjunctival chemosis, and redness. These findings suggest that targeting TRPV1+ sensory nerve-mediated SST-SSTR5 signaling could be a promising therapeutic strategy for AC, offering insights into neuroimmune mechanisms and potential targeted treatments.

Increased Mortality Risk at Septic Condition in Inflammatory Skin Disorders and the Effect of High-Fat Diet Consumption

In recent years, attention has increasingly focused on various infectious diseases. Although some fatalities are directly attributed to the causative virus, many result from complications and reactive inflammation. Patients with comorbidities are at a higher risk of mortality. Refractory skin conditions such as atopic dermatitis, psoriasis, and epidermolysis bullosa, known for an elevated risk of sepsis, partly owe this to compromised surface barrier function. However, the detailed mechanisms underlying this phenomenon remain elusive. Conversely, although the detrimental effects of a high-fat diet on health, including the onset of metabolic syndrome, are widely recognized, the association between diet and susceptibility to sepsis has not been extensively explored. In this study, we examined the potential causes and pathogenesis of increased sepsis susceptibility in inflammatory skin diseases using a mouse dermatitis model: keratin 14-driven caspase-1 is overexpressed (KCASP1Tg) in mice on a high-fat diet. Our findings reveal that heightened mortality in the dermatitis mouse model is caused by the inflamed immune system due to the chronic inflammatory state of the local skin, and administration of LPS causes a rapid increase in inflammatory cytokine levels in the spleen. Intake of a high-fat diet exacerbates these cytokine levels. Interestingly, we also observed a reduced expression of Toll-like receptor 4 (TLR4) in monocytes from KCASP1Tg mice, potentially predisposing these animals to heightened infection risks and associated complications. Histological analysis showed a clear decrease in T and B cells in the spleen of KCASP1Tg mice fed a high-fat diet. Thickening of the alveolar wall, inflammatory cell infiltration, and alveolar hemorrhage were more prominent in the lungs of KCASP1Tg and KCASP1Tg with fat mice. We postulate that the chronic, non-infectious inflammation induces a negative feedback loop within the inflammatory cascade, and the suppressed expression of TLR4 renders the mice more susceptible to infections. Therefore, it is imperative for individuals with chronic skin inflammation to closely monitor disease progression upon infection and seek timely and appropriate treatment. Additionally, chronic inflammation of adipose tissue, induced by high-fat food intake, combined with dermatitis inflammation, may exacerbate infections, necessitating a review of dietary habits.

Dupilumab-associated ocular adverse events are predicted by low tear break-up time and correlate with high IL-33 tear concentrations in patients with atopic dermatitis

Dupilumab, blocking IL-4 and IL-13 signals, improves atopic dermatitis and Quality of Life but might be also associated with the occurrence of ocular adverse events (OAEs). The main objective of our prospective study was to characterize the cytokine and chemokine profile in the tear fluid of dupilumab-treated patients with moderate-to- severe atopic dermatitis and to identify biomarkers predicting the occurrence of ocular adverse events. Patients with moderate-to-severe AD underwent dermatological and ophthalmological evaluation at the baseline (T0) and week 16 or at the time of an eventual ocular adverse events (T1). A multiplex immunoassay measuring multiple cytokines and chemokines in the tear fluid extracted during ocular examination at both T0 and T1 was performed. Thirty-nine patients with moderate-to-severe AD and treated with dupilumab were included in the study. Baseline tear fluid levels revealed a significantly higher concentration of type 2 cytokines and chemokines in AD patients than healthy controls. The occurrence of ocular adverse events during dupilumab therapy was associated with a significant increase of IL-33 tear fluid levels and a significantly lower tear break-up time, this latter also identified as predictive factor. Our findings suggest that the ophthalmological examination should be considered a valid support to identify patients at risk of developing OAEs and to provide their appropriate management.