Effect of intranasal challenge with interleukin-6 on upper airway symptomatology and physiology in allergic and nonallergic patients

IL-6 mediates olfactory dysfunction in a mouse model of allergic rhinitis

BACKGROUND

Immune-inflammatory response is a key element in the occurrence and development of olfactory dysfunction (OD) in patients with allergic rhinitis (AR). As one of the core factors in immune-inflammatory responses, interleukin (IL)-6 is closely related to the pathogenesis of allergic diseases. It may also play an important role in OD induced by diseases, such as Sjögren's syndrome and coronavirus disease 2019. However, there is no study has reported its role in OD in AR. Thus, this study aimed to investigate the role of IL-6 in AR-related OD, in an attempt to discover a new target for the prevention and treatment of OD in patients with AR.

METHODS

Differential expression analysis was performed using the public datasets GSE52804 and GSE140454 for AR, and differentially expressed genes (DEGs) were obtained by obtaining the intersection points between these two datasets. IL-6, a common differential factor, was obtained by intersecting the DEGs with the General Olfactory Sensitivity Database (GOSdb) again. A model of AR mice with OD was developed by sensitizing with ovalbumin (OVA) to verify the reliability of IL-6 as a key factor of OD in AR and explore the potential mechanisms. Furthermore, a supernatant and microglia co-culture model of nasal mucosa epithelial cells stimulated by the allergen house dust mite extract Derp1 was established to identify the cellular and molecular mechanisms of IL-6-mediated OD in AR.

RESULTS

The level of IL-6 in the nasal mucosa and olfactory bulb of AR mice with OD significantly increased and showed a positive correlation with the expression of olfactory bulb microglia marker Iba-1 and the severity of OD. In-vitro experiments showed that the level of IL-6 significantly increased in the supernatant after the nasal mucosa epithelial cells were stimulated by Derp1, along with significantly decreased barrier function of the nasal mucosa. The expression levels of neuroinflammatory markers IL-1β and INOS increased after a conditioned culture of microglia with the supernatant including IL-6. Then knockdown (KD) of IL-6R by small interfering RNA (siRNA), the expression of IL-1β and INOS significantly diminished.

CONCLUSION

IL-6 plays a key role in the occurrence and development of OD in AR, which may be related to its effect on olfactory bulb microglia-mediated neuroinflammation.

Effects of IL-6 Polymorphisms on Individual Susceptibility to Allergic Diseases: A Systematic Review and Meta-Analysis

Background: Many studies have assessed the potential link between interleukin-6 polymorphisms and susceptibility to allergic diseases. However, the results are still conflicting. Therefore, a comprehensive meta-analysis can not only resolve differences but also provide clues for future projects.

Methods: A systematic electronic search was conducted on the databases of Web of Science, PubMed, and Cochrane Library to retrieve all published studies. Revman and Stata software were used for statistical analysis.

Results: This meta-analysis included 11 studies. The results revealed that there was a statistically significant association between IL-6 rs1800795 polymorphism and the risk of asthma and allergic rhinitis in the general population. Subgroup analyses demonstrated that rs1800795 affected allergic diseases risk in different populations.

Conclusion: Our findings suggested that IL-6 rs1800795 was associated with allergic diseases susceptibility among Asians and Caucasians in opposite trends, and it might influence the risk of asthma and allergic rhinitis. None of the IL-6 polymorphisms were shared risk variants of allergic diseases.

Superior effect of MP-AzeFlu than azelastine or fluticasone propionate alone on reducing inflammatory markers

BACKGROUND

MP-AzeFlu, intranasal formulation of azelastine hydrochloride (AZE) and fluticasone propionate (FP), is superior to AZE or FP alone for treatment of allergic rhinitis (AR). However, the precise anti-inflammatory mechanism of action of MP-AzeFlu has not been characterized.

OBJECTIVE

To investigate the anti-inflammatory effects of MP-AzeFlu compared with AZE or FP alone in an established in vitro model of eosinophilic inflammation.

METHODS

Nasal mucosal epithelial cells and peripheral blood eosinophils were obtained from human volunteers. Epithelial cells were stimulated with 10% fetal bovine serum (FBS) in the presence of MP-AzeFlu, AZE, or FP (1:102 to 1:105 dilution). Concentrations of interleukin (IL)-6, IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured by ELISA. Eosinophils were incubated in 10% human epithelial cell-conditioned medium (HECM) and survival assessed by trypan blue dye exclusion. Results are expressed as mean ± SEM percentage secretion/survival compared with FBS/HECM (respectively).

RESULTS

FP and MP-AzeFlu (all dilutions) and AZE (1:102) significantly reduced IL-6 secretion and eosinophil survival compared with positive controls. At 1:102 dilution, IL-6 secretion was significantly lower with MP-AzeFlu (38.3 ± 4.2%, compared with FBS = 100%) than with AZE (76.1 ± 4.9%) or FP (53.0 ± 4.9%). At 1:102 dilution, eosinophil survival was significantly lower with MP-AzeFlu at day 3 (17.5 ± 3.0%) and day 4 (2.4 ± 1.4%, compared with HECM = 100%) than with AZE (day 3: 75.2 ± 7.2%; day 4: 44.0 ± 9.7%) or FP (day 3: 38.5 ± 3.5%; day 4: 14.6 ± 4.0%).

CONCLUSION

Greater reductions in cytokine secretion and eosinophil survival observed with MP-AzeFlu in vitro may underlie MP-AzeFlu's superior clinical efficacy vs. AZE or FP alone observed in AR patients.

Ethyl pyruvate attenuates murine allergic rhinitis partly by decreasing high mobility group box 1 release

High-mobility group box 1 (HMGB1) protein, a pro-inflammatory DNA-binding protein, meditates inflammatory responses through Toll-like receptor-4 signals and amplifies allergic inflammation by interacting with the receptor for advanced glycation end products. Previous studies have shown that HMGB1 is elevated in the nasal lavage fluids (NLF) of children suffering from allergic rhinitis (AR) and is associated with the severity of this disease. Furthermore, HMGB1 has been implicated in the pathogenesis of lower airway allergic diseases, such as asthma. Ethyl pyruvate (EP) has proven to be an effective anti-inflammatory agent for numerous airway diseases. Moreover, EP can inhibit the secretion of HMGB1. However, few studies have examined the effect of EP on AR. We hypothesized that HMGB1 plays an important role in the pathogenesis of AR and studied it using an AR mouse model. Forty BALB/c mice were divided into four groups: the control group, AR group, 50 mg/kg EP group, and 100 mg/kg EP group. The mice in the AR and EP administration groups received ovalbumin (OVA) sensitization and challenge, whereas those in the control group were given sterile saline instead of OVA. The mice in the EP administration group were given an intraperitoneal injection of EP 30 min before each OVA treatment. The number of nasal rubbings and sneezes of each mouse was counted after final treatment. Hematoxylin-eosin staining, AB-PAS staining, interleukin-4 and 13 in NLF, IgE, and the protein expression of HMGB1 were measured. Various features of the allergic inflammation after OVA exposure, including airway eosinophilia, Th-2 cytokine production, total IgE, and goblet cell hyperplasia were significantly inhibited by treatment with EP and the expression and release of HMGB1 were reduced after EP administration in a dose-dependent manner. These results indicate that HMGB1 is a potential therapeutic target of AR and that EP attenuates AR by decreasing HMGB1 expression.

Association of interleukin 6 single nucleotide polymorphisms with allergic rhinitis

OBJECTIVES

Allergic rhinitis (AR) is a polygenic inflammatory disorder of the nasal mucosa with an increasing prevalence worldwide. As interleukin 6 (IL-6) seems to be involved in development of allergic disorders, such as allergic rhinitis, this study was performed to evaluate the association of two promotor variants of IL-6 gene in the AR.

METHODS

Ninety eight patients with AR were enrolled in this study. Genotyping was done for two polymorphisms in a promoter region of IL-6 gene (G/C at -174, rs1800795 and G/A at -597, rs1800797), using a PCR sequence-specific-primers method.

RESULTS

Patients homozygous for the G allele of rs1800795 in IL-6 had a 3.35-fold risk of having AR than those with the C allele. AA genotype in rs1800797 of IL-6 was associated with the increased risk of developing AR. G/G haplotype for IL-6 (rs1800795, rs1800797) was significantly higher in the patient group. In some subgroups of patients, there were significant relationships between IgE levels, eosinophil count, eosinophil percentage, nature of sensitivity and persistency of disease and these two variants.

CONCLUSION

We found that two promotor variants in IL-6, especially rs1800795, were predisposing factors for AR with a negative heterosis pattern. These SNPs could also affect the clinical parameters, the nature of sensitivity and persistency of the disease in some subgroups of the patients.

Nasopharyngeal acute phase cytokines in viral upper respiratory infection: impact on acute otitis media in children

BACKGROUND

The role of acute phase cytokines generated in the nasopharynx during viral upper respiratory infection (URI) in subsequent development of acute otitis media (AOM) has not been examined.

METHODS

We studied 326 virus-positive URI episodes in 151 children aged 6-36 months. Nasopharyngeal secretions collected within 1 to 7 days of URI onset were studied for viruses by conventional and molecular techniques, and for concentrations of IL-1beta, IL-6, and TNFalpha by multiplex enzyme-linked immunosorbent assay. Children were followed up for 28 days to document AOM complication.

RESULTS

IL-1beta, IL-6, and TNFalpha concentrations correlated positively with each other (P<0.001). IL-6 and TNFalpha concentrations were higher in males than in females (P=0.01 and 0.02). IL-6 and TNFalpha concentrations were inversely correlated with age (P=0.02 and 0.05). IL-6 concentrations correlated positively with duration of fever (P=0.006) and correlated negatively with the number of days of URI symptoms (P=0.026). Furthermore, IL-6 concentrations were significantly higher during adenovirus and influenza virus URIs as compared with enterovirus and rhinovirus URIs (P<0.01). IL-1beta concentrations were higher during URI episodes with AOM than those without AOM (P<0.001).

CONCLUSIONS

We found IL-6 nasopharyngeal secretions concentrations to be higher with adenovirus and influenza infection, and in children with systemic febrile response during URI. However, IL-1beta was found to play a more important role in the development of AOM after URI. Additional studies are needed to further define the role of acute phase cytokines in virus-induced AOM.

Capsaicin induces the production of IL-6 in human upper respiratory epithelial cells

Capsaicin, a type of alkaloid and the pungent component of chili peppers, is used as a therapeutic drug against allergic rhinitis and also as an index of bronchial hypersensitivity. Capsaicin receptor (TRPV1) expression has been identified in non-neuronal cells as well as neuronal cells. In our previous study, both TRPV1 protein and its gene expression on nasal epithelial cells were confirmed by immunohistochemistry and RT-PCR, respectively. In order to clarify whether or not TRPV1 acts as a functional receptor, we examined the effects of capsaicin on the production of IL-6 from primary cultured human airway epithelial cells at both protein and mRNA levels. Human nasal epithelial cells (HNECs) and normal human bronchial/tracheal epithelial cells (NHBE cells) were stimulated with increasing concentrations of capsaicin and/or pretreatment with capsazepine (TRPV1 antagonist) at 37 degrees C. The supernatant and total RNA were collected at 0, 4, 12, 24 and 48 h after treatment. IL-6 concentration and the IL-6 mRNA level were evaluated by ELISA and real-time PCR, respectively. Capsaicin (10 nM-10 muM) induced production of IL-6 from HNECs and NHBE cells and this effect was inhibited by pretreatment with capsazepine. Our findings suggest that topical application of capsaicin to the airway induces IL-6 production from respiratory epithelial cells via activation of TRPV1.

Nasal cytokines as mediators of illness during the common cold

Identification of a pharmacologically targeted mediator of the common cold is a desirable, but, to date, elusive goal of current research. The roles of various mediators, such as histamine, leukotrienes, bradykinin, and, more recently, chemokines and cytokines, in the pathophysiology and development of complications of the common cold are the subject of previous and current investigations. Establishing causality of a mediator in the common cold has been difficult for a number of reasons, including the limitations of our research tools and protocols and the complexity of the inflammatory and immune pathways that participate during the common cold. The available evidence for mediation of the common cold is the subject of this manuscript.

Cytokine levels during symptomatic viral upper respiratory tract infection

BACKGROUND

Previous studies suggest a role for locally produced proinflammatory cytokines in the development and expression of illness during experimental infection with a variety of respiratory viruses. However, most of these studies fail to make comparisons between symptomatic and asymptomatic infected subjects.

OBJECTIVE

To compare the pattern of nasal cytokine elaboration in asymptomatic and symptomatic subjects experimentally infected with rhinovirus-39 (RV-39).

METHODS

Healthy adults underwent experimental intranasal inoculation with a safety-tested clinical isolate of RV-39. Nasal lavages were collected, nasal symptoms were recorded, and expelled nasal secretions were weighed before and then daily for 6 days after challenge. Nasal lavages were submitted for viral culture and assayed for cytokine protein levels by enzyme-linked immunosorbent assay.

RESULTS

Twenty-nine subjects were enrolled in the study. All subjects were infected as evidenced by viral shedding and/or seroconversion. Sixteen subjects were symptomatic and 13 were asymptomatic as evaluated by subject self-report. During infection, significant increases in mean levels of nasal interleukin 6 (IL-6) (P = .01) and IL-1 (P = .02) were observed in symptomatic but not asymptomatic subjects. In symptomatic subjects, these increases were temporally related to the development of nasal symptoms and production of secretions. Mean levels of IL-8, IL-10, and tumor necrosis factor a were not increased in either group during infection.

CONCLUSIONS

The results of this study demonstrate elevations in certain locally produced cytokines during symptomatic but not asymptomatic respiratory infection with RV-39. Future studies using selected anticytokine therapies may help elucidate the precise role of cytokines in mediating disease expression.

Cytokine gene polymorphisms moderate illness severity in infants with respiratory syncytial virus infection

Illness severity and frequency of complications in infants with respiratory syncytial virus (RSV) infection may be influenced by the local elaboration of cytokines. Cytokine gene polymorphisms moderate severity of illness in various inflammatory and infectious diseases. We performed cytokine genotyping on 77 infants hospitalized with confirmed RSV infection to determine whether specific cytokine gene polymorphisms are associated with illness severity or complications. DNA was extracted from buccal brushings and assayed for tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-6 and IL-10, and transforming growth factor (TGF)-beta1 genotypes using polymerase chain reaction-sequence-specific primer technology. Clinical outcomes consisted of severity scores of lower respiratory illness, blood oxygen saturation, lengths of oxygen supplementation, and intensive care unit (ICU) and hospital stays, and the presence or absence of pneumonia and otitis media. IFN-gamma genotype was related to severity of lower respiratory illness, duration of ICU stay, and frequency of otitis media. Additionally, IL-6 genotype was related to the length of oxygen (O(2)) supplementation and hospital stay, IL-10 genotype to the frequency of pneumonia, and TGF-beta1 genotype to O(2) saturations at presentation. There were no associations between TNF-alpha genotype and any of the outcome parameters. These results demonstrate that certain cytokine gene polymorphisms contribute to illness severity and complications during RSV infection in infants. If future prospective studies confirm these observations, cytokine genotyping may be a useful tool for identifying "at risk" infants who may benefit from the selective use of preventive or early intervention treatments for RSV.

The link between allergic rhinitis and otitis media

Past studies implicated allergy in the pathogenesis of otitis media. However, definitive proof of the assertion is lacking. Epidemiologic studies, including one recently published by Rylander and Megevand, consistently identify allergy as a risk factor for otitis media. Also, higher than expected frequencies of allergy are reported for patients with otitis media, but it is unclear if this is an epiphenomenon associated with referral bias. This possibility is exemplified by the results of two reviewed papers where Velepic and colleagues reported a 25% prevalence of allergy in otitis media patients while Alles and colleagues reported a prevalence of 89%. Other studies documented biochemical components of allergic inflammation in the effusions recovered from children with otitis media, and Hurst and colleagues published a recent paper continuing on that theme. However, it is not known if a local allergic reaction is required for the production of these components and if they are produced exclusive of other inflammatory products. Three published studies explored mechanisms by which allergy could cause otitis media. Tikkanen and colleagues reexamined at age 10 a group of 56 subjects with previously diagnosed milk allergy and showed that despite decreased reactivity to milk protein a high prevalence of otitis media was retained. This suggests that it is the allergic condition, not the specific allergy to milk that increases otitis media risk. Downs and colleagues exposed the middle ears of rats to histamine and provoked changes in the pressure regulating and clearance functions of the Eustachian tube. Those changes could prolong an otitis media episode, but middle ear histamine is not limited to the allergic condition. Gentile and colleagues challenged the nose of allergic and nonallergic subjects with histamine followed by interleukin-6 or placebo and measured nasal, pulmonary, Eustachian tube and middle ear functions. Interleukin-6 did not change the Eustachian tube or middle ear functions but did cause increased secretions in allergic patients.

Viral rhinitis

Viral rhinitis is a common, morbid, and costly malady, often complicated by otitis media, sinusitis, and asthma. Current therapies are relatively ineffective and aimed at reducing symptoms rather than moderating underlying mechanisms. Nasal elevations of proinflammatory cytokines track symptom expression during viral rhinitis, and it is hypothesized that these chemicals orchestrate a common response to infection with many different viruses that cause rhinitis. Also, recent evidence supports a role for neurogenic inflammation in the development of complications. Future studies should dissect the role of proinflammatory cytokines and neuropeptides in the expression of symptoms, signs, pathophysiologies, and complications of viral rhinitis.