Advances in rhinitis: Models and mechanisms

Clinical Practice Guideline: Immunotherapy for Inhalant Allergy

OBJECTIVE

Allergen immunotherapy (AIT) is the therapeutic exposure to an allergen or allergens selected by clinical assessment and allergy testing to decrease allergic symptoms and induce immunologic tolerance. Inhalant AIT is administered to millions of patients for allergic rhinitis (AR) and allergic asthma (AA) and is most commonly delivered as subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT). Despite its widespread use, there is variability in the initiation and delivery of safe and effective immunotherapy, and there are opportunities for evidence-based recommendations for improved patient care.

PURPOSE

The purpose of this clinical practice guideline (CPG) is to identify quality improvement opportunities and provide clinicians trustworthy, evidence-based recommendations regarding the management of inhaled allergies with immunotherapy. Specific goals of the guideline are to optimize patient care, promote safe and effective therapy, reduce unjustified variations in care, and reduce the risk of harm. The target patients for the guideline are any individuals aged 5 years and older with AR, with or without AA, who are either candidates for immunotherapy or treated with immunotherapy for their inhalant allergies. The target audience is all clinicians involved in the administration of immunotherapy. This guideline is intended to focus on evidence-based quality improvement opportunities judged most important by the guideline development group (GDG). It is not intended to be a comprehensive, general guide regarding the management of inhaled allergies with immunotherapy. The statements in this guideline are not intended to limit or restrict care provided by clinicians based on their experience and assessment of individual patients.

ACTION STATEMENTS

The GDG made a strong recommendation that (Key Action Statement [KAS] 10) the clinician performing allergy skin testing or administering AIT must be able to diagnose and manage anaphylaxis. The GDG made recommendations for the following KASs: (KAS 1) Clinicians should offer or refer to a clinician who can offer immunotherapy for patients with AR with or without AA if their patients' symptoms are inadequately controlled with medical therapy, allergen avoidance, or both, or have a preference for immunomodulation. (KAS 2A) Clinicians should not initiate AIT for patients who are pregnant, have uncontrolled asthma, or are unable to tolerate injectable epinephrine. (KAS 3) Clinicians should evaluate the patient or refer the patient to a clinician who can evaluate for signs and symptoms of asthma before initiating AIT and for signs and symptoms of uncontrolled asthma before administering subsequent AIT. (KAS 4) Clinicians should educate patients who are immunotherapy candidates regarding the differences between SCIT and SLIT (aqueous and tablet) including risks, benefits, convenience, and costs. (KAS 5) Clinicians should educate patients about the potential benefits of AIT in (1) preventing new allergen sensitizations, (2) reducing the risk of developing AA, and (3) altering the natural history of the disease with continued benefit after discontinuation of therapy. (KAS 6) Clinicians who administer SLIT to patients with seasonal AR should offer pre- and co-seasonal immunotherapy. (KAS 7) Clinicians prescribing AIT should limit treatment to only those clinically relevant allergens that correlate with the patient's history and are confirmed by testing. (KAS 9) Clinicians administering AIT should continue escalation or maintenance dosing when patients have local reactions (LRs) to AIT. (KAS 11) Clinicians should avoid repeat allergy testing as an assessment of the efficacy of ongoing AIT unless there is a change in environmental exposures or a loss of control of symptoms. (KAS 12) For patients who are experiencing symptomatic control from AIT, clinicians should treat for a minimum duration of 3 years, with ongoing treatment duration based on patient response to treatment. The GDG offered the following KASs as options: (KAS 2B) Clinicians may choose not to initiate AIT for patients who use concomitant beta-blockers, have a history of anaphylaxis, have systemic immunosuppression, or have eosinophilic esophagitis (SLIT only). (KAS 8) Clinicians may treat polysensitized patients with a limited number of allergens.

Blood Basophils Relevance in Chronic Rhinosinusitis with Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by eosinophilic asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and intolerance to cyclooxygenase-1 inhibitors. Interest is emerging in studying the role of circulating inflammatory cells in CRSwNP pathogenesis and its course, as well as their potential use for a patient-tailored approach. By releasing IL-4, basophils play a crucial role in activating the Th2-mediated response. The main aim of this study was to, first, investigate the level of the pre-operative blood basophils' values, blood basophil/lymphocyte ratio (bBLR) and blood eosinophil-to-basophil ratio (bEBR) as predictors of recurrent polyps after endoscopic sinus surgery (ESS) in AERD patients. The secondary aim was to compare the blood basophil-related variables of the AERD series (study group) with those of a control group of 95 consecutive cases of histologically non-eosinophilic CRSwNP. The AERD group showed a higher recurrence rate than the control group (p < 0.0001). The pre-operative blood basophil count and pre-operative bEBR were higher in AERD patients than in the control group (p = 0.0364 and p = 0.0006, respectively). The results of this study support the hypothesis that polyps removal may contribute to reducing the inflammation and activation of basophils.

Transcriptomic Differentiation of Phenotypes in Chronic Rhinosinusitis and Its Implications for Understanding the Underlying Mechanisms

Chronic rhinosinusitis (CRS) is a multifaceted disease with variable clinical courses and outcomes. We aimed to determine CRS-associated nasal-tissue transcriptome in clinically well-characterized and phenotyped individuals, to gain a novel insight into the biological pathways of the disease. RNA-sequencing of tissue samples of patients with CRS with polyps (CRSwNP), without polyps (CRSsNP), and controls were performed. Characterization of differently expressed genes (DEGs) and functional and pathway analysis was undertaken. We identified 782 common CRS-associated nasal-tissue DEGs, while 375 and 328 DEGs were CRSwNP- and CRSsNP-specific, respectively. Common key DEGs were found to be involved in dendritic cell maturation, the neuroinflammation pathway, and the inhibition of the matrix metalloproteinases. Distinct CRSwNP-specific DEGs were involved in NF-kβ canonical pathways, Toll-like receptor signaling, HIF1α regulation, and the Th2 pathway. CRSsNP involved the NFAT pathway and changes in the calcium pathway. Our findings offer new insights into the common and distinct molecular mechanisms underlying CRSwNP and CRSsNP, providing further understanding of the complex pathophysiology of the CRS, with future research directions for novel treatment strategies.

Effect of Probiotics on Respiratory Tract Allergic Disease and Gut Microbiota

Allergy is a hypersensitivity reaction triggered by specific cell or antibody-mediated immune mechanisms. Allergies have increased in industrialized countries in recent decades. The rise in allergic respiratory diseases such as allergic rhinitis (AR) and allergic asthma (AA) is a potential threat to public health. Searches were conducted using PubMed, Google Scholar and Medline using the following key terms: allergic rhinitis OR asthma AND probiotics, allergic airway inflammation AND immune disorders, probiotics OR gut microbiota AND allergic disease, probiotics AND inflammatory. Studies from all years were included, specifically those published within the last 10 years. Some review articles and their reference lists were searched to identify related articles. The role of microbiota in respiratory allergic diseases has attracted more and more attention. Pieces of evidence suggested that the development of allergic diseases causes a possible imbalance in the composition of the gut microbiota. Compared to colonized mice, germ-free mice exhibit exaggerated allergic airway responses, suggesting that microbial host interactions play an important role in the development of allergic diseases. Probiotics modulate both the innate and adaptive inflammatory immune responses, often used as dietary supplements to provide health benefits in gastrointestinal disorders. Probiotics may serve as immunomodulators and activators of host defense pathways. Besides, oral probiotics can modulate the immune response in the respiratory system. Recently, studies in humans and animals have demonstrated the role of probiotic in RA and AA. To understand the characterization, microbiota, and the potential role of probiotics intervention of AA/AR, this review provides an overview of clinical features of AA and AR, probiotics for the prevention and treatment of AR, AA, changes in gut microbiota, and their mechanisms of action.

Effect of IL-35 on apoptosis, adhesion, migration, and activation of eosinophils in allergic rhinitis

BACKGROUND

Eosinophils play critical roles in the development of allergic rhinitis (AR) by releasing toxic substance. Interleukin-35 (IL-35), a newly identified anti-inflammatory cytokine, had potent inhibitive role for eosinophil infiltration in allergic disease. However, the direct effect of IL-35 on eosinophil was not clear.

METHODS

Twenty AR children and sixteen controls were recruited. The correlation between IL-35 protein expression and blood eosinophil counts and activation was analyzed. The effect of IL-35 on eosinophil apoptosis and adhesion was analyzed by flow cytometry. Transwell system was used for the migration assay. The eosinophil cationic protein (ECP) from supernatant of eosinophils after IL-35 stimulation was detected by enzyme-linked immunosorbent assay kits.

RESULTS

The IL-35 protein levels were negatively correlated with eosinophil counts (p < .01) and ECP concentration (p < .01) in AR children. IL-35 promotes apoptosis and inhibits adhesion, migration, and activation of eosinophils. Moreover, the mRNA expression of IL-12 receptor β2 and glycoprotein 130 were significantly enhanced by eosinophils after IL-35 stimulation. The apoptosis induced by IL-35 was mediated by phosphoinositide 3-kinase (PI3K) pathway. IL-35 inhibits adhesion of eosinophils through extracellular regulated protein kinases (ERK) and PI3K pathways. The eosinophil chemotaxis and activation affected by IL-35 were mediated by PI3K and p38 mitogen-activated protein kinase (MAPK) pathways.

CONCLUSION

Our results confirmed that IL-35 played inhibitive roles in apoptosis, adhesion, migration, and activation of eosinophils in AR, implying that IL-35 may be used as treatment target in future.

Biologic Responses to House Dust Mite Exposure in the Environmental Exposure Unit

Introduction: Allergic rhinitis (AR) is an inflammatory disease of the nasal mucosa that can be modeled using Controlled Allergen Exposure Facilities (CACF). Recently, we clinically validated the house dust mite (HDM) Environmental Exposure Unit (EEU) facility. In the current study, we aimed to assess biological responses in the blood following HDM exposure in the HDM-EEU. Methods: Fifty-five participants passed a screening visit, where they provided consent and completed a skin prick test (SPT), then attended a modest or higher HDM exposure session. Baseline and post-exposure blood samples were collected. Complete blood counts with differentials were measured, and isolated serum was used to determine Dermatophagoides farinae- and Dermatophagoides pteronyssinus-specific IgE (sIgE) and cytokine concentrations (IL-4, IL-5, IL-6, IL-10, IL-13, TNF-α). Results: HDM-allergic participants had significantly greater SPT wheal sizes than healthy controls. sIgE concentrations were significantly greater in allergic participants, with a strong correlation between Dermatophagoides farinae and Dermatophagoides pteronyssinus. Serum eosinophil counts were significantly decreased post-exposure for allergic participants. White blood cell, neutrophil, and lymphocyte counts were significantly increased for both allergic and non-allergic participants post-exposure. Serum IL-13 concentrations were significantly reduced post-exposure in allergics while TNF-α was significantly reduced in non-allergics. Conclusion: The HDM-EEU is a useful model for investigating biologic mechanisms of HDM-induced AR. Allergic participants produced measurable biological changes compared to healthy controls following allergen exposure, specifically with serum expression of eosinophils and related markers, namely IL-5, which promotes the proliferation and differentiation of eosinophils, and IL-13, a cytokine released by eosinophils. The exact mechanisms at play require further investigation.

Effect and mechanism of human umbilical cord mesenchymal stem cells in treating allergic rhinitis in mice

A model of allergic rhinitis (AR) in BALB/c mice was established and evaluated to provide experimental subjects for further research. Preparation of human umbilical cord mesenchymal stem cells (hUCMSCs), including isolation, expansion culture, passaging, cryopreservation, and preparation of cell suspensions, provided materials for experimental research and clinical treatment. The mouse AR model was established by ovalbumin (OVA) intraperitoneal injection and the nasal stimulation induction method, and the model had a good effect and high repeatability. GFP-labeled hUCMSCs had good effects and were stable cells that could be used for tracking in animals. Transplantation of hUCMSCs by intraperitoneal and tail vein injections had a specific effect on the AR model of mice, and tail vein injection had a better effect. Tracking of hUCMSCs in vivo showed that the three groups of mice had the greatest number of hUCMSCs in the nose at week 2. The mouse AR model was used to evaluate the efficacy of hUCMSC transplantation via multiple methods for AR. The distribution of hUCMSCs in vivo was tracked by detecting green fluorescent protein (GFP), and the treatment mechanism of hUCMSCs was elucidated. This study provides technical methods and a theoretical basis for the clinical application of hUCMSCs.

Current and emerging biologic therapies for allergic rhinitis and chronic rhinosinusitis

Introduction: Allergic rhinitis and chronic rhinosinusitis, with and without nasal polyps, are the most common chronic inflammatory diseases of the upper airways. They both cause relevant respiratory symptoms and a substantial detriment to patients' quality of life, mainly in uncontrolled and severe patients.Areas covered: This review aims to present the most recent evidence on current and emerging biologic therapies for allergic rhinitis and chronic rhinosinusitis and discuss their potential implementation in clinical practice. To select relevant literature for inclusion in this review, we conducted a literature search using the PubMed database, using terms 'biologics OR biological agents', 'allergic rhinitis' and 'chronic rhinosinusitis'. The literature review was performed for publication years 2009-2019, restricting the articles to humans and English language publications.Expert opinion: Biological therapies represent a potential step forward in providing individualized care for all patients with uncontrolled severe upper airway diseases. Biologics recently showed promising results for the treatment of severe uncontrolled allergic rhinitis and chronic rhinosinusitis with nasal polyps with or without associated asthma. Endotyping inflammatory pathways and identifying related biomarkers remain the major challenge for positioning biologics in the care pathway of chronic respiratory diseases.

Turbinate hypertrophy in children with allergic rhinitis: clinical relevance

Allergic rhinitis (AR) is the most common immune-mediated disorder in childhood as it may affect up to 40% of children. Turbinate hypertrophy (TH) is an important sign as reliably predicts AR both in children and adults. Consistently, nasal obstruction is a very common symptom in AR patients and is closely linked with turbinate hypertrophy. This study investigated 544 (304 males) children with AR to define factors associated with TH. TH was diagnosed in 438 (80.81%) AR children. The multivariate analysis demonstrated a significant association between age, male gender, and recurrent acute otitis media (RAOM), and TH (p-values: 0.0219, <0.0001, and 0.0003, respectively; OR 0.87, 3.97, and 0.22 respectively). In conclusion, this real-life study showed that TH was very frequent in children with AR and age, male gender, and RAOM were significantly associated with TH.

Chronic rhinosinusitis with nasal polyposis: the role of personalized and integrated medicine

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a frequent disorder. From a clinical and an immunopathological point of view, different phenotypes and endotypes have been identified. The frequent comorbidity with asthma allowed to pave the way to the use of biological agents for the treatment of CRSwNP. Biological agents are targeted to antagonize IgE, interleukin (IL) 4, IL-5, and IL-13 at present. However, a correct and appropriate workup is mandatory, mainly concerning the exact definition of the specific pheno-endotype. The preliminary outcomes are promising, even though there is a need for well-established indications, criteria of responsiveness, duration, and safety. On the other hand, this personalized medicine could be fruitfully integrated with gold-standard medications, such as intranasal corticosteroids. As CRSwNP is a chronic disorder, treatment should be long-lasting, so complementary anti-inflammatory treatments could be opportunely integrated and/or alternated to steroids. (www.actabiomedica.it)

Inflammation, infection, and allergy of upper airways: new insights from national and real-world studies

The upper airways (UA) should be considered as a functional unit. Current functional anatomy divides URT in three, mutually dependent, "junction boxes": i) the ostio-meatal complex (OMC), ii) the spheno-ethmoidal recess (SER), and iii) the rhinopharynx (RP). Correct ventilation and effective mucociliary clearance of these sites significantly affect the healthy physiology of the entire respiratory system. The OMC, SER, and RP obstruction is the first pathogenic step in the inflammatory/infectious cascade of UA disorders. The inflammation of the respiratory mucosa is the main pathogenic factor for airway obstruction. Moreover, bacterial biofilm (a strategy modality of bacterial survival) is an important local cause of systemic antibiotic ineffectiveness, recurrent infections, and antibiotic resistance. Health microbiota guarantees UA wellness; on the contrary, dysbiosis promotes and worsens UA infections. Allergy, namely type 2 inflammation, is a common cause of UA obstruction such as promoting in turn infections. Fiberoptic endoscopy is a mandatory diagnostic tool in clinical practice. Nasal cytology, mainly concerning flow cytometry, allows defining rhinitis phenotypes so allowing a precision medicine approach. Several conventional therapeutic approaches are available, but efficacy and safety should be ever properly considered before the prescription. Also, complementary medicine plays a fruitful role in the management of UA diseases. National and real-world studies are reported and discussed as they may be useful in daily clinical practice.