Upper respiratory infections in children: response to endonasal administration of IGA

A new hope? Possibilities of therapeutic IgA antibodies in the treatment of inflammatory lung diseases

Inflammatory lung diseases represent a persistent burden for patients and the global healthcare system. The combination of high morbidity, (partially) high mortality and limited innovations in the last decades, have resulted in a great demand for new therapeutics. Are therapeutic IgA antibodies possibly a new hope in the treatment of inflammatory lung diseases? Current research increasingly unravels the elementary functions of IgA as protector against infections and as modulator of overwhelming inflammation. With a focus on IgA, this review describes the pathological alterations in mucosal immunity and how they contribute to chronic inflammation in the most common inflammatory lung diseases. The current knowledge of IgA functions in the circulation, and particularly in the respiratory mucosa, are summarized. The interplay between neutrophils and IgA seems to be key in control of inflammation. In addition, the hurdles and benefits of therapeutic IgA antibodies, as well as the currently known clinically used IgA preparations are described. The data highlighted here, together with upcoming research strategies aiming at circumventing the current pitfalls in IgA research may pave the way for this promising antibody class in the application of inflammatory lung diseases.

Egg-Derived Anti-SARS-CoV-2 Immunoglobulin Y (IgY) With Broad Variant Activity as Intranasal Prophylaxis Against COVID-19

COVID-19 emergency use authorizations and approvals for vaccines were achieved in record time. However, there remains a need to develop additional safe, effective, easy-to-produce, and inexpensive prevention to reduce the risk of acquiring SARS-CoV-2 infection. This need is due to difficulties in vaccine manufacturing and distribution, vaccine hesitancy, and, critically, the increased prevalence of SARS-CoV-2 variants with greater contagiousness or reduced sensitivity to immunity. Antibodies from eggs of hens (immunoglobulin Y; IgY) that were administered the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein were developed for use as nasal drops to capture the virus on the nasal mucosa. Although initially raised against the 2019 novel coronavirus index strain (2019-nCoV), these anti-SARS-CoV-2 RBD IgY surprisingly had indistinguishable enzyme-linked immunosorbent assay binding against variants of concern that have emerged, including Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529). This is different from sera of immunized or convalescent patients. Culture neutralization titers against available Alpha, Beta, and Delta were also indistinguishable from the index SARS-CoV-2 strain. Efforts to develop these IgY for clinical use demonstrated that the intranasal anti-SARS-CoV-2 RBD IgY preparation showed no binding (cross-reactivity) to a variety of human tissues and had an excellent safety profile in rats following 28-day intranasal delivery of the formulated IgY. A double-blind, randomized, placebo-controlled phase 1 study evaluating single-ascending and multiple doses of anti-SARS-CoV-2 RBD IgY administered intranasally for 14 days in 48 healthy adults also demonstrated an excellent safety and tolerability profile, and no evidence of systemic absorption. As these antiviral IgY have broad selectivity against many variants of concern, are fast to produce, and are a low-cost product, their use as prophylaxis to reduce SARS-CoV-2 viral transmission warrants further evaluation.

Clinical Trial Registration

https://www.clinicaltrials.gov/ct2/show/NCT04567810, identifier NCT04567810.

The Role of IgA in Chronic Upper Airway Disease: Friend or Foe?

Chronic upper airway inflammation is amongst the most prevalent chronic disease entities in the Western world with prevalence around 30% (rhinitis) and 11% (rhinosinusitis). Chronic rhinitis and rhinosinusitis may severely impair the quality of life, leading to a significant socio-economic burden. It becomes more and more clear that the respiratory mucosa which forms a physiological as well as chemical barrier for inhaled particles, plays a key role in maintaining homeostasis and driving disease. In a healthy state, the mucosal immune system provides protection against pathogens as well as maintains a tolerance toward non-harmful commensal microbes and benign environmental substances such as allergens. One of the most important players of the mucosal immune system is immunoglobulin (Ig) A, which is well-studied in gut research where it has emerged as a key factor in creating tolerance to potential food allergens and maintaining a healthy microbiome. Although, it is very likely that IgA plays a similar role at the level of the respiratory epithelium, very little research has been performed on the role of this protein in the airways, especially in chronic upper airway diseases. This review summarizes what is known about IgA in upper airway homeostasis, as well as in rhinitis and rhinosinusitis, including current and possible new treatments that may interfere with the IgA system. By doing so, we identify unmet needs in exploring the different roles of IgA in the upper airways required to find new biomarkers or therapeutic options for treating chronic rhinitis and rhinosinusitis.

Immunoglobulin Y for Potential Diagnostic and Therapeutic Applications in Infectious Diseases

Antiviral, antibacterial, and antiparasitic drugs and vaccines are essential to maintaining the health of humans and animals. Yet, their production can be slow and expensive, and efficacy lost once pathogens mount resistance. Chicken immunoglobulin Y (IgY) is a highly conserved homolog of human immunoglobulin G (IgG) that has shown benefits and a favorable safety profile, primarily in animal models of human infectious diseases. IgY is fast-acting, easy to produce, and low cost. IgY antibodies can readily be generated in large quantities with minimal environmental harm or infrastructure investment by using egg-laying hens. We summarize a variety of IgY uses, focusing on their potential for the detection, prevention, and treatment of human and animal infections.

Avian antibodies (IgY) targeting spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inhibit receptor binding and viral replication

BACKGROUND

The global pandemic of Coronavirus infectious disease 2019 (COVID-19), caused by SARS-CoV-2, has plunged the world into both social and economic disarray, with vaccines still emerging and a continued paucity of personal protective equipment; the pandemic has also highlighted the potential for rapid emergence of aggressive respiratory pathogens and the need for preparedness. Avian immunoglobulins (IgY) have been previously shown in animal models to protect against new infection and mitigate established infection when applied intranasally. We carried out a proof-of-concept study to address the feasibility of using such antibodies as mucosally-applied prophylaxis against SARS-CoV-2.

METHODS

Hens were immunized with recombinant S1 spike glycoprotein of the virus, and the resulting IgY was evaluated for binding specificity, inhibition of glycoprotein binding to angiotensin converting enzyme-2 (ACE2) protein (the requisite binding site for the virus), and inhibition of viral replication in Vero cell culture.

RESULTS

Titers of anti-S1 glycoprotein IgY were evident in yolks at 14 days post-immunization, peaking at 21 days, and at peak concentrations of 16.8 mg/ml. IgY showed strong and significant inhibition of S1/ACE2 binding interactions, and significantly inhibited viral replication at a concentration of 16.8 mg/ml. Four weeks' collection from eggs of two hens produced a total of 1.55 grams of IgY.

CONCLUSIONS

In this proof-of-concept study we showed that avian immunoglobulins (IgY) raised against a key virulence factor of the SARS-CoV-2 virus successfully inhibited the critical initial adhesion of viral spike glycoproteins to human ACE2 protein receptors and inhibited viral replication in vitro, in a short period using only two laying hens. We conclude that production of large amounts of IgY inhibiting viral binding and replication of SARS-CoV-2 is feasible, and that incorporation of this or similar material into an intranasal spray and/or other mucosal protecting products may be effective at reducing infection and spread of COVID-19.

Multi-faceted functions of secretory IgA at mucosal surfaces

Secretory IgA (SIgA) plays an important role in the protection and homeostatic regulation of intestinal, respiratory, and urogenital mucosal epithelia separating the outside environment from the inside of the body. This primary function of SIgA is referred to as immune exclusion, a process that limits the access of numerous microorganisms and mucosal antigens to these thin and vulnerable mucosal barriers. SIgA has been shown to be involved in avoiding opportunistic pathogens to enter and disseminate in the systemic compartment, as well as tightly controlling the necessary symbiotic relationship existing between commensals and the host. Clearance by peristalsis appears thus as one of the numerous mechanisms whereby SIgA fulfills its function at mucosal surfaces. Sampling of antigen-SIgA complexes by microfold (M) cells, intimate contact occurring with Peyer’s patch dendritic cells (DC), down-regulation of inflammatory processes, modulation of epithelial, and DC responsiveness are some of the recently identified processes to which the contribution of SIgA has been underscored. This review aims at presenting, with emphasis at the biochemical level, how the molecular complexity of SIgA can serve these multiple and non-redundant modes of action.

Recurrent respiratory infections and phagocytosis in childhood

BACKGROUND

About 10% of pre-school children has recurrent respiratory infections (RRI), which could be related to environmental and/or immunological factors. The aim of the present study has been to evaluate the impact of phagocytosis (FAG) and reactive oxygen intermediates (ROI) production deficiencies on pediatric RRI by the measurement of FAG and ROI activity of the polymorphonuclear neutrophils.

METHODS

Serum immunoglobulins, IgG subclasses, lymphocytic subpopulations, FAG and ROI tests were measured in 90 children with RRI, in a moment of well-being and off all medications for at least 4 weeks. FAG and ROI tests were also measured in 19 healthy children.

RESULTS

FAG (91.4 +/- 11.5%) and ROI (81.8 +/- 17.5%) of patients resulted in significantly decreased measurements compared to the control values (95.2 +/- 1.8% and 89.7 +/- 4.8%, respectively). No significant difference was manifest between the mean values of FAG and ROI tests among the patients when they were divided for age (above and below 6 years). A significant decreased likelihood of abnormal ROI (odds ratio, 0.3; 95% confidence interval, 0.07-0.97) was found in the patients with low IgA.

CONCLUSIONS

The authors' results permit only to suppose an etiological role of FAG and ROI deficiencies of polymorphonuclear neutrophils in the genesis of pediatric RRI, irrespective of the age of the patients, and further studies are necessary for confirmation.

Parotid salivary immunoglobulins, recurrent respiratory tract infections and gingival health in institutionalized and non-institutionalized subjects with Down's syndrome

BACKGROUND

The purpose of the present study was to evaluate the possible correlation between recurrent respiratory infections (RRIs), gingival health and the secretion rates of salivary immunoglobulins (Igs) in institutionalized (I) and non-institutionalized (NI) individuals with Down's syndrome (DS).

METHODS

Stimulated parotid saliva was collected from nine I and 14 NI subjects with DS. Salivary flow rate, secretion rates of total salivary IgM, IgG and IgA, and the incidence of RRIs were determined. Gingival health was recorded by using the plaque index, the gingival index and the percentage of bleeding surfaces (BS).

RESULTS

The mean salivary flow rate and parotid Ig secretion rates in the I group were 25% of those of the NI group. The prevalence of RRIs in the I group was more than twice that in the NI group. Oral hygiene and gingival health were significantly better in the NI group.

CONCLUSIONS

The lower parotid Ig secretion rates in I individuals with DS might be a possible factor involved in their susceptibility to recurrent infections compared to NI subjects with DS.

Secretory component: a new role in secretory IgA-mediated immune exclusion in vivo

Secretory immunoglobulin (Ig) A (SIgA) is essential in protecting mucosal surfaces. It is composed of at least two monomeric IgA molecules, covalently linked through the J chain, and secretory component (SC). We show here that a dimeric/polymeric IgA (IgA(d/p)) is more efficient when bound to SC in protecting mice against bacterial infection of the respiratory tract. We demonstrate that SC ensures, through its carbohydrate residues, the appropriate tissue localization of SIgA by anchoring the antibody to mucus lining the epithelial surface. This in turn impacts the localization and the subsequent clearance of bacteria. Thus, SC is directly involved in the SIgA function in vivo. Therefore, binding of IgA(d/p) to SC during the course of SIgA-mediated mucosal response constitutes a crucial step in achieving efficient protection of the epithelial barrier by immune exclusion.

A link between parotid salivary Ig level and recurrent respiratory infections in young Down's syndrome patients

The purpose of the present investigation was to assess the correlation between recurrent respiratory infections and the levels of salivary Ig in a group of young Down's syndrome (DS) individuals. Twenty-three DS and 10 age- and sex-matched healthy individuals were included. DS individuals who had experienced three or more upper respiratory tract infections (n = 10) in the previous 12 months were compared to DS individuals who had not experienced recurrent respiratory infections (n = 13) and to healthy controls (n = 10). A statistically significant reduction in the Ig salivary secretion rate was recorded in the subgroup with recurrent respiratory infections. No significant differences were seen between the subgroup without recurrent respiratory infections and controls. It is suggested that the secretory immune system provides local immune protection against pathogens in the respiratory tract. Detection of salivary Ig levels may serve as a predictor of the susceptibility of DS individuals to recurrent respiratory tract infections.

Intranasal antibody prophylaxis for protection against viral disease

For more than a century, antibody has been used for passive parenteral immunization against viral and bacterial pathogens. This approach has been successful for prevention of viral respiratory infection and has led to testing of intranasal or aerosol delivery of antibody to passively immunize the respiratory tract mucosal surface. Mucosal delivery may be advantageous because it allows the antibody to neutralize the virus particles before they initiate infection and because it concentrates the antibody where viral replication takes place. Animal studies have shown the feasibility of passive intranasal immunization against a number of respiratory tract viruses. Development of nasal antibody treatments for humans is under way, and early clinical studies have confirmed that this approach is safe and can be used to prevent respiratory tract disease. Polyclonal human immunoglobulin from pooled plasma preparations can be used to provide broad protection against a number of different pathogens, while monoclonal antibodies or their fragments can be used to target specific viruses.

Intranasally administered immunoglobulin for the prevention of rhinitis in children

OBJECTIVE

To determine the efficacy of intranasally administered immunoglobulin in preventing symptoms of rhinitis in children.

METHODS

Forty children ages 1 to 4 years who attended day-care centers in Turku, Finland, were enrolled in the double blind, placebo-controlled study. The children were randomly assigned to receive treatment with immunoglobulin, composed mainly of immunoglobulin A, or placebo, both administered as nasal sprays twice daily for 8 weeks. During this medication period and an additional 8-week follow-up period, the parents recorded the symptoms of the children daily in the diaries provided. One child who met an exclusion criterion was withdrawn from the study after a few days of medication.

RESULTS

During the 8-week medication period the 19 children in the immunoglobulin group had 42% fewer days with rhinitis than the 20 children receiving placebo (mean, 10.8 vs. 18.7 days; P=0.004). The total numbers of episodes of rhinitis in the immunoglobulin and placebo groups were 33 and 51, respectively. No significant differences were observed between the groups during the postmedication follow-up period.

CONCLUSIONS

Intranasal administration of immunoglobulin appears to be an effective method to prevent symptoms of rhinitis in children, and further studies of this approach are needed.