Effects of bacterial toxins on air-exposed cultured human respiratory sinus epithelium

A Scoping Analysis of Cathelicidin in Response to Organic Dust Exposure and Related Chronic Lung Illnesses

Over two billion people worldwide are exposed to organic dust, which can cause respiratory disorders. The discovery of the cathelicidin peptide provides novel insights into the lung’s response to organic dust; however, its role in the lung’s response to organic dust exposure and chronic lung diseases remains limited. We conducted a scoping review to map the current evidence on the role of cathelicidin LL-37/CRAMP in response to organic dust exposure and related chronic lung diseases: hypersensitivity pneumonitis (HP), chronic obstructive pulmonary disease (COPD) and asthma. We included a total of n = 53 peer-reviewed articles in this review, following the process of (i) a preliminary screening; (ii) a systematic MEDLINE/PubMed database search; (iii) title, abstract and full-text screening; (iv) data extraction and charting. Cathelicidin levels were shown to be altered in all clinical settings investigated; its pleiotropic function was confirmed. It was found that cathelicidin contributes to maintaining homeostasis and participates in lung injury response and repair, in addition to exerting a positive effect against microbial load and infections. In addition, LL-37 was found to sustain continuous inflammation, increase mucus formation and inhibit microorganisms and corticosteroids. In addition, studies investigated cathelicidin as a treatment modality, such as cathelicidin inhalation in experimental HP, which had positive effects. However, the primary focus of the included articles was on LL-37’s antibacterial effect, leading to the conclusion that the beneficial LL-37 activity has not been adequately examined and that further research is required.

Ototopical drops containing a novel antibacterial synthetic peptide: Safety and efficacy in adults with chronic suppurative otitis media

OBJECTIVE

Chronic suppurative otitis media (CSOM) is a chronic infectious disease with worldwide prevalence that causes hearing loss and decreased quality of life. As current (antibiotic) treatments often unsuccessful and antibiotic resistance is emerging, alternative agents and/or strategies are urgently needed. We considered the synthetic antimicrobial and anti-biofilm peptide P60.4Ac to be an interesting candidate because it also displays anti-inflammatory activities including lipopolysaccharide-neutralizing activity. The aim of the present study was to investigate the safety and efficacy of ototopical drops containing P60.4Ac in adults with CSOM without cholesteatoma.

METHODS

We conducted a range-finding study in 16 subjects followed by a randomized, double blinded, placebo-controlled, multicentre phase IIa study in 34 subjects. P60.4Ac-containing ototopical drops or placebo drops were applied twice a day for 2 weeks and adverse events (AEs) and medication use were recorded. Laboratory tests, swabs from the middle ear and throat for bacterial cultures, and audiometry were performed at intervals up to 10 weeks after therapy. Response to treatment was assessed by blinded symptom scoring on otoscopy.

RESULTS

Application of P60.4Ac-containing ototopical drops (0.25-2.0 mg of peptide/ml) in the ear canal of patients suffering from CSOM was found to be safe and well-tolerated. The optimal dose (0.5 mg of peptide/ml) was selected for the subsequent phase IIa study. Safety evaluation revealed only a few AEs that were unlikely related to study treatment and all, except one, were of mild to moderate intensity. In addition to this excellent safety profile, P60.4Ac ototopical drops resulted in a treatment success in 47% of cases versus 6% in the placebo group.

CONCLUSION

The efficacy/safety balance assessed in the present study provides a compelling justification for continued clinical development of P60.4Ac in therapy-resistant CSOM.

An Experimental Model of Eosinophilic Chronic Rhinosinusitis Induced by Bacterial Toxins in Rabbits

Background

The pathophysiology of chronic rhinosinusitis (CRS) is still not well known due to the multifactorial etiologies involved. Bacteria play a role in the pathogenesis of CRS by various means, including biofilm adhesion, intracellular persistence, or inducing inflammation secondary to toxins. Endotoxins and exotoxins, especially Staphylococcus aureus superantigens, can produce significant immune responses in the host and are implicated in patients with CRS. The majority of animal models described for CRS revalidates the pathophysiology of acute sinusitis, ostium occlusion, or foreign body associated infection.

Objectives

To evaluate an experimental model of eosinophilic CRS using prolonged exposure to bacterial toxins. The histological changes in rabbits exposed to S. aureus enterotoxin B (SEB), lipopolysaccharide (LPS), or lipoteichoic acid (LTA) were compared.

Methods

After induction with ovalbumin (OVA) sensitization with subcutaneous injection for 2 weeks, rabbits underwent surgery to insert an indwelling catheter into the maxillary sinus. The sinus was irrigated with OVA 3 times weekly for 2 weeks, followed by sinus irrigation with bacterial toxin (SEB: 1 µg/mL, LPS: 100 ng/mL, or LTA: 100 ng/mL) 3 times weekly for 4 weeks. The histological changes in the treated sinus were compared with control rabbits.

Results

Sinuses exposed to bacterial toxins (SEB, LPS, and LTA) produced significant mucosal thickening with infiltration of inflammatory cells, notably eosinophils. SEB was the only toxin that promoted a mixed pattern of inflammation, including eosinophilic and neutrophilic infiltration.

Conclusion

Our experimental model of eosinophilic CRS in rabbits produced significant mucosal thickening and inflammation in the sinuses exposed to bacterial toxins, with histological changes analogous to what is observed in patients with CRS with nasal polyps. This model may serve as a basis for future investigation of the pathogenesis of eosinophilic CRS in relation to bacterial toxins or as a model for testing new therapeutic modalities for this disease.

Safety evaluation of the antimicrobial peptide bovicin HC5 orally administered to a murine model

BACKGROUND

Bovicin HC5 is an antimicrobial peptide that shows a broad spectrum of activity and potential for biotechnological and therapeutic applications. To gain insight about the safety of bovicin HC5 application, the histological and immunostimulatory effects of orally administrated bovicin HC5 to BALB/c mice were evaluated. BALB/c mice were divided into three groups: negative control (NC group); mice given purified bovicin HC5 (Bov group); mice given ovalbumin (positive control, PC group; a murine model of enteropathy). The mice were initially pre-sensitized, and PBS, bovicin HC5 or ovalbumin were administered for 30 days by daily gavages. Histological and morphometric analysis were performed and the relative expression of cytokines was analyzed by real-time RT-PCR.

RESULTS

The oral administration of bovicin HC5 to BALB/c mice reduced weight gain and caused alterations in the small intestine, although absorptive changes have not been detected. The number of total goblet cells and the mucopolysaccharides production were not affected by bovicin HC5 administration. A hypertrophy of Paneth cells and an increase in the number of mitotic cells were observed in Bov group, while the number of mast cells remained unaltered. Increased expression of TNF-α, INF-γ and IL-12 was observed in the small intestine upon bovicin HC5 administration.

CONCLUSION

Bovicin HC5 has only minor effects on intestinal permeability and did not elicit an allergenic response upon oral administration to animal models. Considering the low in vivo toxicity of bovicin HC5, it might be a good candidate for enteral applications.

Chronic rhinosinusitis with polyps and without polyps is associated with increased expression of suppressors of cytokine signaling 1 and 3

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) or without nasal polyps (CRSsNP) is associated with expression of various cytokines. Suppressors of cytokine signaling (SOCS) regulate cytokine activity in a variety of cells, modulating inflammatory responses.

OBJECTIVE

We analyzed the expression and distribution pattern of SOCS1 and SOCS3 in CRSwNP and CRSsNP, and their cytokine-driven expression regulation in sinus mucosa. In addition, the expression levels of various cytokines were evaluated in CRSwNP and CRSsNP.

METHODS

The expression levels of SOCS1 and SOCS3 in CRSwNP and CRSsNP and in control samples were assessed by using real-time PCR, Western blot, and immunohistochemistry. Nasal epithelial cell culture was used to elucidate the effect of IL-4, IL-5, IL-6, IL-10, IL-13, IFN-γ, TNF-α, and TGF-β1 on SOCS1 and SOCS3 expression in sinus mucosa. The expression levels of these cytokines were also evaluated in normal and inflammatory sinus mucosa by using real-time PCR and Western blot.

RESULTS

The expression levels of SOCS1 and SOCS3 were increased in CRS, irrespective of the presence of nasal polyp, and they were distributed in superficial epithelium, submucosal glands, and vascular endothelium in sinus mucosa. SOCS1 was induced by IL-4, IL-13, IFN-γ, and TNF-α, while SOCS3 expression was upregulated by IL-6, IL-13, IFN-γ, and TNF-α. IL-4 and IL-13 levels were increased in CRSwNP, while IL-4, IFN-γ, TNF-α, and TGF-β1 levels were increased in CRSsNP.

CONCLUSION

SOCS1 and SOCS3 are increased in CRS, irrespective of nasal polyp presence. This may be a response to elevated levels of various cytokines increasingly expressed in inflammatory sinus mucosa.

Microbiological study of role of fungi in primary atrophic rhinitis

BACKGROUND

Fungal rhinosinusitis has gained much attention in recent years. To our knowledge, no previous studies have addressed the role of fungus in primary atrophic rhinitis.

STUDY DESIGN

Prospective case study.

PATIENTS AND METHODS

All cases of primary atrophic rhinitis presenting to the out-patient department at El-Sahel Teaching Hospital over a five-month period were included in the study. Crusts and purulent secretions removed from patients' nasal cavities underwent microbiological analysis at the Medical Microbiology and Immunology department of the Cairo University Faculty of Medicine. Special emphasis was placed on fungal isolation.

RESULTS

Fourteen consecutive cases of primary atrophic rhinitis were studied in the five-month period starting 26 November 2007. Patients comprised eight females and six males, with an age range of 12 to 65 years (mean 37 years). Microscopy of the crusts and purulent secretions showed pus cells in most of the samples. Klebsiella species were isolated from nine patients (65 per cent), and other bacterial species were isolated in most of the remainder. Fungal elements, most commonly aspergillus species, were isolated in 13 patients (93 per cent).

CONCLUSION

It is proposed that the initial trigger for primary atrophic rhinitis is a virulent bacterial infection of the nasal lining, which leads to damage of the ciliated epithelium. This initiates the cascade of events leading to inflammation of the mucosa and submucosa, with secondary pyogenic osteomyelitis of the turbinate bone. The persistence of purulent secretion, within the setting of impaired mucociliary clearance, leads to saprophytic fungal colonisation which contributes greatly to the clinical picture.

An antimicrobial peptide modulates epithelial responses to bacterial products

INTRODUCTION

Changes in the respiratory epithelium and chronic and recurrent infections are thought to play a central role in the pathogenesis of otitis media and sinusitis. The airway epithelium is the primary defense system of the respiratory tract. Bacterial cell membrane components like lipopolysaccharide (LPS) and lipoteichoic acid (LTA) can affect the mucociliary clearance function of the respiratory epithelium. P60.4-Ac is a synthetic antimicrobial peptide based on the structure of the cathelicidin LL-37 that neutralizes the pro-inflammatory activity of LPS and LTA.

MATERIALS AND METHODS

Normal respiratory sinus epithelium was cultured at the air liquid interface. The cells were incubated with LPS or LTA in the presence or absence of P60.4-Ac.

RESULTS

P60.4-Ac neutralized the LPS- and LTA- induced effect on air-liquid interface cultured epithelial cells. P60.4-Ac significantly inhibited the increase in the epithelial layer caused by LPS or LTA.

CONCLUSION

These data demonstrate that P60.4-Ac might be of clinical benefit in the management of otitis media with effusion and sinusitis.

Development of novel LL-37 derived antimicrobial peptides with LPS and LTA neutralizing and antimicrobial activities for therapeutic application

New peptides for lipopolysaccharide (LPS) and lipoteichoic acid (LTA) neutralization in upper respiratory tract infections were developed and evaluated in terms of efficacy and safety for application in humans. Based on the sequence of the human antimicrobial peptide LL-37 we developed and investigated length variants, substitution analogues and modifications to stabilize the peptides to prevent enzymatic degradation and to improve efficacy. The most promising peptide appears P60.4, a 24 amino acid peptide with similar efficacy as LL-37 in terms of LPS and LTA neutralization and lower pro-inflammatory activity. In addition, the acetylated and amidated version of this peptide shows no toxicity and displays higher or equal antimicrobial activity compared to LL-37.

Bacterial products increase expression of the human cathelicidin hCAP-18/LL-37 in cultured human sinus epithelial cells

The respiratory epithelium plays a major role in the primary defense of the airways against infection. It has been demonstrated that bacterial products are involved in the induction of inflammatory reactions of the upper airways. Little is known about the effects of bacterial products on expression of the antimicrobial peptide hCAP-18/LL-37, the only human cathelicidin identified so far. The aim of this study was to investigate the effects of bacterial products from both gram-positive and gram-negative bacteria on the expression of hCAP-18/LL-37 by sinus epithelial cells using an air-exposed tissue culture model. Lipopolysaccharide and lipoteichoic acid both increased hCAP-18/LL-37 expression in cultured sinus epithelium as assessed by immunohistochemistry, where maximal stimulation occurred at 100 ng ml(-1) lipopolysaccharide or 10 microg ml(-1) lipoteichoic acid. The stimulatory effect of lipopolysaccharide and lipoteichoic acid was not restricted to expression of hCAP-18/LL-37, since also mucin expression and IL-8 release from cultured sinus epithelium cells were increased by lipopolysaccharide and lipoteichoic acid. This suggests that bacterial products may stimulate innate immunity in the upper airways.