Hapivirins and diprovirins: novel θ-defensin analogs with potent activity against influenza A virus.

θ-Defensins are cyclic octadecapeptides found in nonhuman primates whose broad antiviral spectrum includes HIV-1, HSV-1, severe acute respiratory syndrome coronavirus, and influenza A virus (IAV). We previously reported that synthetic θ-defensins called retrocyclins can neutralize and aggregate various strains of IAV and increase IAV uptake by neutrophils. This study describes two families of peptides, hapivirins and diprovirins, whose design was inspired by retrocyclins. The goal was to develop smaller partially cyclic peptides that retain the antiviral activity of retrocyclins, while being easier to synthesize. The novel peptides also allowed for systemic substitution of key residues to evaluate the role of charge or hydrophobicity on antiviral activity. Seventy-two hapivirin or diprovirin peptides are described in this work, including several whose anti-IAV activity equals or exceeds that of normal α- or θ-defensins. Some of these also had strong antibacterial and antifungal activity. These new peptides were active against H3N2 and H1N1 strains of IAV. Structural features imparting strong antiviral activity were identified through iterative cycles of synthesis and testing. Our findings show the importance of hydrophobic residues for antiviral activity and show that pegylation, which often increases a peptide's serum t(1/2) in vivo, can increase the antiviral activity of DpVs. The new peptides acted at an early phase of viral infection, and, when combined with pulmonary surfactant protein D, their antiviral effects were additive. The peptides strongly increased neutrophil and macrophage uptake of IAV, while inhibiting monocyte cytokine generation. Development of modified θ-defensin analogs provides an approach for creating novel antiviral agents for IAV infections.

Interactions of alpha-, beta-, and theta-defensins with influenza A virus and surfactant protein D.

We have reported that the alpha-defensins human neutrophil peptides (HNP)-1 and HNP-2 neutralize and aggregate influenza A virus (IAV) and promote uptake of IAV by neutrophils. These alpha-defensins were also shown to bind to surfactant protein (SP)-D and reduce its antiviral activity. In this study, we examined retrocyclin (RC)1 and RC2, humanized versions of the antiviral theta-defensins found in the leukocytes of certain nonhuman primates. RC1 was just as effective as HNP-1-3 in neutralizing IAV, and RC2 and RC101 (an analog of RC1) were more effective. In contrast, human beta-defensins (HBDs) showed less neutralizing activity. Human defensins 5 and 6 (mainly produced by intestinal Paneth cells) had viral neutralizing activity similar to HNP-1-3. Like HNP-1-3, RCs induced viral aggregation and promoted the uptake of IAV by neutrophils. We used surface plasmon resonance to evaluate binding of defensins to SP-D. HBDs, HD6, and HNP-4 bound minimally to SP-D. HNP-1-3 and RCs bound SP-D with high affinity; however, unlike HNP-1 and HNP-2, RCs did not inhibit SP-D antiviral activity. HBDs also did not inhibit antiviral activity of SP-D. Given their strong neutralizing activity and compatibility with SP-D, RCs may provide attractive prototypes for designing therapeutics that can prevent or treat respiratory infections caused by IAV.

Cranial nerve VI palsy as an initial presentation of necrotizing sarcoid granulomatosis in a 14-year-old female: case report and literature review.

OBJECTIVES: We describe a case of pediatric necrotizing sarcoid granulomatosis (NSG) presenting with right cranial nerve VI palsy and multiple lung nodules, successfully treated with corticosteroids. METHODS: This is a descriptive case report of one patient with review of the literature. RESULTS: A 14-year-old Caucasian female presented with complaints of pain on inspiration and dyspnea on exertion, as well as diplopia that was worse with right gaze. The patient presented to our emergency department with persistent diplopia and was found to have stable right cranial nerve VI palsy. CTA showed multiple pulmonary nodules. Despite continued extensive multispecialty work-up, the patient׳s cranial nerve VI palsy had not resolved, thus tissue confirmation via lung biopsy was performed. Pathologic diagnosis revealed necrotizing sarcoid granulomatosis. The patient was subsequently started on intravenous corticosteroids, which led to the rapid resolution of her presenting symptoms. CONCLUSIONS: Necrotizing sarcoid granulomatosis is a multisystem organ disease that is rare in children. Pathology commonly reveals epithelioid noncaseating granuloma and granulomatous vasculitis with necrosis. We report an unusual presentation involving sixth nerve palsy in a 14-year-old girl. Diagnosis was determined and confirmed by histopathology of a pulmonary nodule biopsy. This is the first case to our knowledge of NSG presenting with cranial nerve palsy in a pediatric patient.

Human defensins and LL-37 in mucosal immunity.

Defensins are widespread in nature and have activity against a broad range of pathogens. Defensins have direct antimicrobial effects and also modulate innate and adaptive immune responses. We consider the role of human defensins and the cathelicidin LL-37 in defense of respiratory, gastrointestinal, and genitourinary tracts and the oral cavity, skin, and eye. Human beta-defensins (hBDs) and human defensins 5 and 6 (HD5 and -6) are involved most obviously in mucosal responses, as they are produced principally by epithelial cells. Human alpha-defensins 1-4 (or HNPs 1-4) are produced principally by neutrophils recruited to the mucosa. Understanding the biology of defensins and LL-37 is the beginning to clarify the pathophysiology of mucosal inflammatory and infectious diseases (e.g., Crohn's disease, atopic dermatitis, lung or urinary infections). Challenges for these studies are the redundancy of innate defense mechanisms and the presence and interactions of many innate defense proteins in mucosal secretions.

Innate immunity to influenza virus: implications for future therapy.

Innate immunity is critical in the early containment of influenza virus infection. The innate response is surprisingly complex. A variety of soluble innate inhibitors in respiratory secretions provide an initial barrier to infection. Dendritic cells, phagocytes and natural killer cells mediate viral clearance and promote further innate and adaptive responses. Toll-like receptors 3 and 7 and cytoplasmic RNA sensors are critical for activating these responses. In general, the innate response restricts viral replication without injuring the lung; however, the 1918 pandemic and H5N1 strains cause more profound, possibly harmful, innate responses. In this review, we discuss the implications of burgeoning knowledge of innate immunity for therapy of influenza.