Combined aerosolized Toll-like receptor ligands are an effective therapeutic agent against influenza pneumonia when co-administered with oseltamivir

Abstract

Influenza pneumonia remains a common and debilitating viral infection despite vaccination programs and antiviral agents developed for prophylaxis and treatment. The neuraminidase inhibitor oseltamivir is frequently prescribed for established influenza A virus infections, but the emergence of neuraminidase inhibitor resistant viruses, a brief therapeutic window and competing diagnoses complicate its use. PUL-042 is a clinical stage, aerosol drug comprised of synthetic ligands for Toll-like receptor (TLR) 2/6 and TLR 9. This host-targeted, innate immune stimulant broadly protects against bacterial, fungal and viral pneumonias, including those caused by influenza, when given prophylactically to animals. This study evaluated the therapeutic antiviral effects of PUL-042 against established influenza A pneumonia, when given alone or in combination with oseltamivir. Mice were treated with PUL-042 aerosol, oseltamivir or both at varying time points before or after challenge with influenza pneumonia. Treating established, otherwise lethal influenza A pneumonia (>1 LD) with multiple inhaled doses of PUL-042 aerosol plus oral oseltamivir resulted in greater mouse survival than treatment with either drug alone. Single agent PUL-042 also protected mice against established infections following challenges with lower viral inocula (approximately 1 LD). Aerosolized oseltamivir further enhanced survival when co-delivered with PUL-042 aerosol. The prophylactic and therapeutic benefits of PUL-042 were similar against multiple strains of influenza virus. In vitro influenza challenge of human HBEC3kt lung epithelial cells revealed PUL-042-induced protection against infection that was comparable to that observed in vivo. These studies offer new insights into means to protect susceptible populations against influenza A pneumonia.

Aerosolized TLR Agonists Suppress Acute Sendai Virus Lung Infection and Chronic Airway Disease in Mice

“…Together, these developments highlight the importance of attenuating the severity of respiratory viral infections to prevent chronic airway diseases. We have previously identified a means of effectively stimulating the airway epithelium to induce innate immune resistance to respiratory viral infection (12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Here we show that treatment of mice with this efficacious combination of aerosolized TLR ligands around the time of SeV infection attenuates chronic lung disease, providing proof-of-principle that this intervention might have clinical efficacy.…”

“…In view of the high incidence and substantial morbidity resulting from virus-induced asthma, treatments to mitigate the severity of respiratory virus infection are greatly needed. We have previously identified a pharmacologic means to stimulate innate immunity of lung epithelium that has shown activity against multiple bacterial, fungal, and viral pathogens in mice (12)(13)(14)(15)(16)(17)(18) and guinea pigs (19). The stimulus consists of a class C oligodeoxynucleotide that is an agonist of the TLR9 homodimer and Pam2CSK4 that is an agonist of the TLR2/6 heterodimer.…”

Inducible epithelial resistance against acute Sendai virus infection prevents chronic asthma‐like lung disease in mice

“…Together, these developments highlight the importance of attenuating the severity of respiratory viral infections to prevent chronic airway diseases. We have previously identified a means of effectively stimulating the airway epithelium to induce innate immune resistance to respiratory viral infection (Alfaro et al, ; Cleaver et al, ; Drake et al, ; Duggan et al, ; Evans et al, ; Kirkpatrick et al, ; Leiva‐Juarez et al, ; Leiva‐Juárez et al, ; Tuvim et al, ; Ware et al, ). Here, we show that treatment of mice with this efficacious combination of aerosolized TLR ligands around the time of SeV infection attenuates chronic lung disease, providing proof‐of‐principle that this intervention might have clinical efficacy.…”

“…We have previously identified a pharmacological means to stimulate Type 3, extracellular pathogen‐directed (Annunziato, Romagnani, & Romagnani, ) innate immunity of lung epithelial cells. This treatment has shown activity against multiple bacterial, fungal and viral pathogens in mice (Alfaro et al, ; Cleaver et al, ; Duggan et al, ; Leiva‐Juarez et al, ; Leiva‐Juárez et al, ; Tuvim, Gilbert, Dickey, & Evans, ; Ware et al, ) and guinea pigs (Drake, Evans, Dickey, Fryer, & Jacoby, ). The stimulus consists of a class C oligodeoxynucleotide (ODN M362), which is an agonist of the Toll‐like receptor 9 (TLR9) homodimer, and Pam2CSK4, which is an agonist of the TLR2/6 heterodimer.…”

Attenuation of Influenza A Virus Disease Severity by Viral Coinfection in a Mouse Model

“…While the mechanisms of protection may differ among coinfecting microbes, protection relies on detection of the initial infection by pattern recognition receptors. Stimulation of TLR signaling by agonists of TLR3 or TLR8 alone or TLR2/6 and TLR9 together provides significant protection against multiple influenza virus strains in mice (35,60,66,67). Protection mediated by TLR2/6 and TLR9 activation is not associated with induction of a type I IFN response, suggesting that expression of proinflammatory cytokines and chemokines is sufficient for protection (35).…”