Treatment with broadly neutralizing influenza antibodies reduces severity of secondary pneumococcal pneumonia in mice

Integrated serum pharmacochemistry and investigation of the anti-influenza A virus pneumonia effect of Qingjin Huatan decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Qingjin Huatan Decoction (QJHTT) consists of 11 herbal medicines: Scutellaria baicalensis Georgi, Gardenia jasminoides J. Ellis, Platycodon grandiflorus (Jacq.) A. DC., Ophiopogon japonicus (Thunb.) Ker Gawl., Morus alba L., Fritillaria thunbergii Miq., Anemarrhena asphodeloides Bunge, Trichosanthes kirilowii Maxim., Citrus reticulata Blanco, Poria cocos (Schw.) Wolf, and Glycyrrhiza uralensis Fisch. As a traditional Chinese medicinal formula, QJHTT has been used for more than 400 years in China. It has shown promising results in treating influenza A virus (IAV) pneumonia.

AIM OF THE STUDY

To elusive the specific pharmacological constituents and mechanisms underlying its anti-IAV pneumonia effects.

MATERIALS AND METHODS

The components in QJHTT were analyzed through the use of a serum pharmacology-based ultra high-performance liquid chromatography Q- Exactive Orbitrap mass spectrometry (UHPLC-Q Exactive Orbitrap-MS) method. Simultaneously, the dynamic changes in IAV-infected mouse lung viral load, lung index, and expression of lung inflammation factors were monitored by qRT-PCR.

RESULTS

We successfully identified 152 chemical components within QJHTT, along with 59 absorbed chemical prototype constituents found in the serum of mice treated with QJHTT. 43.45% of these chemical components and 43.10% of the prototype constituents were derived from the monarch drugs, namely Huangqin and Zhizi, aligning perfectly with traditional Chinese medicine theory. Notably, our analysis led to the discovery of 14 compounds within QJHTT for the first time, three of which were absorbed into the bloodstream. Simultaneously, we observed that QJHTT not only reduced the viral load but also modulated the expression of inflammation factors in the lung tissue including TNF-α, IL-1β, IL-4, IL-6, IFN-γ, and IL17A. A time-effect analysis further revealed that QJHTT intervention effectively suppressed the peak of inflammatory responses, demonstrating a robust anti-IAV pneumonia effect.

CONCLUSIONS

We comprehensively analyzed the pharmacological material basis of QJHTT by a highly sensitive and high-resolution UHPLC-Q Exactive Orbitrap-MS method, and demonstrated its efficacy in combating IAV pneumonia by reducing lung viral load and inflammatory factors. This study has significant importance for elucidating the pharmacological basis and pharmacological mechanism of QJHTT in combating IAV pneumonia.

Virus-Induced Changes of the Respiratory Tract Environment Promote Secondary Infections With Streptococcus pneumoniae

Secondary bacterial infections enhance the disease burden of influenza infections substantially. Streptococcus pneumoniae (the pneumococcus) plays a major role in the synergism between bacterial and viral pathogens, which is based on complex interactions between the pathogen and the host immune response. Here, we discuss mechanisms that drive the pathogenesis of a secondary pneumococcal infection after an influenza infection with a focus on how pneumococci senses and adapts to the influenza-modified environment. We briefly summarize what is known regarding secondary bacterial infection in relation to COVID-19 and highlight the need to improve our current strategies to prevent and treat viral bacterial coinfections.

Treatment with broadly neutralizing influenza antibodies reduces severity of secondary pneumococcal pneumonia in mice

Secondary bacterial pneumonia is a frequent complication of influenza, associated with high morbidity and mortality. We hypothesized that treatment with neutralizing influenza A antibody AT10_002 protects against severe secondary pneumococcal infection in a mouse model of influenza A infection. Influenza A (H3N2) virus–infected male C57Bl6 mice were treated intravenously with either AT10_002 or a control 2 days postinfection. Seven days later, both groups were infected with Streptococcus pneumoniae and killed 18 hours later. Mice receiving AT10_002 showed less loss of bodyweight compared with controls (+1% vs −12%, P < .001), lower viral loads in bronchoalveolar lavage fluids (BALFs) (7 vs 194 RNA copies per µL; P < .001), and reduced bacterial outgrowth in lung homogenates (3.3 × 10¹ vs 2.5 × 10⁵ colony‐forming units per mg; P < .001). The treatment group showed lower pulmonary wet weights, lower cell counts, and lower protein levels in BALF compared with controls. Treatment with AT10_002 was associated with lower levels of tumor necrosis factor‐α, interleukin (IL)‐6, cytokine‐induced neutrophil chemoattractant (KC), and interferon‐γ in BALF and lower IL‐6 and KC in lung homogenates. Treatment with anti‐influenza antibody AT10_002 is associated with reduced weight loss, viral load, bacterial outgrowth, and lung injury in a murine model of secondary pneumococcal pneumonia following influenza infection.