A Lactobacilli-based inhaled live biotherapeutic product attenuates pulmonary neutrophilic inflammation

A groundbreaking preclinical study conducted at the University of Alabama at Birmingham (UAB) has revealed a novel therapeutic approach for chronic lung diseases, demonstrating that the inhalation of a specific mixture of living Lactobacilli bacteria can significantly reduce pulmonary inflammation, improve lung function, and restore lung structure in models of bronchopulmonary dysplasia (BPD) and chronic obstructive pulmonary disease (COPD). This pioneering research, published in the esteemed journal Nature Communications, not only identifies a potent mechanism of action for this live biotherapeutic product but also lays the groundwork for future human clinical trials.

Unraveling the Mechanism: Lactobacilli as Lung Regulators

The study, co-led by Charitharth Vivek Lal, M.D., a neonatologist at UAB, and Amit Gaggar, M.D., Ph.D., a pulmonologist at UAB, meticulously determined how this powder mixture of living Lactobacilli bacteria exerts its therapeutic effects. The research pinpointed the bacteria’s ability to curb neutrophilic inflammation, a hallmark of many chronic lung conditions, and to diminish a wide spectrum of inflammatory markers. This finding is particularly significant as neutrophilic inflammation, characterized by an overabundance of neutrophils, a type of white blood cell, is a primary driver of tissue damage in diseases like COPD and BPD.

Dr. Lal elaborated on the study’s implications, stating that their findings "provide a paradigm for the progression of structural lung disease." The research established Lactobacilli as crucial regulators of lung protease activity. Proteases are enzymes that break down proteins, and in the context of lung disease, their dysregulation contributes to the destructive processes. Specifically, the study identified a link between Lactobacilli and the modulation of protease activity that leads to matrikine generation, extracellular matrix turnover, and chronic neutrophilic inflammation. These processes collectively damage the delicate air sacs in the lungs, known as alveoli, leading to impaired gas exchange and reduced lung function.

A Foundation in Observation: From Infant Airways to Novel Therapy

The initial spark for investigating Lactobacilli’s role in lung health emerged in 2016 from a pivotal discovery by Dr. Lal and his UAB colleagues. They observed that infants suffering from severe BPD exhibited a reduced presence of Lactobacilli in their airways, accompanied by an increased abundance of proteobacteria and elevated concentrations of proteobacterial endotoxin. This correlation suggested a potential protective role for Lactobacilli and hinted at their therapeutic potential in managing chronic lung disease.

Building upon this foundational observation, the current study provides a concrete mechanism by which Lactobacilli can mitigate downstream disease development. The researchers successfully demonstrated the safety and efficacy of the live biotherapeutic treatment in preclinical models. This included a mouse pup model specifically designed to mimic BPD and three distinct mouse models representing different facets of COPD. The results from these animal studies offer compelling evidence for the potential of inhaled Lactobacilli as a treatment.

Understanding the Diseases: BPD and COPD

To fully appreciate the significance of these findings, it is essential to understand the nature of the diseases being targeted. Bronchopulmonary dysplasia (BPD) is a serious chronic lung condition that primarily affects extremely premature infants. These vulnerable newborns often require mechanical ventilation and high concentrations of oxygen to survive, interventions that, while life-saving, can paradoxically cause significant damage to their developing lungs. BPD can lead to lifelong breathing difficulties, increased susceptibility to respiratory infections, and other serious health complications.

Chronic obstructive pulmonary disease (COPD), on the other hand, is a progressive and debilitating lung disease that predominantly affects older adults, with a strong association with smoking. It encompasses conditions like emphysema and chronic bronchitis, characterized by persistent airflow limitation and inflammation of the lungs. COPD is a major global health concern, responsible for approximately 130,000 deaths annually in the United States alone and impacting an estimated 3 million more worldwide. The economic and societal burden of COPD is immense, highlighting the urgent need for effective new therapeutic strategies.

The Role of Ac-PGP: A Key Inflammatory Mediator

A critical aspect of the UAB researchers’ investigation involved exploring the role of acetylated proline-glycine-proline (Ac-PGP), an extracellular matrix-derived peptide. They hypothesized, based on prior observations in premature infants with BPD, that mouse models of BPD would exhibit heightened levels of Ac-PGP. This hypothesis was indeed validated in their BPD mouse models.

Further "gain- or loss-of-function" studies provided crucial insights into the impact of Ac-PGP. The intranasal instillation of Ac-PGP in the animal models led to increased neutrophilic inflammation and degradation of lung tissue. Conversely, when an inhibitor of Ac-PGP was administered alongside Ac-PGP, the researchers observed a significant decrease in markers of neutrophilic inflammation and notable improvements in lung structure. This demonstrated that Ac-PGP plays a direct role in driving inflammation and lung damage, making it a potential therapeutic target.

Lactobacilli’s Symphony of Action: Targeting MMP-9 and Lactic Acid

The study then delved into the specific mechanisms by which the proprietary Lactobacilli blend, comprising L. plantarum, L. acidophilus, and L. rhamnosus, exerts its anti-inflammatory effects. A key finding was the synergistic action of these bacteria in reducing matrix metalloproteinase-9 (MMP-9). MMP-9 is a crucial protease that facilitates the release of Ac-PGP from the extracellular matrix. By inhibiting MMP-9, Lactobacilli effectively curtail the production and release of this pro-inflammatory peptide.

Remarkably, the researchers also found that the supernatant from Lactobacilli growth medium, even without the live bacteria, demonstrated a comparable ability to reduce MMP-9 levels. This led to the identification of another vital component in Lactobacilli’s therapeutic arsenal: L(+) lactic acid. This organic acid, produced during Lactobacilli fermentation, was found to directly reduce MMP-9 in vitro, establishing it as a significant anti-inflammatory molecule. The live Lactobacilli, when administered via inhalation, were shown to provide a sustained and controlled release of L(+) lactic acid within the lungs, offering a continuous anti-inflammatory effect in a well-tolerated manner.

Technological Innovation: Engineering Inhaled Probiotics

A significant technological advancement reported in this study was the development of a method to create an inhaled Lactobacilli powder. This involved particle engineering to produce particles small enough to reach deep into the lung’s intricate network of airways and alveoli, while crucially preserving the viability of the bacteria. This innovative delivery system is essential for the effective therapeutic action of the live biotherapeutic product.

Promising Results in COPD Models

The engineered inhaled Lactobacilli powder was subsequently tested in the COPD mouse models. The results were highly encouraging. The blend successfully reduced inflammation within the lung microenvironment, demonstrating anti-inflammatory effects regardless of whether treatment was administered concurrently with the injury or post-injury. Furthermore, the treatment led to a decrease in several pro-inflammatory markers and an elevation of the anti-inflammatory marker immunoglobulin A (IgA), a crucial component of the immune system’s defense in mucosal tissues like the lungs.

An particularly noteworthy observation was the competitive performance of the live biotherapeutic product compared to a well-established pharmaceutical. In several instances, the Lactobacilli blend reduced MMP-9 and other pro-inflammatory cytokines as effectively as, or even better than, fluticasone furoate. Fluticasone furoate is an FDA-approved inhaled corticosteroid commonly found in combination therapies for COPD. This suggests that inhaled Lactobacilli could potentially offer a novel, microbiome-based alternative or adjunct to existing treatments.

Safety and Biodistribution: Addressing Key Concerns

A critical aspect of any new therapeutic development is ensuring its safety. In one of the COPD mouse models, comprehensive safety and biodistribution studies were conducted. The inhalation of the bacterial powder did not induce any adverse reactions or disease progression. Crucially, the Lactobacilli did not translocate to distant tissues or accumulate abnormally in the lungs, indicating a favorable safety profile and localized action within the respiratory system.

Future Directions: Clinical Trials and Broader Implications

Dr. Lal expressed optimism about the future of this research, stating, "Inhaled live biotherapeutic products show promise in addressing common pathways of disease progression that in the future can be targeted at a variety of lung diseases." He emphasized that while the preclinical animal data is highly suggestive, the safety of this potential drug in humans will be rigorously tested in an upcoming clinical trial. The initial phase of this trial will focus on adult safety data in COPD patients, which will then de-risk the pathway for seeking approval for its use in infants with bronchopulmonary disease.

The implications of this research extend beyond BPD and COPD. By targeting common inflammatory pathways, inhaled Lactobacilli hold potential for treating a broader spectrum of lung diseases. This microbiome-based approach represents a significant shift in therapeutic strategy, moving towards harnessing the body’s own beneficial bacteria to combat disease.

Recognition and Commercialization

The study, titled "A Lactobacilli-based inhaled live biotherapeutic product attenuates pulmonary neutrophilic inflammation," acknowledges Teodora Nicola and Nancy Wenger from the UAB Department of Pediatrics, Division of Neonatology, as co-first authors. The research was supported by grants from the National Heart, Lung and Blood Institute of the National Institutes of Health.

Furthermore, a significant step in translating this research into a tangible treatment has been taken. A patent for "Inhaled respiratory probiotics for lung diseases of infancy, childhood and adulthood" (U.S. 11,141,443 B2) has been granted to the University of Alabama at Birmingham Research Foundation. Dr. Lal, Dr. Gaggar, and Namasivayam Ambalavanan are listed as inventors. This proprietary product has been commercialized through a UAB startup company, Alveolus Bio, Inc., based in Birmingham, Alabama, and Boston, Massachusetts, signifying a strong commitment to advancing this promising therapeutic from the laboratory to the clinic. Dr. Lal’s continued involvement through his roles as director of Clinical Innovation at the Marnix E. Heersink Institute for Biomedical Innovation and founder of Alveolus Bio, Inc., underscores the university’s dedication to fostering innovation and bringing life-changing therapies to patients.