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

In preclinical models, the inhalation of a mixture of living Lactobacilli bacteria attenuated pulmonary inflammation and improved lung function and structure for the chronic lung diseases bronchopulmonary dysplasia and chronic obstructive pulmonary disease. This groundbreaking research, published in the esteemed journal Nature Communications, unveils a novel therapeutic approach with the potential to significantly impact the management of debilitating lung conditions affecting both vulnerable infants and millions of adults worldwide.

Unraveling the Mechanism: Lactobacilli’s Protective Role in the Lungs

The study, co-led by Charitharth Vivek Lal, M.D., a neonatologist at the University of Alabama at Birmingham (UAB), and Amit Gaggar, M.D., Ph.D., a UAB pulmonologist, meticulously determined the mechanism by which this live biotherapeutic product – a finely engineered powder mixture of living Lactobacilli bacteria – exerts its beneficial effects. Researchers found that the inhaled Lactobacilli effectively reduce neutrophilic inflammation, a key driver of lung damage in chronic respiratory diseases. Furthermore, the treatment demonstrably lowered a broad spectrum of inflammatory markers implicated in the pathogenesis of both bronchopulmonary dysplasia (BPD) and chronic obstructive pulmonary disease (COPD).

Dr. Lal articulated the significance of these findings, stating that they "provide a paradigm for the progression of structural lung disease." The research pinpoints Lactobacilli as crucial regulators of lung protease activity. Proteases are enzymes that can break down proteins, and in the context of lung disease, their unchecked activity contributes to the destructive processes driven by the generation of matrikines (fragments of extracellular matrix proteins), the continuous turnover of the extracellular matrix, and chronic neutrophilic inflammation. This cascade of events ultimately leads to the damage and destruction of delicate air sacs in the lungs, known as alveoli.

A Foundation Built on Discovery: From Infant Airways to Therapeutic Potential

The conceptualization of a protective role for Lactobacilli in the lung and their potential use in treating chronic lung disease has roots dating back to 2016. In a seminal discovery, Dr. Lal and his UAB colleagues observed that infants suffering from severe bronchopulmonary dysplasia exhibited significantly decreased numbers of Lactobacilli in their airways. Concurrently, these infants showed an increased abundance of proteobacteria and elevated concentrations of proteobacterial endotoxin, a potent inflammatory trigger. This initial observation laid the groundwork for the hypothesis that a deficiency in beneficial Lactobacilli might predispose infants to the severe lung damage characteristic of BPD.

Building upon this foundational knowledge, the latest study provides a concrete mechanistic explanation for how Lactobacilli treatment can curb downstream disease development. The UAB researchers successfully demonstrated the safety and effectiveness of this live biotherapeutic treatment in both a mouse pup model specifically engineered to mimic BPD and in three distinct mouse models representing various facets of COPD.

Understanding the Diseases: BPD and COPD

Bronchopulmonary dysplasia is a severe, chronic lung disease that can develop in extremely premature infants. These fragile newborns often require intensive medical support, including high concentrations of oxygen and mechanical ventilation, to survive. While life-saving, these interventions can inadvertently lead to lung injury, inflammation, and impaired lung development, culminating in BPD. The long-term consequences for affected children can include recurrent respiratory infections, persistent breathing difficulties, and an increased risk of developing other lung conditions later in life.

Chronic obstructive pulmonary disease (COPD), on the other hand, primarily affects older adults, with a significant portion of cases linked to long-term exposure to cigarette smoke. COPD is a progressive and irreversible lung disease characterized by airflow limitation and breathing-related disability. It encompasses both chronic bronchitis and emphysema, leading to debilitating symptoms such as persistent cough, excessive mucus production, shortness of breath, and wheezing. Globally, COPD is a leading cause of death and disability, impacting an estimated 3 million lives annually and claiming approximately 130,000 American lives each year.

A Unified Therapeutic Strategy: Targeting Common Disease Pathways

Dr. Lal emphasized the broader implications of their findings, 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." This suggests that the therapeutic strategy developed for BPD and COPD may hold potential for other inflammatory lung conditions, offering a unified approach to tackling a spectrum of respiratory ailments.

The promising preclinical data has paved the way for human trials. "Preclinical animal data is suggestive, and safety of the potential drug in humans will be tested in a forthcoming clinical trial," Dr. Lal confirmed. The plan is to initiate human adult safety studies in COPD patients. Data gathered from these trials will be instrumental in de-risking the regulatory pathway for eventual approval of the drug for use in infants with bronchopulmonary disease, underscoring a carefully considered phased approach to clinical translation.

The Role of Ac-PGP: A Key Inflammatory Mediator

The UAB researchers’ initial hypothesis was that mouse models of BPD would exhibit heightened levels of acetylated proline-glycine-proline, or Ac-PGP. This peptide is derived from the extracellular matrix, the structural scaffolding that surrounds cells, and had previously been identified in premature infants diagnosed with BPD.

Their experimental findings strongly supported this hypothesis. In the BPD mouse models, elevated Ac-PGP levels were indeed observed. Through carefully designed gain- and loss-of-function studies, the researchers elucidated the impact of Ac-PGP on lung health. When Ac-PGP was administered intranasally to healthy mice, it triggered increased neutrophilic inflammation and led to degradation of lung tissue. Conversely, when an inhibitor designed to block Ac-PGP activity was administered alongside Ac-PGP, markers of neutrophilic inflammation were significantly reduced, and the structural integrity of the lungs improved. This demonstrated a direct causal link between Ac-PGP and the inflammatory processes that damage the lungs.

Lactobacilli’s Precise Action: Targeting MMP-9 and L(+) 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 therapeutic effects. Researchers discovered that this blend performed optimally in synergy to reduce the activity of matrix metalloproteinase-9 (MMP-9). MMP-9 is a crucial enzyme that plays a significant role in releasing Ac-PGP from the extracellular matrix. By inhibiting MMP-9, Lactobacilli effectively limit the production and release of this inflammatory peptide.

Intriguingly, the researchers also found that the supernatant – the liquid portion obtained after separating cells from a culture medium – derived from Lactobacilli growth medium also demonstrated a remarkable ability to reduce MMP-9. This reduction was comparable in magnitude to that achieved by live Lactobacilli bacteria, suggesting that soluble factors produced by Lactobacilli are also potent anti-inflammatory agents.

A pivotal finding of the study was the identification of L(+) lactic acid as a key anti-inflammatory molecule produced by Lactobacilli. When researchers analyzed the supernatant from Lactobacilli growth medium, they discovered that L(+) lactic acid was a significant component and was responsible for reducing MMP-9 in vitro. This revealed an important biochemical pathway through which Lactobacilli exert their protective effects. The live Lactobacilli, when introduced into the lungs, were found to provide a continuous and sustained release of L(+) lactic acid in a controlled and well-tolerated manner, offering a consistent anti-inflammatory environment.

Technological Innovation: Engineering Inhaled Probiotics

A major technological advancement underpinning this research was the development of a method to create an inhaled Lactobacilli powder through advanced particle engineering. This process ensures that the particles are sufficiently small to reach deep into the lungs, where they can exert their therapeutic effects, while crucially preserving the viability of the bacteria. This innovation is critical for the effective delivery of live biotherapeutic products to the respiratory system.

This specially engineered live biotherapeutic product was then rigorously tested in both the BPD and COPD mouse models. In the COPD models, the Lactobacilli blend proved highly effective in reducing inflammation within the lung microenvironment. Notably, the treatment demonstrated significant anti-inflammatory effects whether administered concurrently with the injury or after the injury had already occurred, highlighting its versatility. The blend successfully decreased several pro-inflammatory markers and concurrently elevated the levels of the anti-inflammatory marker immunoglobulin A (IgA).

A Competitive Edge: Outperforming Existing Therapies

Perhaps one of the most compelling findings of the study was the competitive performance of the live biotherapeutic product compared to established treatments. In several instances, the Lactobacilli blend matched or even surpassed the efficacy of fluticasone furoate, a United States Food and Drug Administration (FDA)-approved inhaled corticosteroid commonly used in combination therapies for COPD. This suggests that inhaled Lactobacilli could potentially offer a new therapeutic avenue with comparable or superior benefits, potentially with a different safety profile or fewer side effects than corticosteroids, which can have systemic implications with long-term use.

Safety and Biodistribution: Ensuring a Favorable Profile

Crucially, safety and biodistribution studies were conducted in one of the COPD mouse models to assess the potential risks associated with inhaling the bacterial powder. The results were highly encouraging. The inhalation of the Lactobacilli powder did not trigger any adverse reactions or exacerbate existing disease conditions in the animal models. Furthermore, the Lactobacilli did not translocate to distal tissues beyond the lungs or accumulate in unintended areas, indicating a localized and safe therapeutic action. This is a critical consideration for any inhaled therapeutic, particularly for vulnerable populations like premature infants.

The Research Team and Funding Landscape

The study, titled "A Lactobacilli-based inhaled live biotherapeutic product attenuates pulmonary neutrophilic inflammation," boasts a strong cohort of researchers. The co-first authors are Teodora Nicola and Nancy Wenger, both from the UAB Department of Pediatrics, Division of Neonatology.

Other key contributors to this significant research include Xin Xu, Camilla Margaroli, Kristopher Genschmer, and J. Edwin Blalock from the UAB Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine. Additionally, Michael Evans, Luhua Qiao, Gabriel Rezonzew, Youfeng Yang, Tamas Jilling, Kent Willis, and Namasivayam Ambalavanan from the UAB Department of Pediatrics, Division of Neonatology, played vital roles.

This pioneering work was supported by substantial funding from the National Heart, Lung, and Blood Institute of the National Institutes of Health, through grants HL141652, HL135710, HL166433, HL156275, and HL164156. This robust financial backing underscores the national importance placed on addressing chronic lung diseases.

Intellectual Property and Commercialization: Bridging Research and Application

Further highlighting the innovative nature of this research, a portion of the findings is protected by a patent titled "Inhaled respiratory probiotics for lung diseases of infancy, childhood and adulthood" (U.S. 11,141,443 B2). This patent is held by the University of Alabama at Birmingham Research Foundation, an integral part of the Bill L. Harbert Institute for Innovation and Entrepreneurship. Dr. Lal, Dr. Gaggar, and Dr. Ambalavanan are listed as inventors on this patent.

This proprietary product has already transitioned from the laboratory to the commercial sphere through the UAB startup Alveolus Bio, Inc. This company, with operations in Birmingham, Alabama, and Boston, Massachusetts, is poised to drive the development and potential market introduction of this novel therapeutic.

The research is embedded within the UAB Marnix E. Heersink School of Medicine, where Pediatrics and Medicine are prominent departments. Dr. Lal holds a leadership position as the director of Clinical Innovation at the Marnix E. Heersink Institute for Biomedical Innovation and is an associate professor in the Division of Neonatology. Dr. Gaggar serves as a professor in the Division of Pulmonary, Allergy and Critical Care Medicine. Dr. Lal is also a visionary entrepreneur, having founded UAB startups Alveolus Bio, Inc., and Resbiotic Nutrition, Inc., demonstrating a commitment to translating scientific breakthroughs into tangible health solutions.