By Gilang Cahya 
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, elucidates a novel therapeutic avenue for debilitating respiratory conditions affecting both vulnerable infants and adults. The study, led by a collaborative team at the University of Alabama at Birmingham (UAB), has identified a specific mechanism by which these beneficial bacteria can combat chronic lung damage, offering a beacon of hope for millions worldwide.
Unveiling the Mechanism: Lactobacilli as Lung Regulators
The core of this discovery lies in understanding how a powder mixture of living Lactobacilli bacteria, termed a live biotherapeutic product (LBP), exerts its beneficial effects. Charitharth Vivek Lal, M.D., a neonatologist at UAB, and Amit Gaggar, M.D., Ph.D., a UAB pulmonologist, co-led the research that meticulously detailed this process. Their findings reveal that Lactobacilli play a critical role in mitigating neutrophilic inflammation, a hallmark of many chronic lung diseases, by reducing a broad spectrum of inflammatory markers.
"Our findings provide a paradigm for the progression of structural lung disease," Dr. Lal explained, highlighting the significance of identifying Lactobacilli as key regulators of lung protease activity. This activity is intrinsically linked to the destructive processes driven by matrikine generation and extracellular matrix turnover, ultimately leading to chronic neutrophilic inflammation that damages the delicate air sacs in the lungs.
A Foundation Built on Observational Evidence and Mechanistic Discovery
The investigation into the potential protective role of Lactobacilli in the lungs and their application in treating chronic lung disease did not emerge in a vacuum. The initial seeds of this research were sown in 2016 when Dr. Lal and his UAB colleagues observed a striking correlation: infants suffering from severe bronchopulmonary dysplasia (BPD) exhibited significantly decreased numbers of Lactobacilli in their airways, coupled with an increased presence of proteobacteria and higher concentrations of proteobacterial endotoxin. This observation suggested a potential imbalance in the lung microbiome, with a deficiency in beneficial bacteria contributing to disease severity.
Building upon this foundational insight, the latest study provides the crucial mechanistic link. The UAB researchers demonstrated how Lactobacilli treatment effectively curtails downstream disease development. Furthermore, they rigorously established the safety and efficacy of this inhaled live biotherapeutic treatment in both a mouse pup model for BPD and three distinct mouse models of chronic obstructive pulmonary disease (COPD).
Understanding the Diseases: BPD and COPD
To fully appreciate the implications of this research, it is essential to understand the diseases it targets. Bronchopulmonary dysplasia (BPD) is a chronic lung condition that primarily affects extremely premature infants. These vulnerable newborns often require prolonged mechanical ventilation and high concentrations of oxygen to survive, interventions that can inadvertently damage their developing lungs, leading to BPD. This condition can result in lifelong respiratory challenges.
Chronic obstructive pulmonary disease (COPD), on the other hand, is a progressive and largely irreversible lung disease that primarily affects older adults, with a significant portion of cases linked to smoking. COPD is characterized by airflow limitation and breathing difficulties, and it imposes a substantial burden on healthcare systems globally. In the United States alone, COPD is responsible for approximately 130,000 deaths annually and affects around 3 million individuals.
The Promise of Inhaled Live Biotherapeutics
The potential of inhaled live biotherapeutic products to address common pathways of disease progression across a variety of lung ailments is a compelling prospect. "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," Dr. Lal stated.
While preclinical animal data is highly suggestive, the path to human application requires rigorous clinical evaluation. The safety of this potential drug in humans will be assessed in a forthcoming clinical trial. The data gathered from human adult safety trials in COPD patients is anticipated to de-risk the approval pathway for its use in infants with bronchopulmonary dysplasia. This phased approach underscores the commitment to both innovation and patient safety.
Decoding the Molecular Pathway: Ac-PGP and its Role
A critical hypothesis driving the UAB researchers’ investigation was that mouse models of BPD would exhibit heightened levels of acetylated proline-glycine-proline (Ac-PGP). This extracellular matrix-derived peptide had previously been observed in premature infants with BPD, hinting at its potential involvement in the disease process.
This hypothesis was indeed validated in the BPD mouse models. Through meticulously designed gain- and loss-of-function studies, the researchers elucidated the significant impact of Ac-PGP. They found that intranasal instillation of Ac-PGP exacerbated neutrophilic inflammation and led to lung degradation. Conversely, when an inhibitor of Ac-PGP was administered alongside Ac-PGP, markers of neutrophilic inflammation were significantly reduced, and lung structure showed marked improvement. This finding established Ac-PGP as a key player in the inflammatory cascade of BPD.
Lactobacilli’s Precision Attack: Targeting MMP-9 and L(+) Lactic Acid
The research then pivoted to the direct action of the Lactobacilli blend. The UAB team identified a proprietary blend of three Lactobacilli species – L. plantarum, L. acidophilus, and L. rhamnosus – as performing optimally in synergy. This blend was found to effectively reduce the activity of matrix metalloproteinase-9 (MMP-9), an inflammatory proteinase crucial for releasing Ac-PGP from the extracellular matrix.
Intriguingly, the researchers also discovered that the supernatant from Lactobacilli growth medium, even without the live bacteria, demonstrated a similar magnitude of MMP-9 reduction. This led to a pivotal revelation: L(+) lactic acid, a metabolic byproduct of Lactobacilli fermentation, played a significant role. In vitro studies confirmed that L(+) lactic acid alone could reduce MMP-9, establishing it as an important anti-inflammatory molecule.
The presence of live Lactobacilli in the lungs was shown to provide an ongoing, sustained release of L(+) lactic acid in a controlled and well-tolerated manner, offering a continuous anti-inflammatory effect. This continuous, localized delivery of a therapeutic molecule represents a significant advantage over intermittent dosing of traditional medications.
Technological Innovation: Engineering for Lung Delivery
A major technological hurdle in developing inhaled probiotics is ensuring the viability of the bacteria during delivery and their ability to reach the deep lung. The UAB researchers achieved a significant breakthrough by developing particle engineering techniques to create an inhaled Lactobacilli powder. This process resulted in particles small enough to penetrate deep into the lungs while crucially preserving the viability of the bacteria. This advanced formulation of the live biotherapeutic product was then rigorously tested in both BPD and COPD models.
Promising Efficacy in COPD Models
In the COPD mouse models, the Lactobacilli blend demonstrated remarkable efficacy. It successfully reduced inflammation within the lung microenvironment, regardless of whether treatment was administered concurrently with injury or post-injury. This versatility suggests potential applications in both preventative and therapeutic settings. The blend also effectively decreased several pro-inflammatory markers and notably elevated the anti-inflammatory marker immunoglobulin A (IgA).
Competitive Performance Against Established Therapies
Perhaps one of the most compelling findings was the favorable performance of the live biotherapeutic product when compared to existing treatments. 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 a United States Food and Drug Administration-approved inhaled corticosteroid commonly used in combination therapies for COPD. This direct comparison highlights the potential of this novel probiotic approach to rival or even surpass the efficacy of established pharmacological interventions, potentially with a different safety profile.
Ensuring Safety and Understanding Biodistribution
Crucially, safety and biodistribution studies were conducted in one of the COPD mouse models to address potential concerns associated with introducing live bacteria into the body. The inhalation of the bacterial powder did not elicit adverse reactions or exacerbate existing disease. Furthermore, the Lactobacilli did not translocate to distal tissues or accumulate in unintended organs, indicating a favorable safety profile and localized action within the lungs. This is a critical consideration for any live biotherapeutic.
The Research Team and Future Directions
The collaborative effort behind this groundbreaking research involved a multidisciplinary team at UAB. The co-first authors of the study, titled "A Lactobacilli-based inhaled live biotherapeutic product attenuates pulmonary neutrophilic inflammation," are Teodora Nicola and Nancy Wenger, both from the UAB Department of Pediatrics, Division of Neonatology.
Other key contributors 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.
Support for this extensive research was provided by several grants from the National Heart, Lung, and Blood Institute of the National Institutes of Health, including HL141652, HL135710, HL166433, HL156275, and HL164156.
From Bench to Bedside: Commercialization and Intellectual Property
The significance of this research is further underscored by its translation into intellectual property and commercialization efforts. A patent, titled "Inhaled respiratory probiotics for lung diseases of infancy, childhood and adulthood" (U.S. 11,141,443 B2), 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.
This proprietary product has been commercialized through Alveolus Bio, Inc., a UAB startup company based in Birmingham, Alabama, and Boston, Massachusetts. This initiative signifies a commitment to bringing this promising therapeutic from the laboratory to patients who can benefit from it.
At UAB, the Departments of Pediatrics and Medicine are within the Marnix E. Heersink School of Medicine. Dr. Lal serves as the Director of Clinical Innovation at the Marnix E. Heersink Institute for Biomedical Innovation and holds the position of associate professor in the Division of Neonatology. Dr. Gaggar is a professor in the Division of Pulmonary, Allergy and Critical Care Medicine. Dr. Lal is also the founder of UAB startups Alveolus Bio, Inc., and Resbiotic Nutrition, Inc., demonstrating his dedication to fostering innovation in the biomedical field.
The journey from observing a deficiency in beneficial bacteria in infants with BPD to developing a precisely engineered, inhaled probiotic therapy for both infant and adult lung diseases represents a significant leap forward in respiratory medicine. The rigorous scientific validation and the clear path towards clinical translation offer substantial hope for improved treatments and outcomes for individuals suffering from chronic lung conditions.