A novel microbe-based treatment that attenuates the inflammatory profile in a mouse model of allergic airway disease

Tracking the fate of bacteria-derived site-specific immunomodulators by positron emission tomography

INTRODUCTION

Site-specific immunomodulators (SSIs) are a novel class of therapeutics made from inactivated bacterial species designed to regulate the innate immune system in targeted organs. QBECO is a gut-targeted SSI that is being advanced clinically to treat and/or prevent inflammatory bowel disease, cancer, and serious infections of the gastrointestinal (GI) tract and proximal organs, and QBKPN is a lung-targeted SSI that is in clinical development for the treatment and/or prevention of chronic inflammatory lung disease, lung cancers and respiratory tract infections. While these SSIs have demonstrated both safety and proof-of-concept in preclinical and clinical studies, detailed understanding of their trafficking and biodistribution is yet to be fully characterized.

METHODS

QBECO and QBKPN were radiolabeled with [89Zr] and injected subcutaneously into healthy mice. The mice underwent Positron Emission Tomography (PET) imaging every day for eight days to track biodistribution of the SSIs. Tissue from the site of injection was collected and immunohistologically probed for immune cell infiltration.

RESULTS

Differential biodistribution of the two SSIs was seen, adhering to their site-specific targeting. QBKPN appeared to migrate from the site of injection (abdomen) to the cervical lymph nodes which are nearer to the respiratory tract and lungs. QBECO remained in the abdominal region, with lymphatic trafficking to the inguinal lymph nodes, which are nearer to GI-proximal tissues/organs. Immune infiltration at the site of injection comprised of neutrophils for both SSIs, and macrophages for only QBKPN.

CONCLUSION

Radiolabeling of SSIs allows for longitudinal in vivo imaging of biodistribution and trafficking. PET imaging revealed differential biodistribution of the SSIs based on the organotropism of the bacteria from which the SSI is derived. Trafficking from the site of injection to the targeted site is in part mediated via the lymphatics and involves macrophages and neutrophils.

Multi-View Feature Aggregation for Predicting Microbe-Disease Association

Microbes play a crucial role in human health and disease. Figuring out the relationship between microbes and diseases leads to significant potential applications in disease treatments. It is an urgent need to devise robust and effective computational methods for identifying disease-related microbes. This work proposes a Multi-View Feature Aggregation (MVFA) scheme that integrates the linear and nonlinear features to identify disease-related microbes. We introduce a non-negative matrix tri-factorization (NMTF) model to extract linear features for diseases and microbes. Then we learn another type of linear feature by utilizing a bi-random walk model. The nonlinear feature is obtained by inputting the two kinds of linear features into a capsule neural network. These three types of features describe the associations between diseases and microbes from different views. Finally, considering the complementary of these features, we leverage a logistic regression model to combine the NMTF model predictions, bi-random walk model predictions, and the capsule neural network predictions to obtain the final microbe-disease pair scores. We apply our method to predict human microbe-disease associations on two datasets. Experimental results show that our multi-view model outperforms the state-of-the-art models in recovering missing microbe-disease associations and predicting associations for new microbes. The ablation study shows that aggregating multi-view linear and nonlinear features can improve the prediction performance. Case studies on two diseases, i.e. Type 1 diabetes and Liver cirrhosis, further validate our method effectiveness.

Distinct inactivated bacterial-based immune modulators vary in their therapeutic efficacies for treating disease based on the organ site of pathology

Recent developments in understanding how the functional phenotype of the innate immune system is programmed has led to paradigm-shifting views on immunomodulation. These advances have overturned two long-held dogmas: (1) only adaptive immunity confers immunological memory; and, (2) innate immunity lacks specificity. This work describes the observation that innate immune effector cells appear to be differentially recruited to specific pathological sites when mobilized by distinct inactivated bacterial-based stimuli administered subcutaneously. The studies presented suggest that the immune system, upon detecting the first signs of a potential infection by a specific pathogen, tends to direct its resources to the compartment from which that pathogen is most likely originating. The findings from this work puts forth the novel hypothesis that the immunotherapeutic efficacy of a microbial-based stimulus for innate immune mobilization depends on the correct selection of the microbial species used as the stimulant and its relationship to the organ in which the pathology is present.

Immune Stimulation Using a Gut Microbe-Based Immunotherapy Reduces Disease Pathology and Improves Barrier Function in Ulcerative Colitis

Background: Current ulcerative colitis (UC) treatments are focused on symptom management primarily via immune suppression. Despite the current arsenal of immunosuppressant treatments, the majority of patients with UC still experience disease progression. Importantly, aggressive long-term inhibition of immune function comes with consequent risk, such as serious infections and malignancy. There is thus a recognized need for new, safe and effective treatment strategies for people living with UC that work upstream of managing the symptoms of the disease. The objective of this study was to evaluate a microbial-based treatment, QBECO, that functions to productively activate rather than suppress mucosal immune function as a novel approach to treat UC. Methods: Two established models of experimental colitis, namely chemically-induced DSS colitis and the spontaneous colitis that develops in Muc2 deficient mice, were used to assess whether QBECO treatment could ameliorate gastrointestinal disease. A small exploratory 16-week QBECO open-label trial was subsequently conducted to test the safety and tolerability of this approach and also to determine whether similar improvements in clinical disease and histopathology could be demonstrated in patients with moderate-to-severe UC. Results: QBECO treatment successfully reduced inflammation and promoted mucosal and histological healing in both experimental models and in UC patients. The preclinical models of colitis showed that QBECO ameliorated mucosal pathology, in part by reducing inflammatory cell infiltration, primarily that induced by neutrophils and inflammatory T cells. The most rapid and noticeable change observed in QBECO treated UC patients was a marked reduction in rectal bleeding. Conclusion: Collectively, this work demonstrates for the first time that strategically activating immune function rather than suppressing it, not only does not worsen colitis induced-damage, but may lead to an objective reduction in UC disease pathology.

The Role of Regulatory T Cell in Nontypeable Haemophilus influenzae-Induced Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is associated with irreversible persistent airflow limitation and enhanced inflammation. The episodes of acute exacerbation (AECOPD) largely depend on the colonized pathogens such as nontypeable Haemophilus influenzae (NTHi), one of the most commonly isolated bacteria. Regulatory T cells (Tregs) are critical in controlling inflammatory immune responses and maintaining tolerance; however, their role in AECOPD is poorly understood. In this study, we hypothesized a regulatory role of Tregs, as NTHi participated in the progress of COPD. Immunological pathogenesis was investigated in a murine COPD model induced by cigarette smoke (CS). NTHi was administrated through intratracheal instillation for an acute exacerbation. Weight loss and lung function decline were observed in smoke-exposed mice. Mice in experimental groups exhibited serious inflammatory responses via histological and cytokine assessment. Expression levels of Tregs and Th17 cells with specific cytokines TGF-β1 and IL-17 were detected to assess the balance of pro-/anti-inflammatory influence partially. Our findings suggested an anti-inflammatory activity of Tregs in CS-induced model. But this activity was suppressed after NTHi administration. Collectively, these data suggested that NTHi might play a necessary role in downregulating Foxp3 to impair the function of Tregs, helping development into AECOPD.

Acellular filtrate of a microbial-based cleaning product potentiates house dust mite allergic lung inflammation

Microbial-based cleaning products (MBCPs) contain bacteria and chemical constituents. They are used in consumer applications such as odor reduction, unclogging drains, and surface cleaning. To determine the capacity of a model MBCP to contribute to acute allergic lung inflammation, a two-week repeated exposure regimen was used. Mice were exposed by endotracheal instillation to saline alone, MBCP alone, house dust mites (HDM) alone, or sequentially (i.e., MBCP followed by HDM, HDM followed by MBCP, or HDM + MBCP followed by HDM). Both whole MBCP and acellular MBCP filtrate were investigated, and showed minimal differences in the endpoints examined. HDM exposure caused pulmonary perivascular inflammation, bronchiolar mucous cell metaplasia, elevated bronchoalveolar lavage fluid (BALF) eosinophils, and HDM-specific IgG1. For MBCP, notable changes were associated with sequential exposures. MBCP/HDM caused elevated T_H2 cytokines in BALF, and elevated neutrophils, eosinophils and IL-5 in peripheral blood. Co-administration of MBCP and HDM followed by HDM resulted in elevated blood and BALF eosinophils and HDM-specific IgE and IgG1. These results demonstrated that acellular MBCP filtrate, and not bacteria within MBCPs, potentiated the acute allergic inflammation to HDM. This methodology could be extended to investigate chronic allergic inflammation and inflammatory potential of other MBCPs and biotechnology products with complex compositions.

Harnessing innate lung anti-cancer effector functions with a novel bacterial-derived immunotherapy

Acute infection is known to induce strong anti-tumor immune responses, but clinical translation has been hindered by the lack of an effective strategy to safely and consistently provoke a therapeutic response. These limitations are overcome with a novel treatment approach involving repeated subcutaneous delivery of a Klebsiella-derived investigational immunotherapeutic, QBKPN. In preclinical models of lung cancer, QBKPN administration consistently showed anti-cancer efficacy, which was dependent on Klebsiella pre-exposure, but was independent of adaptive immunity. Rather, QBKPN induced anti-tumor innate immunity that required NK cells and NKG2D engagement. QBKPN increased NK cells and macrophages in the lungs, altered macrophage polarization, and augmented the production of cytotoxic molecules. An exploratory trial in patients with non-small cell lung cancer demonstrated QBKPN was well tolerated, safe, and induced peripheral immune changes suggestive of macrophage polarization and reduction of PD-1 and PD-L1 expression on leukocytes. These data demonstrate preclinical efficacy, and clinical safety and tolerability, for this cancer immunotherapy strategy that exploits innate anti-tumor immune mechanisms.

Regulation of xanthine dehydrogensase gene expression and uric acid production in human airway epithelial cells

Introduction

The airway epithelium is a physical and immunological barrier that protects the pulmonary system from inhaled environmental insults. Uric acid has been detected in the respiratory tract and can function as an antioxidant or damage associated molecular pattern. We have demonstrated that human airway epithelial cells are a source of uric acid. Our hypothesis is that uric acid production by airway epithelial cells is induced by environmental stimuli associated with chronic respiratory diseases. We therefore examined how airway epithelial cells regulate uric acid production.

Materials and methods

Allergen and cigarette smoke mouse models were performed using house dust mite (HDM) and cigarette smoke exposure, respectively, with outcome measurements of lung uric acid levels. Primary human airway epithelial cells isolated from clinically diagnosed patients with asthma and chronic obstructive pulmonary disease (COPD) were grown in submerged cultures and compared to age-matched healthy controls for uric acid release. HBEC-6KT cells, a human airway epithelial cell line, were grown under submerged monolayer conditions for mechanistic and gene expression studies.

Results

HDM, but not cigarette smoke exposure, stimulated uric acid production in vivo and in vitro. Primary human airway epithelial cells from asthma, but not COPD patients, displayed elevated levels of extracellular uric acid in culture. In HBEC-6KT, production of uric acid was sensitive to the xanthine dehydrogenase (XDH) inhibitor, allopurinol, and the ATP Binding Cassette C4 (ABCC4) inhibitor, MK-571. Lastly, the pro-inflammatory cytokine combination of TNF-α and IFN-γ elevated extracellular uric acid levels and XDH gene expression in HBEC-6KT cells.

Conclusions

Our results suggest that the active production of uric acid from human airway epithelial cells may be intrinsically altered in asthma and be further induced by pro-inflammatory cytokines.

Attenuating immune pathology using a microbial-based intervention in a mouse model of cigarette smoke-induced lung inflammation

Background

Cigarette smoke exposure is the major risk factor for developing COPD. Presently, available COPD treatments focus on suppressing inflammation and providing bronchodilation. However, these options have varying efficacy in controlling symptoms and do not reverse or limit the progression of COPD. Treatments strategies using bacterial-derived products have shown promise in diseases characterized by inflammation and immune dysfunction. This study investigated for the first time whether a novel immunotherapy produced from inactivated Klebsiella (hereafter referred to as KB) containing all the major Klebsiella macromolecules, could attenuate cigarette smoke exposure-induced immune responses. We hypothesized that KB, by re-directing damaging immune responses, would attenuate cigarette smoke-induced lung inflammation and bronchoalveolar (BAL) cytokine and chemokine production.

Methods

KB was administered via a subcutaneous injection prophylactically before initiating a 3-week acute nose-only cigarette smoke exposure protocol. Control mice received placebo injection and room air. Total BAL and differential cell numbers were enumerated. BAL and serum were analysed for 31 cytokines, chemokines, and growth factors. Lung tissue and blood were analysed for Ly6C^HI monocytes/macrophages and neutrophils. Body weight and clinical scores were recorded throughout the experiment.

Results

We demonstrate that KB treatment attenuated cigarette smoke-induced lung inflammation as shown by reductions in levels of BAL IFNγ, CXCL9, CXCL10, CCL5, IL-6, G-CSF, and IL-17. KB additionally attenuated the quantity of BAL lymphocytes and macrophages. In parallel to the attenuation of lung inflammation, KB induced a systemic immune activation with increases in Ly6C^HI monocytes/macrophages and neutrophils.

Conclusions

This is the first demonstration that subcutaneous administration of a microbial-based immunotherapy can attenuate cigarette smoke-induced lung inflammation, and modulate BAL lymphocyte and macrophage levels, while inducing a systemic immune activation and mobilization. These data provide a foundation for future studies exploring how KB may be used to either reverse or prevent progression of established emphysema and small airways disease associated with chronic cigarette smoke exposure. The data suggest the intriguing possibility that KB, which stimulates rather than suppresses systemic immune responses, might be a novel means by which the course of COPD pathogenesis may be altered.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0577-y) contains supplementary material, which is available to authorized users.