Lactobacillus delivery of bioactive interleukin-22

Therapeutic activation of IL-22-producing innate lymphoid cells enhances host defenses to Clostridioides difficile infection

Clostridioides difficile causes debilitating colitis via secreted toxins that disrupt the intestinal barrier, and toxemia is associated with severe disease. Thus, therapies that fortify the intestinal barrier will reduce the severity of infection. Innate lymphoid cells (ILCs) are critical in the defense against acute C. difficile infection and represent a promising therapeutic target to limit disease. Here, we report that oral administration of the Toll-like receptor (TLR) 7 agonist R848 limits intestinal damage and protects mice from lethal C. difficile infection without impacting pathogen burden or altering the intestinal microbiome. R848 induced interleukin (IL)-22 secretion by ILCs, leading to STAT3 phosphorylation in the intestinal epithelium and increased stem cell proliferation. Genetic ablation of ILCs, IL-22, or epithelial-specific STAT3 abrogated R848-mediated protection. R848 reduced intestinal permeability following infection and limited systemic toxin dissemination. Combined, these data identify an immunostimulatory molecule that activates IL-22 production in ILCs to enhance host tissue defenses following C. difficile infection.

Lipidated IL-22 Alone or Combined with Immunomodulatory Agents Improves Disease Endpoints and Promotes Mucosal Healing in a Mouse Model of Chronic Dextran Sodium Sulfate-Induced Colitis

BACKGROUND

IL-22 facilitates mucosal healing by directly inducing epithelial regeneration and barrier integrity, which is essential for achieving remission and thereby treating inflammatory bowel disease.

AIMS

Here, we evaluated efficacy of a novel lipidated IL-22 alone and in combination with immunomodulatory agents in addressing chronic dextran sodium sulfate (DSS)-induced colitis in mice and demonstrated action of IL-22 on mucosal healing.

METHODS

Mice were treated with DSS, followed by various doses of lipidated IL-22, anti-TNF antibody, fingolimod, or anti-mouse α4β7 integrin antibody. Additionally, gene expression was determined in colonic biopsies from ulcerative colitis patients to assess effects of IL-22 stimulation.

RESULTS

Lipidated IL-22 significantly improved all aspects of chronic DSS-induced colitis in mice, with dose-dependent efficacy. Combinations of a range of immunomodulatory agents with lipidated IL-22 showed further additive reductions in disease activity, significantly greater than those of monotherapies. Immunohistochemistry revealed that lipidated IL-22 increased epithelial cell proliferation and reduced CD3+ T-cell infiltration, indicating enhanced mucosal healing. This was further supported gene expression data from colonic biopsies from ulcerative colitis patients after IL-22 stimulation.

CONCLUSIONS

Given the challenges in achieving long-term remission in IBD due to inflammation and mucosal damage, lipidated IL-22 presents a promising treatment option that directly promotes mucosal healing, unlike traditional immunomodulatory therapies.

Diagnostic and Therapeutic Microbial Circuit with Application to Intestinal Inflammation

Bacteria genetically engineered to execute defined therapeutic and diagnostic functions in physiological settings can be applied to colonize the human microbiome, providing in situ surveillance and conditional disease modulation. However, many engineered microbes can only respond to single-input environmental factors, limiting their tunability, precision, and effectiveness as living diagnostic and therapeutic systems. For engineering microbes to improve complex chronic disorders such as inflammatory bowel disease, the bacteria must respond to combinations of stimuli in the proper context and time. This work implements a previously characterized split activator AND logic gate in the probiotic Escherichia coli strain Nissle 1917 (EcN). Our system can respond to two input signals: the inflammatory biomarker tetrathionate and a second input signal, anhydrotetracycline (aTc), for manual control. We report 4-6 fold induction with a minimal leak when the two chemical signals are present. We model the AND gate dynamics using chemical reaction networks and tune parameters in silico to identify critical perturbations that affect our circuit's selectivity. Finally, we engineer the optimized AND gate to secrete a therapeutic anti-inflammatory cytokine IL-22 using the hemolysin secretion pathway in the probiotic E. coli strain. We used a germ-free transwell model of the human gut epithelium to show that our engineering bacteria produce similar host cytokine responses compared to recombinant cytokine. Our study presents a scalable workflow to engineer cytokine-secreting microbes driven by logical signal processing. It demonstrates the feasibility of IL-22 derived from probiotic EcN with minimal off-target effects in a gut epithelial context.

Human IL-22 receptor-targeted small protein antagonist suppress murine DSS-induced colitis

BACKGROUND

Human interleukin-22 (IL-22) is known as a "dual function" cytokine that acts as a master regulator to maintain homeostasis, structural integrity of the intestinal epithelial barrier, and shielding against bacterial pathogens. On the other hand, the overexpression of IL-22 is associated with hyper-proliferation and recruitment of pathologic effector cells, leading to tissue damage and chronic inflammation in specific diseases including inflammatory bowel disease (IBD). To study a role of IL-22-mediated signaling axis during intestinal inflammation, we generated a set of small protein blockers of IL-22R1 and verified their inhibitory potential on murine model of colitis.

METHODS

We used directed evolution of proteins to identify binders of human IL-22 receptor alpha (IL-22R1), designated as ABR ligands. This approach combines the assembly of a highly complex combinatorial protein library derived from small albumin-binding domain scaffold and selection of promising protein variants using ribosome display followed by large-scale ELISA screening. The binding affinity and specificity of ABR variants were analyzed on transfected HEK293T cells by flow cytometry and LigandTracer. Inhibitory function was further verified by competition ELISA, HEK-Blue IL-22 reporter cells, and murine dextran sulfate sodium (DSS)-induced colitis.

RESULTS

We demonstrate that ABR specifically recognizes transgenic IL-22R1 expressed on HEK293T cells and IL-22R1 on TNFα/IFNγ-activated HaCaT cells. Moreover, some ABR binders compete with the IL-22 cytokine and function as IL-22R1 antagonists in HEK-Blue IL22 reporter cells. In a murine model of DSS-induced acute intestinal inflammation, daily intraperitoneal administration of the best IL-22R1 antagonist, ABR167, suppressed the development of clinical and histological markers of colitis including prevention of mucosal inflammation and architecture deterioration. In addition, ABR167 reduces the DSS-induced increase in mRNA transcript levels of inflammatory cytokines such as IL-1β, IL-6, IL-10, and IL-17A.

CONCLUSIONS

We developed small anti-human IL-22R1 blockers with antagonistic properties that ascertain a substantial role of IL-22-mediated signaling in the development of intestinal inflammation. The developed ABR blockers can be useful as a molecular clue for further IBD drug development.

Function of stem cells in radiation-induced damage

PURPOSE

The aim of this review is to discuss previous studies on the function of stem cells in radiation-induced damage, and the factors affecting these processes, in the hope of improving our understanding of the different stem cells and the communication networks surrounding them. This is essential for the development of effective stem cell-based therapies to regenerate or replace normal tissues damaged by radiation.

CONCLUSION

In salivary glands, senescence-associated cytokines and inflammation-associated cells have a greater effect on stem cells. In the intestinal glands, Paneth cells strongly affect stem cell-mediated tissue regeneration after radiation treatment. In the pancreas, β-cells as well as protein C receptor positive (Procr) cells are expected to be key cells in the treatment of diabetes. In the bone marrow, a variety of cytokines such as CXC-chemokine ligand 12 (CXCL12) and stem cell factor (SCF), contribute to the functional recovery of hematopoietic stem cells after irradiation.

Lactobacilli as a Vector for Delivery of Nanobodies against Norovirus Infection

Passive administration of neutralizing antibodies (Abs) is an attractive strategy for the control of gastrointestinal infections. However, an unanswered practical concern is the need to assure the stability of sufficient amounts of orally administered neutralizing Abs against intestinal pathogens (e.g., norovirus) in the harsh environment of the gastrointestinal tract. To this end, we expressed a single-domain Ab (VHH, nanobody) against norovirus on the cell surface of Lactobacillus, a natural and beneficial commensal component of the gut microbiome. First, we used intestinal epithelial cells generated from human induced pluripotent stem cells to confirm that VHH 1E4 showed neutralizing activity against GII.17 norovirus. We then expressed VHH 1E4 as a cell-wall-anchored form in Lactobacillus paracasei BL23. Flow cytometry confirmed the expression of VHH 1E4 on the surface of lactobacilli, and L. paracasei that expressed VHH 1E4 inhibited the replication of GII.17 norovirus in vitro. We then orally administered VHH 1E4-expressing L. paracasei BL23 to germ-free BALB/c mice and confirmed the presence of lactobacilli with neutralizing activity in the intestine for at least 10 days after administration. Thus, cell-wall-anchored VHH-displaying lactobacilli are attractive oral nanobody deliver vectors for passive immunization against norovirus infection.

Protective function of interleukin-22 in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive scarring disease with unknown etiology. The evidence of a pathogenic role for transforming growth factor-beta (TGF-β) in the development and progression of IPF is overwhelming. In the present study, we investigated the role of interleukin-22 (IL-22) in the pathogenesis of IPF by regulating the TGF-β pathway. We measured parameters and tissue samples from a clinical cohort of IPF. IL-22R knock out (IL-22RA1-/- ) and IL-22 supplementation mouse models were used to determine if IL-22 is protective in vivo. For the mechanistic study, we tested A549, primary mouse type II alveolar epithelial cell, human embryonic lung fibroblast, and primary fibroblast for their responses to IL-22 and/or TGF-β1. In a clinical cohort, the expression level of IL-22 in the peripheral blood and lung tissues of IPF patients was lower than healthy controls, and the lower IL-22 expression was associated with poorer pulmonary function. IL-22R-/- mice demonstrated exacerbated inflammation and fibrosis. Reciprocally, IL-22 augmentation by intranasal instillation of recombinant IL-22 repressed inflammation and fibrotic phenotype. In vitro, IL-22 treatment repressed TGF-β1 induced gene markers representing epithelial-mesenchymal-transition and fibroblast-myofibroblast-transition, likely via the inhibition of TGF-β receptor expression and subsequent Smad2/3 activation. IL-22 appears to be protective against pulmonary fibrosis by inhibiting TGF-β1 signaling, and IL-22 augmentation may be a promising approach to treat IPF.

Mechanisms and regulation of IL-22-mediated intestinal epithelial homeostasis and repair

AIMS

Ulcerative colitis and Crohn's disease, collectively known as inflammatory bowel disease (IBD), are chronic inflammatory disorders of the intestine for which key elements in disease initiation and perpetuation are defects in epithelial barrier integrity. Achieving mucosal healing is essential to ameliorate disease outcome and so new therapies leading to epithelial homeostasis and repair are under investigation. This study was designed to determine the mechanisms by which IL-22 regulates intestinal epithelial cell function.

MAIN METHODS

Human intestinal organoids and resections, as well as mice were used to evaluate the effect of IL-22 on stem cell expansion, proliferation and expression of mucus components. IL-22 effect on barrier function was assessed in polarized T-84 cell monolayers. Butyrate co-treatments and organoid co-cultures with immune cells were performed to monitor the impact of microbial-derived metabolites and inflammatory environments on IL-22 responses.

KEY FINDINGS

IL-22 led to epithelial stem cell expansion, proliferation, barrier dysfunction and anti-microbial peptide production in human and mouse models evaluated. IL-22 also altered the mucus layer by inducing an increase in membrane mucus but a decrease in secreted mucus and goblet cell content. IL-22 had the same effect on anti-microbial peptides and membrane mucus in both healthy and IBD human samples. In contrast, this IL-22-associated epithelial phenotype was different when treatments were performed in presence of butyrate and organoids co-cultured with immune cells.

SIGNIFICANCE

Our data indicate that IL-22 promotes epithelial regeneration, innate defense and membrane mucus production, strongly supporting the potential clinical utility of IL-22 as a mucosal healing therapy in IBD.

Harnessing the potential of Lactobacillus species for therapeutic delivery at the lumenal-mucosal interface

Lactobacillus species have been studied for over 30 years in their role as commensal organisms in the human gut. Recently there has been a surge of interest in their abilities to natively and recombinantly stimulate immune activities, and studies have identified strains and novel molecules that convey particular advantages for applications as both immune adjuvants and immunomodulators. In this review, we discuss the recent advances in Lactobacillus-related activity at the gut/microbiota interface, the efforts to probe the boundaries of the direct and indirect therapeutic potential of these bacteria, and highlight the continued interest in harnessing the native capacity for the production of biogenic compounds shown to influence nervous system activity. Taken together, these aspects underscore Lactobacillus species as versatile therapeutic delivery vehicles capable of effector production at the lumenal-mucosal interface, and further establish a foundation of efficacy upon which future engineered strains can expand.

A quantitative model for metabolic intervention using gut microbes

As medicine shifts toward precision-based and personalized therapeutics, utilizing more complex biomolecules to treat increasingly difficult and rare conditions, microorganisms provide an avenue for realizing the production and processing necessary for novel drug pipelines. More so, probiotic microbes can be co-opted to deliver therapeutics by oral administration as living drugs, able to survive and safely transit the digestive tract. As living therapeutics are in their nascency, traditional pharmacokinetic-pharmacodynamic (PK-PD) models for evaluating drug candidates are not appropriate for this novel platform. Using a living therapeutic in late-stage clinical development for phenylketonuria (PKU) as a case study, we adapt traditional oral drug delivery models to properly evaluate and inform the engineering of living therapeutics. We develop the adapted for living therapeutics compartmental absorption and transit (ALT-CAT) model to provide metrics for drug efficacy across nine age groups of PKU patients and evaluate model parameters that are influenced by patient physiology, microbe selection and therapeutic production, and dosing formulations. In particular, the ALT-CAT model describes the mathematical framework to model the behavior of orally delivered engineered bacteria that act as living therapeutics by adapting similar methods that have been developed and widely-used for small molecular drug delivery and absorption.

Plant production and functional characterization of catfish interleukin-22 as a natural immune stimulant for aquaculture fish

As the world population increases and wild caught fisheries decline, aquaculture offers a sustainable solution addressing this global challenge. However, disease management remains difficult. With limited options, there is a need for innovative solutions. The cytokine interleukin-22 (IL-22) has emerged as a possible therapeutic target for fish and has been correlated with protection under pathogen challenge. Plant-based production systems have the potential to effectively manufacture and bring unique efficacy-enhancing features to the aquaculture industry; namely, the advantages of low cost for this commodity market, ready scalability, and reduced environmental impact. Catfish IL-22 produced at significant yield and purity highlights the use of plants as a promising production platform for therapeutic proteins with utility to the aquaculture industry. Purified cfIL-22 shows similar in vitro bioactivity to its mammalian homolog that include increased proliferation of catfish cells highlighting the tissue preservation capabilities associated with this protein. Recombinant cfIL-22 also upregulated expression of genes encoding a tissue repair protein, fibronectin, an antimicrobial peptide, Natural killer lysin-1, and a common innate immune protein, interferon. These findings support plant-made recombinant catfish interleukin-22 as a potential therapeutic for the aquaculture industry and further analysis of this protein for promoting animal health.

IL-22 Signaling in the Tumor Microenvironment

Interleukin (IL)-22 belongs to the IL-10 cytokine family which performs biological functions by binding to heterodimer receptors comprising a type 1 receptor chain (R1) and a type 2 receptor chain (R2). IL-22 is mainly derived from CD4+ helper T cells, CD8+ cytotoxic T cells, innate lymphocytes, and natural killer T cells. It can activate downstream signaling pathways such as signal transducer and activator of transcription (STAT)1/3/5, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) through these heterodimer receptors. Although IL-22 is produced by immune cells, its specific receptor IL-22R1 is selectively expressed in nonimmune cells, such as hepatocytes, colonic epithelial cells, and pancreatic epithelial cells (Jiang et al. Hepatology 54(3):900-9, 2011; Jiang et al. BMC Cancer 13:59, 2013; Curd et al. Clin Exp Immunol 168(2):192-9, 2012). Immune cells do not respond to IL-22 stimulation directly within tumors, reports from different groups have revealed that IL-22 can indirectly regulate the tumor microenvironment (TME). In the present chapter, we discuss the roles of IL-22 in malignant cells and immunocytes within the TME, meanwhile, the potential roles of IL-22 as a target for drug discovery will be discussed.

Anchoring of heterologous proteins in multiple Lactobacillus species using anchors derived from Lactobacillus plantarum

Members of the genus Lactobacillus have a long history in food applications and are considered as promising and safe hosts for delivery of medically interesting proteins. We have assessed multiple surface anchors derived from Lactobacillus plantarum for protein surface display in multiple Lactobacillus species, using a Mycobacterium tuberculosis hybrid antigen as test protein. The anchors tested were a lipoprotein anchor and two cell wall anchors, one non-covalent (LysM domain) and one covalent (sortase-based anchoring using the LPXTG motif). Thus, three different expression vectors for surface-anchoring were tested in eight Lactobacillus species. When using the LPXTG and LysM cell wall anchors, surface display, as assessed by flow cytometry and fluorescence microscopy, was observed in all species except Lactobacillus acidophilus. Use of the cell membrane anchor revealed more variation in the apparent degree of surface-exposure among the various lactobacilli. Overproduction of the secreted and anchored antigen impaired bacterial growth rate to extents that varied among the lactobacilli and were dependent on the type of anchor. Overall, these results show that surface anchors derived from L. plantarum are promising candidates for efficient anchoring of medically interesting proteins in other food grade Lactobacillus species.

Challenges and Pitfalls in the Engineering of Human Interleukin 22 (hIL-22) Secreting Lactobacillus reuteri

Engineered microbes for the delivery of intestinally directed therapeutics is a promising avenue for the treatment of various intestinal diseases including inflammatory bowel disease (IBD) and intestinal graft vs. host disease (GVHD). This modality of treatment would allow for the targeted delivery of therapeutics to the site of inflammation or disease while minimizing the systemic side effects that often accompany treatment of these pathologies. Here, we show the challenges encountered and overcome in successfully engineering Lactobacillus reuteri to secrete high levels of biologically active human interleukin 22 (hIL-22). Initial hIL-22 constructs secreted high levels of hIL-22, however we found the majority of hIL-22 was cleaved and not biologically active. Several strategies were explored to improve the production of intact hIL-22, with the optimization of the signal sequence for peptide secretion having the most impact of production of intact hIL-22. This resulted in L. reuteri secreting high concentrations (up to 700 ng/mL) of hIL-22. Bioactivity of hIL-22 was confirmed by the secretion of interleukin 10 (IL-10) from the colon cancer derived epithelial cell line Colo205 and the secretion of Regenerating islet-derived protein 3 alpha (Reg3α) from human jejunal enteroids. The secretion of bioactive hIL-22 imposed a significant cost for L. reuteri as bacterial growth was significantly impaired upon induction. Future challenges and optimization strategies for the delivery of hIL-22 to the human intestinal tract are discussed.

IL-22: There Is a Gap in Our Knowledge

IL-22 is a critical cytokine in modulating tissue responses during inflammation. IL-22 is upregulated in many chronic inflammatory diseases, making IL-22 biology a potentially rewarding therapeutic target. However, this is complicated by the dual-natured role of IL-22 in inflammation, as the cytokine can be protective or inflammatory depending on the disease model. Although scientific interest in IL-22 has increased considerably in the past 10 y, there is still much we do not know about the environmental, cellular, and molecular factors that regulate the production and function of this cytokine. A better understanding of IL-22 biology will allow us to develop new or improved therapeutics for treating chronic inflammatory diseases. In this article, I will highlight some of the outstanding questions in IL-22 biology.