A Phase 2 Randomized Controlled Study of Tralokinumab in Subjects with Idiopathic Pulmonary Fibrosis

Evidence from recent clinical trials in fibrotic interstitial lung diseases

PURPOSE OF REVIEW

Idiopathic pulmonary fibrosis (IPF) is the prototype of fibrosing interstitial lung diseases. It is mirrored by progressive pulmonary fibrosis (PPF), an umbrella term which characterizes disease behavior of various fibrotic interstitial lung diseases with irreversible progression, accounting for loss of lung function, exercise intolerance and respiratory failure leading to early mortality. Pirfenidone and nintedanib halve the decline in lung function but do not halt disease progression.

RECENT FINDINGS

Since the publication in 2014 of pivotal pirfenidone and nintedanib studies, a number of clinical trials were conducted, many of them did not reach their primary endpoints. In IPF, promising phase 2 trials were followed by large phase 3 trials that did not confirm a favorable efficacy to tolerability favorable profile, including those with ziritaxestat, an autotaxin-1 inhibitor, zinpentraxin-alpha (human recombinant pentraxin-2), and the monoclonal antibody pamrevlumab targeting connective tissue growth factor. Nevertheless, newer compounds that hold promise are currently being evaluated in phase 3 or phase 2b randomized controlled trials, including: nerandomilast, a preferential phosphodiesterase 4B inhibitor; admilparant, a lysophosphatidic acid receptor antagonist; inhaled treprostinil, a prostacyclin agonist; and bexotegrast, a dual-selective inhibitor of αvβ6 and αvβ1 integrins. Nerandomilast, admilparant, inhaled treprostinil, and inhaled AP01 (pirfenidone), are currently studied in patients with PPF.

SUMMARY

Despite recent frustrating negative results, there is a growing portfolio of candidate drugs developed in both IPF and PPF.

IL-4-induced SOX9 confers lineage plasticity to aged adult lung stem cells

Wound healing in response to acute injury is mediated by the coordinated and transient activation of parenchymal, stromal, and immune cells that resolves to homeostasis. Environmental, genetic, and epigenetic factors associated with inflammation and aging can lead to persistent activation of the microenvironment and fibrosis. Here, we identify opposing roles of interleukin-4 (IL-4) cytokine signaling in interstitial macrophages and type II alveolar epithelial cells (ATIIs). We show that IL4Ra signaling in macrophages promotes regeneration of the alveolar epithelium after bleomycin-induced lung injury. Using organoids and mouse models, we show that IL-4 directly acts on a subset of ATIIs to induce the expression of the transcription factor SOX9 and reprograms them toward a progenitor-like state with both airway and alveolar lineage potential. In the contexts of aging and bleomycin-induced lung injury, this leads to aberrant epithelial cell differentiation and bronchiolization, consistent with cellular and histological changes observed in interstitial lung disease.

Immune mechanisms in fibrotic interstitial lung disease

Fibrotic interstitial lung diseases (fILDs) have poor survival rates and lack effective therapies. Despite evidence for immune mechanisms in lung fibrosis, immunotherapies have been unsuccessful for major types of fILD. Here, we review immunological mechanisms in lung fibrosis that have the potential to impact clinical practice. We first examine innate immunity, which is broadly involved across fILD subtypes. We illustrate how innate immunity in fILD involves a complex interplay of multiple cell subpopulations and molecular pathways. We then review the growing evidence for adaptive immunity in lung fibrosis to provoke a re-examination of its role in clinical fILD. We close with future directions to address key knowledge gaps in fILD pathobiology: (1) longitudinal studies emphasizing early-stage clinical disease, (2) immune mechanisms of acute exacerbations, and (3) next-generation immunophenotyping integrating spatial, genetic, and single-cell approaches. Advances in these areas are essential for the future of precision medicine and immunotherapy in fILD.

The current landscape of antifibrotic therapy across different organs: A systematic approach

Fibrosis is a common pathological process that can affect virtually all the organs, but there are hardly any effective therapeutic options. This has led to an intense search for antifibrotic therapies over the last decades, with a great number of clinical assays currently underway. We have systematically reviewed all current and recently finished clinical trials involved in the development of new antifibrotic drugs, and the preclinical studies analyzing the relevance of each of these pharmacological strategies in fibrotic processes affecting tissues beyond those being clinically studied. We analyze and discuss this information with the aim of determining the most promising options and the feasibility of extending their therapeutic value as antifibrotic agents to other fibrotic conditions.

Leukemia inhibitory factor (LIF) receptor amplifies pathogenic activation of fibroblasts in lung fibrosis

Fibrosis drives end-organ damage in many diseases. However, clinical trials targeting individual upstream activators of fibroblasts, such as TGFβ, have largely failed. Here, we target the leukemia inhibitory factor receptor (LIFR) as a "master amplifier" of multiple upstream activators of lung fibroblasts. In idiopathic pulmonary fibrosis (IPF), the most common fibrotic lung disease, we found that lung myofibroblasts had high LIF expression. Further, TGFβ1, one of the key drivers of fibrosis, upregulated LIF expression in IPF fibroblasts. In vitro anti-LIFR antibody blocking on human IPF lung fibroblasts reduced induction of profibrotic genes downstream of TGFβ1, IL-4 and IL-13. Further, siRNA silencing of LIFR in IPF precision cut lung slices reduced expression of fibrotic proteins. Together, we find that LIFR drives an autocrine positive feedback loop that amplifies and sustains pathogenic activation of IPF fibroblasts downstream of multiple external stimuli, implicating LIFR as a therapeutic target in fibrosis.

Significance Statement

Fibroblasts have a central role in the pathogenesis of fibrotic diseases. However, due to in part to multiple profibrotic stimuli, targeting a single activator of fibroblasts, like TGFβ, has not yielded successful clinical treatments. We hypothesized that a more effective therapeutic strategy is identifying a downstream "master amplifier" of a range of upstream profibrotic stimuli. This study identifies the leukemia inhibitory factor receptor (LIFR) on fibrotic lung fibroblasts amplifies multiple profibrotic stimuli, such as IL-13 and TGFβ. Blocking LIFR reduced fibrosis in ex vivo lung tissue from patients with idiopathic pulmonary fibrosis (IPF). LIFR, acting as a master amplifier downstream of fibroblast activation, offers an alternative therapeutic strategy for fibrotic diseases.

Comprehensive review of potential drugs with anti-pulmonary fibrosis properties

Pulmonary fibrosis is a chronic and progressive lung disease characterized by the accumulation of scar tissue in the lungs, which leads to impaired lung function and reduced quality of life. The prognosis for idiopathic pulmonary fibrosis (IPF), which is the most common form of pulmonary fibrosis, is generally poor. The median survival for patients with IPF is estimated to be around 3-5 years from the time of diagnosis. Currently, there are two approved drugs (Pirfenidone and Nintedanib) for the treatment of IPF. However, Pirfenidone and Nintedanib are not able to reverse or cure pulmonary fibrosis. There is a need for new pharmacological interventions that can slow or halt disease progression and cure pulmonary fibrosis. This review aims to provide an updated overview of current and future drug interventions for idiopathic pulmonary fibrosis, and to summarize possible targets of potential anti-pulmonary fibrosis drugs, providing theoretical support for further clinical combination therapy or the development of new drugs.

Emerging delivery approaches for targeted pulmonary fibrosis treatment

Pulmonary fibrosis (PF) is a progressive, and life-threatening interstitial lung disease which causes scarring in the lung parenchyma and thereby affects architecture and functioning of lung. It is an irreversible damage to lung functioning which is related to epithelial cell injury, immense accumulation of immune cells and inflammatory cytokines, and irregular recruitment of extracellular matrix. The inflammatory cytokines trigger the differentiation of fibroblasts into activated fibroblasts, also known as myofibroblasts, which further increase the production and deposition of collagen at the injury sites in the lung. Despite the significant morbidity and mortality associated with PF, there is no available treatment that efficiently and effectively treats the disease by reversing their underlying pathologies. In recent years, many therapeutic regimens, for instance, rho kinase inhibitors, Smad signaling pathway inhibitors, p38, BCL-xL/ BCL-2 and JNK pathway inhibitors, have been found to be potent and effective in treating PF, in preclinical stages. However, due to non-selectivity and non-specificity, the therapeutic molecules also result in toxicity mediated severe side effects. Hence, this review demonstrates recent advances on PF pathology, mechanism and targets related to PF, development of various drug delivery systems based on small molecules, RNAs, oligonucleotides, peptides, antibodies, exosomes, and stem cells for the treatment of PF and the progress of various therapeutic treatments in clinical trials to advance PF treatment.

An adjudication algorithm for respiratory-related hospitalisation in idiopathic pulmonary fibrosis

Background

There is no standard definition of respiratory-related hospitalisation, a common end-point in idiopathic pulmonary fibrosis (IPF) clinical trials. As diverse aetiologies and complicating comorbidities can present similarly, external adjudication is sometimes employed to achieve standardisation of these events.

Methods

An algorithm for respiratory-related hospitalisation was developed through a literature review of IPF clinical trials with respiratory-related hospitalisation as an end-point. Experts reviewed the algorithm until a consensus was reached. The algorithm was validated using data from the phase 3 ISABELA trials (clinicaltrials.gov identifiers NCT03711162 and NCT03733444), by assessing concordance between nonadjudicated, investigator-defined, respiratory-related hospitalisations and those defined by the adjudication committee using the algorithm.

Results

The algorithm classifies respiratory-related hospitalisation according to cause: extraparenchymal (worsening respiratory symptoms due to left heart failure, volume overload, pulmonary embolism, pneumothorax or trauma); other (respiratory tract infection, right heart failure or exacerbation of COPD); "definite" acute exacerbation of IPF (AEIPF) (worsening respiratory symptoms within 1 month, with radiological or histological evidence of diffuse alveolar damage); or "suspected" AEIPF (as for "definite" AEIPF, but with no radiological or histological evidence of diffuse alveolar damage). Exacerbations ("definite" or "suspected") with identified triggers (infective, post-procedural or traumatic, drug toxicity- or aspiration-related) are classed as "known AEIPF"; "idiopathic AEIPF" refers to exacerbations with no identified trigger. In the ISABELA programme, there was 94% concordance between investigator- and adjudication committee-determined causes of respiratory-related hospitalisation.

Conclusion

The algorithm could help to ensure consistency in the reporting of respiratory-related hospitalisation in IPF trials, optimising its utility as an end-point.

Emerging role of immune cells as drivers of pulmonary fibrosis

The pathogenesis of pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF) and other forms of interstitial lung disease, involves a complex interplay of various factors including host genetics, environmental pollutants, infection, aberrant repair and dysregulated immune responses. Highly variable clinical outcomes of some ILDs, in particular IPF, have made it difficult to identify the precise mechanisms involved in disease pathogenesis and thus the development of a specific cure or treatment to halt and reverse the decline in patient health. With the advent of in-depth molecular diagnostics, it is becoming evident that the pathogenesis of IPF is unlikely to be the same for all patients and therefore will likely require different treatment approaches. Chronic inflammation is a cardinal feature of IPF and is driven by both innate and adaptive immune responses. Inflammatory cells and activated fibroblasts secrete various pro-inflammatory cytokines and chemokines that perpetuate the inflammatory response and contribute to the recruitment and activation of more immune cells and fibroblasts. The balance between pro-inflammatory and regulatory immune cell subsets, as well as the interactions between immune cell types and resident cells within the lung microenvironment, ultimately determines the extent of fibrosis and the potential for resolution. This review examines the role of the innate and adaptive immune responses in pulmonary fibrosis, with an emphasis on IPF. The role of different immune cell types is discussed as well as novel anti-inflammatory and immunotherapy approaches currently in clinical trial or in preclinical development.

Engineering the IL-4/IL-13 axis for targeted immune modulation

The structurally and functionally related interleukin-4 (IL-4) and IL-13 cytokines play pivotal roles in shaping immune activity. The IL-4/IL-13 axis is best known for its critical role in T helper 2 (Th2) cell-mediated Type 2 inflammation, which protects the host from large multicellular pathogens, such as parasitic helminth worms, and regulates immune responses to allergens. In addition, IL-4 and IL-13 stimulate a wide range of innate and adaptive immune cells, as well as non-hematopoietic cells, to coordinate various functions, including immune regulation, antibody production, and fibrosis. Due to its importance for a broad spectrum of physiological activities, the IL-4/IL-13 network has been targeted through a variety of molecular engineering and synthetic biology approaches to modulate immune behavior and develop novel therapeutics. Here, we review ongoing efforts to manipulate the IL-4/IL-13 axis, including cytokine engineering strategies, formulation of fusion proteins, antagonist development, cell engineering approaches, and biosensor design. We discuss how these strategies have been employed to dissect IL-4 and IL-13 pathways, as well as to discover new immunotherapies targeting allergy, autoimmune diseases, and cancer. Looking ahead, emerging bioengineering tools promise to continue advancing fundamental understanding of IL-4/IL-13 biology and enabling researchers to exploit these insights to develop effective interventions.

Circulating inflammatory cytokines and risk of idiopathic pulmonary fibrosis: a Mendelian randomization study

BACKGROUND

The previous epidemiological and experimental evidence has implied the linkage between chronic inflammation to idiopathic pulmonary fibrosis (IPF). However, it was still unclear whether there were casual associations between circulating inflammatory cytokines and IPF development. The objective of present study was to examine whether altered genetically predicted concentration of circulating cytokines were associated with IPF development using a two-sample Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

The causal effects of 23 circulating inflammatory cytokines were evaluated on IPF using MR analysis. The primary approach of MR analysis was the inverse variance-weighted (IVW) method. The sensitivity analyses were conducted by simple median, weighted median, penalized weighted median and MR-Egger regression methods.

RESULTS

The present MR study found suggestive evidence that a higher circulating IL-14 level was associated with an increased risk of IPF (random effects IVW method: odds ratio: 1.001, 95% confidence interval: 1.000-1.001, P = 0.026). The sensitivity analysis yielded directionally similar results for IL-14. There was no significant association found between other circulating inflammatory cytokines and IPF.

CONCLUSION

The high level of IL14 predicted by genes had a casual relationship with the increased risk of IPF. This finding provided epidemiological evidence for drug therapy targeting inflammatory factors in the prevention and treatment of IPF. It's warranted further exploration to validate the clinical significance of IL14 associated with developmental risk of IPF.

Molecular Features and Stages of Pulmonary Fibrosis Driven by Type 2 Inflammation

Systemic sclerosis (SSc) is a progressive, multiorgan disease with limited treatment options. Although a recent proof-of-concept study using romilkimab or SAR156597, a bispecific IL-4/IL-13 antibody, suggests a direct role of these cytokines in the pathophysiology of SSc, their contributions to the balance between inflammation and fibrosis are unclear. Here, we determine the roles of type 2 inflammation in fibrogenesis using FRA2-Tg (Fos-related antigen 2-overexpressing transgenic) mice, which develop spontaneous, age-dependent progressive lung fibrosis. We defined the molecular signatures of inflammation and fibrosis at three key stages in disease progression, corresponding to preonset, inflammatory dominant, and fibrosis dominant biology, and revealed an early increase in cytokine-cytokine receptor interactions and antigen-processing and presentation pathways followed by enhanced Th2- and M2 macrophage-driven type 2 responses. This type 2 inflammation progressed to extensive fibrotic pathology by 14-18 weeks of age, with these gene signatures overlapping significantly with those seen in the lungs of patients with SSc with interstitial lung disease (ILD). These changes were also evident in the histopathology, which showed perivascular and peribronchiolar inflammation with prominent eosinophilia and accumulation of profibrotic M2-like macrophages followed by rapid progression to fibrosis with thickened alveolar walls with multifocal fibrotic bands and signs of interstitial pneumonia. Critically, treatment with a bispecific antibody targeting IL-4 and IL-13 during the inflammatory phase abrogated the Th2 and M2 responses and led to near-complete abrogation of lung fibrosis. These data recapitulate important features of fibrotic progression in the lungs of patients with SSc-ILD and enhance our understanding of the progressive pathobiology of SSc. This study also further establishes FRA2-Tg mice as a valuable tool for testing future therapeutic agents in SSc-ILD.

Type 1 invariant natural killer T cells in chronic inflammation and tissue fibrosis

Chronic tissue inflammation often results in fibrosis characterized by the accumulation of extracellular matrix components remodeling normal tissue architecture and function. Recent studies have suggested common immune mechanisms despite the complexity of the interactions between tissue-specific fibroblasts, macrophages, and distinct immune cell populations that mediate fibrosis in various tissues. Natural killer T (NKT) cells recognizing lipid antigens bound to CD1d molecules have been shown to play an important role in chronic inflammation and fibrosis. Here we review recent data in both experimental models and in humans that suggest a key role of type 1 invariant NKT (iNKT) cell activation in the progression of inflammatory cascades leading to recruitment of neutrophils and activation of the inflammasome, macrophages, fibroblasts, and, ultimately, fibrosis. Emerging evidence suggests that iNKT-associated mechanisms contribute to type 1, type 2 and type 3 immune pathways mediating tissue fibrosis, including idiopathic pulmonary fibrosis (IPF). Thus, targeting a pathway upstream of these immune mechanisms, such as the inhibition of iNKT activation, may be important in modulating various fibrotic conditions.

Pulmonary inflammation and fibroblast immunoregulation: from bench to bedside

In recent years, there has been an explosion of interest in how fibroblasts initiate, sustain, and resolve inflammation across disease states. Fibroblasts contain heterogeneous subsets with diverse functionality. The phenotypes of these populations vary depending on their spatial distribution within the tissue and the immunopathologic cues contributing to disease progression. In addition to their roles in structurally supporting organs and remodeling tissue, fibroblasts mediate critical interactions with diverse immune cells. These interactions have important implications for defining mechanisms of disease and identifying potential therapeutic targets. Fibroblasts in the respiratory tract, in particular, determine the severity and outcome of numerous acute and chronic lung diseases, including asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome, and idiopathic pulmonary fibrosis. Here, we review recent studies defining the spatiotemporal identity of the lung-derived fibroblasts and the mechanisms by which these subsets regulate immune responses to insult exposures and highlight past, current, and future therapeutic targets with relevance to fibroblast biology in the context of acute and chronic human respiratory diseases. This perspective highlights the importance of tissue context in defining fibroblast-immune crosstalk and paves the way for identifying therapeutic approaches to benefit patients with acute and chronic pulmonary disorders.

The ins and outs of innate and adaptive type 2 immunity

Type 2 immunity is orchestrated by a canonical group of cytokines primarily produced by innate lymphoid cells, group 2, and their adaptive counterparts, CD4+ helper type 2 cells, and elaborated by myeloid cells and antibodies that accumulate in response. Here, we review the cytokine and cellular circuits that mediate type 2 immunity. Building from insights in cytokine evolution, we propose that innate type 2 immunity evolved to monitor the status of microbe-rich epithelial barriers (outside) and sterile parenchymal borders (inside) to meet the functional demands of local tissue, and, when necessary, to relay information to the adaptive immune system to reinforce demarcating borders to sustain these efforts. Allergic pathology likely results from deviations in local sustaining units caused by alterations imposed by environmental effects during postnatal developmental windows and exacerbated by mutations that increase vulnerabilities. This framework positions T2 immunity as central to sustaining tissue repair and regeneration and provides a context toward understanding allergic disease.

T cells in idiopathic pulmonary fibrosis: crucial but controversial

Idiopathic pulmonary fibrosis (IPF) has been extensively studied in recent decades due to its rising incidence and high mortality. Despite an abundance of research, the mechanisms, immune-associated mechanisms, of IPF are poorly understood. While defining immunopathogenic mechanisms as the primary pathogenesis is controversial, recent studies have verified the contribution of the immune system to the fibrotic progression of IPF. Extensive evidence has shown the potential role of T cells in fibrotic progression. In this review, we emphasize the features of T cells in IPF and highlight the controversial roles of different subtypes of T cells or even two distinct effects of one type of T-cell in diverse settings, and multiple chemokines and cell products are discussed. Furthermore, we discuss the potential development of treatments targeting the immune molecules of T cells and the feasibility of immune therapies for IPF in clinical practice.

Regulation of Progression and Resolution of Liver Fibrosis by Immune Cells

The excessive accumulation of extracellular matrix proteins results in fibrosis-a condition implicated in several diseased conditions, such as nonalcoholic steatohepatitis, viral hepatitis, and autoimmune hepatitis. Despite its prevalence, direct and effective treatments for fibrosis are lacking, warranting the development of better therapeutic strategies. Accumulating evidence has shown that liver fibrosis-a condition previously considered irreversible-is reversible in specific conditions. Immune cells residing in or infiltrating the liver (e.g., macrophages) are crucial in the pathogenesis of fibrosis. Given this background, the roles and action mechanisms of various immune cells and their subsets in the progression and recovery of liver fibrosis, particularly concerning nonalcoholic steatohepatitis, are discussed in this review. Furthermore, the development of better therapeutic strategies based on stage-specific properties and using advanced techniques as well as the mechanisms underlying recovery are elaborated. In conclusion, we consider the review comprehensively provides the present achievements and future possibilities revolving around fibrosis treatment.

Exosomal Micro-RNAs as Intercellular Communicators in Idiopathic Pulmonary Fibrosis

Communication between neighboring or distant cells is made through a complex network that includes extracellular vesicles (EVs). Exosomes, which are a subgroup of EVs, are released from most cell types and have been found in biological fluids such as urine, plasma, and airway secretions like bronchoalveolar lavage (BAL), nasal lavage, saliva, and sputum. Mainly, the cargo exosomes are enriched with mRNAs and microRNAs (miRNAs), which can be transferred to a recipient cell consequently modifying and redirecting its biological function. The effects of miRNAs derive from their role as gene expression regulators by repressing or degrading their target mRNAs. Nowadays, various types of research are focused on evaluating the potential of exosomal miRNAs as biomarkers for the prognosis and diagnosis of different pathologies. Nevertheless, there are few reports on their role in the pathophysiology of idiopathic pulmonary fibrosis (IPF), a chronic lung disease characterized by progressive lung scarring with no cure. In this review, we focus on the role and effect of exosomal miRNAs as intercellular communicators in the onset and progression of IPF, as well as discussing their potential utility as therapeutic agents for the treatment of this disease.

Efficacy and safety of Jin-shui Huan-xian granule for idiopathic pulmonary fibrosis: study protocol for a multicenter, randomized, double-blind, placebo-controlled trial

BACKGROUND AND RATIONALE

Idiopathic pulmonary fibrosis is a critical disease with a poor prognosis. Although different studies have been conducted for the treatment of idiopathic pulmonary fibrosis, limited treatments are available. Jin-shui Huan-xian granule (JHG), which is a Chinese medicine herbal compound, has shown promising efficacy in reducing frequencies of acute exacerbations, improving exercise capacity the quality of life of patients with idiopathic pulmonary fibrosis. This study is to evaluate the efficacy and safety of JHG for IPF.

SUBJECTS AND METHODS

This is a multicenter, randomized, double-blind, placebo-controlled clinical trial. A total of 312 idiopathic pulmonary fibrosis patients will be enrolled and randomly allocated to one of the two groups with 1:1. After a 2-week washout period, 52-week treatment will also be performed for all the patients. Patients in the experimental group and the control group will be given JHG and JHG placebo, respectively. Outcome measures including acute exacerbations, pulmonary function, dyspnea, exercise capacity, and quality of life will be evaluated in this study.

DISCUSSION

Based on our previous study, it is hypothesized that JHG will reduce acute exacerbations; improve exercise capacity, pulmonary function, and quality of life; and delay the disease progression-free. High-level evidence-based support for TCM in IPF will also be obtained in this study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04187690. Register on December 11, 2019.

The role of immune response in the pathogenesis of idiopathic pulmonary fibrosis: far beyond the Th1/Th2 imbalance

INTRODUCTION

. Idiopathic pulmonary fibrosis (IPF) is a chronic disease of unknown origin characterized by progressive scarring of the lung leading to irreversible loss of function. Despite the availability of two drugs that are able to slow down disease progression, IPF remains a deadly disease. The pathogenesis of IPF is poorly understood, but a dysregulated wound healing response following recurrent alveolar epithelial injury is thought to be crucial. Areas covered. In the last few years, the role of the immune system in IPF pathobiology has been reconsidered; indeed, recent data suggest that a dysfunctional immune system may promote and unfavorable interplay with pro-fibrotic pathways thus acting as a cofactor in disease development and progression. In this article, we review and critically discuss the role of T cells in the pathogenesis and progression of IPF in the attempt to highlight ways in which further research in this area may enable the development of targeted immunomodulatory therapies for this dreadful disease.

EXPERT OPINION

A better understanding of T cells interactions has the potential to facilitate the development of immune modulators targeting multiple T cell-mediated pathways thus halting disease initiation and progression.

Mesenchymal Stem Cell-Derived Extracellular Vesicles as Idiopathic Pulmonary Fibrosis Microenvironment Targeted Delivery

Idiopathic pulmonary fibrosis (IPF) affects an increasing number of people globally, yet treatment options remain limited. At present, conventional treatments depending on drug therapy do not show an ideal effect in reversing the lung damage or extending the lives of IPF patients. In recent years, more and more attention has focused on extracellular vesicles (EVs) which show extraordinary therapeutic effects in inflammation, fibrosis disease, and tissue damage repair in many kinds of disease therapy. More importantly, EVs can be modified or used as a drug or cytokine delivery tool, targeting injury sites to enhance treatment efficiency. In light of this, the treatment strategy of mesenchymal stem cell-extracellular vesicles (MSC-EVs) targeting the pulmonary microenvironment for IPF provides a new idea for the treatment of IPF. In this review, we summarized the inflammation, immune dysregulation, and extracellular matrix microenvironment (ECM) disorders in the IPF microenvironment in order to reveal the treatment strategy of MSC-EVs targeting the pulmonary microenvironment for IPF.

Autologous Skin Fibroblast-Based PLGA Nanoparticles for Treating Multiorgan Fibrosis

Fibrotic diseases remain a substantial health burden with few therapeutic approaches. A hallmark of fibrosis is the aberrant activation and accumulation of myofibroblasts, which is caused by excessive profibrotic cytokines. Conventional anticytokine therapies fail to undergo clinical trials, as simply blocking a single or several antifibrotic cytokines cannot abrogate the profibrotic microenvironment. Here, biomimetic nanoparticles based on autologous skin fibroblasts are customized as decoys to neutralize multiple fibroblast-targeted cytokines. By fusing the skin fibroblast membrane onto poly(lactic-co-glycolic) acid cores, these nanoparticles, termed fibroblast membrane-camouflaged nanoparticles (FNPs), are shown to effectively scavenge various profibrotic cytokines, including transforming growth factor-β, interleukin (IL)-11, IL-13, and IL-17, thereby modulating the profibrotic microenvironment. FNPs are sequentially prepared into multiple formulations for different administration routines. As a proof-of-concept, in three independent animal models with various organ fibrosis (lung fibrosis, liver fibrosis, and heart fibrosis), FNPs effectively reduce the accumulation of myofibroblasts, and the formation of fibrotic tissue, concomitantly restoring organ function and indicating that FNPs are a potential broad-spectrum therapy for fibrosis management.

Lung Fibrosis and Fibrosis in the Lungs: Is It All about Myofibroblasts?

In the lungs, fibrosis is a growing clinical problem that results in shortness of breath and can end up in respiratory failure. Even though the main fibrotic disease affecting the lung is idiopathic pulmonary fibrosis (IPF), which affects the interstitial space, there are many fibrotic events that have high and dangerous consequences for the lungs. Asthma, chronic obstructive pulmonary disease (COPD), excessive allergies, clearance of infection or COVID-19, all are frequent diseases that show lung fibrosis. In this review, we describe the different kinds of fibrosis and analyse the main types of cells involved-myofibroblasts and other cells, like macrophages-and review the main fibrotic mechanisms. Finally, we analyse present treatments for fibrosis in the lungs and highlight potential targets for anti-fibrotic therapies.

Ongoing Clinical Trials in Aging-Related Tissue Fibrosis and New Findings Related to AhR Pathways

Fibrosis is a pathological manifestation of wound healing that replaces dead/damaged tissue with collagen-rich scar tissue to maintain homeostasis, and complications from fibrosis contribute to nearly half of all deaths in the industrialized world. Ageing is closely associated with a progressive decline in organ function, and the prevalence of tissue fibrosis dramatically increases with age. Despite the heavy clinical and economic burden of organ fibrosis as the population ages, to date, there is a paucity of therapeutic strategies that are specifically designed to slow fibrosis. Aryl hydrocarbon receptor (AhR) is an environment-sensing transcription factor that exacerbates aging phenotypes in different tissues that has been brought back into the spotlight again with economic development since AhR could interact with persistent organic pollutants derived from incomplete waste combustion. In addition, gut microbiota dysbiosis plays a pivotal role in the pathogenesis of numerous diseases, and microbiota-associated tryptophan metabolites are dedicated contributors to fibrogenesis by acting as AhR ligands. Therefore, a better understanding of the effects of tryptophan metabolites on fibrosis modulation through AhR may facilitate the exploitation of new therapeutic avenues for patients with organ fibrosis. In this review, we primarily focus on how tryptophan-derived metabolites are involved in renal fibrosis, idiopathic pulmonary fibrosis, hepatic fibrosis and cardiac fibrosis. Moreover, a series of ongoing clinical trials are highlighted.

The role of precision medicine in interstitial lung disease

The management of interstitial lung disease (ILD) may benefit from a conceptual shift. Increased understanding of this complex and heterogeneous group of disorders over the past 20 years has highlighted the need for individualised treatment strategies that encompass diagnostic classification and disease behaviour. Biomarker-based approaches to precision medicine hold the greatest promise. Robust, large-scale biomarker-based technologies supporting ILD diagnosis have been developed, and future applications relating to staging, prognosis and assessment of treatment response are emerging. Artificial intelligence may redefine our ability to base prognostic evaluation on both diagnosis and underlying disease processes, sharpening individualised treatment algorithms to a level not previously achieved. Compared with therapeutic areas such as oncology, precision medicine in ILD is still in its infancy. However, the heterogeneous nature of ILD suggests that many relevant molecular, environmental and behavioural targets may serve as useful biomarkers if we are willing to invest in their identification and validation.

Phenotypic drug screening in a human fibrosis model identified a novel class of antifibrotic therapeutics

Fibrogenic processes instigate fatal chronic diseases leading to organ failure and death. Underlying biological processes involve induced massive deposition of extracellular matrix (ECM) by aberrant fibroblasts. We subjected diseased primary human lung fibroblasts to an advanced three-dimensional phenotypic high-content assay and screened a repurposing drug library of small molecules for inhibiting ECM deposition. Fibrotic Pattern Detection by Artificial Intelligence identified tranilast as an effective inhibitor. Structure-activity relationship studies confirmed N-(2-butoxyphenyl)-3-(phenyl)acrylamides (N23Ps) as a novel and highly potent compound class. N23Ps suppressed myofibroblast transdifferentiation, ECM deposition, cellular contractility, and altered cell shapes, thus advocating a unique mode of action. Mechanistically, transcriptomics identified SMURF2 as a potential therapeutic target network. Antifibrotic activity of N23Ps was verified by proteomics in a human ex vivo tissue fibrosis disease model, suppressing profibrotic markers SERPINE1 and CXCL8. Conclusively, N23Ps are a novel class of highly potent compounds inhibiting organ fibrosis in patients.

Development of Neutralizing Multimeric Nanobody Constructs Directed against IL-13: From Immunization to Lead Optimization

IL-13 is a pleiotropic cytokine mainly secreted by Th2 cells. It reacts with many different types of cells involved in allergy, inflammation, and fibrosis, e.g., mastocytes, B cells, and fibroblasts. The role of IL-13 in conditions involving one or several of these phenotypes has therefore been extensively investigated. The inhibition of this cytokine in animal models for various pathologies yielded highly promising results. However, most human trials relying on anti-IL-13 conventional mAbs have failed to achieve a significant improvement of the envisaged disorders. Where some studies might have suffered from several weaknesses, the strategies themselves, such as targeting only IL-13 using conventional mAbs or employing a systemic administration, could be questioned. Nanobodies are recombinant Ag-binding fragments derived from the variable part of H chain-only Abs occurring in Camelidae. Thanks to their single-domain structure, small size (≈15 kDa), good stability, and solubility, they can be engineered into multispecific constructs for combined therapies or for use in new strategies such as formulations for local administration, e.g., pulmonary administration. In this study, we describe the generation of 38 nanobodies that can be subdivided into five CDR3 families. Nine nanobodies were found to have a good affinity profile (K_D = 1-200 nM), but none were able to strongly inhibit IL-13 biological activity in vitro (IC₅₀ > 50 µM: HEK-Blue IL-13/IL-4 cells). Multimeric constructs were therefore designed from these inhibitors and resulted in an up to 36-fold improvement in affinity and up to 300-fold enhancement of the biological activity while conserving a high specificity toward IL-13.

Idiopathic Interstitial Pneumonias: A Review of the Past and Emerging Therapies

PURPOSE

This article is an in-depth review of the complex classification, diagnosis, and treatment of idiopathic interstitial pneumonias (IIP), as well as emergence of new treatment options.

SUMMARY

Idiopathic interstitial pneumonias consist of various subgroup classifications that require expert analysis of imaging and histology to accurately diagnose this broad group of patients. Timely and accurate assessment of these patients is key in developing an appropriate pharmacological plan. The pathophysiology of IIP is not well understood but has been linked to an immune response resulting in inflammation, fibrosis, or proliferation of lung tissue which reduces lung function. Lung transplantation is currently the only curative option for treatment, but many new antiproliferative and immunosuppressive agents are being used to effectively slow the progression of lung dysfunction.

CONCLUSION

An often mixed radiological and histological pattern along with the invasive nature of biopsy for gold standard diagnosis create a challenge for the accurate identification of IIP. Further understanding of these idiopathic interstitial pneumonias will pave the way forward to the emergence of new treatment options and updates to standards of care.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

Interpreting Immunoregulation in Lung Fibrosis: A New Branch of the Immune Model

Immunostimulation is recognized as an important contribution in lung fibrosis in some animal models and patient subsets. With this review, we illustrate an additional scenario covering the possible implication of immunoregulation during fibrogenesis. Available animal and human data indicate that pulmonary fibrosis also includes diverse and discrete immunoregulating populations comprising regulatory lymphocytes (T and B regs) and myeloid cells (immunosuppressive macrophages and myeloid-derived suppressive cells; MDSC). They are initially recruited to limit the establishment of deleterious inflammation but participate in the development of lung fibrosis by producing immunoregulatory mediators (mainly TGF-β1 and IL-10) that directly or indirectly stimulate fibroblasts and matrix protein deposition. The existence of this silent immunoregulatory environment sustains an alternative mechanism of fibrosis that explains why in some conditions neither pro-inflammatory cytokine deficiency nor steroid and immunosuppressive therapies limit lung fibrosis. Therefore, the persistent presence of immunoregulation is an important parameter to consider for refining therapeutical strategies in lung fibrotic disorders under non-immunostimulatory conditions.

Post-transcriptional regulation of immunological responses by Regnase-1-related RNases

Regulation of messenger RNA (mRNA) decay plays a crucial role in the control of gene expression. Canonical mRNA decay pathways are initiated by deadenylation and decapping, and are followed by exonucleolytic degradation. However, recent studies revealed that endoribonucleolytic cleavage also mediates mRNA decay, and both exoribonucleolytic and endoribonucleolytic decay pathways are important for the regulation of immune responses. Regnase-1 functions as an endoribonuclease to control immunity by damping mRNAs. Particularly, Regnase-1 controls cytokines and other inflammatory mediators by recognizing their mRNAs via stem-loop structures present in the 3' untranslated regions. Regnase-1 was found to be critical for human inflammatory diseases such as ulcerative colitis and idiopathic pulmonary fibrosis. Furthermore, a set of Regnase-1-related RNases contribute to immune regulation as well as antiviral host defense. In this review, we provide an overview of recent findings as to immune-related RNA-binding proteins (RBPs) with an emphasis on stem-loop-mediated mRNA decay via Regnase-1 and related RNases and discuss how the function of these RBPs is regulated and contributes to inflammatory disorders.

Pathological Roles and Clinical Usefulness of Periostin in Type 2 Inflammation and Pulmonary Fibrosis

Periostin is known to be a useful biomarker for various diseases. In this article, we focus on allergic diseases and pulmonary fibrosis, for which we and others are now developing detection systems for periostin as a biomarker. Biomarker-based precision medicine in the management of type 2 inflammation and fibrotic diseases since heterogeneity is of utmost importance. Periostin expression is induced by type 2 cytokines (interleukin-4/-13) or transforming growth factor-β, and plays a vital role in the pathogenesis of allergic inflammation or interstitial lung disease, respectively, andits serum levels are correlated disease severity, prognosis and responsiveness to the treatment. We first summarise the importance of type 2 biomarker and then describe the pathological role of periostin in the development and progression of type 2 allergic inflammation and pulmonary fibrosis. In addition, then, we summarise the recent development of assay methods for periostin detection, and analyse the diseases in which periostin concentration is elevated in serum and local biological fluids and its usefulness as a biomarker. Furthermore, we describe recent findings of periostin as a biomarker in the use of biologics or anti-fibrotic therapy. Finally, we describe the factors that influence the change in periostin concentration under the healthy conditions.

The perplexing role of RAGE in pulmonary fibrosis: causality or casualty?

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease in which most patients die within 3 years of diagnosis. With an unknown etiology, IPF results in progressive fibrosis of the lung parenchyma, diminishing normal lung function, which results in respiratory failure, and eventually, death. While few therapies are available to reduce disease progression, patients continue to advance toward respiratory failure, leaving lung transplantation the only viable option for survival. As incidence and mortality rates steadily increase, the need for novel therapeutics is imperative. The receptor for advanced glycation endproducts (RAGE) is most highly expressed in the lungs and plays a significant role in a number of chronic lung diseases. RAGE has long been linked to IPF; however, confounding data from both human and experimental studies have left an incomplete and perplexing story. This review examines the present understanding of the role of RAGE in human and experimental models of IPF, drawing parallels to recent advances in RAGE biology. Moreover, this review discusses the role of RAGE in lung injury response, type 2 immunity, and cellular senescence, and how such mechanisms may relate to RAGE as both a biomarker of disease progression and potential therapeutic target in IPF.The reviews of this paper are available via the supplemental material section.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

Idiopathic pulmonary fibrosis and systemic sclerosis: pathogenic mechanisms and therapeutic interventions

Fibrotic diseases take a very heavy toll in terms of morbidity and mortality equal to or even greater than that caused by metastatic cancer. In this review, we examine the pathogenesis of fibrotic diseases, mainly addressing triggers for induction, processes that lead to progression, therapies and therapeutic trials. For the most part, we have focused on two fibrotic diseases with lung involvement, idiopathic pulmonary fibrosis, in which the contribution of inflammatory mechanisms may be secondary to non-immune triggers, and systemic sclerosis in which the contribution of adaptive immunity may be predominant.

Emerging drugs for the treatment of idiopathic pulmonary fibrosis: 2020 phase II clinical trials

INTRODUCTION

The enthusiasm generated by the approval of pirfenidone and nintedanib as the first effective therapies for IPF led the IPF scientific community to investigate an increasing number of novel agents in well-designed randomized controlled trials, in the hope to find a cure for these patients.

AREAS COVERED

This reviews the evidence from IPF phase II trials that were completed or started in 2020. Literature search was performed using Medline and Clinicaltrials.org databases.

EXPERT OPINION

Randomized clinical trials revolutionized the management of IPF, leading to the discovery of the first therapies capable of slowing down functional deterioration in these patients. The recently published findings of the first successful phase II trials since pirfenidone and nintedanib will hopefully inaugurate a new era in the therapeutic scenario of IPF, where consolidated treatments of proven efficacy and novel targeted agents contribute together to reach the final goal of halting the fibrotic process of this dreadful disease.

The Epithelial-Immune Crosstalk in Pulmonary Fibrosis

Interactions between the lung epithelium and the immune system involve a tight regulation to prevent inappropriate reactions and have been connected to several pulmonary diseases. Although the distal lung epithelium and local immunity have been implicated in the pathogenesis and disease course of idiopathic pulmonary fibrosis (IPF), consequences of their abnormal interplay remain less well known. Recent data suggests a two-way process, as illustrated by the influence of epithelial-derived periplakin on the immune landscape or the effect of macrophage-derived IL-17B on epithelial cells. Additionally, damage associated molecular patterns (DAMPs), released by damaged or dying (epithelial) cells, are augmented in IPF. Next to “sterile inflammation”, pathogen-associated molecular patterns (PAMPs) are increased in IPF and have been linked with lung fibrosis, while outer membrane vesicles from bacteria are able to influence epithelial-macrophage crosstalk. Finally, the advent of high-throughput technologies such as microbiome-sequencing has allowed for the identification of a disease-specific microbial environment. In this review, we propose to discuss how the interplays between the altered distal airway and alveolar epithelium, the lung microbiome and immune cells may shape a pro-fibrotic environment. More specifically, it will highlight DAMPs-PAMPs pathways and the specificities of the IPF lung microbiome while discussing recent elements suggesting abnormal mucosal immunity in pulmonary fibrosis.

Regulatory Immune Cells in Idiopathic Pulmonary Fibrosis: Friends or Foes?

The immune system is receiving increasing attention for interstitial lung diseases, as knowledge on its role in fibrosis development and response to therapies is expanding. Uncontrolled immune responses and unbalanced injury-inflammation-repair processes drive the initiation and progression of idiopathic pulmonary fibrosis. The regulatory immune system plays important roles in controlling pathogenic immune responses, regulating inflammation and modulating the transition of inflammation to fibrosis. This review aims to summarize and critically discuss the current knowledge on the potential role of regulatory immune cells, including mesenchymal stromal/stem cells, regulatory T cells, regulatory B cells, macrophages, dendritic cells and myeloid-derived suppressor cells in idiopathic pulmonary fibrosis. Furthermore, we review the emerging role of regulatory immune cells in anti-fibrotic therapy and lung transplantation. A comprehensive understanding of immune regulation could pave the way towards new therapeutic or preventive approaches in idiopathic pulmonary fibrosis.

Therapeutic targets in lung tissue remodelling and fibrosis

Structural changes involving tissue remodelling and fibrosis are major features of many pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Abnormal deposition of extracellular matrix (ECM) proteins is a key factor in the development of tissue remodelling that results in symptoms and impaired lung function in these diseases. Tissue remodelling in the lungs is complex and differs between compartments. Some pathways are common but tissue remodelling around the airways and in the parenchyma have different morphologies. Hence it is critical to evaluate both common fibrotic pathways and those that are specific to different compartments; thereby expanding the understanding of the pathogenesis of fibrosis and remodelling in the airways and parenchyma in asthma, COPD and IPF with a view to developing therapeutic strategies for each. Here we review the current understanding of remodelling features and underlying mechanisms in these major respiratory diseases. The differences and similarities of remodelling are used to highlight potential common therapeutic targets and strategies. One central pathway in remodelling processes involves transforming growth factor (TGF)-β induced fibroblast activation and myofibroblast differentiation that increases ECM production. The current treatments and clinical trials targeting remodelling are described, as well as potential future directions. These endeavours are indicative of the renewed effort and optimism for drug discovery targeting tissue remodelling and fibrosis.

Role of interleukins in the pathogenesis of pulmonary fibrosis

Interleukins, a group of cytokines participating in inflammation and immune response, are proved to be involved in the formation and development of pulmonary fibrosis. In this article, we reviewed the relationship between interleukins and pulmonary fibrosis from the clinical, animal, as well as cellular levels, and discussed the underlying mechanisms in vivo and in vitro. Despite the effects of interleukin-targeted treatment on experimental pulmonary fibrosis, clinical applications are lacking and unsatisfactory. We conclude that intervening in one type of interleukins with similar functions in IPF may not be enough to stop the development of fibrosis as it involves a complex network of regulation mechanisms. Intervening interleukins combined with other existing therapy or targeting interleukins affecting multiple cells/with different functions at the same time may be one of the future directions. Furthermore, the intervention time is critical as some interleukins play different roles at different stages. Further elucidation on these aspects would provide new perspectives on both the pathogenesis mechanism, as well as the therapeutic strategy and drug development.

Phase 2 trial to assess lebrikizumab in patients with idiopathic pulmonary fibrosis

This phase 2, randomised, double-blind, placebo-controlled trial evaluated the efficacy and safety of lebrikizumab, an interleukin (IL)-13 monoclonal antibody, alone or with background pirfenidone therapy, in patients with idiopathic pulmonary fibrosis (IPF).

Patients with IPF aged ≥40 years with forced vital capacity (FVC) of 40%–100% predicted and diffusing capacity for carbon monoxide of 25%–90% predicted and who were treatment-naïve (cohort A) or receiving pirfenidone (2403 mg·day⁻¹; cohort B) were randomised 1:1 to receive lebrikizumab 250 mg or placebo subcutaneously every 4 weeks. The primary endpoint was annualised rate of FVC % predicted decline over 52 weeks.

In cohort A, 154 patients were randomised to receive lebrikizumab (n=78) or placebo (n=76). In cohort B, 351 patients receiving pirfenidone were randomised to receive lebrikizumab (n=174) or placebo (n=177). Baseline demographics were balanced across treatment arms in both cohorts. The primary endpoint (annualised rate of FVC % predicted decline) was not met in cohort A (lebrikizumab versus placebo, −5.2% versus −6.2%; p=0.456) or cohort B (lebrikizumab versus placebo, −5.5% versus −6.0%; p=0.557). In cohort B, a non-statistically significant imbalance in mortality favouring combination therapy was observed (hazard ratio 0.42 (95% CI 0.17–1.04)). Pharmacodynamic biomarkers indicated lebrikizumab activity. The safety profile was consistent with that in previous studies of lebrikizumab and pirfenidone as monotherapies.

Lebrikizumab alone or with pirfenidone was not associated with reduced FVC % predicted decline over 52 weeks despite evidence of pharmacodynamic activity. Lebrikizumab was well tolerated with a favourable safety profile. These findings suggest that blocking IL-13 may not be sufficient to achieve a lung function benefit in patients with IPF.

This phase 2 RCT found no benefit in FVC decline over 52 weeks in IPF patients for lebrikizumab versus placebo as monotherapy (n=78 versus 76) or in combination with pirfenidone (n=174 versus 177); pirfenidone therapy was consistent with previous resultshttps://bit.ly/313NVR8

Immune dysregulation as a driver of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) affects hundreds of thousands of people worldwide, reducing their quality of life and leading to death from respiratory failure within years of diagnosis. Treatment options remain limited, with only two FDA-approved drugs available in the United States, neither of which reverse the lung damage caused by the disease or prolong the life of individuals with IPF. The only cure for IPF is lung transplantation. In this review, we discuss recent major advances in our understanding of the role of the immune system in IPF that have revealed immune dysregulation as a critical driver of disease pathophysiology. We also highlight ways in which an improved understanding of the immune system's role in IPF may enable the development of targeted immunomodulatory therapies that successfully halt or potentially even reverse lung fibrosis.

Inhibition of IL-13: A New Pathway for Atopic Dermatitis [Formula: see text]

Dupilumab, a monoclonal antibody against the common receptor of interleukin (IL)-4 and IL-13, was the first biologic therapy approved in Canada for treatment of moderate-to-severe atopic dermatitis (AD). While it is considered safe and effective, dupilumab is not universally effective and 8%-38% of patients develop conjunctivitis, while some patients develop head and neck dermatitis. Thus, new therapeutic options are warranted. While both IL-4 and IL-13 play important roles in the pathogenesis of AD, it has been recently demonstrated that IL-13 is the primary upregulated cytokine in AD skin biopsy samples. A placebo-controlled phase 2b clinical trial evaluating the efficacy and safety of lebrikizumab, an IL-13 inhibitor, in AD demonstrated that, at 16 weeks, Eczema Area and Severity Index (EASI) 75 and Investigator's Global Assessment (IGA) 0/1 were achieved by 60.6% and 44.6% of patients taking lebrikizumab at its highest dose (vs 24.3% and 15.3% of patients taking placebo, respectively). Moreover, treatment with lebrikizumab was associated with rapid improvement of pruritus and low rates of conjunctivitis (1.4%-3.8%). Another IL-13 monoclonal antibody, tralokinumab, was evaluated for safety and efficacy in moderate-to-severe AD. By week 12, among adults receiving 300 mg tralokinumab, 42.5% achieved EASI-75 and 26.7% achieved IGA 0/1 score (vs 15.5% and 11.8% in the placebo group, respectively). Both lebrikizumab and tralokinumab demonstrated acceptable safety profiles in AD (and non-AD) trials with adverse events often being comparable between treatment and control groups. Thus, IL-13 inhibitors may provide a safe and effective treatment alternative for patients with moderate-to-severe AD.

Interleukin-11 signaling underlies fibrosis, parenchymal dysfunction, and chronic inflammation of the airway

Interleukin (IL)-11 evolved as part of the innate immune response. In the human lung, IL-11 upregulation has been associated with viral infections and a range of fibroinflammatory diseases, including idiopathic pulmonary fibrosis. Transforming growth factor-beta (TGFβ) and other disease factors can initiate an autocrine loop of IL-11 signaling in pulmonary fibroblasts, which, in a largely ERK-dependent manner, triggers the translation of profibrotic proteins. Lung epithelial cells also express the IL-11 receptor and transition into a mesenchymal-like state in response to IL-11 exposure. In mice, therapeutic targeting of IL-11 with antibodies can arrest and reverse bleomycin-induced pulmonary fibrosis and inflammation. Intriguingly, fibroblast-specific blockade of IL-11 signaling has anti-inflammatory effects, which suggests that lung inflammation is sustained, in part, through IL-11 activity in the stroma. Proinflammatory fibroblasts and their interaction with the damaged epithelium may represent an important but overlooked driver of lung disease. Initially thought of as a protective cytokine, IL-11 is now increasingly recognized as an important determinant of lung fibrosis, inflammation, and epithelial dysfunction.

The Therapy of Pulmonary Fibrosis in Paracoccidioidomycosis: What Are the New Experimental Approaches?

Pulmonary fibrosis (PF) is considered the most important sequela developed in patients suffering from the chronic form of paracoccidioidomycosis (PCM), which leads to the loss of respiratory function in 50% of cases; this residual pulmonary abnormality is present even after antifungal treatment. To date, there is no effective treatment for PF. However, the use of antifungal drugs in combination with other antibiotics or immunomodulatory compounds, as well as biological therapies that include a monoclonal antibody specific to neutrophils, or prophylactic vaccination employing a recombinant antigen of Paracoccidioides brasiliensis that successfully attenuated PF, has been reported. Additionally, mesenchymal stem cell transplantation in combination with antifungal therapy slightly reduced the inflammatory response and profibrotic molecules induced by P. brasiliensis infection. In this review, I report experimental findings from several studies aiming to identify promising therapeutic strategies for treating PF developed in PCM.

Fibroblast-specific IL11 signaling drives chronic inflammation in murine fibrotic lung disease

Repetitive pulmonary injury causes fibrosis and inflammation that underlies chronic lung diseases such as idiopathic pulmonary fibrosis (IPF). Interleukin 11 (IL11) is important for pulmonary fibroblast activation but the contribution of fibroblast-specific IL11 activity to lung fibro-inflammation is not known. To address this gap in knowledge, we generated mice with loxP-flanked Il11ra1 and deleted the IL11 receptor in adult fibroblasts (CKO mice). In the bleomycin (BLM) model of lung fibrosis, CKO mice had reduced fibrosis, lesser fibroblast ERK activation, and diminished immune cell STAT3 phosphorylation. Following BLM injury, acute inflammation in CKO mice was similar to controls but chronic immune infiltrates and pro-inflammatory gene activation, including NF-kB phosphorylation, were notably reduced. Therapeutic prevention of IL11 activity with neutralizing antibodies mirrored the effects of genetic deletion of Il11ra1 in fibroblasts. These data reveal a new function for IL11 in pro-inflammatory lung fibroblasts and highlight the important contribution of the stroma to inflammation in pulmonary disease.