Healthcare utilisation and costs in the diagnosis and treatment of progressive-fibrosing interstitial lung diseases

Health care costs and utilization of progressive fibrosing lung disease by underlying interstitial lung disease type

BACKGROUND

Fibrosing interstitial lung disease (ILD) encompasses more than 200 diverse pulmonary disorders, of which up to 40% become progressive. The 4 underlying ILD types most likely to result in progression are unclassified ILD/idiopathic interstitial pneumonia (IIP), autoimmune ILDs, exposure-related ILD/hypersensitivity pneumonitis, and sarcoidosis.

OBJECTIVE

To compare health care resource utilization (HCRU) and costs among patients with fibrosing ILD that has progressed ("progressive" fibrosing cohort) vs patients whose fibrosis did not meet criteria set for progression ("not yet progressed" cohort).

METHODS

This was a noninterventional study of commercial enrollees and Medicare Advantage with Part D beneficiaries, which used administrative claims data for the period from October 1, 2015, through May 31, 2021. Adult patients (aged ≥18 years) with fibrosing ILD and 12 months of continuous health plan enrollment were included. Patients with idiopathic pulmonary fibrosis, baseline ILD diagnoses, or missing demographic data were excluded. Patients were first classified according to the underlying type of fibrosing ILD. For statistical analyses of outcomes, 2 cohorts were compared within each subtype: progressive fibrosing ILD vs not yet progressed ILD. The final study population included propensity score-matched (PSM) patients (1:1) based on pre-ILD baseline demographic and clinical characteristics. HCRU categories included inpatient hospitalization counts and the number of inpatient days and total costs (in 2021 US dollars), analyzed descriptively and weighted by the per-patient-per-month cost. Lin's regression was used to predict 12-month total cost estimates for comparison by cohort.

RESULTS

The distribution by underlying conditions was as follows: autoimmune ILD (n = 4,156), HP (n = 8,181), sarcoidosis (n = 775), and unclassified ILD/IIP (n = 18,635). After PSM, pre-ILD baseline variables were generally well balanced between the progressive and not yet progressed fibrosing ILD cohorts. For all underlying subtypes of ILD, patients in the progressive cohort had significantly more utilization and higher costs compared with patients in the not yet progressed cohort. Progressive cohorts had significantly higher adjusted rates of inpatient days among patients with at least 1 inpatient stay compared with the not yet progressed cohorts (all P < 0.01). In addition, the progressive cohorts had significantly higher adjusted 12-month total costs, with the differences ranging from $24,493 to $55,072 (all comparisons P < 0.001).

CONCLUSIONS

Irrespective of underlying ILD type, patients with progressive fibrosing ILD had significantly increased HCRU and cost relative to those whose fibrosing ILD had not yet progressed.

Burden of illness in progressive fibrosing interstitial lung disease

BACKGROUND: Progressive fibrosing interstitial lung disease (ILD) is a relatively new clinical concept describing a variety of ILDs characterized by progressive pulmonary fibrosis with associated lung function decline and worsening chest imaging. Little is known about health care resource utilization (HCRU) and costs associated with progressive fibrosing ILDs other than idiopathic pulmonary fibrosis (IPF). This study analyzed the adjusted HCRU and cost burden among patients with incident non-IPF progressive fibrosing ILD vs matched patients with incident fibrosing ILD that had not yet progressed. METHODS: This was a retrospective study of insured US adults newly diagnosed with non-IPF fibrosing ILD from October 2016 to June 2019, conducted using administrative claims data from the Optum Research Database. Progressive disease was identified using claims-based proxies comprising health care utilization associated with management of progressive fibrosing ILD. Patients in the progressive population were 1:1 propensity score matched to not-yet-progressed patients on the basis of baseline demographic and clinical characteristics. All-cause HCRU and health care costs were presented as weighted per-patient-per-month (PPPM) measures to account for variable follow-up. Differences in study outcomes between matched cohorts were evaluated using Z-tests for continuous measures and Rao-Scott tests for binary measures. RESULTS: The postmatch cohorts comprised 11,025 patients with evidence of progression matched to 11,025 patients with not-yet-progressed fibrosing ILD. Mean (SD) weighted PPPM counts of follow-up health care encounters were significantly higher for the progressive vs not-yet-progressed cohort: ambulatory visits, 4.2 (3.6) vs 3.1 (3.3); emergency department visits, 0.3 (0.5) vs 0.1 (0.3); and inpatient (IP) stays, 0.1 (0.2) vs 0.0 (0.1) (P < 0.001 for all). Among patients with an IP stay, those with progressive disease had more inpatient days than those with not-yet-progressed disease (mean [SD] 1.6 [2.4] days vs 1.0 [1.3] days, P < 0.001). Mean weighted PPPM (SD) all-cause health care costs were also significantly higher for progressive vs not-yet-progressed patients, including total costs ($4,382 [$9,597] vs $2,243 [$4,162], P < 0.001), medical costs ($3,662 [$9,150] vs $1,627 [$3,524], P < 0.001), and pharmacy costs ($720 [$2,097] vs $616 [$2,070], P = 0.002). The difference in medical costs between cohorts was driven primarily by higher inpatient costs for progressive vs not-yet-progressed patients ($1,729 [$7,557] vs $523 [$2,118], P < 0.001). CONCLUSIONS: Progressive fibrosing ILD carries a substantial economic and health care burden. Among patients with incident non-IPF fibrosing ILD, all-cause HCRU and costs were significantly higher for those with a progressive phenotype than for matched patients whose disease had not yet progressed. The cost differential was driven primarily by hospitalizations, which were longer and more frequent for the progressive cohort. Disclosures: This work was funded by Boehringer Ingelheim Pharmaceuticals, Inc. Drs Conoscenti and Shetty are employees of Boehringer Ingelheim (BI). Dr Singer was an employee of BI at the time the study was conducted. Dr Brown was a paid consultant for BI for this study. Dr Bengtson, Ms Anderson, and Dr Brekke are employees of Optum, which was contracted by BI to conduct the study. Medical writing assistance was provided by Yvette Edmonds, PhD (Optum), and was contracted and funded by Boehringer Ingelheim Pharmaceuticals, Inc.

Prognostic Predictive Characteristics in Patients With Fibrosing Interstitial Lung Disease: A Retrospective Cohort Study

Background: Limited data are available regarding the entire spectrum of interstitial lung disease with a progressive fibrosing feature. We investigated the prevalence and prognostic predictive characteristics in patients with PF-ILD.

Methods: This retrospective cohort study included patients with fibrosing ILD who were investigated between 1 January 2015 and 30 April 2021. We recorded clinical features and outcomes to identify the possible risk factors for fibrosing progression as well as mortality.

Results: Of the 579 patients with fibrosing ILD, 227 (39.21%) met the criteria for progression. Clubbing of fingers [odds ratio (OR) 1.52, 95% confidence interval (CI) 1.03 to 2.24, p = 0.035] and a high-resolution computed tomography (HRCT)-documented usual interstitial pneumonia (UIP)-like fibrotic pattern (OR 1.95, 95% CI 1.33 to 2.86, p = 0.001) were risk factors for fibrosis progression. The mortality was worse in patients with PF with hypoxemia [hazard ratio (HR) 2.08, 95% CI 1.31 to 3.32, p = 0.002], in those with baseline diffusion capacity of the lung for carbon monoxide (DLCO) % predicted &lt;50% (HR 2.25, 95% CI 1.45 to 3.50, p &lt; 0.001), or in those with UIP-like fibrotic pattern (HR 1.68, 95% CI 1.04 to 2.71, p &lt; 0.001).

Conclusion: Clubbing of fingers and an HRCT-documented UIP-like fibrotic pattern were more likely to be associated with progressive fibrosing with varied prevalence based on the specific diagnosis. Among patients with progressive fibrosing, those with hypoxemia, lower baseline DLCO% predicted, or UIP-like fibrotic pattern showed poor mortality.

C/EBP homologous protein promotes Sonic Hedgehog secretion from type II alveolar epithelial cells and activates Hedgehog signaling pathway of fibroblast in pulmonary fibrosis

Background

Endoplasmic reticulum (ER) stress is involved in the pathological process of pulmonary fibrosis, including IPF. It affects a broad scope of cellular types during pulmonary fibrosis but the role in epithelial-mesenchymal crosstalk has not been fully defined. The present study aimed to investigate the effects of Shh secretion by ER  stress-challenged type II alveolar epithelial cells (AECII) on fibroblast and pulmonary fibrosis.

Methods

Conditioned medium (CM) from tunicamycin (TM)-treated AECII was collected and incubated with fibroblast. Short hairpin RNA (shRNA) was used for RNA interference of C/EBP homologous protein (CHOP). The effects of CHOP and HH signaling were evaluated by TM administration under the background of bleomycin-induced pulmonary fibrosis in mice.

Results

Both expression of CHOP and Shh in AECII, and HH signaling in mesenchyme were upregulated in IPF lung. TM-induced Shh secretion from AECII activates HH signaling and promotes pro-fibrotic effects of fibroblast. Interfering CHOP expression reduced ER stress-induced Shh secretion and alleviated pulmonary fibrosis in mice.

Conclusions

Our work identified a novel mechanism by which ER stress is involved in pulmonary fibrosis. Inhibition of ER stress or CHOP in epithelial cells alleviated pulmonary fibrosis by suppressing Shh/HH signaling pathway of fibroblasts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02012-x.

Healthcare Resource Utilization and Related Costs in Chronic Fibrosing Interstitial Lung Diseases with a Progressive Phenotype: A US Claims Database Analysis

INTRODUCTION

We aimed to describe healthcare resource utilization (HCRU) patterns and costs in patients with fibrosing interstitial lung disease (ILD) and those with a progressive phenotype of fibrosing ILD in a US claims database.

METHODS

Data from the IBM^® MarketScan^® databases (1 October 2011-30 September 2015) were used. Diagnosis codes documented on medical claims on two occasions (without any claims during the 12 months prior) identified patients with incident fibrosing ILD. Patients with chronic fibrosing ILD with a progressive phenotype were identified by proxies for progression. Patients aged ≥ 18 years with 365 days of continuous coverage before the index date were eligible for inclusion. Data were analyzed for 12 months prior to identification of fibrosing ILD/progressive phenotype (baseline) and 12 months after (follow-up). Outcomes included treatment patterns, outpatient and inpatient claims, and costs.

RESULTS

We identified 23,577 patients with incident fibrosing ILD and 14,722 with the progressive phenotype. Follow-up data were available for 9986 and 5840 patients, respectively. The most frequent ILD-related medications during baseline were corticosteroids (49.4% and 56.6%). Mean (± standard deviation [SD]) annualized number of outpatient claims was 30.0 (± 26.4) and 34.1 (± 27.7) in the baseline period and 36.2 (± 28.6) and 41.9 (± 30.2) in the follow-up in fibrosing ILD and with a progressive phenotype, respectively. Mean (SD) number of all-cause hospitalizations was 0.5 (± 1.1) and 0.7 (± 1.2) during baseline and 0.6 (± 1.1) and 0.7 (± 1.2) during follow-up. Mean (SD) total costs were $40,907 (± 92,496) and $49,561 (± 98,647) during baseline and $46,157 (± 102,858) and $54,215 (± 116,833) during follow-up. Inpatient mortality during follow-up was 53.50 and 77.44 per 1000 patient-years.

CONCLUSION

HCRU and costs were high in patients with chronic fibrosing ILD with a progressive phenotype, likely reflecting the disease severity and the need for close monitoring and acute care. Outpatient claims accounted for a substantial proportion of the total costs.

Claims-based Prevalence of Disease Progression among Patients with Non-IPF Fibrosing Interstitial Lung Disease in the US

Rationale

Chronic fibrosing interstitial lung disease (ILD) with a progressive phenotype is a clinical concept describing the broad group of ILDs characterized by progressive pulmonary fibrosis. The prevalence of progressive fibrotic ILDs other than idiopathic pulmonary fibrosis (IPF) is not well understood.

Objectives

We used a novel algorithm to estimate the prevalence range of disease progression among patients with non-IPF fibrotic ILD in a U.S. claims database.

Methods

This was a retrospective study including adults with commercial or Medicare Advantage with Part D (MAPD) insurance using administrative claims data from October 2015 to September 2019. Patients likely to have non-IPF fibrosing ILD with a progressive phenotype were identified via an algorithm that incorporated ILD-related diagnosis codes (excluding IPF) and claims-based proxies for fibrotic ILD progression, including pulmonary function tests, chest imaging, oral corticosteroid (OCS) medications, immunosuppressive medications, lung transplant, oxygen therapy, palliative care, and respiratory hospitalization. The prevalence range of non-IPF fibrotic ILD with progressive disease behavior was calculated using strict and lenient case definitions to account for potential imprecision in the progression proxies.

Results

Of nearly 9 million study-eligible patients, 17,136 were identified with non-IPF fibrosing ILD. The prevalence of disease progression per 10,000 (95% confidence interval) ranged from 12.14 (11.74–12.54) to 29.05 (28.43–29.67) over a mean observation time of 1.44 years for MAPD enrollees (n = 14,686), and from 0.89 (0.81–0.97) to 2.36 (2.24–2.48) over a mean observation time of 1.29 years for commercial enrollees (n = 2,450). Prevalence estimates increased with age for both insurance types. Among patients with progression, 4,097 met at least two progression proxies not considering OCS (strict case definition) and 9,946 met at least one progression proxy (lenient case definition). The mean (standard deviation) number of proxies met was 2.1 (1.3), and the most common individual proxies met (alone or in combination with other proxies) were OCS use (48.9%), respiratory hospitalization (44.2%), and oxygen therapy (44.1%).

Conclusions

This is among the first claims-based estimates of the prevalence of non-IPF chronic fibrosing ILD with a progressive phenotype. Our analysis indicates that this phenotype is rare in the overall population but increases substantially with increasing age.

Global and regional burden of interstitial lung disease and pulmonary sarcoidosis from 1990 to 2019: results from the Global Burden of Disease study 2019

BACKGROUND

Interstitial lung disease (ILD) and pulmonary sarcoidosis are common respiratory diseases with a heterogeneous distribution worldwide. The global burden and temporal trends of ILD and sarcoidosis are rarely explored.

METHODS

Using the classification 'ILD and pulmonary sarcoidosis' from the Global Burden of Disease 2019 dataset, we described the age-standardised rates of incidence, mortality, disability-adjusted life-years (DALYs), and their average annual percentage change from 1990 to 2019 by sex, Sociodemographic Index (SDI) and region.

RESULTS

In 2019, the global incidence and mortality of ILD and pulmonary sarcoidosis were 24.2 million and 169 833 cases, respectively. From 1990 to 2019, the global incidence, deaths and DALYs due to ILD and pulmonary sarcoidosis increased by 118.6%, 166.63% and 122.87% respectively. The global incidence of ILD and pulmonary sarcoidosis was higher in men and was mainly concentrated among persons aged 70‒79 of both sexes. Significant regional differences could be seen in the disease burden of ILD and pulmonary sarcoidosis: since 2006, high-SDI regions had higher age-standardised incidence rates but lower age-standardised death rates compared with the low-SDI regions.

CONCLUSIONS

Our study suggests the incidence, mortality and DALYs from ILD and pulmonary sarcoidosis are increasing globally. To reduce the ongoing burden of this condition, early diagnosis and treatment are vital, and more targeted and specific strategies should be established in high-burden regions. Differences in incidence and mortality across regions may reflect the influence of genetic, environmental, diagnostic, pharmacotherapeutic, and health system factors.

Care programs and their components for patients with idiopathic pulmonary fibrosis: a systematic review

BACKGROUND

The multidimensional and complex care needs of patients with idiopathic pulmonary fibrosis (IPF) call for appropriate care models. This systematic review aimed to identify care models or components thereof that have been developed for patients with IPF in the outpatient clinical care, to describe their characteristics from the perspective of chronic integrated care and to describe their outcomes.

METHODS

A systematic review was conducted using state-of-the-art methodology with searches in PubMed/Medline, Embase, CINAHL and Web Of Science. Researchers independently selected studies and collected data, which were described according to the Chronic Care Model (CCM).

RESULTS

Eighteen articles were included describing 13 new care models or components. The most commonly described CCM elements were 'delivery system design' (77%) and 'self-management support' (69%), with emphasis on team-based and multidisciplinary care provision and education. The most frequently described outcome was health-related quality of life.

CONCLUSIONS

Given the high need for integrated care and the scarcity and heterogeneity of data, developing, evaluating and implementing new models of care for patients with IPF and the comprehensive reporting of these endeavours should be a priority for research and clinical care.

Cost drivers in the pharmacological treatment of interstitial lung disease

INTRODUCTION

Treatments of interstitial lung diseases (ILDs) mainly focus on disease stabilization and relief of symptoms by managing inflammation or suppressing fibrosis by (in part costly) drugs. To highlight economic burden of drug treatment in different ILD-subtypes we assessed cost trends and therewith-associated drivers.

METHODS

Using data from the German, observational HILDA study we estimated adjusted mean medication costs over 36-month intervals using one- and two-part Generalized Estimating Equation (GEE) regression models with a gamma distribution and log link. Next, we determined factors associated with costs.

RESULTS

In Idiopathic pulmonary fibrosis (IPF) mean per capita medication costs increased from €1442 before to €11,000€ at the end of study. In non-IPF subtypes, the increase took place at much lower level. Mean per capita ILD-specific medication costs at the end of the study ranged between €487 (other ILD) and €9142 (IPF). At baseline, higher FVC %predicted values were associated with lower medication costs in IPF (-9%) and sarcoidosis (-1%). During follow up higher comorbidity burden escalated costs in progressive fibrosing ILD (PF-ILD) (+52%), sarcoidosis (+60%) and other ILDs (+24%). The effect of disease duration was not uniform, with cost savings in PF-ILD (-8%) and sarcoidosis (-6%), but increased spending in IPF (+11%).

CONCLUSION

Pharmacological management of ILD, in particular of IPF imposes a substantial economic burden on the healthcare system. Strategies to reduce comorbidity burden and early treatment may reduce the impact of ILDs on the healthcare system.

Epidemiology of Adult Pleural Disease in the United States

BACKGROUND

Comprehensive US epidemiologic data for adult pleural disease are not available.

RESEARCH QUESTION

What are the epidemiologic measures related to adult pleural disease in the United States?

STUDY DESIGN AND METHODS

Retrospective cohort study using Healthcare Utilization Project databases (2007-2016). Adults (≥ 18 years of age) with malignant pleural mesothelioma, malignant pleural effusion, nonmalignant pleural effusion, empyema, primary and secondary spontaneous pneumothorax, iatrogenic pneumothorax, and pleural TB were studied.

RESULTS

In 2016, ED treat-and-discharge (T&D) visits totaled 42,215, accounting for charges of $286.7 million. In 2016, a total of 361,270 hospitalizations occurred, resulting in national costs of $10.1 billion. A total of 64,174 readmissions contributed $1.16 billion in additional national costs. Nonmalignant pleural effusion constituted 85.5% of ED T&D visits, 63.5% of hospitalizations, and 66.3% of 30-day readmissions. Contemporary sex distribution (male to female ratio) in primary spontaneous pneumothorax (2.1:1) differs from older estimates (6.2:1). Decadal analyses of annual hospitalization rates/100,000 adult population (2007 vs 2016) showed a significant (P < .001) decrease for malignant pleural mesothelioma (1.3 vs 1.09, respectively), malignant pleural effusion (33.4 vs 31.9, respectively), iatrogenic pneumothorax (17.9 vs 13.9, respectively), and pleural TB (0.20 vs 0.09, respectively) and an increase for empyema (8.1 vs 11.1, respectively) and nonmalignant pleural effusion (78.1 vs 100.1, respectively). Empyema hospitalizations have high costs per case ($38,591) and length of stay (13.8 days). The mean proportion of readmissions attributed to a pleural cause varied widely: malignant pleural mesothelioma, 49%; malignant pleural effusion, 45%; nonmalignant pleural effusion, 31%; empyema, 27%; primary spontaneous pneumothorax, 27%; secondary spontaneous pneumothorax, 27%; and iatrogenic pneumothorax, 20%.

INTERPRETATION

Significant epidemiologic trends and changes in various pleural disease were observed. The analysis identifies multiple opportunities for improvement in management of pleural disease.

Current monitoring and treatment of progressive fibrosing interstitial lung disease: a survey of physicians in Japan, the United States, and the European Union

OBJECTIVE

To understand assumptions about and approaches to interstitial lung disease (ILD), including those of the progressive phenotype (progressive fibrosing ILD), this multinational survey assessed physicians' attitudes toward, knowledge of, and management strategies for progressive fibrosing ILD.

METHODS

This internet-based survey of physicians was conducted between November 2018 and February 2019. Practical management strategies for progressive fibrosing ILD, and current approaches to the assessment and treatment of ILD, were compared between countries/regions (Japan vs. United States and European Union) and specialties (pulmonologists vs. rheumatologists).

RESULTS

The survey was completed by 574 respondents. Compared with Western countries, the progressive fibrosing phenotype concept was not widely understood by Japanese respondents, with no notable differences in the understanding of this phenotype between pulmonologists and rheumatologists. Across all regions, pulmonary function tests, diffusing capacity of the lungs for carbon monoxide assessments, and pulse oximeter measurements were commonly performed at intervals of ≤6 months. In general, physicians in the United States and European Union preferred physiologic approaches for follow-up, while those in Japan preferred imaging and blood monitoring. Compared with rheumatologists, pulmonologists performed more frequent monitoring of autoimmune ILDs, and the differences between specialties were most pronounced in Japan. Regional differences in treatment approaches were observed, probably reflecting the local availability of agents and healthcare environments.

CONCLUSIONS

Awareness and management of progressive fibrosing ILD varied between specialties and regions, highlighting an unmet need for standardized diagnosis, treatment guidelines, and specialist education in this area.

Estimation of the Prevalence of Progressive Fibrosing Interstitial Lung Diseases: Systematic Literature Review and Data from a Physician Survey

Some patients with interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis exhibit a progressive clinical phenotype. These chronic progressive fibrosing ILDs have a variety of underlying diseases, and their prevalence is currently unknown. Here we carry out the first systematic review of literature on the prevalence of fibrosing ILDs and progressive fibrosing ILDs using data from physician surveys to estimate frequency of progression among different ILDs. We searched MEDLINE and Embase for studies assessing prevalence of ILD, individual ILDs associated with fibrosis and progressive fibrosing ILDs. These were combined with data from previously published physician surveys to obtain prevalence estimates of each chronic fibrosing ILD with a progressive phenotype and of progressive fibrosing ILDs overall. We identified 16 publications, including five reporting overall ILD prevalence, estimated at 6.3-76.0 per 100,000 people in Europe (four studies) and 74.3 per 100,000 in the USA (one study). In total, 13-40% of ILDs were estimated to develop a progressive fibrosing phenotype, with overall prevalence estimates for progressive fibrosing ILDs of 2.2-20.0 per 100,000 in Europe and 28.0 per 100,000 in the USA. Prevalence estimates for individual progressive fibrosing ILDs varied up to 16.7 per 100,000 people. These conditions represent a sizeable fraction of chronic respiratory disorders and have a high unmet need.

The Burden of Progressive Fibrosing Interstitial Lung Disease: A DELPHI Approach

Introduction

The term progressive fibrosing interstitial lung disease (ILD) describes patients with fibrotic ILDs who, irrespective of the aetiology of the disease, show a progressive course of their disease despite current available (and non-licensed) treatment. Besides in idiopathic pulmonary fibrosis, little is known about management and the burden of patients with fibrotic ILD, particularly those with a progressive behaviour.

Methods

Using the Delphi method, 40 European experts in ILD management delivered information on management of (progressive) fibrosing ILD and on the impact of the disease on patients’ quality of life (QoL) and healthcare resource utilisation (HCRU). Annual costs were calculated for progressive and non-/slow-progressive fibrosing ILD for diagnosis, follow-up management, exacerbation management, and end-of-life care based on the survey data.

Results

Physicians reported that progression in fibrosing ILD worsens QoL in both patients and their caregivers. Progression of fibrosing ILD was associated with a greater use of HCRU for follow-up visits and maintenance treatment compared with the non-/slow progression. The number of patients who suffered at least one acute exacerbation was reported to be more than three times higher in progressive fibrosing ILD patients than in patients with non-/slow-progressive fibrosing ILD. On average, annual estimated costs of progressive fibrosing ILD per patient were 1.8 times higher than those of the non-/slow-progressive form of the disease.

Conclusions

Progression in fibrosing ILD causes a significant impact on QoL and HCRU and costs. These survey data underline the need for safe and effective therapies to slow the disease progression.

Electronic supplementary material

The online version of this article (10.1007/s12325-020-01384-0) contains supplementary material, which is available to authorized users.

The role of MIF in chronic lung diseases: looking beyond inflammation

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has been associated with many diseases. Most studies found in literature describe MIF as a proinflammatory cytokine involved in chronic inflammatory conditions, but evidence from last years suggests that many of its key effects are not directly related to inflammation. In fact, MIF is constitutively expressed in most human tissues and in some cases in high levels, which does not reflect the pattern of expression of a classic proinflammatory cytokine. Moreover, MIF is highly expressed during embryonic development and decreases during adulthood, which point toward a more likely role as growth factor. Accordingly, MIF knockout mice develop age-related spontaneous emphysema, suggesting that MIF presence (e.g., in younger individuals and wild-type animals) is part of a healthy lung. In view of this new line of evidence, we aimed to review data on the role of MIF in the pathogenesis of chronic lung diseases.