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Interstitial lung disease (ILD) including idiopathic pulmonary fibrosis increases the risk of developing lung cancer. Diagnosing and staging lung cancer in patients with ILD is challenging and requires careful interpretation of computed tomography (CT) and fluorodeoxyglucose PET/CT to distinguish nodules from areas of fibrosis. Minimally invasive tissue sampling is preferred but may be technically challenging given tumor location, coexistent fibrosis, and pneumothorax risk. Current treatment options include surgery, radiation therapy, percutaneous thermal ablation, and systemic therapy; however, ILD increases the risks associated with each treatment option, especially acute ILD exacerbation.

Fewer than ten reported cases of cryptogenic organizing pneumonia (COP) have been managed with intravenous immunoglobulins (IVIg). We report a case of a 72-year-old man who presented with a worsening cough and diffuse opacities on chest radiograph. Following no improvement with antibiotics and negative complementary investigations for infectious, malignant, and autoimmune etiologies, COP was confirmed on lung biopsy. Due to continued clinical deterioration despite high-dose steroids and new severe steroid-induced hallucinations, the patient was placed on intravenous immunoglobulins (IVIg) and mycophenolate mofetil and made a satisfactory recovery. IVIg should be considered as an important steroid-sparing alternative in patients with COP.

Pulmonary vascular disease is associated with poor outcomes in individuals affected by interstitial lung disease. The pulmonary vessels can be quantified with noninvasive imaging, but whether radiographic indicators of vasculopathy are associated with early interstitial changes is not known.Are pulmonary vascular volumes, quantified from CT scans, associated with interstitial lung abnormalities (ILA) in a community-based sample with a low burden of lung disease?In 2,386 participants of the Framingham Heart Study, we used CT imaging to calculate pulmonary vascular volumes, including the small vessel fraction (a surrogate of vascular pruning). We constructed multivariable logistic regression models to investigate associations of vascular volumes with ILA, progression of ILA, and restrictive pattern on spirometry. In secondary analyses, we additionally adjusted for diffusing capacity and emphysema, and performed a sensitivity analysis restricted to participants with normal FVC and diffusing capacity.In adjusted models, we found that lower pulmonary vascular volumes on CT were associated with greater odds of ILA, antecedent ILA progression, and restrictive pattern on spirometry. For example, each SD lower small vessel fraction was associated with 1.81-fold greater odds of ILA (95% CI, 1.41-2.31; P .0001), and 1.63-fold greater odds of restriction on spirometry (95% CI, 1.18-2.24; P = .003). Similar patterns were seen after adjustment for diffusing capacity for carbon monoxide, emphysema, and among participants with normal lung function.In this cohort of community-dwelling adults not selected on the basis of lung disease, more severe vascular pruning on CT was associated with greater odds of ILA, ILA progression, and restrictive pattern on spirometry. Pruning on CT may be an indicator of early pulmonary vasculopathy associated with interstitial lung disease.

Interstitial lung disease (ILD) is a cause of substantial morbidity and mortality amongst autoimmune diseases, including myositis. Despite first-line therapy with immunosuppression, many inflammatory ILDs advance to a fibrotic stage. In such patients, progressive fibrosis may be amenable to treatment with antifibrotic medications, which were initially studied and approved for the treatment of idiopathic pulmonary fibrosis. We here review the available data that support the use of antifibrotics in connective tissue diseases and progressive fibrosing ILDs. There is now a growing body of evidence in both large randomized clinical trials and on the evolving pathophysiologic pathways to support the use of antifibrotics in select patients with autoimmune ILD and a fibrotic phenotype. Further study of antifibrotics in combination with immunosuppressive medications, and in the myositis-ILD population, is needed.

Aerosol furosemide may be an option to treat refractory dyspnea, though doses, methods of delivery, and outcomes have been variable. We hypothesized that controlled delivery of high dose aerosol furosemide would reduce variability of dyspnea relief in patients with underlying pulmonary disease. Seventeen patients with chronic exertional dyspnea were recruited. Patients rated recently recalled breathing discomfort on a numerical rating scale (NRS) and the multidimensional dyspnea profile (MDP). They then performed graded exercise using an arm-ergometer. The NRS was completed following each exercise grade, and the MDP was repeated after a pre-defined dyspnea threshold was reached. During separate visits, patients received either aerosol saline or 80 mg of aerosol furosemide in a randomized, double-blind, crossover design. After treatment, graded exercise to the pre-treatment level was repeated, followed by completion of the NRS and MDP. Treatment effect was defined as the difference between pre- and post-treatment NRS at end exercise, expressed in absolute terms as % Full Scale. “Responders” were defined as those showing treatment effect ≥ 20% of full scale. Final analysis included 15 patients. Neither treatment produced a statistically significant change in NRS and there was no significant difference between treatments (p = 0.45). There were four “responders” and one patient whose dyspnea worsened with furosemide; two patients were responders with saline, of whom one also responded to furosemide. No adverse events were reported. High dose controlled delivery aerosol furosemide was not statistically different from saline placebo at reducing exercise-induced dyspnea. However, a clinically meaningful improvement was noted in some patients.

We aimed to determine if antibody type is an indicator of pulmonary histopathology, using antisynthetase antibody positive interstitial lung disease (ILD) cases with lung biopsy or autopsy findings.We conducted a comprehensive review of the English language literature in PubMed to identify ILD histopathology results for cases with antibodies against anti-aminoacyl-transfer RNA (tRNA) synthetases (anti-ARS antibodies), including Jo1, PL-12, PL-7, KS, ES, and OJ. We additionally identified patients who had ILD, anti-ARS antibodies, and a lung biopsy between 2015 and 2020 at Beth Israel Deaconess Medical Center. For each case, we documented the specific anti-ARS antibody and major histopathologic patterns identified on biopsy or autopsy, including usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), organizing pneumonia (OP), and acute lung injury (ALI). To determine if histopathology varied by antibody type, we compared the proportion of each of four major patterns by antibody type using the Fisher's Exact test.We identified 310 cases with pathology findings and anti-ARS antibody positivity, including 12 cases from our institution. The proportion of NSIP differed significantly across antibody type, found in 31% of Jo1 (p 0.01), 67% of EJ (p 0.01), and 63% of KS (p 0.01) cases. OP was common in Jo1 (23%, p = 0.07), but rare in EJ (4%, p = 0.04) and KS (4%, p = 0.04). UIP was common in PL-12 alone (36%, p = 0.03).The frequency of histopathologic findings in ILD with anti-ARS positivity varies significantly by antibody type, and NSIP occurs in less than half of all cases.

Purpose: Nintedanib is an approved treatment for idiopathic pulmonary fibrosis (IPF), which slows disease progression. Management of patients with IPF receiving nintedanib can be complicated by tolerability issues, comorbidities, and concomitant medications. We developed consensus recommendations on the management of dosing, adverse events and comorbidities in patients with IPF treated with nintedanib. Methods: A modified Delphi process using 3 questionnaires was used to survey 14 pulmonologists experienced in using nintedanib. Panelists rated their agreement with statements on a Likert scale from −5 (strongly disagree) to +5 (strongly agree). Consensus was predefined as a mean score of ⩽−2.5 or ⩾+2.5 with a standard deviation not crossing zero. Results: The panelists’ recommendations were largely aligned with clinical trial data, real-world evidence, and the prescribing information, and provided additional guidance regarding minimizing gastrointestinal effects, periodic monitoring for liver dysfunction, caution with respect to concomitant administration of cytochrome P450 3A4 and P-glycoprotein 1 inhibitors and inducers and anticoagulants, and management of comorbidities. The panelists unanimously agreed that adverse event management should be individualized, based on careful consideration of the risks and benefits of each possible intervention and discussion with the patient. Conclusions: These consensus recommendations provide additional guidance on the appropriate management of IPF with nintedanib, for use alongside evidence-based literature and the prescribing information.

Interstitial lung disease (ILD) frequently complicates the inflammatory myopathies and at times is the most prominent clinical feature. Over the years, there has been a growing recognition for the strong association between seropositivity of several myositis-specific antibodies (MSAs) and lung involvement. Growing literature suggests that individual MSAs may influence the risk of developing ILD and are associated with pulmonary disease severity and various clinical sub-phenotypes. The presence of ILD in patients with myositis correlates with increased morbidity and mortality. As such, it presents a unique treatment challenge for both the rheumatology and pulmonary communities and requires a multidisciplinary approach to management. This review will discuss the role of serologies and invasive and non-invasive testing modalities utilised to diagnose and monitor patients with myositis-ILD. Current studies pertaining to the wide array of immunomodulatory therapies utilized in cases of progressive disease are also highlighted in detail.

A Man with Dyspnea and Abnormalities on Chest Imaging A 20-year-old man with a history of electronic-cigarette use presented to the hospital because of a history of dyspnea, intermittent fever, joi...

Immune checkpoint inhibitors are known to cause a variety of immune-related adverse events, including pneumonitis. When symptomatic, treatment typically consists of temporary or permanent cessation of the checkpoint inhibitor and several weeks of corticosteroid therapy. However, a subset of patients may suffer from severe pneumonitis, and the optimal treatment for this group is not known. Here we describe the case of a patient receiving pembrolizumab for non-small cell lung cancer who developed severe checkpoint inhibitor pneumonitis. After treatment with high-dose corticosteroids failed to produce a response, a course of intravenous immunoglobulin catalyzed rapid and durable improvement. In this review, we discuss the current evidence regarding the incidence and outcomes of severe checkpoint inhibitor pneumonitis and propose a role for intravenous immunoglobulin as a possible treatment strategy. Keywords: Immune checkpoint inhibitor, Pneumonitis, Pulmonary toxicity, Intravenous immunoglobulin

Alternatively activated macrophages (M2) have an important function in innate immune responses to parasitic helminths, and emerging evidence also indicates these cells are regulators of systemic metabolism. Here we show a critical role for mTORC2 signalling in the generation of M2 macrophages. Abrogation of mTORC2 signalling in macrophages by selective conditional deletion of the adaptor molecule Rictor inhibits the generation of M2 macrophages while leaving the generation of classically activated macrophages (M1) intact. Selective deletion of Rictor in macrophages prevents M2 differentiation and clearance of a parasitic helminth infection in mice, and also abrogates the ability of mice to regulate brown fat and maintain core body temperature. Our findings define a role for mTORC2 in macrophages in integrating signals from the immune microenvironment to promote innate type 2 immunity, and also to integrate systemic metabolic and thermogenic responses., mTORC1 and mTORC2 are alternatively required for differentiation of T cells into Th1/Th17 or Th2 cells. Here the authors show mTORC2 signalling is also needed for IL-4-induced M2 activation with functional evidence provided by a N. brasiliensis infection model and cold challenge to model adaptive thermogenesis.

Background Interstitial lung disease-associated antisynthetase syndrome (AS-ILD) carries significant morbidity and mortality. Corticosteroids and immunosuppressive drugs are the mainstay of treatment. Human immunoglobulin (IVIg), an immunomodulator without immunosuppressive properties, is effective in myositis but the evidence supporting its use in ILD is scarce. Objective To describe clinical outcomes of AS-ILD patients receiving IVIg. Methods Retrospective analysis of AS-ILD patients. Linear mixed models using restricted maximum likelihood estimation was used to estimate the change in lung function and corticosteroid dose over time. Results Data from 17 patients was analyzed. Median follow-up was 24.6 months. Fourteen patients had refractory disease. The mean percent-predicted forced vital capacity (FVC%) (p = 0.048) and percent-predicted diffusing capacity of the lung for carbon monoxide (DLCO%) (p = 0.0223) increased over time, while the mean prednisone dose (p 10% increase in FVC%, including two who used IVIg as initial treatment. Five patients showed a >10% increase in DLCO% and TLC%. Nine (53%) patients experienced side effects. Conclusions IVIg may be a useful complementary therapy in active progressive AS-ILD but is associated with potential side effects. Fssssurther investigation is required to determine the value of IVIg as an initial treatment in AS-ILD.

BackgroundAmbient air pollution accelerates lung function decline among adults, however, there are limited data about its role in the development and progression of early stages of interstitial lung disease.AimsTo evaluate associations of long-term exposure to traffic and ambient pollutants with odds of interstitial lung abnormalities (ILA) and progression of ILA on repeated imaging.MethodsWe ascertained ILA on chest CT obtained from 2618 Framingham participants from 2008 to 2011. Among 1846 participants who also completed a cardiac CT from 2002 to 2005, we determined interval ILA progression. We assigned distance from home address to major roadway, and the 5-year average of fine particulate matter (PM2.5), elemental carbon (EC, a traffic-related PM2.5 constituent) and ozone using spatio-temporal prediction models. Logistic regression models were adjusted for age, sex, body mass index, smoking status, packyears of smoking, household tobacco exposure, neighbourhood household value, primary occupation, cohort and date.ResultsAmong 2618 participants with a chest CT, 176 (6.7%) had ILA, 1361 (52.0%) had no ILA, and the remainder were indeterminate. Among 1846 with a preceding cardiac CT, 118 (6.4%) had ILA with interval progression. In adjusted logistic regression models, an IQR difference in 5-year EC exposure of 0.14 µg/m3 was associated with a 1.27 (95% CI 1.04 to 1.55) times greater odds of ILA, and a 1.33 (95% CI 1.00 to 1.76) times greater odds of ILA progression. PM2.5 and O3 were not associated with ILA or ILA progression.ConclusionsExposure to EC may increase risk of progressive ILA, however, associations with other measures of ambient pollution were inconclusive.

A proportion of patients with interstitial lung diseases (ILDs) are at risk of developing a progressive-fibrosing phenotype, which is associated with a deterioration in lung function and early mortality. In addition to idiopathic pulmonary fibrosis (IPF), fibrosing ILDs that may present a progressive phenotype include idiopathic nonspecific interstitial pneumonia, connective tissue disease-associated ILDs, hypersensitivity pneumonitis, unclassifiable idiopathic interstitial pneumonia, ILDs related to other occupational exposures and sarcoidosis. Corticosteroids and/or immunosuppressive therapies are sometimes prescribed to patients with these diseases. However, this treatment regimen may not be effective, adequate on its own or well tolerated, suggesting that there is a pressing need for efficacious and better tolerated therapies. Currently, the only approved treatments to slow disease progression in patients with IPF are nintedanib and pirfenidone. Similarities in pathobiological mechanisms leading to fibrosis between IPF and other ILDs that may present a progressive-fibrosing phenotype provide a rationale to suggest that nintedanib and pirfenidone may be therapeutic options for patients with the latter diseases.This review provides an overview of the therapeutic options currently available for patients with fibrosing ILDs, including fibrosing ILDs that may present a progressive phenotype, and explores the status of the randomised controlled trials that are underway to determine the efficacy and safety of nintedanib and pirfenidone.

Oncologists are increasingly managing drug-induced pneumonitis in lung cancer patients treated with PD-1/PD-L1 immune checkpoint inhibitors. To date only few studies on the topic have described both radiologic and pathologic findings in these patients. Here, we report a fatal case of immune checkpoint inhibitor-associated pneumonitis initially presenting with an organizing pneumonia, but who rapidly developed acute respiratory distress syndrome (confirmed histologically at the time of autopsy). As such, this case illustrates the need for clinicians to maintain a high index of suspicion for immune checkpoint inhibitor associated pneumonitis and have a low threshold to perform CT imaging in any symptomatic patient receiving checkpoint inhibition therapy. CLINICAL PRACTICE POINTS.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease characterized by the destruction of articular joint structures. RA is a systemic condition that often affects multiple organs, including the heart, lungs, and kidneys. Pulmonary complications of RA are relatively common and include pleural effusion, rheumatoid nodules, bronchiectasis, obliterative bronchiolitis, and opportunistic infections. Interstitial lung disease (ILD) is a common occurrence in patients with RA, and can range in severity from an asymptomatic incidental finding to a rapidly progressing life-threatening event. Usual interstitial pneumonia and non-specific interstitial pneumonia are the two most common patterns, though others have been reported. Various disease-modifying anti-rheumatic drugs-in particular, methotrexate and the tumor necrosis factor-alpha inhibitors-have been associated with RA-ILD in numerous case reports and case series, though it is often difficult to distinguish association from causality. Treatment for RA-ILD typically involves the use of high-dose corticosteroids, often in conjunction with alternative immunosuppressant agents such as azathioprine or mycophenolate mofetil, and outcomes vary widely depending on the initial pattern of lung disease. Additional research into the mechanisms driving RA-ILD is needed to guide future therapy.

Intravenous Ig (IVIg) is a pooled plasma product consisting primarily of monomeric IgG. For the past several decades, the use of IVIg has expanded to include the treatment of various autoimmune and inflammatory disorders, including Kawasaki's disease, antineutrophil cytoplasmic antibody-associated vasculitis, systemic lupus erythematosis, and the inflammatory myopathies. IVIg is thought to exert its immunomodulatory effects through a variety of mechanisms: neutralization of pathogenic autoantibodies; alteration of immune cell effector function; suppression of cytokine and chemokine activity; and interference with complement activation. Interstitial lung disease (ILD) is a frequent complication of autoimmune disorders and connective tissue diseases, and the presence of ILD is associated with significant morbidity and mortality. Although there are currently no large studies to support the use of IVIg in the treatment of ILD, it is being used off-label with increasing frequency for refractory cases that have failed to respond to standard immunosuppression. Although associated with less systemic toxicity and global immunosuppression than traditional agents, IVIg is much more costly. Therefore, although the routine use of IVIg to treat ILD is not currently recommended, future studies to determine its role in pulmonary disease are warranted.

Pulmonary hypertension (PH) is a common complication of interstitial lung disease (ILD), particularly in idiopathic pulmonary fibrosis (IPF) and ILD associated with connective tissue disease, where the underlying pathology is often a nonspecific interstitial pneumonia (NSIP) pattern. The degree of PH in ILD is typically mild to moderate and radiographic changes of ILD are usually prominent. We describe four patients with idiopathic NSIP and severe PH (mPAP > 40 mmHg). The average mean pulmonary artery pressure was 51±7 mmHg and pulmonary vascular resistance was 13±4 Wood's units. Pulmonary function was characterized by mild restriction (total lung capacity 63–94% predicted) and profound reductions in DLCO (19–53% predicted). Computed tomographic imaging revealed minimal to moderate interstitial thickening without honeycombing. In two of the cases, an initial clinical diagnosis of idiopathic pulmonary arterial hypertension was made. Both were treated with intravenous epoprostenol, which was associated with worsening of hypoxemia. All four patients died or underwent lung transplant within 4 years of PH diagnonsis. Lung pathology in all four demonstrated fibrotic NSIP with medial thickening of the small and medium pulmonary arteries, and proliferative intimal lesions that stained negative for endothelial markers (CD31 and CD34) and positive for smooth muscle actin. There were no plexiform lesions. Severe pulmonary hypertension can therefore occur in idiopathic NSIP, even in the absence of advanced radiographic changes. Clinicians should suspect underlying ILD as the basis for PH when DLCO is severely reduced or gas exchange deteriorates with pulmonary vasodilator therapy.

To highlight recent advances in understanding the clinical spectrum, pathogenesis, and treatment of interstitial lung disease associated with inflammatory myositis and the antisynthetase syndrome.In recent years, serologic tests to identify the less common antisynthetase antibodies and the anti-MDA-5 antibody have become commercially available. As a result, several large, retrospective analyses have illustrated both the pulmonary and non-pulmonary features associated with the antisynthetase syndrome and myositis-related interstitial lung disease. Notably, there is now a better appreciation for the heterogeneity of these syndromes and the prognostic value in accurately identifying the associated autoantibodies. Human cytokine profiling and murine models of muscle inflammation suggest that tRNA synthetases themselves may act to trigger an initial innate immune response, thus offering new insights into the pathophysiology of these diseases. Finally, although randomized clinical trials in patients with myositis-associated interstitial lung disease have not occurred, new observational studies suggest that cyclosporine, tacrolimus, and rituximab may be effective treatment options.Recent research has provided a better understanding of the phenotype and prognosis that define interstitial lung disease in the setting of myositis and the antisynthetase syndrome. Although several therapeutic agents demonstrate promise, randomized trials are needed in order to establish the best clinical approach in these patients. Furthermore, additional research into the pathophysiology of this disease will be necessary to develop newer, more targeted therapeutics.

Background Pulmonary fibrosis is an untreatable, fatal disease characterized by excess deposition of extracellular matrix and inflammation. Although the etiology of pulmonary fibrosis is unknown, recent studies have implicated dysregulated immune responses and wound healing. Since n-3 polyunsaturated fatty acids (n-3 PUFAs) may beneficially modulate immune responses in a variety of inflammatory disorders, we investigated the therapeutic role of docosahexaenoic acid (DHA), a single n-3 PUFA, in lung fibrosis. Methods Intratracheal DHA or PBS was administered to mouse lungs 4 days prior to intratracheal bleomycin treatment. Body weight and survival were monitored for 21 days. Bronchoalveolar fluid (BALF) and lung inflammatory cells, cytokines, eicosanoids, histology and lung function were determined on serial days (0, 3, 7, 14, 21) after bleomycin injury. Results Intratracheal administration of DHA mitigated bleomycin-induced lung injury. Mice pretreated with DHA had significantly less weight loss and mortality after bleomycin injury. The lungs from DHA-pretreated mice had markedly less fibrosis. DHA pretreatment also protected the mice from the functional changes associated with bleomycin injury. Bleomycin-induced cellular inflammation in BALF and lung tissue was blunted by DHA pretreatment. These advantageous effects of DHA pretreatment were associated with decreased IL-6, LTB4, PGE2 and increased IL-10. Conclusions Our findings demonstrate that intratracheal administration of DHA, a single PUFA, protected mice from the development of bleomycin-induced pulmonary inflammation and fibrosis. These results suggest that further investigations regarding the role of n-3 polyunsaturated fatty acids in fibrotic lung injury and repair are needed.

The idiopathic inflammatory myopathies are a group of connective tissue diseases marked by varying degrees of muscle inflammation and clinical involvement of multiple organs, most notably, the lung. Pulmonary manifestations consist primarily of interstitial lung disease (ILD), which is associated with significant morbidity and mortality in myositis patients. Several myositis-specific antibodies have been discovered, as well as antibodies targeting various aminoacyl-tRNA synthetase enzymes. These antibodies are associated with various clinical features and a risk for developing ILD, and their presence carries a prognostic value in myositis patients. Steroids remain the first-line treatment for myositis-associated ILD and the antisynthetase syndrome, though other traditional immunosuppressants have demonstrated efficacy in numerous studies. While a majority of patients experience either stabilization or improvement in lung imaging and function, fatal progression is still reported in a significant number of cases. Further research is needed to develop more effective and targeted therapies.

Thalidomide is an infamous drug whose use by pregnant women in the middle of last century tragically resulted in serious birth defects. However, as a result of its potent immunomodulatory, anti-inflammatory and antiangiogenic properties, thalidomide may be a potential therapy in many diseases. In recent years, thalidomide has been used effectively to treat various malignancies, including multiple myeloma, myelodysplastic syndromes, renal cell cancer, glioblastoma multiforme and prostate cancer. In addition, thalidomide has also proven effective against other immune-related diseases, including erythema nodosum leprosum and sarcoidosis. Idiopathic pulmonary fibrosis (IPF) is a deadly fibrotic disease with no effective treatment options. However, there is data to suggest that thalidomide may be useful in treating the chronic, disabling cough that accompanies IPF. It remains to be seen whether the immunomodulatory and antiangiogenic properties of thalidomide will also make it a potential therapy against the clinical progression of IPF.

Background The extracellular matrix plays a critical role in insuring tissue integrity and water homeostasis. However, breakdown products of the extracellular matrix have emerged as endogenous danger signals, designed to rapidly activate the immune system against a potential pathogen breach. Type I interferons play a critical role in the immune response against viral infections. In the lungs, hylauronan (HA) exists as a high molecular weight, biologically inert extracellular matrix component that is critical for maintaining lung function. When lung tissue is injured, HA is broken down into lower molecular weight fragments that alert the immune system to the breach in tissue integrity by activating innate immune responses. HA fragments are known to induce inflammatory gene expression via TLR-MyD88-dependent pathways. Methods Primary peritoneal macrophages from C57BL/6 wild type, TLR4 null, TLR3 null, MyD88 null, and TRIF null mice as well as alveolar and peritoneal macrophage cell lines were stimulated with HA fragments and cytokine production was assessed by rt-PCR and ELISA. Western blot analysis for IRF3 was preformed on cell lysates from macrophages stimulate with HA fragments Results We demonstrate for the first time that IFNβ is induced in murine macrophages by HA fragments. We also show that HA fragments induce IFNβ using a novel pathway independent of MyD88 but dependent on TLR4 via TRIF and IRF-3. Conclusions Overall our findings reveal a novel signaling pathway by which hyaluronan can modulate inflammation and demonstrate the ability of hyaluronan fragments to induce the expression of type I interferons in response to tissue injury even in the absence of viral infection. This is independent of the pathway of the TLR2-MyD88 used by these matrix fragments to induce inflammatory chemokines. Thus, LMW HA may be modifying the inflammatory milieu simultaneously via several pathways.

Pulmonary fibrosis is an untreatable, uniformly fatal disease of unclear etiology that is the result of unremitting chronic inflammation. Recent studies have implicated bone marrow derived fibrocytes and M2 macrophages as playing key roles in propagating fibrosis. While the disease process is characterized by the accumulation of lymphocytes in the lung parenchyma and alveolar space, their role remains unclear. In this report we definitively demonstrate the ability of T cells to regulate lung inflammation leading to fibrosis. Specifically we demonstrate the ability of intranasal vaccinia vaccination to inhibit M2 macrophage generation and fibrocyte recruitment and hence the accumulation of collagen and death due to pulmonary failure. Mechanistically, we demonstrate the ability of lung Th1 cells to prevent fibrosis as vaccinia failed to prevent disease in Rag-/- mice or in mice in which the T cells lacked IFN-γ. Furthermore, vaccination 3 months prior to the initiation of fibrosis was able to mitigate the disease. Our findings clearly demonstrate the role of T cells in regulating pulmonary fibrosis as well as suggest that vaccinia-induced immunotherapy in the lung may prove to be a novel treatment approach to this otherwise fatal disease.