Clinical significance of serum autoantibodies in idiopathic interstitial pneumonia

Presence of anti-modified protein antibodies in idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Studies of autoimmunity and anti-citrullinated protein antibodies (ACPA) in idiopathic pulmonary fibrosis (IPF) have been confined to investigations of anti-cyclic citrullinated peptide (anti-CCP) antibodies which utilize synthetic peptides as surrogate markers for in vivo citrullinated antigens. We studied immune activation by analysing the prevalence of in vivo anti-modified protein antibodies (AMPA) in IPF.

METHODS

We included patients with incident and prevalent IPF (N = 120), sex and smoking-matched healthy controls (HC) (N = 120) and patients with RA (N = 104). Serum (median time: 11 months [Q1-Q3: 1-28 months] from diagnosis) was analysed for presence of antibodies towards native and posttranslational modified (citrullinated [Cit, N = 25]; acetylated [Acet, N = 4] and homocitrullinated [Carb, N = 1]) peptides derived from tenascin (TNC, N = 9), fibrinogen (Fib, N = 11), filaggrin (Fil, N = 5), histone (N = 8), cathelicidin (LL37, N = 4) and vimentin (N = 5) using a custom-made peptide microarray.

RESULTS

AMPA were more frequent and in increased levels in IPF than in HC (44% vs. 27%, p < 0.01), but less than in RA (44% vs. 79%, p < 0.01). We specifically observed AMPA in IPF towards certain citrullinated, acetylated and carbamylated peptides versus HC: tenascin (Cit(2033) -TNC2025-2040 ; Cit(2197) -TNC2177-2200 ; Cit(2198) -TNC2177-2200 ), fibrinogen (Cit(38,42) -Fibα36-50 ; Cit(72) -Fibβ60-74 ) and filaggrin (Acet-Fil307-324 , Carb-Fil307-324 ). No differences in survival (p = 0.13) or disease progression (p = 0.19) between individuals with or without AMPA was observed in IPF. However, patients with incident IPF had better survival if AMPA were present (p = 0.009).

CONCLUSION

A significant proportion of IPF patients present with specific AMPA in serum. Our results suggest autoimmunity as a possible characteristic for a subgroup of IPF that may affect disease outcome.

Anti-UBE2T antibody: A novel biomarker of progressive-fibrosing interstitial lung disease

BACKGROUND

Anti-fibrotic therapy has demonstrated efficacy against progressive-fibrosing interstitial lung disease (PF-ILD); therefore, identifying disease behavior before progression has become a priority. As autoimmunity is implicated in the pathogenesis of various ILDs, this study explored circulating biomarkers that could predict the chronic progressive behavior of ILDs.

METHODS

A single-center retrospective cohort study was conducted. Circulating autoantibodies in patients with ILD were screened using microarray analysis to identify candidate biomarkers. An enzyme-linked immunosorbent assay was performed with a larger sample set for the quantification of antibodies. After 2 years of follow-up, ILDs were reclassified as PF or non-PF. The relationship between the participants' autoantibody levels measured at enrolment and final diagnosis of PF-ILD was determined.

RESULTS

In total, 61 healthy participants and 66 patients with ILDs were enrolled. Anti-ubiquitin-conjugating enzyme E2T (UBE2T) antibody was detected as a candidate biomarker. Anti-UBE2T antibody levels were elevated in patients with idiopathic pulmonary fibrosis (IPF). After following up on the study participants for 2 years, anti-UBE2T levels measured at enrolment significantly correlated with the new PF-ILD diagnosis. Immunohistochemical staining of normal lung tissues revealed sparsely located UBE2T in the bronchiole epithelium and macrophages, whereas IPF lung tissues showed robust expression in the epithelial lining of honeycomb structures.

CONCLUSION

To our knowledge, this is the first report to describe an anti-UBE2T antibody, a new biomarker that is significantly elevated in patients with ILD who present future disease progression.

Clinical Characterization and Predictive Factors for Progression in a Cohort of Patients with Interstitial Lung Disease and Features of Autoimmunity: The Need for a Revision of IPAF Classification Criteria

Background and Objectives: The "interstitial pneumonia with autoimmune features" (IPAF) criteria have been criticized because of the exclusion of usual interstitial pneumonia (UIP) patients with a single clinical or serological feature. To classify these patients, the term UIPAF was proposed. This study aims to describe clinical characteristics and predictive factors for progression of a cohort of interstitial lung disease (ILD) patients with at least one feature of autoimmunity, applying criteria for IPAF, specific connective tissue diseases (CTD), and a definition of UIPAF when possible. Methods: We retrospectively evaluated data on 133 consecutive patients with ILD at onset associated with at least one feature of autoimmunity, referred by pulmonologists to rheumatologists from March 2009 to March 2020. Patients received 33 (16.5-69.5) months of follow-up. Results: Among the 101 ILD patients included, 37 were diagnosed with IPAF, 53 with ILD-onset CTD, and 11 with UIPAF. IPAF patients had a lower prevalence of UIP pattern compared to CTD-ILD and UIPAF patients (10.8% vs. 32.1% vs. 100%, p < 0.01). During the follow-up, 4 IPAF (10.8%) and 2 UIPAF (18.2%) patients evolved into CTD-ILD. IPAF patients presented features not included in IPAF criteria, such as sicca syndrome (8.1%), and were more frequently affected by systemic hypertension (p < 0.01). Over one year, ILD progression (greater extent of fibrosis on HRCT and/or decline in PFTs) was less frequent in the IPAF group compared to CTD-ILD and UIPAF (32.3% vs. 58.8% vs. 72.7, p = 0.02). A UIP pattern and an IPAF predicted a faster (OR: 3.80, p = 0.01) and a slower (OR: 0.28, p = 0.02) ILD progression, respectively. Conclusions: IPAF criteria help identify patients who might develop a CTD-ILD, even though a single clinical or serological feature is respected. Future revisions of IPAF criteria should include sicca syndrome and separate UIP-pattern into a different definition (UIPAF), given its association with a different prognosis, independently from ILD classification.

Clinical implications of interstitial pneumonia with autoimmune features diagnostic criteria in idiopathic pulmonary fibrosis: A case control study

Background

A subgroup of IPF patients can meet IPAF criteria (features suggesting an underlying autoimmune process without fulfilling established criteria for a CTD). This study was aimed to evaluate whether IPAF/IPF patients compared to IPF patients differ in clinical profile, prognosis and disease course.

Methods

This is a retrospective, single center, case-control study. We evaluated 360 consecutive IPF patients (Forlì Hospital, between 1/1/2002 and 28/12/2016) and compared characteristics and outcome of IPAF/IPF to IPF.

Results

Twenty-two (6%) patients met IPAF criteria. IPAF/IPF patients compared to IPF were more frequently females (N = 9/22, 40.9% vs. N = 68/338, 20.1%, p = 0.02), suffered more frequently from gastroesophageal reflux (54.5% vs. 28.4%, p = 0.01), and showed a higher prevalence of arthralgias (86.4% vs. 4.8%, p < 0.0001), myalgias (14.3% vs. 0.3%, p = 0.001) and fever (18.2% vs. 1.9%, p = 0.002). The serologic domain was detected in all cases (the most frequent were ANA in 17 and RF in nine cases) and morphologic domain (histology features) was positive in 6 out of 10 lung biopsies (lymphoid aggregates). Only patients with IPAF/IPF evolved to CTD at follow-up (10/22, 45.5%; six rheumatoid arthritis, one Sjögren's and three scleroderma). The presence of IPAF was a positive prognostic determinant (HR 0.22, 95% CI 0.08-0.61, p = 0.003), whereas the isolated presence of circulating autoantibody did not impact prognosis (HR 1.00, 95% CI 0.67-1.49, p = 0.99).

Conclusion

The presence of IPAF criteria in IPF has a major clinical impact correlating with the risk of evolution to full blown-CTD during follow-up and identifying a subgroup of patients with a better prognosis.

A retrospective analysis of the relationship between anti-cyclic citrullinated peptide antibody and interstitial lung disease in systemic sclerosis

Anti-cyclic citrullinated peptide antibody testing is used to diagnose rheumatoid arthritis and associated with interstitial lung disease in RA. Herein, we investigate the relationship between anti-CCP antibody and ILD in SSc. We performed a retrospective analysis at a tertiary medical center between 2005 and 2019. Patients with SSc, systemic lupus erythematosus, and polymyositis/dermatomyositis (PM/DM) were evaluated for anti-CCP antibody and ILD. Additionally, medical records of SSc patients with ILD were reviewed. SSc patients had the highest anti-CCP antibody positivity rate compared to those with SLE and PM/DM. The incidence of ILD was higher in SSc patients with anti-CCP antibody than in those without. The usual interstitial pneumonia (UIP) incidence was higher in the anti-CCP antibody-positive group than in the anti-CCP antibody-negative group. The DLCO was lower in the anti-CCP antibody-positive group than in the anti-CCP antibody-negative group. On multivariable analysis, factors associated with SSc-ILD were anti-CCP antibody or rheumatoid factor (β coefficient, 2.652 [95% CI 1.472 to 4.776]) and anti-Scl70 antibody (β coefficient, 4.011 [95% CI 2.142 to 7.508]). Anti-CCP antibody may be associated with a higher incidence of ILD in SSc. SSc patients with anti-CCP antibody may have more UIP pattern and lower DLCO.Trial Registration Retrospectively registered.

Clinical relevance of circulating autoantibodies in idiopathic pulmonary fibrosis; A NAt hard to break

Patients with idiopathic pulmonary fibrosis are screened for circulating autoantibodies as part of the initial interstitial lung disease workup. Management of seropositive idiopathic pulmonary fibrosis is currently considered no different than that of lone idiopathic pulmonary fibrosis. Emerging data however suggest that the former may possess distinct characteristics in terms of pathophysiology, histopathology, prognosis and amenability to immunomodulation. In that context, the aim of our study was to evaluate the influence of autoantibody status on: (i) the decline of forced vital capacity; (ii) the decline of diffusing capacity of lung for carbon monoxide; and (iii) 3-year survival; in a cohort of 102 idiopathic pulmonary fibrosis patients. In a pilot sub-study, we also sought to evaluate whether changes in antibody status during disease course affect the aforementioned parameters by potentially reflecting activity of the autoimmunity component of the pro-fibrotic mechanism.

Antineutrophil cytoplasmic antibody-associated interstitial lung disease: a review

Over the past three decades, an increasing number of publications have reported the association between interstitial lung disease (ILD) and anti-neutrophil cytoplasmic antibody (ANCA) or ANCA-associated vasculitis (AAV). With this increased awareness, we have reviewed the literature to date and provide an update in this narrative review. The vast majority of cases of ILD have been shown to be in the setting of positive anti-myeloperoxidase antibody and can be present in up to 45% of patients of microscopic polyangiitis, though cases of ILD associated with proteinase 3 ANCA have rarely been reported. Pulmonary fibrosis and ANCA positivity can occur with or without systemic involvement. The pathogenetic mechanisms establishing the relationship between ANCA and the development of pulmonary fibrosis remain unclear. Histologic and radiographic features of ANCA-ILD most commonly reveal usual interstitial pneumonia or non-specific interstitial pneumonia patterns, though other atypical features such as bronchiolitis have been described. ILD in the setting of AAV has been associated with worse outcomes, and thus early identification and treatment in these patients is appropriate. We advocate that ANCA antibody testing be performed as a baseline evaluation in patients presenting with idiopathic interstitial pneumonia. Suggested treatment of ANCA-ILD includes immunosuppression and/or antifibrotic agents, though supporting data and clinical trials to substantiate use of these therapies are needed.

Interstitial Lung Disease and Anti-Myeloperoxidase Antibodies: Not a Simple Association

Anti-neutrophil cytoplasmic antibodies (ANCA), mainly anti-myeloperoxidase (MPO) antibodies, have been frequently identified in patients with idiopathic pulmonary fibrosis (IPF). However, their role remains unclear, and only 7–23% of these patients develops clinically overt vasculitis. We aimed to investigate the clinical, serological, and radiological features and prognosis of anti-MPO-positive interstitial lung disease (ILD) patients. Fifty-eight consecutive patients firstly referred for idiopathic interstitial pneumonia and showing serological positivity of anti-MPO antibodies were retrospectively enrolled. For each patient, clinical data, lung function testing, chest high-resolution computed tomography (HRCT) pattern, and survival were recorded. Thirteen patients developed a rheumatic disease during a median follow-up of 39 months. Usual interstitial pneumonia (UIP) was the most frequent ILD pattern, significantly influencing the patients’ survival. In fact, while the 52-week survival of the overall population was 71.4 ± 7.5%, significantly higher than IPF, survivals of anti-MPO patients with UIP pattern and IPF were similar. Forced vital capacity and diffusion lung capacity for CO significantly declined in 37.7 and 41.5% of cases, respectively, while disease progression at chest HRCT was observed in 45.2%. A careful clinical history and evaluation should always be performed in ILD patients with anti-MPO antibodies to quickly identify patients who are developing a systemic rheumatic disease.

Clinical features and long-term outcomes of interstitial lung disease with anti-neutrophil cytoplasmic antibody

Background

Patients with interstitial lung disease (ILD) are occasionally positive for anti-neutrophil cytoplasmic antibodies (ANCAs). Differences between ILDs secondary to microscopic polyangiitis (MPA) and isolated ANCA-positive idiopathic interstitial pneumonia (IIP) remain unclear. The aim of this study was to explore the differences in clinical features and outcomes between MPA-associated ILDs and isolated ANCA-positive IIPs.

Methods

We reviewed 1338 ILDs patients with available ANCA results and retrospectively analysed 80 patients who were ANCA-positive. MPA-associated ILDs (MPA-ILDs group) and isolated ANCA-positive IIPs (ANCA-IIPs group) were compared.

Results

Among 80 patients with ANCA-positive ILDs, 31 (38.75%) had MPA-ILDs, and 49 (61.25%) had isolated ANCA-positive IIPs. Compared with ANCA-IIPs group, patients in MPA-ILDs group had a higher proportion of fever (p = 0.006) and higher neutrophil count (p = 0.011), erythrocyte sedimentation rate (ESR) (p < 0.001) and C-reactive protein (CRP) (p = 0.005). Multivariable analysis showed that ESR level was an independent risk factor for mortality in all 80 ANCA-positive ILDs patients (HR 1.028, p = 0.001). Survival in MPA-ILDs group was lower than that in ANCA-IIPs group, and further stratified analysis revealed that ANCA-IIPs patients with elevated ESR or CRP had a worse prognosis than those with normal inflammation markers, with 5-year cumulative survival rates of 60.00%, 86.90% and 100.00% in MPA-ILDs and ANCA-IIPs with and without elevated inflammation markers, respectively.

Conclusions

Among patients with ANCA-positive ILDs, the prognoses of ANCA-IIPs with normal inflammation markers, ANCA-IIPs with elevated inflammation markers and MPA-ILDs were sequentially poorer. Therefore, stratified treatment should be considered in the management of ILDs patients positive for ANCAs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01451-4.

Interstitial pneumonia with autoimmune features

Interstitial lung disease (ILD) is an umbrella term for lung disease characterised by inflammation and fibrosis of the interstitium. ILD can be idiopathic or secondary to connective tissue disorders, drugs or environmental exposures. Before labelling it as idiopathic we have to rule out secondary causes. ILD is one of the most common extra-articular manifestations of connective tissue diseases (CTDs), causing significant morbidity and mortality. Patients with pre-existing CTD can develop ILD; some patients develop ILD against the background of either one or two clinical features of a CTD or isolated auto-antibody positivity. The current terminology for such an entity is interstitial pneumonia with autoimmune features (IPAF). The current criterion is based on three domains: clinical, serologic and morphologic. To satisfy the IPAF classification criteria, one needs to satisfy the mandatory criterion with one feature from two of the three domains. Classifying patients with this criterion helps in early initiation of immunosuppression and in monitoring them closely for development of features of a well defined CTD. There are a few limitations like the clinical domain being more skewed towards systemic sclerosis and in˜flammatory myositis, exclusion of antineutrophilic cytoplasmic antibody (ANCA) and cytoplasmic pattern in antinuclear antibody (ANA). There are no clear protocols for treatment of IPAF and most of the data has been extrapolated from the management of systemic sclerosis (SSc) ILD and idiopathic non-specific c interstitial pneumonia (NSIP). Progressive disease in spite of treatment demands stronger immunosuppressive agents. Studies on the role of antifibrotics in IPAF are underway, with few small studies showing positive outcomes. There are con˜flicting reports on the survival and outcome of the IPAF cohort. Certain studies suggest that they have better survival compared with idiopathic pulmonary fibrosis (IPF) though other studies contradict this statement.

Revisiting Cell Death Responses in Fibrotic Lung Disease: Crosstalk between Structured and Non-Structured Cells

Fibrosis is a life-threatening disorder caused by excessive formation of connective tissue that can affect several critical organs. Innate immune cells are involved in the development of various disorders, including lung fibrosis. To date, several hematopoietic cell types have been implicated in fibrosis, including pro-fibrotic monocytes like fibrocytes and segregated-nucleus-containing atypical monocytes (SatMs), but the precise cellular and molecular mechanisms underlying its development remain unclear. Repetitive injury and subsequent cell death response are triggering events for lung fibrosis development. Crosstalk between lung structured and non-structured cells is known to regulate the key molecular event. We recently reported that RNA-binding motif protein 7 (RBM7) expression is highly upregulated in the fibrotic lung and plays fundamental roles in fibrosis development. RBM7 regulates nuclear degradation of NEAT1 non-coding RNA, resulting in sustained apoptosis in the lung epithelium and fibrosis. Apoptotic epithelial cells produce CXCL12, which leads to the recruitment of pro-fibrotic monocytes. Apoptosis is also the main source of autoantigens. Recent studies have revealed important functions for natural autoantibodies that react with specific sets of self-antigens and are unique to individual diseases. Here, we review recent insights into lung fibrosis development in association with crosstalk between structured cells like lung epithelial cells and non-structured cells like migrating immune cells, and discuss their relevance to acquired immunity through natural autoantibody production.

Clinical significance of autoantibody positivity in idiopathic pulmonary fibrosis

RATIONALE

The concept of interstitial pneumonia with autoimmune features (IPAF) was recently proposed by the American Thoracic Society. However, the clinical significance of the serologic domain of IPAF has not yet been established in idiopathic pulmonary fibrosis (IPF).

OBJECTIVES

We aimed to investigate the clinical significance of autoantibody positivity in IPF.

METHODS

We retrospectively reviewed the records of 512 patients diagnosed as IPF from January 2007 through March 2014. The patients were divided into two subgroups: (i) an autoantibody-positive IPF subgroup (n = 138), consisting of patients with anti-neutrophil cytoplasmic antibody (ANCA) or autoantibodies that met the criteria for the IPAF serologic domain; (ii) a lone IPF subgroup (n = 374), consisting of the rest of the IPF patients.

MEASUREMENTS AND MAIN RESULTS

Autoantibody-positivity (HR 0.736, p = 0.043) was an independent risk factors for 5-year mortality on multivariable analysis in the overall IPF patients. In the autoantibody-positive IPF patients, use of glucocorticoid (not for management of acute exacerbation, HR 2.121, p = 0.019), use of immunomodulators (HR 0.310, p = 0.002), malignancy (HR 3.359, p = 0.002), baseline forced vital capacity (HR 0.974, p = 0.017), baseline diffusing capacity of the lung for carbon monoxide (HR 0.981, p = 0.041), and baseline 6-min walk test distance (HR 0.996, p = 0.002) were independent risk factors for 5-year mortality.

CONCLUSIONS

Presence of ANCA or autoantibodies of the IPAF serologic domain in IPF patients is associated with better survival outcomes, and the use of immunomodulators is associated with superior survival outcomes.

Frequency and clinical relevance of anti-cyclic citrullinated peptide antibody in idiopathic interstitial pneumonias

RATIONALE

Although anti-cyclic citrullinated peptide antibody (ACPA) is highly specific for rheumatoid arthritis (RA), some patients with idiopathic interstitial pneumonia (IIP) are ACPA-positive, but do not fulfill the diagnostic criteria for RA. The clinical significance of ACPA in such patients is as yet unclear.

OBJECTIVE

We aimed to investigate the frequency of ACPA positivity and its clinical significance in patients initially diagnosed with IIP.

METHODS

We retrospectively analyzed 370 consecutive patients who were diagnosed with IIP and for whom serum ACPA results were available. The incidence of ACPA positivity and its predictive role for subsequent onset of RA was examined. Risk factors for development of RA were evaluated by Cox hazards analysis.

RESULTS

Of 370 patients, 24 (6.5%) were ACPA-positive, including 7 of 144 patients (4.9%) initially diagnosed with idiopathic pulmonary fibrosis (IPF) and 17 of 226 patients (7.5%) with non-IPF. The cumulative 3-year incidence of overt RA was significantly higher in patients who were positive rather than negative for ACPA (28.9% vs. 1.1%, P < 0.01). On multivariate analysis, younger age was independently associated with development of RA in patients who were ACPA-positive (per one year increase: hazard ratio = 0.93, 95% confidence interval 0.87-0.99, P = 0.03).

CONCLUSION

Among patients initially diagnosed with IIP, a small proportion was positive for ACPA, of whom approximately one-third subsequently developed RA within 3 years from IIP diagnosis. Clinicians should be alert to the possibility of RA developing in patients with IIP who are ACPA-positive, particularly those patients who are younger.

Systematic review and meta-analysis of clinical significance of autoantibodies for idiopathic pulmonary fibrosis

OBJECTIVE

To clarify clinical significance of the sole presence of autoantibodies for idiopathic pulmonary fibrosis (IPF) without any other symptoms or signs suggestive of autoimmune disease.

DESIGN

Systematic review and meta-analysis DATA SOURCES: Medline, EMBASE, Science Citation Index Expanded and Google Scholar were searched from 1 January 2002 through 12 February 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Primary studies addressing all-cause mortality and the development of a defined autoimmune disease for IPF with autoantibodies were included for the review.

DATA EXTRACTION AND SYNTHESIS

Two reviewers extracted relevant data and assessed risk of bias independently. Meta-analysis was conducted using a random-effects model if three or more studies reported the same outcome for a certain autoantibody. The quality of evidence was assessed by the Grades of Recommendation, Assessment, Development and Evaluation system.

RESULTS

Out of 4603 records retrieved nine studies were included in this review. All studies contained some risk of bias. Based on pooled data myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) was significantly associated with microscopic polyangiitis incidence with risk ratio (RR) of 20.2 (95% CI: 7.22 to 56.4) and antinuclear antibody (ANA) was also significantly associated with the development of connective tissue diseases with RR of 7.11 (p=0.001) (10 cases in 157 patients with ANA) in one study. However, there was no significant association of autoantibodies with all-cause mortality aside from MPO-ANCA and proteinase 3-ANCA in one study each. MPO-ANCA was not demonstrated to be associated with all-cause mortality by meta-analysis. The quality of evidence was deemed as either low or very low.

CONCLUSIONS

The presence of autoantibodies such as MPO-ANCA and ANA was demonstrated to be associated with the development of some autoimmune diseases for patients with IPF although there was no difference of all-cause mortality. However, the results should be interpreted with caution due to low evidence level.

PROSPERO REGISTRATION NUMBER

CRD42017077336.

Autoantibody status is not associated with change in lung function or survival in patients with idiopathic pulmonary fibrosis

INTRODUCTION

A proportion of patients with idiopathic pulmonary fibrosis (IPF) have autoantibodies directed against intracellular targets. This study aimed to determine the relationship between serologic status, lung function decline and survival.

METHODS

IPF patients assessed for antinuclear antibody (ANA) and related antigen-specific serology detected by addressable laser bead immunoassay (ALBIA) were included. Demographics, serial pulmonary function tests and survival were compared between patients with and without autoantibodies. Linear mixed models were used to estimate changes in forced vital capacity (FVC) and diffusion capacity for carbon monoxide (DLCO) over time. Cox-proportional hazards models were used to compare survival, adjusted for a composite score including age, sex and baseline lung function.

RESULTS

Of 61 included patients, the mean baseline age was 70 years (SD = 9), 77% were male, and 87% were Caucasian. Either ANA or antigen-specific serology by ALBIA was positive in 25 (41%) during follow-up. ANA was detected in 23 (38%), and specific autoantibodies by ALBIA in 6 (10%). There was no difference in age, sex, race, smoking status, anti-fibrotic use or baseline FVC or DLCO in patients with and without autoantibodies. There was no association between autoantibody status and survival (HR = 1.18, 95% CI 0.61, 2.29), rate of decline in FVC or DLCO (difference in FVC = 4.2 mL/year, p = 0.82; difference in DLCO = 4.6*10^-4mL/min/mmHg/year, p = 0.20).

CONCLUSION

These data suggest that autoantibodies are common in IPF and that patients with a subset of autoantibodies, but without features of autoimmunity, demonstrate similar disease behaviour to those without autoantibodies.

Prognosis and Follow-Up of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF), a devastating progressive interstitial lung disease (ILD) with no known cause, is the most common and deadly of the idiopathic interstitial pneumonias. With a median survival of 3⁻5 years following diagnosis, IPF is characterized by a progressive decline in lung function and quality of life in most patients. Prognostic factors recognized classically that influence mortality include functional, clinical and radiological parameters. However, in recent years, there has also been progress in the knowledge of genetic factors and biomarkers that may be useful in the prognostic evaluation of these patients. On the other hand, the monitoring of the disease throughout its evolution is key to improving the prognosis of the patients, as it allows for taking therapeutic measures based on this evolution, even early remission for lung transplantation. This article reviews the main prognostic factors of the disease, as well as the most useful way to monitor the disease follow-up.

N-acetylcysteine exposure is associated with improved survival in anti-nuclear antibody seropositive patients with usual interstitial pneumonia

Background

Mortality is similarly high among individuals with usual interstitial pneumonia (UIP) due to idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with autoimmune features (IPAF). Circulating anti-nuclear antibodies (ANA) are commonly found in this patient population, suggesting possible aberrant immune activation. Because an environment of oxidative stress can result from immunologic activation, we hypothesized that ANA positive patients with UIP would have improved outcome when exposed to the antioxidant N-acetylcysteine (NAC) compared to ANA negative patients.

Methods

A single center, retrospective cohort analysis was performed. Patients with UIP due to IPF and IPAF were stratified according to ANA status to and NAC exposure. Transplant-free survival (TFS) was assessed using the Kaplan-Meier estimator and multivariable Cox regression adjusted for diagnosis, gender/age/physiology score, immunosuppressant exposure and anti-fibrotic exposure.

Results

Of 293 individuals with UIP due to IPF (74%) or IPAF (26%), NAC exposure was documented in 58 (19.8%). Among NAC exposed individuals, 33 (56.9%) were ANA seropositive and 25 (43.1%) were seronegative. NAC exposure was associated with improved TFS survival among ANA seropositive individuals in unadjusted analysis (p_logrank = 0.02) and after multi-variable adjustment (HR 0.51, 95% CI 0.30–0.87; p = 0.01). There was no association between NAC exposure and TFS in ANA seronegative individuals (HR 1.26, 95% CI 0.69–2.32; p = 0.45). Formal interaction testing confirmed NAC*ANA interaction (p = 0.04) and sensitivity analysis demonstrated an increasing effect size associated with NAC therapy as ANA titer increased. Among patients with available genetic data, a marginally higher proportion of ANA positive patients (p = 0.08) carried the rs3750920 (TOLLIP) genotype previously shown to predict favorable outcome in NAC exposed patients.

Conclusion

NAC exposure is associated with improved transplant-free survival ANA positive patients with UIP. These findings support the prospective collection of ANA data in in future NAC clinical trials performed in patients with UIP.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0599-3) contains supplementary material, which is available to authorized users.

The interstitial lung disease multidisciplinary meeting: A position statement from the Thoracic Society of Australia and New Zealand and the Lung Foundation Australia

Interstitial lung diseases (ILD) are a diverse group of pulmonary diseases for which accurate diagnosis is critical for optimal treatment outcomes. Diagnosis of ILD can be challenging and a multidisciplinary approach is recommended in international guidelines. The purpose of this position paper is to review the evidence for the use of the multidisciplinary meeting (MDM) in ILD and suggest an approach to its governance and constitution, in an attempt to provide a standard methodology that could be applied across Australia and New Zealand. This position paper is endorsed by the Thoracic Society of Australia and New Zealand (TSANZ) and the Lung Foundation Australia (LFA).

Utility of autoimmune serology testing in the assessment of uncharacterized interstitial lung disease: a large retrospective cohort review

BACKGROUND

Autoimmune serologies are often obtained in the initial evaluation of uncharacterized interstitial lung disease (ILD). Whether this practice is helpful in delineating connective-tissue disease related ILD (CTD-ILD) is not well known. We assessed the frequency of incident CTD-ILD as detected by autoimmune serology testing and presenting clinical signs and symptoms.

METHODS

Consecutive patients seen at our institution over a four year period with newly diagnosed uncharacterized ILD and autoimmune serologic testing were included. Serologic assessment was performed as a standardized order set of 13 laboratory tests. Presenting demographics and clinical signs or symptoms suggestive of autoimmune disease were correlated with the presence or absence of positive serology studies and final CTD-ILD diagnoses.

RESULTS

Overall prevalence of newly diagnosed CTD-ILD was 6.9% (42 of 605). Positive serology was seen in 35.2% (213 of 605) of screened ILD. CTD-ILD was diagnosed in 19.2% of those with positive serology, and 52.8% of those with both positive serology and suggestive clinical signs or symptoms. Only 1.4% of those with positive serology and negative review of systems were diagnosed with CTD-ILD. CTD-ILD diagnoses were made more frequently in younger patients ≤60 years with no diagnoses made after the age of 80 (P = 0.009). Positive serology in non-CTD-ILD cases did not appear to confer any survival advantage.

CONCLUSIONS

The yield of autoimmune serology testing in uncharacterized ILD appears greatest in those with suggestive clinical signs or symptoms on presentation for CTD-ILD.

Role of Autoantibodies in the Diagnosis of Connective-Tissue Disease ILD (CTD-ILD) and Interstitial Pneumonia with Autoimmune Features (IPAF)

The diagnosis of interstitial lung disease (ILD) requires meticulous evaluation for an underlying connective tissue disease (CTD), with major implications for prognosis and management. CTD associated ILD (CTD-ILD) occurs most commonly in the context of an established CTD, but can be the first and/or only manifestation of an occult CTD or occur in patients who have features suggestive of an autoimmune process, but not meeting diagnostic criteria for a defined CTD-recently defined as "interstitial pneumonia with autoimmune features" (IPAF). The detection of specific autoantibodies serves a critical role in the diagnosis of CTD-ILD, but there remains a lack of data to guide clinical practice including which autoantibodies should be tested on initial assessment and when or in whom serial testing should be performed. The implications of detecting autoantibodies in patients with IPAF on disease behaviour and management remain unknown. The evaluation of CTD-ILD is challenging due to the heterogeneity of presentations and types of CTD and ILD that may be encountered, and thus it is imperative that immunologic tests are interpreted in conjunction with a detailed rheumatologic history and examination and multidisciplinary collaboration between respiratory physicians, rheumatologists, immunologists, radiologists and pathologists.

Interstital lung disease in ANCA vasculitis

Anti-neutrophil cytoplasmic antibodies (ANCA) vasculitides are immune-mediated disorders that primarily affect small blood vessels of the airway and kidneys. Lung involvement, one of the hallmarks of microscopic polyangiitis and granulomatosis with polyangiitis, is associated with increased mortality and morbidity. In recent years, several retrospective series and case reports have described the association of interstitial lung disease (ILD) and ANCA vasculitis, particularly those positive for ANCA specific for myeloperoxidase. In the majority of these patients pulmonary fibrosis occurs concurrently or predates the diagnosis of ANCA vasculitis. More importantly, these studies have shown that ILD has an adverse impact on the long-term prognosis of ANCA vasculitis. This review focuses on the main clinical and radiologic features of pulmonary fibrosis associated with anti-neutrophil cytoplasmic antibodies. Major histopathology features, prognosis and therapeutic options are summarized.

Interstitial pneumonia related to undifferentiated connective tissue disease: pathologic pattern and prognosis

BACKGROUND

Undifferentiated connective tissue disease (UCTD) involves conditions characterized by both having symptoms of connective tissue disease (CTD) and autoantibodies but not fulfilling the criteria of a specific CTD. The frequency or prognosis of the usual interstitial pneumonia (UIP) pattern in UCTD is unknown, which may be confused with idiopathic pulmonary fibrosis (IPF). This study aimed to investigate the frequency of the UIP pattern in interstitial pneumonia related to UCTD and compare its prognosis with that of IPF and UCTD-nonspecific interstitial pneumonia (UCTD-NSIP).

METHODS

The medical records of 788 patients presumptively diagnosed with idiopathic interstitial pneumonia at Asan Medical Center from January 2005 to December 2012 were retrospectively reviewed. UCTD was diagnosed according to the criteria by Corte and colleagues, and the prognoses were compared between UCTD-UIP and UCTD-NSIP and between UCTD-UIP and IPF.

RESULTS

Among 105 patients with UCTD (13.3% of total subjects), 44 had a UIP pattern (by surgical lung biopsy: 24; by high-resolution CT scan: 20), 29 had a nonspecific interstitial pneumonia pattern (by surgical lung biopsy), and nine had an organizing pneumonia pattern (by biopsy). The overall survival of the UCTD-UIP group was shorter than that of the UCTD-NSIP group (P = .021) but significantly better than that of the IPF group (P = .042).

CONCLUSIONS

A UIP pattern, which seems to be frequent in UCTD, showed a poorer prognosis than that of UCTD-NSIP. However, the prognosis of UCTD-UIP was significantly better than that of IPF, highlighting the importance of searching for underlying UCTD in suspected IPF cases.

Antineutrophil cytoplasmic antibody-positive conversion and microscopic polyangiitis development in patients with idiopathic pulmonary fibrosis

Background

Increasing evidence indicates that antineutrophil cytoplasmic antibody (ANCA)-positive conversion occurs in patients initially diagnosed with idiopathic pulmonary fibrosis (IPF) and as a result, some of these patients develop microscopic polyangiitis (MPA). However, the incidence density of these patients is not well known.

Objectives

To explore the incidence of ANCA-positive conversion and development of MPA during the disease course in patients with IPF and to evaluate whether corticosteroid therapy reduces MPA development in patients with IPF with myeloperoxidase (MPO)-ANCA positivity at diagnosis or who later acquire MPO-ANCA positivity.

Methods

We retrospectively analysed the medical records of 504 Asian patients with IPF treated at our institution in Saitama, Japan.

Results

Of the 504 patients with IPF, 20 (4.0%) had MPO-ANCA and 16 (3.2%) had PR-3-ANCA when first evaluated. In 264 of 504 patients with IPF, ANCA was measured repeatedly and seroconversion to MPO-ANCA and PR3-ANCA occurred in 15 (5.7%) and 14 (5.3%) patients, respectively, and 9 of 35 patients who were either MPO-ANCA positive at IPF diagnosis or who subsequently seroconverted developed MPA. None of the nine patients who developed MPA had been previously treated with steroids. The incidence of MPA tended to be lower in patients treated than not treated with corticosteroids although this was not statistically significant.

Conclusions

Some patients with IPF with MPO-ANCA positivity at IPF diagnosis or with MPO-ANCA-positive conversion during follow-up developed MPA. Clinical trials to determine whether corticosteroid therapy can reduce MPA development and prolong survival in MPO-ANCA-positive patients with IPF should be considered.

Organizing pneumonia preceding rheumatoid arthritis

Rheumatoid arthritis patients are susceptible to interstitial lung disease, and joint manifestations of rheumatoid arthritis usually precede lung involvements by several years. Organizing pneumonia, as the first manifestation of rheumatoid arthritis, is extremely rare, and its clinical features remain currently unknown. We present a case and a literature review of patients who were pathologically diagnosed with organizing pneumonia first and met the diagnostic criteria of rheumatoid arthritis later. In this review, we observed the following: (1) patients with organizing pneumonia preceding rheumatoid arthritis have a high prevalence of rheumatoid factor or anticyclic citrullinated peptide antibodies; (2) almost all patients developed rheumatoid arthritis within one year after the diagnosis of organizing pneumonia. We suggest that patients with organizing pneumonia and positive for either rheumatoid factor or anticyclic citrullinated peptide antibody should be cautiously followed up regarding the development of rheumatoid arthritis, particularly during the first year after the diagnosis of organizing pneumonia.