Sarcoidosis and interstitial pulmonary fibrosis; two distinct disorders or two ends of the same spectrum

High-Resolution CT Scan Fibrotic Patterns in Stage IV Pulmonary Sarcoidosis: Impact on Pulmonary Function and Survival

BACKGROUND

Different patterns of fibrosis on high-resolution CT scans (HRCT) have been associated with reduced survival in some interstitial lung diseases. Nothing is known about HRCT scan patterns and survival in sarcoidosis.

RESEARCH QUESTION

Will a detailed description of the extent and pattern of HRCT scan fibrosis in patients with stage IV pulmonary sarcoidosis impact pulmonary function and survival?

STUDY DESIGN AND METHODS

Two hundred forty patients with stage IV sarcoidosis at two large tertiary institutions were studied. The earliest HRCT scan with fibrosis was reviewed for extent of fibrosis (< 10%, 10%-20%, and > 20%) and presence of bronchiectasis, upper lobe fibrocystic changes, basal subpleural honeycombing, ground-glass opacities (GGOs), large bullae, and mycetomas. Presence of sarcoidosis-associated pulmonary hypertension (SAPH) and pulmonary function testing performed within 1 year of HRCT were recorded. Patients were followed up until last clinic visit, death, or lung transplantation.

RESULTS

The mean age was 58.4 years. Seventy-four percent were Black, 63% were female, and mean follow-up was 7.4 years. Death or LT occurred in 53 patients (22%). Thirty-one percent had > 20% fibrosis, 25% had 10%-20% fibrosis, and 44% had < 10% fibrosis. The most common HRCT abnormalities were bronchiectasis (76%), upper lobe fibrocystic changes (36%), and GGOs (28%). Twelve percent had basal subpleural honeycombing, and 32% had SAPH. Patients with > 20% fibrosis had more severe pulmonary impairment, were more likely to have SAPH (53%), and had worse survival (44% mortality; P < .001). Upper lobe fibrocystic changes, basal subpleural honeycombing, and large bullae were associated with worse pulmonary function and worse survival. Patients with basal subpleural honeycombing had the worst pulmonary function and survival (55% mortality; P < .001). GGOs were associated with worse pulmonary function but not worse survival, and mycetomas were associated with worse survival but not worse pulmonary function. A Cox proportional hazards model indicated that basal subpleural honeycombing (hazard ratio, 7.95), diffusion capacity for carbon monoxide < 40% (HR, 5.67) and White race (hazard ratio, 2.61) were independent predictors of reduced survival.

INTERPRETATION

HRCT scan features of fibrotic pulmonary sarcoidosis had an impact on pulmonary function and survival. Presence of >20% fibrosis and basal subpleural honeycombing are predictive of worse pulmonary function and worse survival in patients with stage IV pulmonary sarcoidosis.

Fibrotic Pulmonary Sarcoidosis

Fibrotic pulmonary sarcoidosis (fPS) affects about 20% of patients. fPS carries a significant morbidity and mortality. However, its prognosis is highly variable, depending mainly on fibrosis extent, functional impairment severity, and the development of pulmonary hypertension. Moreover, fPS outcomes are also influenced by several other complications, including acute exacerbations, and infections. fPS natural history is unknown, in particular regarding the risk of progressive self-sustaining fibrosis. The management of fPS is challenging, including anti-inflammatory treatment if granulomatous activity persists, rehabilitation, and in highly selected patients antifibrotic treatment and lung transplantation.

Sarcoidosis-associated pulmonary fibrosis: joining the dots

Sarcoidosis is a multisystem granulomatous disorder of unknown aetiology. A minority of patients with sarcoidosis develop sarcoidosis-associated pulmonary fibrosis (SAPF), which may become progressive. Genetic profiles differ between patients with progressive and self-limiting disease. The mechanisms of fibrosis in SAPF are not fully understood, but SAPF is likely a distinct clinicopathological entity, rather than a continuum of acute inflammatory sarcoidosis. Risk factors for the development of SAPF have been identified; however, at present, it is not possible to make a robust prediction of risk for an individual patient. The bulk of fibrotic abnormalities in SAPF are located in the upper and middle zones of the lungs. A greater extent of SAPF on imaging is associated with a worse prognosis. Patients with SAPF are typically treated with corticosteroids, second-line agents such as methotrexate or azathioprine, or third-line agents such as tumour necrosis factor inhibitors. The antifibrotic drug nintedanib is an approved treatment for slowing the decline in lung function in patients with progressive fibrosing interstitial lung diseases, but more evidence is needed to assess its efficacy in SAPF. The management of patients with SAPF should include the identification and treatment of complications such as bronchiectasis and pulmonary hypertension. Further research is needed into the mechanisms underlying SAPF and biomarkers that predict its clinical course.

Overview on the Link Between the Complement System and Auto-Immune Articular and Pulmonary Disease

Complement system (CS) dysregulation is a key factor in the pathogenesis of different autoimmune diseases playing a central role in many immune innate and adaptive processes. Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by ta breach of self-tolerance leading to a synovitis and extra-articular manifestations. The CS is activated in RA and seems not only to mediate direct tissue damage but also play a role in the initiation of RA pathogenetic mechanisms through interactions with citrullinated proteins. Interstitial lung disease (ILD) represents the most common extra-articular manifestation that can lead to progressive fibrosis. In this review, we focused on the evidence of CS dysregulation in RA and in ILD, and highlighted the role of the CS in both the innate and adaptive immune responses in the development of diseases, by using idiopathic pulmonary fibrosis as a model of lung disease. As a proof of concept, we dissected the evidence that several treatments used to treat RA and ILD such as glucocorticoids, pirfenidone, disease modifying antirheumatic drugs, targeted biologics such as tumor necrosis factor (TNF)-inhibitors, rituximab, tocilizumab, and nintedanib may act indirectly on the CS, suggesting that the CS might represent a potential therapeutic target in these complex diseases.

Sarcoidosis: Updates on therapeutic drug trials and novel treatment approaches

Sarcoidosis is a systemic granulomatous inflammatory disease of unknown etiology. It affects the lungs in over 90% of patients yet extra-pulmonary and multi-organ involvement is common. Spontaneous remission of disease occurs commonly, nonetheless, over 50% of patients will require treatment and up to 30% of patients will develop a chronic progressive non-remitting disease with marked pulmonary fibrosis leading to significant morbidity and death. Guidelines outlining an immunosuppressive treatment approach to sarcoidosis were recently published, however, the strength of evidence behind many of the guideline recommended drugs is weak. None of the drugs currently used for the treatment of sarcoidosis have been rigorously studied and prescription of these drugs is often based on off-label” indications informed by experience with other diseases. Indeed, only two medications [prednisone and repository corticotropin (RCI) injection] currently used in the treatment of sarcoidosis are approved by the United States Food and Drug Administration. This situation results in significant reimbursement challenges especially for the more advanced (and often more effective) drugs that are favored for severe and refractory forms of disease causing an over-reliance on corticosteroids known to be associated with significant dose and duration dependent toxicities. This past decade has seen a renewed interest in developing new drugs and exploring novel therapeutic pathways for the treatment of sarcoidosis. Several of these trials are active randomized controlled trials (RCTs) designed to recruit relatively large numbers of patients with a goal to determine the safety, efficacy, and tolerability of these new molecules and therapeutic approaches. While it is an exciting time, it is also necessary to exercise caution. Resources including research dollars and most importantly, patient populations available for trials are limited and thus necessitate that several of the challenges facing drug trials and drug development in sarcoidosis are addressed. This will ensure that currently available resources are judiciously utilized. Our paper reviews the ongoing and anticipated drug trials in sarcoidosis and addresses the challenges facing these and future trials. We also review several recently completed trials and draw lessons that should be applied in future.

Combined Sarcoidosis and Idiopathic Pulmonary Fibrosis (CSIPF): A New Phenotype or a Fortuitous Overlap? Scoping Review and Case Series

Idiopathic pulmonary fibrosis (IPF) and sarcoidosis are two distinct clinical entities with different aetiology, epidemiology, risk factors, symptoms and chest imaging. A number of papers have reported an overlap of the two diseases and have suggested the existence of a distinct phenotype defined as combined sarcoidosis and idiopathic pulmonary fibrosis (CSIPF). We used the scoping review protocol to review the literature on CSIPF. We also enrolled a cohort of nine CSIPF patients and compared them with lone-IPF and fibrotic sarcoidosis patients. Our CSIPF cohort showed male prevalence and only ex-smokers. Functional assessment at baseline showed mild to moderate restrictive impairment of lung volumes in lone-IPF and CSIPF patients, associated with moderate-to-severe reduction in DLco percentages. Although all CSIPF patients were on antifibrotic treatments, functional impairment occurred in the two years of follow up. This suggests the importance of considering these patients at high risk of rapid deterioration and lung damage.

Local and Systemic Concentrations of Pattern Recognition Receptors of the Lectin Pathway of Complement in a Cohort of Patients With Interstitial Lung Diseases

Background

The role of the lectin pathway of complement in the pathogenesis of interstitial lung diseases (ILDs) is largely unknown. Pattern recognition receptors (PRR) of the lectin pathway are involved in the clearance of apoptotic cells either via activation of the complement system or as direct opsonins. As recent findings suggest a role of apoptosis in the development of pulmonary fibrosis, the influence of plasma lectins has lately been considered in various ILDs, but data on local concentrations in the lungs are lacking. This study investigated the role of mannose-binding lectin (MBL), ficolin-2 and ficolin-3 in ILD patients with a focus on idiopathic pulmonary fibrosis (IPF) and sarcoidosis.

Methods

A case control study was conducted involving 80 patients with different forms of ILD as well as 40 control patients undergoing routine flexible bronchoscopy with bronchoalveolar lavage (BAL). Plasma and BAL fluid (BALF) levels of MBL, ficolin-2 and ficolin-3 as well as complement split products C4d and C5a (only in BALF) were measured by enzyme-linked immunosorbent assays. Eight single-nucleotide polymorphisms (SNPs) of MBL and ficolin-2 were determined by genotyping and tested for their association with ILDs.

Results

We included 35, 35, 10, and 40 patients with sarcoidosis, idiopathic pulmonary fibrosis (IPF), other ILD, and a control group, respectively. BALF but not plasma levels of the three PRR were significantly elevated in sarcoidosis patients compared to a control group without ILD (MBL: median 66.8 vs. 24.6 ng/ml, p = 0.02, ficolin-2: 140 vs. 58.8 ng/ml, p = 0.01, ficolin-3: 2523 vs. 1180 ng/ml, p = 0.02), whereas the frequency of the investigated SNPs was similar. In line, complement split products were markedly elevated in BALF of sarcoidosis patients (C4d, median 97.4 vs. 0 ng/ml, p = 0.10; C5a, 23.9 vs. 9.1 ng/ml, p = 0.01). There was a weak positive correlation of BALF ficolin-3 with serum neopterin, a marker of sarcoidosis activity. In IPF patients, we observed numerically higher MBL plasma and BALF levels (plasma, median 1511 vs. 879 ng/ml, p = 0.44; BALF, 37.5 vs. 24.6 ng/ml, p = 0.7) as well as lower ficolin-2 plasma levels (plasma 1111 vs. 1647 ng/ml, p = 0.11). Ficolin-2 plasma levels were inversely correlated with the forced vital capacity (r = 0.55, p = 0.1).

Conclusion

This is the first study to simultaneously assess systemic and local lectin pathway protein levels in ILD patients. Our data suggest an involvement of PRR of the lectin pathway in the pathogenesis of sarcoidosis given the significantly higher BALF levels compared to a control group. Additional analyses in a larger patient cohort are required to confirm or refute a potential effect of local and/or systemic ficolin-2 levels in IPF patients.

Radiographic and Histopathologic Features in Sarcoidosis: A Pictorial Display

Sarcoidosis is a multisystemic granulomatous disorder that can affect virtually any organ. However, pulmonary and thoracic lymph node involvement predominates; abnormalities on chest radiographs are present in 80 to 90% of patients with sarcoidosis. High-resolution computed tomographic (HRCT) scans are superior to chest X-rays in assessing extent of disease, and some CT features may discriminate an active inflammatory component (which may be amenable to therapy) from fibrosis (for which therapy is not indicated). Typical findings on HRCT include micronodules, perilymphatic and bronchocentric distribution, perihilar opacities, and varying degrees of fibrosis. Less common findings on CT include mass-like or alveolar opacities, miliary opacities, mosaic attenuation, honeycomb cysts, and cavitation. With progressive disease, fibrosis, architectural distortion, upper lobe volume loss with hilar retraction, coarse linear bands, cysts, and bullae may be observed. We discuss the salient CT findings in patients with sarcoidosis (with a major focus on pulmonary features) and present classical radiographic and histopathological images of a few extrapulmonary sites.

The Role of HMGB1, a Nuclear Damage-Associated Molecular Pattern Molecule, in the Pathogenesis of Lung Diseases

Significance: High-mobility group protein box 1 (HMGB1), a ubiquitous nuclear protein, regulates chromatin structure and modulates the expression of many genes involved in the pathogenesis of lung cancer and many other lung diseases, including those that regulate cell cycle control, cell death, and DNA replication and repair. Extracellular HMGB1, whether passively released or actively secreted, is a danger signal that elicits proinflammatory responses, impairs macrophage phagocytosis and efferocytosis, and alters vascular remodeling. This can result in excessive pulmonary inflammation and compromised host defense against lung infections, causing a deleterious feedback cycle. Recent Advances: HMGB1 has been identified as a biomarker and mediator of the pathogenesis of numerous lung disorders. In addition, post-translational modifications of HMGB1, including acetylation, phosphorylation, and oxidation, have been postulated to affect its localization and physiological and pathophysiological effects, such as the initiation and progression of lung diseases. Critical Issues: The molecular mechanisms underlying how HMGB1 drives the pathogenesis of different lung diseases and novel therapeutic approaches targeting HMGB1 remain to be elucidated. Future Directions: Additional research is needed to identify the roles and functions of modified HMGB1 produced by different post-translational modifications and their significance in the pathogenesis of lung diseases. Such studies will provide information for novel approaches targeting HMGB1 as a treatment for lung diseases.

New advances in the management of pulmonary sarcoidosis

Sarcoidosis is a highly variable granulomatous multisystem syndrome. It affects individuals in the prime years of life; both the frequency and severity of sarcoidosis are greater in economically disadvantaged populations. The diagnosis, assessment, and management of pulmonary sarcoidosis have evolved as new technologies and therapies have been adopted. Transbronchial needle aspiration guided by endobronchial ultrasound has replaced mediastinoscopy in many centers. Advanced imaging modalities, such as fluorodeoxyglucose positron emission tomography scanning, and the widespread availability of magnetic resonance imaging have led to more sensitive assessment of organ involvement and disease activity. Although several new insights about the pathogenesis of sarcoidosis exist, no new therapies have been specifically developed for use in the disease. The current or proposed use of immunosuppressive medications for sarcoidosis has been extrapolated from other disease states; various novel pathways are currently under investigation as therapeutic targets. Coupled with the growing recognition of corticosteroid toxicities for managing sarcoidosis, the use of corticosteroid sparing anti-sarcoidosis medications is likely to increase. Besides treatment of granulomatous inflammation, recognition and management of the non-granulomatous complications of pulmonary sarcoidosis are needed for optimal outcomes in patients with advanced disease.

Comparison of lymphocyte immune phenotypes in bronchoalveolar lavage of non-smoking patients with sarcoidosis and other interstitial lung diseases

Background

Bronchoalveolar lavage (BAL) as complementary method is still used as ancillary tool in diagnosis of interstitial lung diseases. Tobacco smoking has been described to affect the BAL lavage cellular profile. To our knowledge, only few reports have so far investigated CD3⁺CD4⁺ and CD3⁺CD8⁺ lymphocyte subsets in non-smoking sarcoidosis patients additionally stratified according to CXR stage, and compared them to other non-smoking patients with interstitial lung diseases (ILDs).

Methods

We compared lymphocytes immune phenotypes, subsets, with CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺ cell markers, in the non-smoking subjects (n=297) including the patients with pulmonary sarcoidosis (S), idiopathic pulmonary fibrosis (IPF) (n=22), hypersensitivity pneumonitis (HP) (n=15), other interstitial idiopathic pneumonias (OIIPs) (n=39). According to prognosis, the patients with S were divided into four groups: 18 patients with Löfgren's syndrome (LS) in chest X-ray (CXR) ≤1 stage, 64 patients without LS in CXR ≤1 stage, 113 patients in CXR 2 stage and 26 patients with advanced CXR ≥3 stage.

Results

After the use of false discovery rate (FDR) correction, relative numbers (%) of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ and CD3⁺CD4/CD3⁺CD8 ratio showed the most significant differences between the non-smokers with S (both with/without LS) and the non-smokers with other ILDs (IPF, OIIPs, HP). These lymphocytes subsets were further altered in the non-smokers with CXR stage 2 compared to the non-smokers with other ILDs (IPF, OIIPs, HP). We did not observe any differences in these lymphocyte subsets and CD3⁺CD4⁺/CD3⁺CD8⁺ ratio between the non-smokers with advanced sarcoidosis stage (CXR ≥3) and the non-smokers with IPF.

Conclusions

Our data on the non-smokers confirmed the presence of the typical BAL cellular profile in sarcoidosis. The BAL cellular profile was helpful namely for differentiation of less advanced sarcoidosis. Its definite diagnostic utility should be the subject of further clinical studies with large numbers of the well characterized patients taking into consideration other clinical factors influencing BAL cellular profile, such as smoking or treatment.

Advanced pulmonary sarcoidosis

PURPOSE OF REVIEW

To present an update on the most recent contributions in advanced pulmonary sarcoidosis (APS).

RECENT FINDINGS

Pathology is better described and the differences between fibrosing pulmonary sarcoidosis and usual interstitial pneumonia (UIP) are clarified. Serial spirometry is the most reliable tool for monitoring evolution. Survival may be predicted by an integrative algorithm based on pulmonary function and computed tomography (CT).

SUMMARY

APS is characterized by significant fibrocystic pulmonary lesions at CT and pathology. There are two main patterns of APS, one with predominant central bronchovascular distortion, often associated with airflow limitation, and the other with predominant honeycombing with a different location than in UIP with severe restrictive impairment and very low diffusion capacity of the lung for carbon monoxide. APS may be burnt out but is most often still active as evidenced by several findings, including on F-fluorodeoxyglucose-PET. There is an increased mortality and morbidity with chronic respiratory insufficiency, pulmonary hypertension stemming from multiple mechanisms, chronic pulmonary aspergillosis and extra infections. Acute worsening episodes are frequent. Serial spirometry, particularly forced vital capacity, is the most reliable tool for monitoring evolution. A new elegant algorithm based on pulmonary function and CT may predict survival. Despite important stakes, there is still a lack of therapeutic recommendations. However, the use of antisarcoidosis treatment is most often required at least as a temporary trial. Finally, the effect of pulmonary hypertension treatment has recently been the object of further evaluation.

Influence of age on manifestation, VC and TLCO values, and bronchoalveolar lavage cell counts of sarcoidosis and extrinsic allergic alveolitis

INTRODUCTION

Immune response probably changes during human life, being influenced by cumulative exposure to environmental factors and individual genetic background.

METHODS

Patients investigated for suspected interstitial lung disease were prospectively enrolled. After completing the diagnostic process, 121 patients were diagnosed extrinsic allergic alveolitis (EAA) and 136 sarcoidosis. Three groups according to age were established (<30 years, 30-60 years, >60 years), clinical manifestation, vital capacity (VC), forced expired volume in 1 s (FEV1 ), lung diffusing capacity for carbon monoxide-transfer factor (TLCO ) and bronchoalveolar lavage fluid (BALF) differential cell count were compared among the groups.

RESULTS

Age subgroups of EAA patients did not significantly differ in lung functions. In the group above 60 years, non-significantly higher neutrophils and eosinophils counts and CD4/CD8 ratio were observed. Sarcoidosis patients were significantly younger than EAA group and had significantly better lung functions (VC, FEV1 , TLCO ). Patients with sarcoidosis above 60 years of age had significantly higher percentages of neutrophils in BALF compared with younger patients. BALF percentage of neutrophils positively correlated with age.

CONCLUSIONS

Presented results may support the hypothesis that reactivity of immune system changes during the life, which may result in different manifestation of interstitial lung diseases according to age.

Meta-analysis of genetic programs between idiopathic pulmonary fibrosis and sarcoidosis

Background

Idiopathic pulmonary fibrosis (IPF) and pulmonary sarcoidosis are typical interstitial lung diseases with unknown etiology that cause lethal lung damages. There are notable differences between these two pulmonary disorders, although they do share some similarities. Gene expression profiles have been reported independently, but differences on the transcriptional level between these two entities have not been investigated.

Methods/Results

All expression data of lung tissue samples for IPF and sarcoidosis were from published datasets in the Gene Expression Omnibus (GEO) repository. After cross platform normalization, the merged sample data were grouped together and were subjected to statistical analysis for finding discriminate genes. Gene enrichments with their corresponding functions were analyzed by the online analysis engine “Database for Annotation, Visualization and Integrated Discovery” (DAVID) 6.7, and genes interactions and functional networks were further analyzed by STRING 9.0 and Cytoscape 3.0.0 Beta1. One hundred and thirty signature genes could potentially differentiate one disease state from another. Compared with normal lung tissue, tissue affected by IPF and sarcoidosis displayed similar signatures that concentrated on proliferation and differentiation. Distinctly expressed genes that could distinguish IPF from sarcoidosis are more enriched in processes of cilium biogenesis or degradation and regulating T cell activations. Key discriminative network modules involve aspects of bone morphogenetic protein receptor two (BMPR2) related and v-myb myeloblastosis viral oncogene (MYB) related proliferation.

Conclusions

This study is the first attempt to examine the transcriptional regulation of IPF and sarcoidosis across different studies based on different working platforms. Groups of significant genes were found to clearly distinguish one condition from the other. While IPF and sarcoidosis share notable similarities in cell proliferation, differentiation and migration, remarkable differences between the diseases were found at the transcription level, suggesting that the two diseases are regulated by overlapping yet distinctive transcriptional networks.

Interferon regulatory factor 5 polymorphisms in sarcoidosis

OBJECTIVE

Interferon regulatory factor 5 (IRF5) gene polymorphisms are associated with susceptibility to autoimmune diseases. The aim of this study is to determine the roles of IRF5 single-nucleotide polymorphisms (SNPs) in sarcoidosis.

METHODS

A total of 175 Japanese patients with biopsy-proven sarcoidosis and 150 sex-matched controls were genotyped for four IRF5 SNPs: rs729302A/C, rs2004640G/T, rs10954213A/G, and rs2280714G/A. The associations of these SNPs with susceptibility to sarcoidosis were examined.

RESULTS

Carriage of rs10954213A and rs2280714A conferred significant risks for sarcoidosis [carriage of rs10954213A: odds ratio (OR) = 1.96, 95% confidence interval (CI) = 1.15-3.33, P = 0.01, corrected P = 0.04; carriage of rs2280714A: OR = 1.97, 95% CI = 1.22-3.16, P = 0.005, corrected P = 0.02]. The haplotype carrying rs10954213A and rs2280714A (haplotype 2) was significantly associated with susceptibility to sarcoidosis (OR = 2.00, 95% CI = 1.24-3.24, P = 0.004, corrected P = 0.01). rs729302 and rs2004640 were not associated with susceptibility to sarcoidosis, whereas carriage of rs2004640G was protective against pulmonary hypertension (OR = 0.017, 95% CI = 0.002-0.15, P < 0.001, corrected P < 0.001).

CONCLUSION

A haplotype carrying two functional SNPs of IRF5, rs10954213A and rs2280714A, was associated with the risk of sarcoidosis in the Japanese population.

The treatment of pulmonary sarcoidosis

This manuscript offers an approach to the treatment of pulmonary sarcoidosis based on current available information. The treatment of pulmonary sarcoidosis is not mandatory as the disease may be self-limiting and therapy is often associated with significant drug side effects. The decision to treat rests predominantly on the presence of significant symptoms or functional limitation. Corticosteroids are the drug of choice. Alternative agents to corticosteroids may be useful primarily as corticosteroid sparing agents.

Floating between the poles of pathology and protection: can we pin down the granuloma in tuberculosis?

The granuloma in tuberculosis (TB), referred to as the tubercle, is a lesion containing multiple cell types and is the one definite hallmark of this disease. A number of tubercle phenotypes are seen during infection yet how these contribute to development of TB remains unclear. Here we highlight recent results using diverse models of tubercle development as well as recent findings from studies of human TB in an attempt to illustrate the plasticity of the tubercle and to place it between the poles of pathology and protection. Such insights could lead to future interventions to address TB as a global health issue.