Leah J. Witt

TOLLIP, MUC5B, and the Response to N-Acetylcysteine among Individuals with Idiopathic Pulmonary Fibrosis

RATIONALE Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease of unknown etiology. The genes TOLLIP and MUC5B play important roles in lung host defense, which is an immune process influenced by oxidative signaling. Whether polymorphisms in TOLLIP and MUC5B modify the effect of immunosuppressive and antioxidant therapy in individuals with IPF is unknown. OBJECTIVES To determine whether single-nucleotide polymorphisms (SNPs) within TOLLIP and MUC5B modify the effect of interventions in subjects participating in the Evaluating the Effectiveness of Prednisone, Azathioprine, and N-Acetylcysteine in Patients with Idiopathic Pulmonary Fibrosis (PANTHER-IPF) clinical trial. METHODS SNPs within TOLLIP (rs5743890/rs5743894/rs5743854/rs3750920) and MUC5B (rs35705950) were genotyped. Interaction modeling was conducted with multivariable Cox regression followed by genotype-stratified survival analysis using a composite endpoint of death, transplantation, hospitalization, or a decline of ≥ 10% in FVC. MEASUREMENTS AND MAIN RESULTS Significant interaction was observed between N-acetylcysteine (NAC) therapy and rs3750920 within TOLLIP (P interaction = 0.001). After stratifying by rs3750920 genotype, NAC therapy was associated with a significant reduction in composite endpoint risk (hazard ratio, 0.14; 95% confidence interval, 0.02-0.83; P = 0.03) in those with a TT genotype, but a nonsignificant increase in composite endpoint risk (hazard ratio, 3.23; 95% confidence interval, 0.79-13.16; P = 0.10) was seen in those with a CC genotype. These findings were then replicated in an independent IPF cohort. CONCLUSIONS NAC may be an efficacious therapy for individuals with IPF with an rs3750920 (TOLLIP) TT genotype, but it was associated with a trend toward harm in those with a CC genotype. A genotype-stratified prospective clinical trial should be conducted before any recommendation regarding the use of off-label NAC to treat IPF.

Characterisation of patients with interstitial pneumonia with autoimmune features.

Patients with interstitial lung disease (ILD) may have features of connective tissue disease (CTD), but lack findings diagnostic of a specific CTD. A recent European Respiratory Society/American Thoracic Society research statement proposed criteria for patients with interstitial pneumonia with autoimmune features (IPAF). We applied IPAF criteria to patients with idiopathic interstitial pneumonia and undifferentiated CTD-ILD (UCTD). We then characterised the clinical, serological and morphological features of the IPAF cohort, compared outcomes to other ILD cohorts and validated individual IPAF domains using survival as an endpoint. Of 422 patients, 144 met IPAF criteria. Mean age was 63.2 years with a slight female predominance. IPAF cohort survival was marginally better than patients with idiopathic pulmonary fibrosis, but worse than CTD-ILD. A non-usual interstitial pneumonia pattern was associated with improved survival, as was presence of the clinical domain. A modified IPAF cohort of those meeting the clinical domain and a radiographic or histological feature within the morphological domain displayed survival similar to those with CTD-ILD. IPAF is common among patients with idiopathic interstitial pneumonia and UCTD. Specific IPAF features can identify subgroups with differential survival. Further research is needed to replicate these findings and determine whether patients meeting IPAF criteria benefit from immunosuppressive therapy. IPAF is common among patients with IIP and has distinct subgroups that demonstrate differential survival http://ow.ly/Z0ShD

HIF-1α is required for disturbed flow-induced metabolic reprogramming in human and porcine vascular endothelium

Hemodynamic forces regulate vascular functions. Disturbed flow (DF) occurs in arterial bifurcations and curvatures, activates endothelial cells (ECs), and results in vascular inflammation and ultimately atherosclerosis. However, how DF alters EC metabolism, and whether resulting metabolic changes induce EC activation, is unknown. Using transcriptomics and bioenergetic analysis, we discovered that DF induces glycolysis and reduces mitochondrial respiratory capacity in human aortic ECs. DF-induced metabolic reprogramming required hypoxia inducible factor-1α (HIF-1α), downstream of NAD(P)H oxidase-4 (NOX4)-derived reactive oxygen species (ROS). HIF-1α increased glycolytic enzymes and pyruvate dehydrogenase kinase-1 (PDK-1), which reduces mitochondrial respiratory capacity. Swine aortic arch endothelia exhibited elevated ROS, NOX4, HIF-1α, and glycolytic enzyme and PDK1 expression, suggesting that DF leads to metabolic reprogramming in vivo. Inhibition of glycolysis reduced inflammation suggesting a causal relationship between flow-induced metabolic changes and EC activation. These findings highlight a previously uncharacterized role for flow-induced metabolic reprogramming and inflammation in ECs. DOI: http://dx.doi.org/10.7554/eLife.25217.001

Benefit of adjunctive tacrolimus in connective tissue disease-interstitial lung disease.

We evaluated the safety and effectiveness of adjunctive tacrolimus therapy with conventional immunosuppression in patients with severe connective tissue disease-related interstitial lung disease (CTD-ILD). We included patients from our interstitial lung disease (ILD) registry with CTD-ILD, in whom tacrolimus was added to corticosteroids and an additional immunosuppressive agent. Demographic data, clinical features, lung function, radiographic images, and pathologic findings were reviewed. Effectiveness was assessed by comparing pulmonary function tests (PFTs) closest to tacrolimus initiation to PFTs approximately 6-12 months later. Corticosteroid dose at these time points was also evaluated. We report adverse events attributed to tacrolimus. Seventeen patients with CTD-ILD were included in adverse event analysis; twelve were included in efficacy analysis. Length of tacrolimus therapy ranged from 6 to 110 months (mean 38.8 months ± 31.4). The mean improvement in percent predicted total lung capacity was 7.5% ± 11.7 (p = 0.02). Forced vital capacity mean improvement was 7.4% ± 12.5 (p = 0.06). The average decrease in corticosteroid dose at follow-up was 20.3 mg ± 25.2 (p = 0.02) with complete discontinuation in six patients. No patients experienced a life-threatening adverse event attributed to tacrolimus. Tacrolimus can be effective and is well tolerated as an adjunctive therapy and allows tapering of corticosteroids.

Transforming Growth Factor (TGF)-β Promotes de Novo Serine Synthesis for Collagen Production

TGF-β promotes excessive collagen deposition in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF). The amino acid composition of collagen is unique due to its high (33%) glycine content. Here, we report that TGF-β induces expression of glycolytic genes and increases glycolytic flux. TGF-β also induces the expression of the enzymes of the de novo serine synthesis pathway (phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH)) and de novo glycine synthesis (serine hydroxymethyltransferase 2 (SHMT2)). Studies in fibroblasts with genetic attenuation of PHGDH or SHMT2 and pharmacologic inhibition of PHGDH showed that these enzymes are required for collagen synthesis. Furthermore, metabolic labeling experiments demonstrated carbon from glucose incorporated into collagen. Lungs from humans with IPF demonstrated increased expression of PHGDH and SHMT2. These results indicate that the de novo serine synthesis pathway is necessary for TGF-β-induced collagen production and suggest that this pathway may be a therapeutic target for treatment of fibrotic diseases including IPF.

TGF-β Promotes de novo Serine Synthesis for Collagen Production

TGF-β promotes excessive collagen deposition in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF). The amino acid composition of collagen is unique due to its high (33%) glycine content. Here, we report that TGF-β induces expression of glycolytic genes and increases glycolytic flux. TGF-β also induces the expression of the enzymes of the de novo serine synthesis pathway (phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH)) and de novo glycine synthesis (serine hydroxymethyltransferase 2 (SHMT2)). Studies in fibroblasts with genetic attenuation of PHGDH or SHMT2 and pharmacologic inhibition of PHGDH showed that these enzymes are required for collagen synthesis. Furthermore, metabolic labeling experiments demonstrated carbon from glucose incorporated into collagen. Lungs from humans with IPF demonstrated increased expression of PHGDH and SHMT2. These results indicate that the de novo serine synthesis pathway is necessary for TGF-β-induced collagen production and suggest that this pathway may be a therapeutic target for treatment of fibrotic diseases including IPF.

The Diagnosis and Treatment of Antisynthetase Syndrome.

Antisynthetase syndrome is an autoimmune condition, characterized by antibodies directed against an aminoacycl transfer RNA synthetase along with clinical features that can include interstitial lung disease (ILD), myositis, Raynaud’s phenomenon, and arthritis. There is a higher prevalence and increased severity of ILD in patients with antisynthetase syndrome, as compared with dermatomyositis and polymyositis, inflammatory myopathies with which it may overlap phenotypically. The diagnosis is made by a multidisciplinary approach, synthesizing rheumatology and pulmonary evaluations, along with serologic, radiographic, and occasionally muscle and/or lung biopsy results. Patients with antisynthetase syndrome often require multimodality immunosuppressive therapy to control the muscle and/or pulmonary manifestations of their disease. The long-term care of these patients mandates careful attention to the adverse effects and complications of chronic immunosuppressive therapy, and disease-related sequelae that can include progressive ILD necessitating lung transplantation, pulmonary hypertension, malignancy, and a decreased survival. It is expected that a greater awareness of the clinical features of this syndrome will allow for an earlier diagnosis and appropriate treatment to improve outcomes in patients with antisynthetase syndrome.

Interstitial Pneumonia With Autoimmune Features: Value of Histopathology

CONTEXT - Patients with idiopathic interstitial pneumonia may display evidence of autoimmunity without meeting criteria for a defined connective tissue disease. A recent European Respiratory Society/American Thoracic Society statement proposed research criteria for interstitial pneumonia with autoimmune features (IPAF), which includes findings from the clinical, serologic, and morphologic domains. OBJECTIVES - To investigate the importance of histopathologic criteria within the morphologic domain and to report our methodology for identifying these features. DESIGN - Patients with idiopathic interstitial pneumonia at the University of Chicago who underwent surgical lung biopsy or lung transplantation were assessed for IPAF histopathologic features, using the initial pathology interpretation in the electronic records. A focused rereview of available slides by a pulmonary pathologist was then performed for patients who failed to meet IPAF criteria on initial pathology assessment. RESULTS - Of 422 patients with idiopathic interstitial pneumonia, 176 (41.7%) underwent surgical lung biopsy or lung transplant. Forty-six of those 176 patients (26.1%) met IPAF criteria by initial pathology interpretation and a positive clinical or serologic feature. Of the remaining 130 patients, 73 (56.2%) met either the clinical or serologic domains without meeting the morphologic domain, whereas 36 (27.7%) had slides available for pathology rereview. This rereview demonstrated nonspecific interstitial pneumonia in 8 of 36 patients (22.2%) and lymphoplasmacytic infiltrates in 6 of 36 patients (16.7%), resulting in an additional 7 of 36 patients (19.4%) with idiopathic interstitial pneumonia that met the IPAF criteria. In IPAF, pulmonary vasculopathy was the most prevalent finding (45 of 84; 53.6%) and predicted increased mortality (hazard ratio, 2.5; P = .04). CONCLUSIONS - Using a methodological approach to identifying IPAF pathology, we demonstrate a significant increase in the number of patients meeting IPAF criteria because of focused pathologic review and highlight the prognostic value of the IPAF pathologic findings.

No Exit: Identifying Avoidable Terminal Oncology Intensive Care Unit Hospitalizations

PURPOSE Terminal oncology intensive care unit (ICU) hospitalizations are associated with high costs and inferior quality of care. This study identifies and characterizes potentially avoidable terminal admissions of oncology patients to ICUs. METHODS This was a retrospective case series of patients cared for in an academic medical centers ambulatory oncology practice who died in an ICU during July 1, 2012 to June 30, 2013. An oncologist, intensivist, and hospitalist reviewed each patients electronic health record from 3 months preceding terminal hospitalization until death. The primary outcome was the proportion of terminal ICU hospitalizations identified as potentially avoidable by two or more reviewers. Univariate and multivariate analysis were performed to identify characteristics associated with avoidable terminal ICU hospitalizations. RESULTS Seventy-two patients met inclusion criteria. The majority had solid tumor malignancies (71%), poor performance status (51%), and multiple encounters with the health care system. Despite high-intensity health care utilization, only 25% had documented advance directives. During a 4-day median ICU length of stay, 81% were intubated and 39% had cardiopulmonary resuscitation. Forty-seven percent of these hospitalizations were identified as potentially avoidable. Avoidable hospitalizations were associated with factors including: worse performance status before admission (median 2 v 1; P = .01), worse Charlson comorbidity score (median 8.5 v 7.0, P = .04), reason for hospitalization (P = .006), and number of prior hospitalizations (median 2 v 1; P = .05). CONCLUSION Given the high frequency of avoidable terminal ICU hospitalizations, health care leaders should develop strategies to prospectively identify patients at high risk and formulate interventions to improve end-of-life care.

Inhibition of Phosphoglycerate Dehydrogenase Attenuates Bleomycin-induced Pulmonary Fibrosis

&NA; Organ fibrosis, including idiopathic pulmonary fibrosis, is associated with significant morbidity and mortality. Because currently available therapies have limited effect, there is a need to better understand the mechanisms by which organ fibrosis occurs. We have recently reported that transforming growth factor (TGF)‐&bgr;, a key cytokine that promotes fibrogenesis, induces the expression of the enzymes of the de novo serine and glycine synthesis pathway in human lung fibroblasts, and that phosphoglycerate dehydrogenase (PHGDH; the first and rate‐limiting enzyme of the pathway) is required to promote collagen protein synthesis downstream of TGF‐&bgr;. In this study, we investigated whether inhibition of de novo serine and glycine synthesis attenuates lung fibrosis in vivo. We found that TGF‐&bgr; induces mRNA and protein expression of PHGDH in murine fibroblasts. Similarly, intratracheal administration of bleomycin resulted in increased expression of PHGDH in mouse lungs, localized to fibrotic regions. Using a newly developed small molecule inhibitor of PHGDH (NCT‐503), we tested whether pharmacologic inhibition of PHGDH could inhibit fibrogenesis both in vitro and in vivo. Treatment of murine and human lung fibroblasts with NCT‐503 decreased TGF‐&bgr;‐induced collagen protein synthesis. Mice treated with the PHGDH inhibitor beginning 7 days after intratracheal instillation of bleomycin had attenuation of lung fibrosis. These results indicate that the de novo serine and glycine synthesis pathway is necessary for TGF‐&bgr;‐induced collagen synthesis and bleomycin‐induced pulmonary fibrosis. PHGDH and other enzymes in the de novo serine and glycine synthesis pathway may be a therapeutic target for treatment of fibrotic diseases, including idiopathic pulmonary fibrosis.