YAP1-TFE3-fused hemangioendothelioma: a multi-institutional clinicopathologic study of 24 genetically-confirmed cases.

YAP1-TFE3-fused hemangioendothelioma is an extremely rare malignant vascular tumor. We present the largest multi-institutional clinicopathologic study of YAP1-TFE3-fused hemangioendothelioma to date. The 24 cases of YAP1-TFE3-fused hemangioendothelioma showed a female predominance (17 female, 7 male) across a wide age range (20-78 years old, median 44). Tumors were most commonly located in soft tissue (50%), followed by bone (29%), lung (13%), and liver (8%), ranging from 3 to 115 mm in size (median 40 mm). About two-thirds presented with multifocal disease, including 7 cases with distant organ metastasis. Histopathologically, we describe three dominant architectural patterns: solid sheets of coalescing nests, pseudoalveolar and (pseudo)vasoformative pattern, and discohesive strands and clusters of cells set in a myxoid to myxohyaline stroma. These patterns were present in variable proportions across different tumors and often coexisted within the same tumor. The dominant cytomorphology (88%) was large epithelioid cells with abundant, glassy eosinophilic to vacuolated cytoplasm, prominent nucleoli and well-demarcated cell borders. Multinucleated or binucleated cells, prominent admixed erythrocytic and lymphocytic infiltrates, and intratumoral fat were frequently present. Immunohistochemically, ERG, CD31, and TFE3 were consistently expressed, while expression of CD34 (83%) and cytokeratin AE1/AE3 (20%) was variable. CAMTA1 was negative in all but one case. All cases were confirmed by molecular testing to harbor YAP1-TFE3 gene fusions: majority with YAP1 exon 1 fused to TFE3 exon 4 (88%), or less commonly, TFE3 exon 6 (12%). Most patients (88%) were treated with primary surgical resection. Over a follow-up period of 4-360 months (median 36 months) in 17 cases, 35% of patients remained alive without disease, and 47% survived many years with stable, albeit multifocal and/or metastatic disease. Five-year progression-free survival probability was 88%. We propose categorizing YAP1-TFE3-fused hemangioendothelioma as a distinct disease entity given its unique clinical and histopathologic characteristics in comparison to conventional epithelioid hemangioendothelioma.

CDHR3 Asthma-Risk Genotype Affects Susceptibility of Airway Epithelium to Rhinovirus C Infections.

CDHR3 (cadherin-related family member 3) is a transmembrane protein that is highly expressed in airway epithelia and the only known receptor for rhinovirus C (RV-C). A CDHR3 SNP (rs6967330) with G to A base change has been linked to severe exacerbations of asthma and increased susceptibility to RV-C infections in young children. The goals of this study were to determine the subcellular localization of CDHR3 and to test the hypothesis that CDHR3 asthma-risk genotype affects epithelial cell function and susceptibility to RV-C infections of the airway epithelia. We used immunofluorescence imaging, Western blot analysis, and transmission electron microscopy to show CDHR3 subcellular localization in apical cells, including expression in the cilia of airway epithelia. Polymorphisms in CDHR3 rs6967330 locus (G→A) that were previously associated with childhood asthma were related to differences in CDHR3 expression and epithelial cell function. The rs6967330 A allele was associated with higher overall protein expression and RV-C binding and replication compared with the rs6967330 G allele. Furthermore, the rs6967330 A allele was associated with earlier ciliogenesis and higher FOXJ1 expression. Finally, CDHR3 genotype had no significant effects on membrane integrity or ciliary beat function. These findings provide information on the subcellular localization and possible functions of CDHR3 in the airways and link CDHR3 asthma-risk genotype to increased RV-C binding and replication.

A case of Pneumocystis pneumonia, with a granulomatous response and vitamin D-mediated hypercalcemia, presenting 13 years after renal transplantation.

Vitamin D-mediated hypercalcemia is an uncommon complication of Pneumocystis infection. A granulomatous response resulting from Pneumocystis infection is also atypical. In this report, we describe an exceptional case of granulomatous Pneumocystis pneumonia associated with vitamin D-mediated hypercalcemia, in a patient who presented unusually late after renal transplantation. The patient's hypercalcemia resolved with treatment of the infection.

Involvement of c-Jun N-Terminal Kinase in TNF-α-Driven Remodeling.

Lung tissue remodeling in chronic obstructive pulmonary disease (COPD) is characterized by airway wall thickening and/or emphysema. Although the bronchial and alveolar compartments are functionally independent entities, we recently showed comparable alterations in matrix composition comprised of decreased elastin content and increased collagen and hyaluronan contents of alveolar and small airway walls. Out of several animal models tested, surfactant protein C (SPC)-TNF-α mice showed remodeling in alveolar and airway walls similar to what we observed in patients with COPD. Epithelial cells are able to undergo a phenotypic shift, gaining mesenchymal properties, a process in which c-Jun N-terminal kinase (JNK) signaling is involved. Therefore, we hypothesized that TNF-α induces JNK-dependent epithelial plasticity, which contributes to lung matrix remodeling. To this end, the ability of TNF-α to induce a phenotypic shift was assessed in A549, BEAS2B, and primary bronchial epithelial cells, and phenotypic markers were studied in SPC-TNF-α mice. Phenotypic markers of mesenchymal cells were elevated both in vitro and in vivo, as shown by the expression of vimentin, plasminogen activator inhibitor-1, collagen, and matrix metalloproteinases. Concurrently, the expression of the epithelial markers, E-cadherin and keratin 7 and 18, was attenuated. A pharmacological inhibitor of JNK attenuated this phenotypic shift in vitro, demonstrating involvement of JNK signaling in this process. Interestingly, activation of JNK signaling was also clearly present in lungs of SPC-TNF-α mice and patients with COPD. Together, these data show a role for TNF-α in the induction of a phenotypic shift in vitro, resulting in increased collagen production and the expression of elastin-degrading matrix metalloproteinases, and provide evidence for involvement of the TNF-α-JNK axis in extracellular matrix remodeling.

Glutaredoxin-1 attenuates S-glutathionylation of the death receptor fas and decreases resolution of Pseudomonas aeruginosa pneumonia.

RATIONALE: The death receptor Fas is critical for bacterial clearance and survival of mice after Pseudomonas aeruginosa infection. OBJECTIVES: Fas ligand (FasL)-induced apoptosis is augmented by S-glutathionylation of Fas (Fas-SSG), which can be reversed by glutaredoxin-1 (Grx1). Therefore, the objective of this study was to investigate the interplay between Grx1 and Fas in regulating the clearance of P. aeruginosa infection. METHODS: Lung samples from patients with bronchopneumonia were analyzed by immunofluorescence. Primary tracheal epithelial cells, mice lacking the gene for Grx1 (Glrx1(-/-)), Glrx1(-/-) mice treated with caspase inhibitor, or transgenic mice overexpressing Grx1 in the airway epithelium were analyzed after infection with P. aeruginosa. MEASUREMENTS AND MAIN RESULTS: Patient lung samples positive for P. aeruginosa infection demonstrated increased Fas-SSG compared with normal lung samples. Compared with wild-type primary lung epithelial cells, infection of Glrx1(-/-) cells with P. aeruginosa showed enhanced caspase 8 and 3 activities and cell death in association with increases in Fas-SSG. Infection of Glrx1(-/-) mice with P. aeruginosa resulted in enhanced caspase activity and increased Fas-SSG as compared with wild-type littermates. Absence of Glrx1 significantly enhanced bacterial clearance, and decreased mortality postinfection with P. aeruginosa. Inhibition of caspases significantly decreased bacterial clearance postinfection with P. aeruginosa, in association with decreased Fas-SSG. In contrast, transgenic mice that overexpress Grx1 in lung epithelial cells had significantly higher lung bacterial loads, enhanced mortality, decreased caspase activation, and Fas-SSG in the lung after infection with P. aeruginosa, compared with wild-type control animals. CONCLUSIONS: These results suggest that S-glutathionylation of Fas within the lung epithelium enhances epithelial apoptosis and promotes clearance of P. aeruginosa and that glutaredoxin-1 impairs bacterial clearance and increases the severity of pneumonia in association with deglutathionylation of Fas.

Ablation of glutaredoxin-1 attenuates lipopolysaccharide-induced lung inflammation and alveolar macrophage activation.

Protein S-glutathionylation (PSSG), a reversible posttranslational modification of reactive cysteines, recently emerged as a regulatory mechanism that affects diverse cell-signaling cascades. The extent of cellular PSSG is controlled by the oxidoreductase glutaredoxin-1 (Grx1), a cytosolic enzyme that specifically de-glutathionylates proteins. Here, we sought to evaluate the impact of the genetic ablation of Grx1 on PSSG and on LPS-induced lung inflammation. In response to LPS, Grx1 activity increased in lung tissue and bronchoalveolar lavage (BAL) fluid in WT (WT) mice compared with PBS control mice. Glrx1(-/-) mice consistently showed slight but statistically insignificant decreases in total numbers of inflammatory cells recovered by BAL. However, LPS-induced concentrations of IL-1ß, TNF-α, IL-6, and Granulocyte/Monocyte Colony-Stimulating Factor (GM-CSF) in BAL were significantly decreased in Glrx1(-/-) mice compared with WT mice. An in situ assessment of PSSG reactivity and a biochemical evaluation of PSSG content demonstrated increases in the lung tissue of Glrx1(-/-) animals in response to LPS, compared with WT mice or PBS control mice. We also demonstrated that PSSG reactivity was prominent in alveolar macrophages (AMs). Comparative BAL analyses from WT and Glrx1(-/-) mice revealed fewer and smaller AMs in Glrx1(-/-) mice, which showed a significantly decreased expression of NF-κB family members, impaired nuclear translocation of RelA, and lower levels of NF-κB-dependent cytokines after exposure to LPS, compared with WT cells. Taken together, these results indicate that Grx1 regulates the production of inflammatory mediators through control of S-glutathionylation-sensitive signaling pathways such as NF-κB, and that Grx1 expression is critical to the activation of AMs.

Cigarette smoke targets glutaredoxin 1, increasing s-glutathionylation and epithelial cell death.

It is established that cigarette smoke (CS) causes irreversible oxidations in lung epithelial cells, and can lead to their death. However, its impact on reversible and physiologically relevant redox-dependent protein modifications remains to be investigated. Glutathione is an important antioxidant against inhaled reactive oxygen species as a direct scavenger, but it can also covalently bind protein thiols upon mild oxidative stress to protect them against irreversible oxidation. This posttranslational modification, known as S-glutathionylation, can be reversed under physiological conditions by the enzyme, glutaredoxin 1 (Grx1). The aim of this study was to investigate if CS modifies Grx1, and if this impacts on protein S-glutathionylation and epithelial cell death. Upon exposure of alveolar epithelial cells to CS extract (CSE), a decrease in Grx1 mRNA and protein expression was observed, in conjunction with decreased activity and increased protein S-glutathionylation. Using mass spectrometry, irreversible oxidation of recombinant Grx1 by CSE and acrolein was demonstrated, which was associated with attenuated enzyme activity. Furthermore, carbonylation of Grx1 in epithelial cells after exposure to CSE was shown. Overexpression of Grx1 attenuated CSE-induced increases in protein S-glutathionylation and increased survival. Conversely, primary tracheal epithelial cells of mice lacking Grx1 were more sensitive to CS-induced cell death, with corresponding increases in protein S-glutathionylation. These results show that CS can modulate Grx1, not only at the expression level, but can also directly modify Grx1 itself, decreasing its activity. These findings demonstrate a role for the Grx1/S-glutathionylation redox system in CS-induced lung epithelial cell death.

Pulmonary Pathology of COVID-19 Following 8 Weeks to 4 Months of Severe Disease: A Report of Three Cases, Including One With Bilateral Lung Transplantation.

OBJECTIVES: Current knowledge of the pulmonary pathology of coronavirus disease 2019 (COVID-19) is based largely on postmortem studies. In most, the interval between disease onset and death is relatively short (<1 month). Information regarding lung pathology in patients who survive for longer periods is scant. We describe the pathology in three patients with severe COVID-19 who underwent antemortem examination of lung tissue at least 8 weeks after initial diagnosis. METHODS: We conducted a retrospective case series. RESULTS: The first patient developed acute respiratory failure and was started on extracorporeal membrane oxygenation (ECMO) on day 21, with subsequent hemothorax. Debridement (day 38) showed extensive lung infarction with diffuse alveolar damage and Candida overgrowth. The second patient developed acute respiratory failure requiring mechanical ventilation that did not improve despite ECMO. Surgical lung biopsy on day 74 showed diffuse interstitial fibrosis with focal microscopic honeycomb change. The third patient also required ECMO and underwent bilateral lung transplantation on day 126. The explanted lungs showed diffuse interstitial fibrosis with focal microscopic honeycomb change. CONCLUSIONS: This series provides histologic confirmation that complications of COVID-19 after 8 weeks to 4 months of severe disease include lung infarction and diffuse interstitial fibrosis.

A 51-year-old man with chronic cough and left hilar prominence.

What is the diagnosis of this man with a chronic dry cough and left hilar prominence on chest radiography? https://bit.ly/3fL7QMx.

In situ analysis of protein S-glutathionylation in lung tissue using glutaredoxin-1-catalyzed cysteine derivatization.

Protein S-glutathionylation (PSSG) is a posttranslational modification that involves the conjugation of the small antioxidant molecule glutathione to cysteine residues and is emerging as a critical mechanism of redox-based signaling. PSSG levels increase under conditions of oxidative stress and are controlled by glutaredoxins (Grx) that, under physiological conditions, preferentially deglutathionylate cysteines and restore sulfhydryls. Both the occurrence and distribution of PSSG in tissues is unknown because of the labile nature of this oxidative event and the lack of specific reagents. The goal of this study was to establish and validate a protocol that enables detection of PSSG in situ, using the property of Grx to deglutathionylate cysteines. Using Grx1-catalyzed cysteine derivatization, we evaluated PSSG content in mice subjected to various models of lung injury and fibrosis. In control mice, PSSG was detectable primarily in the airway epithelium and alveolar macrophages. Exposure of mice to NO(2) resulted in enhanced PSSG levels in parenchymal regions, while exposure to O(2) resulted in minor detectable changes. Finally, bleomycin exposure resulted in marked increases in PSSG reactivity both in the bronchial epithelium as well as in parenchymal regions. Taken together, these findings demonstrate that Grx1-based cysteine derivatization is a powerful technique to specifically detect patterns of PSSG expression in lungs, and will enable investigations into regional changes in PSSG content in a variety of diseases.

Five simple reasons to discard DIP, or why we should stop calling dolphins big fish.

The aim of this review is to explain why the term 'desquamative interstitial pneumonia' (DIP) should be discarded and replaced with modern terminology. Reason 1: DIP is a misnomer. Within a few years after the term was coined, it was shown that the airspace cells in DIP are macrophages not desquamated pneumocytes. Reason 2: As a result of overly simplistic and poorly defined histologic criteria, DIP is currently a mixed bag of smoking-related diseases and unrelated processes in never-smokers. Reason 3: DIP obfuscates the modern concept that smoking causes some forms of parenchymal lung disease. Despite the fact that >80% of cases of DIP are caused by smoking, it is currently classified as a 'smoking-related idiopathic interstitial pneumonia', an oxymoron. Reason 4: The premise that the presence of numerous macrophages within airspaces defines an entity creates problematic histologic overlap with other lung diseases that may feature prominent airspace macrophages. Reason 5: DIP is outdated. It was coined in 1965, when many entities in interstitial lung disease had not been described, smoking-related interstitial lung disease was an unknown concept, computed tomograms of the chest had not been introduced and immunohistochemistry was unavailable. We suggest a way forward, which includes eliminating the term DIP and separating smoking-related lung abnormalities (including accumulation of pigmented airspace macrophages) from cases characterised by numerous non-pigmented macrophages in never-smokers. The laudable goal of smoking cessation is not served well by muddying the relationship between smoking and lung disease with inaccurate, outdated terminology.

Mediastinal Synovial Sarcoma: Clinicopathologic Analysis of 21 Cases With Molecular Confirmation.

Synovial sarcoma (SS), a translocation-associated sarcoma characterized by SS18-SSX1/2 fusion, presents most often in the extremities of young adults. While SS regularly occurs in the pleuropulmonary parenchyma, the mediastinum is an exceedingly rare primary site; the literature on this subject is predominantly composed of case reports and small series, mostly without molecular confirmation. Cases of mediastinal SS were selected from our institutional and consultation archives. Diagnoses were confirmed by either SS18 fluorescence in situ hybridization (n=6) or reverse transcription polymerase chain reaction for SS18-SSX1/2 (n=15). Mediastinal SSs occurred in 21 patients (15 men; mean age, 38 y; range, 21 to 75). Only 1 patient was older than 50 years. Average tumor size was 13.5 cm (range: 6.4 to 23 cm). One tumor was biphasic and the rest were monophasic, 11 of which were poorly differentiated (52%). Of 10 cases with known fusion transcripts, 6 had SS18-SSX2 and 4 had SS18-SSX1. Follow-up was known for 16 patients (mean: 18.9 mo; range: 5 to 45): 14 had local disease progression or recurrence, and 6 had metastasis. Death from disease occurred in 11 of 16 patients (69%) at 5 to 32 months, and 5 (36%) were alive with disease at last follow-up (6 to 45 mo). Mediastinal SS is a rare and aggressive malignancy most common in patients younger than 50 years. Most are monophasic and reach large size before detection. Poorly differentiated morphology is common. SS should be included in the differential diagnosis of spindle cell, biphasic and poorly differentiated mediastinal tumors. Because of the rarity of SS at this site, molecular testing is recommended to confirm the diagnosis.

Mycophenolate therapy in interstitial pneumonia with autoimmune features: a cohort study.

OBJECTIVES: International experts recently characterized interstitial pneumonia with autoimmune features (IPAF) as a provisional diagnosis for patients with interstitial lung disease who have characteristics of autoimmune disease but do not meet criteria for a specific autoimmune disease. We describe clinical characteristics of IPAF patients and examine responses to mycophenolate as a therapy for IPAF. METHODS: This retrospective cohort included adult patients meeting European Respiratory Society/American Thoracic Society classification criteria for IPAF. Sociodemographic, clinical, and pulmonary function test data were abstracted for patients with and without mycophenolate treatment and followed longitudinally from interstitial lung disease diagnosis for change in pulmonary function test results. RESULTS: We identified 52 patients who met criteria for IPAF. Of 52 IPAF patients, 24 did not receive mycophenolate and 28 did, with median time to mycophenolate treatment 22 months. Changes in FVC% and percentage predicted lung diffusion capacity for carbon monoxide (DLCO%) between the mycophenolate-treated and untreated groups were not significantly different (FVC% change P=0.08, DLCO% change P=0.17). However, there was a trend toward more rapid baseline decline of both FVC% and DLCO% in the mycophenolate-treated cohort before vs after mycophenolate therapy. The slope of both FVC% and DLCO% values improved after onset of mycophenolate exposure for the treated group, although this finding was not statistically significant. CONCLUSION: Patients with IPAF might benefit from mycophenolate therapy. Larger prospective clinical trials are needed to evaluate the efficacy of mycophenolate for patients who meet criteria for IPAF.

Loss of p16INK4A Expression and Homozygous CDKN2A Deletion Are Associated with Worse Outcome and Younger Age in Thymic Carcinomas.

INTRODUCTION: Thymic carcinomas are aggressive tumors. Biomarkers and alternative treatment modalities are needed. We studied the expression of p16 and cytogenetic abnormalities of cyclin-dependent kinase inhibitor 2A gene (CDKN2A) and correlated findings with clinical features and outcome in a large cohort of thymic carcinomas. METHODS: Thymic carcinomas (1963-2013) were stained with p16. Fluorescence in situ hybridization was utilized to assess for the presence of CDKN2A gene (at 9p21). Statistical analysis was performed. RESULTS: A total of 27 patients (including 15 men) with thymic carcinoma at a median age of 51.7 years at time of surgery and available follow-up information were included. Loss of p16 expression was found in 12 of 26 cases (46.2%) and was associated with worse recurrence and metastasis-free survival (p = 0.01), which in multivariate analysis was independent of resection status (p = 0.007) and T stage (p = 0.01). Four of 22 tumors (18.2%) showed homozygous CDKN2A deletion that was correlated with loss of p16 expression (p=0.02). In tumors of the squamous cell carcinoma subtype, loss of p16 expression was associated with worse recurrence and metastasis-free survival (p = 0.006) and overall survival (p = 0.0009). Patients with thymic squamous cell carcinomas lacking p16 expression were younger (p = 0.006). Although similar trends for younger age were noted in patients with thymic squamous cell carcinomas with homozygous CDKN2A deletion, the small number of such cases (n = 2) did not allow for statistical analysis. CONCLUSIONS: Loss of p16 expression and homozygous deletion of CDKN2A are promising prognostic biomarkers in thymic carcinoma. On the basis of our findings, a subset of thymic carcinomas have the potential to respond to CDK4/6 inhibitors; however, further functional studies are needed.

Ciliated Muconodular Papillary Tumors of the Lung Can Occur in Western Patients and Show Mutations in BRAF and AKT1.

Ciliated muconodular papillary tumors (CMPTs) are rare peripheral lung lesions, characterized by papillary architecture and ciliated columnar cells admixed with mucinous cells and basal cells. They often have prominent surrounding intra-alveolar mucin, which can lead to diagnostic confusion with mucinous adenocarcinoma. Recognition of the ciliated component is the key to diagnosis of CMPT. The literature contains few reported cases to date, all occurring in East-Asian patients. Although follow-up data are limited, CMPT seems to be an indolent tumor with very good prognosis, leading some to question whether it is a reactive or hamartomatous lesion. However, a very recent molecular study has identified BRAF (40%) and EGFR (30%) alterations in CMPT, supporting a truly neoplastic process. Here for the first time, we report 4 cases of morphologically typical CMPT in western patients, occurring in 1 man (60 y) and 3 women (71 to 83 y). Interestingly, 1 case occurred in background of pronounced small airway disease with necrotizing bronchiolitis and multiple carcinoid tumorlets. We further analyzed 1 tumor using a 50 gene next-generation sequencing oncology panel that identified 2 pathogenic mutations (BRAF V600E and AKT1 E17K). Our study is the first to describe that CMPT can occur in western (non-Asian) patients. Our data confirm BRAF V600E mutation as a probable driver in a subset of these tumors, along with AKT1 mutation, which further supports that CMPT are indolent pulmonary neoplasms.

A cost-effective interdisciplinary approach to microbiologic send-out test use.

CONTEXT: Use of reference laboratories for selected laboratory testing (send-out tests) represents a significant source of laboratory costs. As the use of more complex molecular analyses becomes common in the United States, strategies to reduce costs in the clinical laboratory must evolve in order to provide high-value, cost-effective medicine. OBJECTIVE: To report a strategy that employs clinical pathology house staff and key hospital clinicians in the effective use of microbiologic send-out testing. DESIGN: The George Washington University Hospital is a 370-bed academic hospital in Washington, DC. In 2012 all requisitions for microbiologic send-out tests were screened by the clinical pathology house staff prior to final dispensation. Tests with questionable utility were brought to the attention of ordering clinicians through the use of interdisciplinary rounds and direct face-to-face consultation. RESULTS: Screening resulted in a cancellation rate of 38% of send-out tests, with proportional cost savings. Nucleic acid tests represented most of the tests screened and the largest percentage of cost saved through screening. Following consultation, requested send-out tests were most often canceled because of a lack of clinical indication. CONCLUSIONS: Direct face-to-face consultation with ordering physicians is an effective, interdisciplinary approach to managing the use of send-out testing in the microbiology laboratory.

Altered cigarette smoke-induced lung inflammation due to ablation of Grx1.

Glutaredoxins (Grx) are redox enzymes that remove glutathione bound to protein thiols, know as S-glutathionylation (PSSG). PSSG is a reservoir of GSH and can affect the function of proteins. It inhibits the NF-κB pathway and LPS aspiration in Grx1 KO mice with decreased inflammatory cytokine levels. In this study we investigated whether absence of Grx1 similarly repressed cigarette smoke-induced inflammation in an exposure model in mice. Cigarette smoke exposure for four weeks decreased lung PSSG levels, but increased PSSG in lavaged cells and lavage fluid (BALF). Grx1 KO mice had increased levels of PSSG in lung tissue, BALF and BAL cells in response to smoke compared to wt mice. Importantly, levels of multiple inflammatory mediators in the BALF were decreased in Grx1 KO animals following cigarette smoke exposure compared to wt mice, as were levels of neutrophils, dendritic cells and lymphocytes. On the other hand, macrophage numbers were higher in Grx1 KO mice in response to smoke. Although cigarette smoke in vivo caused inverse effects in inflammatory and resident cells with respect to PSSG, primary macrophages and epithelial cells cultured from Grx1 KO mice both produced less KC compared to cells isolated from WT mice after smoke extract exposure. In this manuscript, we provide evidence that Grx1 has an important role in regulating cigarette smoke-induced lung inflammation which seems to diverge from its effects on total PSSG. Secondly, these data expose the differential effect of cigarette smoke on PSSG in inflammatory versus resident lung cells.

Activation of the glutaredoxin-1 gene by nuclear factor κB enhances signaling.

The transcription factor nuclear factor κB (NF-κB) is a critical regulator of inflammation and immunity and is negatively regulated via S-glutathionylation. The inhibitory effect of S-glutathionylation is overcome by glutaredoxin-1 (Grx1), which under physiological conditions catalyzes deglutathionylation and enhances NF-κB activation. The mechanisms whereby expression of the Glrx1 gene is regulated remain unknown. Here we examined the role of NF-κB in regulating activation of Glrx1. Transgenic mice that express a doxycycline-inducible constitutively active version of inhibitory κB kinase-ß (CA-IKKß) demonstrate elevated expression of Grx1. Transient transfection of CA-IKKß also resulted in significant induction of Grx1. A 2-kb region of the Glrx1 promoter that contains two putative NF-κB binding sites was activated by CA-IKKß, RelA/p50, and lipopolysaccharide (LPS). Chromatin immunoprecipitation experiments confirmed binding of RelA to the promoter of Glrx1 in response to LPS. Stimulation of C10 lung epithelial cells with LPS caused transient increases in Grx1 mRNA expression and time-dependent increases in S-glutathionylation of IKKß. Overexpression of Grx1 decreased S-glutathionylation of IKKß, prolonged NF-κB activation, and increased levels of proinflammatory mediators. Collectively, this study demonstrates that the Glrx1 gene is positively regulated by NF-κB and suggests a feed-forward mechanism to promote NF-κB signaling by decreasing S-glutathionylation.

Protocols for the detection of s-glutathionylated and s-nitrosylated proteins in situ.

The oxidation of protein cysteine residues represents significant posttranslational modifications that impact a wide variety of signal transduction cascades and diverse biological processes. Oxidation of cysteines occurs through reactions with reactive oxygen as well as nitrogen species. These oxidative events can lead to irreversible modifications, such as the formation of sulfonic acids, or manifest as reversible modifications such as the conjugation of glutathione with the cysteine moiety, a process termed S-glutathionylation (also referred to as S-glutathiolation, or protein mixed disulfides). Similarly, S-nitrosothiols can also react with the thiol group in a process known as S-nitrosylation (or S-nitrosation). It is the latter two events that have recently come to the forefront of cellular biology through their ability to reversibly impact numerous cellular processes. Herein we describe two protocols for the detection of S-glutathionylated or S-nitrosylated proteins in situ. The protocol for the detection of S-glutathionylated proteins relies on the catalytic specificity of glutaredoxin-1 for the reduction of S-glutathionylated proteins. The protocol for the detection of S-nitrosylated proteins represents a modification of the previously described biotin switch protocol, which relies on ascorbate in the presence of chelators to decompose S-nitrosylated proteins. These techniques can be applied in situ to elucidate which compartments in tissues are affected in diseased states whose underlying pathologies are thought to represent a redox imbalance.