CCR5 drives NK cell-associated airway damage in pulmonary ischemia-reperfusion injury

Primary graft dysfunction (PGD) limits clinical benefit after lung transplantation, a life-prolonging therapy for patients with end-stage disease. PGD is the clinical syndrome resulting from pulmonary ischemia-reperfusion injury (IRI), driven by innate immune inflammation. We recently demonstrated a key role for NK cells in the airways of mouse models and human tissue samples of IRI. Here, we used 2 mouse models paired with human lung transplant samples to investigate the mechanisms whereby NK cells migrate to the airways to mediate lung injury. We demonstrate that chemokine receptor ligand transcripts and proteins are increased in mouse and human disease. CCR5 ligand transcripts were correlated with NK cell gene signatures independently of NK cell CCR5 ligand secretion. NK cells expressing CCR5 were increased in the lung and airways during IRI and had increased markers of tissue residency and maturation. Allosteric CCR5 drug blockade reduced the migration of NK cells to the site of injury. CCR5 blockade also blunted quantitative measures of experimental IRI. Additionally, in human lung transplant bronchoalveolar lavage samples, we found that CCR5 ligand was associated with increased patient morbidity and that the CCR5 receptor was increased in expression on human NK cells following PGD. These data support a potential mechanism for NK cell migration during lung injury and identify a plausible preventative treatment for PGD.

Decreased Lymphocytic Bronchitis Severity in the Era of Azithromycin Prophylaxis

Large-airway lymphocytic inflammation (LB), assessed on endobronchial biopsies, has been associated with acute cellular rejection and chronic lung allograft dysfunction (CLAD). Azithromycin (AZI) prophylaxis has been used to prevent airway inflammation and subsequent CLAD, with inconsistent results. We hypothesized that AZI prophylaxis would be associated with reduced LB, changes in bronchoalveolar lavage (BAL) immune cell populations, and improved CLAD-free survival.

Methods

We compared frequencies of LB from endobronchial biopsies before (N = 1856) and after (N = 975) protocolized initiation of AZI prophylaxis at our center. LB was classified as none, minimal, mild, or moderate by histopathologic analysis. LB grades were compared using ordinal mixed-model regression. Corresponding automated BAL leukocyte frequencies were compared using mixed-effects modeling. The effect of AZI prophylaxis on CLAD-free survival was assessed by a Cox proportional hazards model adjusted for age, sex, ethnicity, transplant indication, and cytomegalovirus serostatus.

Results

Biopsies in the pre-AZI era had 2-fold increased odds (95% confidence interval, 1.5-2.7; P < 0.001) of higher LB grades. LB was associated with BAL neutrophilia in both eras. However, there was no difference in risk for CLAD or death between AZI eras (hazard ratio 1.3; 95% confidence interval, 0.7-2.0; P = 0.45).

Conclusions

Decreased airway inflammation in the era of AZI prophylaxis may represent a direct effect of AZI therapy or reflect other practices or environmental changes. In this cohort, AZI prophylaxis was not associated with improved CLAD-free survival.

Development of the Lung Transplant Frailty Scale (LT-FS)

BACKGROUND

Existing measures of frailty developed in community dwelling older adults may misclassify frailty in lung transplant candidates. We aimed to develop a novel frailty scale for lung transplantation with improved performance characteristics.

METHODS

We measured the short physical performance battery (SPPB), fried frailty phenotype (FFP), Body Composition, and serum Biomarkers representative of putative frailty mechanisms. We applied a 4-step established approach (identify frailty domain variable bivariate associations with the outcome of waitlist delisting or death; build models sequentially incorporating variables from each frailty domain cluster; retain variables that improved model performance ability by c-statistic or AIC) to develop 3 candidate "Lung Transplant Frailty Scale (LT-FS)" measures: 1 incorporating readily available clinical data; 1 adding muscle mass, and 1 adding muscle mass and research-grade Biomarkers. We compared construct and predictive validity of LT-FS models to the SPPB and FFP by ANOVA, ANCOVA, and Cox proportional-hazard modeling.

RESULTS

In 342 lung transplant candidates, LT-FS models exhibited superior construct and predictive validity compared to the SPPB and FFP. The addition of muscle mass and Biomarkers improved model performance. Frailty by all measures was associated with waitlist disability, poorer HRQL, and waitlist delisting/death. LT-FS models exhibited stronger associations with waitlist delisting/death than SPPB or FFP (C-statistic range: 0.73-0.78 vs. 0.57 and 0.55 for SPPB and FFP, respectively). Compared to SPPB and FFP, LT-FS models were generally more strongly associated with delisting/death and improved delisting/death net reclassification, with greater improvements with increasing LT-FS model complexity (range: 0.11-0.34). For example, LT-FS-Body Composition hazard ratio for delisting/death: 6.0 (95%CI: 2.5, 14.2), SPPB HR: 2.5 (95%CI: 1.1, 5.8), FFP HR: 4.3 (95%CI: 1.8, 10.1). Pre-transplant LT-FS frailty, but not SPPB or FFP, was associated with mortality after transplant.

CONCLUSIONS

The LT-FS is a disease-specific physical frailty measure with face and construct validity that has superior predictive validity over established measures.

Design and implementation of a digital health home spirometry intervention for remote monitoring of lung transplant function

BACKGROUND

We developed an automated, chat-based, digital health intervention using Bluetooth-enabled home spirometers to monitor for complications of lung transplantation in a real-world application.

METHODS

A chat-based application prompted patients to perform home spirometry, enter their forced expiratory volume in 1 second (FEV1), answer symptom queries, and provided patient education. The program alerted patients and providers to substantial FEV1 decreases and concerning symptoms. Data was integrated into the electronic health record (EHR) system and dashboards were developed for program monitoring.

RESULT

Between May 2020 and December 2021, 544 patients were invited to enroll, of whom 427 were invited remotely and 117 were enrolled in-person. 371 (68%) participated by submitting ≥1 FEV1 values. Overall engagement was high, with an average of 197 unique patients submitting FEV1 data per month. In-person enrollees submitted an average of 4.6 FEV1 values per month and responded to 55% of scheduled chats. Home and laboratory FEV1 values correlated closely (rho = 0.93). There was an average of 133 ± 59 FEV1 decline alerts and 59 ± 23 symptom alerts per month. 72% of patients accessed education modules, and the program had a high net promoter score (53) amongst users.

CONCLUSIONS

We demonstrate that a novel, automated, chat-based, and EHR-integrated home spirometry intervention is well accepted, generates reliable assessments of graft function, and can deliver automated feedback and education resulting in moderately-high adherence rates. We found that in-person onboarding yields better engagement and adherence. Future work will aim to demonstrate the impact of remote care monitoring on early detection of lung transplant complications.

Subphenotypes of frailty in lung transplant candidates

Heterogeneous frailty pathobiology might explain the inconsistent associations observed between frailty and lung transplant outcomes. A Subphenotype analysis could refine frailty measurement. In a 3-center pilot cohort study, we measured frailty by the Short Physical Performance Battery, body composition, and serum biomarkers reflecting causes of frailty. We applied latent class modeling for these baseline data. Next, we tested class construct validity with disability, waitlist delisting/death, and early postoperative complications. Among 422 lung transplant candidates, 2 class model fit the best (P = .01). Compared with Subphenotype 1 (n = 333), Subphenotype 2 (n = 89) was characterized by systemic and innate inflammation (higher IL-6, CRP, PTX3, TNF-R1, and IL-1RA); mitochondrial stress (higher GDF-15 and FGF-21); sarcopenia; malnutrition; and lower hemoglobin and walk distance. Subphenotype 2 had a worse disability and higher risk of waitlist delisting or death (hazards ratio: 4.0; 95% confidence interval: 1.8-9.1). Of the total cohort, 257 underwent transplant (Subphenotype 1: 196; Subphenotype 2: 61). Subphenotype 2 had a higher need for take back to the operating room (48% vs 28%; P = .005) and longer posttransplant hospital length of stay (21 days [interquartile range: 14-33] vs 18 days [14-28]; P = .04). Subphenotype 2 trended toward fewer ventilator-free days, needing more postoperative extracorporeal membrane oxygenation and dialysis, and higher need for discharge to rehabilitation facilities (P ≤ .20). In this early phase study, we identified biological frailty Subphenotypes in lung transplant candidates. A hyperinflammatory, sarcopenic Subphenotype seems to be associated with worse clinical outcomes.

NKG2D receptor activation drives primary graft dysfunction severity and poor lung transplantation outcomes

Clinical outcomes after lung transplantation, a life-saving therapy for patients with end-stage lung diseases, are limited by primary graft dysfunction (PGD). PGD is an early form of acute lung injury with no specific pharmacologic therapies. Here, we present a large multicenter study of plasma and bronchoalveolar lavage (BAL) samples collected on the first posttransplant day, a critical time for investigations of immune pathways related to PGD. We demonstrated that ligands for NKG2D receptors were increased in the BAL from participants who developed severe PGD and were associated with increased time to extubation, prolonged intensive care unit length of stay, and poor peak lung function. Neutrophil extracellular traps (NETs) were increased in PGD and correlated with BAL TNF-α and IFN-γ cytokines. Mechanistically, we found that airway epithelial cell NKG2D ligands were increased following hypoxic challenge. NK cell killing of hypoxic airway epithelial cells was abrogated with NKG2D receptor blockade, and TNF-α and IFN-γ provoked neutrophils to release NETs in culture. These data support an aberrant NK cell/neutrophil axis in human PGD pathogenesis. Early measurement of stress ligands and blockade of the NKG2D receptor hold promise for risk stratification and management of PGD.

Depressive symptoms in lung transplant recipients: trajectory and association with mortality and allograft dysfunction

OBJECTIVE

Most studies observing an association between depressive symptoms following lung transplantation and mortality are limited to depressive symptom measurement at a single time point, unrelated to allograft function. We aimed to test the association of depressive symptoms over multiple assessments with allograft dysfunction and with mortality.

METHODS

We assessed depressive symptoms before and serially up to 3 years after lung transplantation in lung transplant recipients. We quantified depressive symptoms with the Geriatric Depression Scale (GDS; range 0-15; minimally important difference (MID): 2). We quantified changes in GDS using linear mixed effects models and tested the association with mortality using Cox proportional hazards models with GDS as a time-dependent predictor. To determine if worsening in GDS preceded declines in lung function, we tested the association of GDS as a time-dependent predictor with the lagged outcome of FEV₁ at the following study visit.

RESULTS

Among 266 participants, depressive symptoms improved early after transplantation. Worsening in post-transplant GDS by the MID was associated with mortality (HR 1.25, 95% CI 1.05 to 1.50), and in lagged outcome analyses with decreased per cent predicted FEV₁ (Δ, -1.62%, 95% CI -2.49 to -0.76). Visual analyses of temporal changes in GDS demonstrated that worsening depressive symptoms could precede chronic lung allograft dysfunction.

CONCLUSIONS

Depressive symptoms generally improve after lung transplantation. When they worsen, however, there is an association with declines in lung function and mortality. Depression is one of the few, potentially modifiable, risk factors for chronic lung allograft dysfunction and death.

Lung Allograft Epithelium DNA Methylation Age Is Associated With Graft Chronologic Age and Primary Graft Dysfunction

Advanced donor age is a risk factor for poor survival following lung transplantation. However, recent work identifying epigenetic determinants of aging has shown that biologic age may not always reflect chronologic age and that stressors can accelerate biologic aging. We hypothesized that lung allografts that experienced primary graft dysfunction (PGD), characterized by poor oxygenation in the first three post-transplant days, would have increased biologic age. We cultured airway epithelial cells isolated by transbronchial brush at 1-year bronchoscopies from 13 subjects with severe PGD and 15 controls matched on age and transplant indication. We measured epigenetic age using the Horvath epigenetic clock. Linear models were used to determine the association of airway epigenetic age with chronologic ages and PGD status, adjusted for recipient PGD risk factors. Survival models assessed the association with chronic lung allograft dysfunction (CLAD) or death. Distributions of promoter methylation within pathways were compared between groups. DNA methyltransferase (DNMT) activity was quantified in airway epithelial cells under hypoxic or normoxic conditions. Airway epigenetic age appeared younger but was strongly associated with the age of the allograft (slope 0.38 per year, 95% CI 0.27–0.48). There was no correlation between epigenetic age and recipient age (P = 0.96). Epigenetic age was 6.5 years greater (95% CI 1.7–11.2) in subjects who had experienced PGD, and this effect remained significant after adjusting for donor and recipient characteristics (P = 0.03). Epigenetic age was not associated with CLAD-free survival risk (P = 0.11). Analysis of differential methylation of promoters of key biologic pathways revealed hypomethylation in regions related to hypoxia, inflammation, and metabolism-associated pathways. Accordingly, airway epithelial cells cultured in hypoxic conditions showed suppressed DNMT activity. While airway methylation age was primarily determined by donor chronologic age, early injury in the form of PGD was associated with increased allograft epigenetic age. These data show how PGD might suppress key promoter methylation resulting in long-term impacts on the allograft.

Type-1 immunity and endogenous immune regulators predominate in the airway transcriptome during chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) remains the major complication limiting long-term survival among lung transplant recipients (LTRs). Limited understanding of CLAD immunopathogenesis and a paucity of biomarkers remain substantial barriers for earlier detection and therapeutic interventions for CLAD. We hypothesized the airway transcriptome would reflect key immunologic changes in disease. We compared airway brush-derived transcriptomic signatures in CLAD (n = 24) versus non-CLAD (n = 21) LTRs. A targeted assessment of the proteome using concomitant bronchoalveolar lavage (BAL) fluid for 24 cytokines/chemokines and alloimmune T cell responses was performed to validate the airway transcriptome. We observed an airway transcriptomic signature of differential genes expressed (DGEs) in CLAD marked by Type-1 immunity and striking upregulation of two endogenous immune regulators: indoleamine 2, 3 dioxygenase 1 (IDO-1) and tumor necrosis factor receptor superfamily 6B (TNFRSF6B). Advanced CLAD staging was associated with a more intense airway transcriptome signature. In a validation cohort using the identified signature, we found an area under the curve (AUC) of 0.77 for CLAD LTRs. Targeted proteomic analyses revealed a predominant Type-1 profile with detection of IFN-γ, TNF-α, and IL-1β as dominant CLAD cytokines, correlating with the airway transcriptome. The airway transcriptome provides novel insights into CLAD immunopathogenesis and biomarkers that may impact diagnosis of CLAD.

Enabling antibiotic allergy evaluations and reintroduction of first-line antibiotics for patients with cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) often have a history of antibiotic adverse drug reactions (ADRs) that pose a barrier to receiving recommended first-line treatment. Targeted antibiotic allergy evaluations are increasingly recognized as an important strategy for optimization of antimicrobial stewardship.

OBJECTIVE

To improve first-line antibiotic use in patients with CF with antibiotic ADRs by streamlining access to antibiotic allergy evaluations and standardizing documentation of plans for antibiotic reintroduction.

METHODS

We incorporated allergy evaluations into a multidisciplinary CF clinic and used telemedicine when allergy evaluations could not be performed during CF clinic. Standard documentation of antibiotic allergy plans was used to enable safe reintroduction of first-line antibiotics by CF providers.

RESULTS

Strategies used in this study allowed 81.3% (26 of 32) of patients with CF to receive allergy evaluations and antibiotic allergy plans for prioritized antibiotics (penicillin, cephalosporin, sulfonamide), with removal of 41.0% (16 of 39) of prioritized antibiotic ADRs. Only 5.1% (2 of 39) of prioritized antibiotic ADRs evaluated required strict avoidance after evaluation. There were 9 patients who received at least 1 prioritized antibiotic, with 66.6% (6 of 9) of these patients given the antibiotic after only 1 allergy evaluation visit. Furthermore, these strategies allowed allergy evaluations of 23 nonprioritized antibiotics to occur, with removal of the ADR in 39.1% (9 of 23) and use of 77.8% (7 of 9) of nonprioritized antibiotics after removal.

CONCLUSION

Incorporating allergy evaluations into a multidisciplinary CF clinic can liberalize first-line antibiotic use in patients with CF. Standard documentation of antibiotic allergy plans allowed antibiotic reintroduction to occur even before complete removal of documented antibiotic ADRs.

The association of post-operative delirium with patient-reported outcomes and mortality after lung transplantation

Post-operative delirium after lung transplantation is common. Its associations with health-related quality of life (HRQL), depression, and mortality remains unknown. In 236 lung transplant recipients, HRQL and depressive symptoms were assessed as part of a structured survey battery before and after transplantation. Surveys included the Geriatric Depressive Scale (GDS) and Short Form 12 (SF12). Delirium was assessed throughout the post-operative intensive care unit (ICU) stay with Confusion Assessment Method for ICU. Delirium and mortality data were extracted from electronic medical records. We examined associations between delirium and changes in depressive symptoms and HRQL using linear mixed effects models and association between delirium and mortality with Cox-proportional hazard models. Post-operative delirium occurred in 34 participants (14%). Delirium was associated with attenuated improvements in SF12-PCS (difference ₋4.0; 95%CI: -7.4, -0.7) but not SF12-MCS (difference 2.2; 95%CI: -0.7,5.7) or GDS (difference ₋0.4; 95%CI: -1.5,0.7). Thirty-two participants died during the study period. Delirium was associated with increased adjusted hazard risk of mortality (HR 17.9, 95%CI: 4.4,72.5). Delirium after lung transplantation identifies a group at increased risk for poorer HRQL and death within the first post-operative year. Further studies should investigate potential causal links between delirium, and poorer HRQL and mortality risk after lung transplantation.

Primary graft dysfunction attenuates improvements in health-related quality of life after lung transplantation, but not disability or depression

Disability, depressive symptoms, and impaired health-related quality of life (HRQL) are common among patients with life-threatening respiratory compromise. We sought to determine if primary graft dysfunction (PGD), a syndrome of acute lung injury, attenuates improvements in patient-reported outcomes after transplantation. In a single-center prospective cohort, we assessed disability, depressive symptoms, and HRQL before and at 3- to 6-month intervals after lung transplantation. We estimated the magnitude of change in disability, depressive symptoms, and HRQL with hierarchical segmented linear mixed-effects models. Among 251 lung transplant recipients, 50 developed PGD Grade 3. Regardless of PGD severity, participants had improvements in disability and depressive symptoms, as well as generic-physical, generic-mental, respiratory-specific, and health-utility HRQL, exceeding 1- to 4-fold the minimally clinically important difference across all instruments. Participants with PGD Grade 3 had a lower magnitude of improvement in generic-physical HRQL and health-utility than in all other participants. Among participants with PGD Grade 3, prolonged mechanical ventilation was associated with greater attenuation of improvements. PGD remains a threat to the 2 primary aims of lung transplantation, extending survival and improving HRQL. Attenuation of improvement persists long after hospital discharge. Future studies should assess if interventions can mitigate the impact of PGD on patient-reported outcomes.

Chronic lung allograft dysfunction small airways reveal a lymphocytic inflammation gene signature

Chronic lung allograft dysfunction (CLAD) is the major barrier to long-term survival following lung transplantation, and new mechanistic biomarkers are needed. Lymphocytic bronchitis (LB) precedes CLAD and has a defined molecular signature. We hypothesized that this LB molecular signature would be associated with CLAD in small airway brushings independent of infection. We quantified RNA expression from small airway brushings and transbronchial biopsies, using RNAseq and digital RNA counting, respectively, for 22 CLAD cases and 27 matched controls. LB metagene scores were compared across CLAD strata by Wilcoxon rank sum test. We performed unbiased host transcriptome pathway and microbial metagenome analysis in airway brushes and compared machine-learning classifiers between the two tissue types. This LB metagene score was increased in CLAD airway brushes (p = .002) and improved prediction of graft failure (p = .02). Gene expression classifiers based on airway brushes outperformed those using transbronchial biopsies. While infection was associated with decreased microbial alpha-diversity (p ≤ .04), neither infection nor alpha-diversity was associated with LB gene expression. In summary, CLAD was associated with small airway gene expression changes not apparent in transbronchial biopsies in this cohort. Molecular analysis of airway brushings for diagnosing CLAD merits further examination in multicenter cohorts.

Cystic Fibrosis Lung Transplant Recipients Have Suppressed Airway Interferon Responses during Pseudomonas Infection

Lung transplantation can be lifesaving in end-stage cystic fibrosis (CF), but long-term survival is limited by chronic lung allograft dysfunction (CLAD). Persistent upper airway Pseudomonas aeruginosa (PsA) colonization can seed the allograft. While de novo PsA infection is associated with CLAD in non-CF recipients, this association is less clear for CF recipients experiencing PsA recolonization. Here, we evaluate host and pathogen contributions to this phenomenon. In the context of PsA infection, brushings from the airways of CF recipients demonstrate type 1 interferon gene suppression. Airway epithelial cell (AEC) cultures demonstrate similar findings in the absence of pathogens or immune cells, contrasting with the pre-transplant CF AEC phenotype. Type 1 interferon promoters are relatively hypermethylated in CF AECs. CF subjects in this cohort have more mucoid PsA, while non-CF PsA subjects have decreased microbiome α diversity. Peri-transplant protocols may benefit from consideration of this host and microbiome equilibrium.

Lung allograft Pseudomonas infection outcomes are better for recipients with CF

In CF, infected allograft airway cells demonstrate suppression of interferon genes

Differential DNA methylation may contribute to this distinct epithelial phenotype

Increased α diversity and mucoid forms characterize CF Pseudomonas infection

Improvements in frailty contribute to substantial improvements in quality of life after lung transplantation in patients with cystic fibrosis

BACKGROUND

While lung transplantation (LTx) improves health-related quality of life (HRQL) in cystic fibrosis (CF), the determinants of this improvement are unknown. In other populations, frailty-a syndrome of vulnerability to physiologic stressors-is associated with disability and poor HRQL. We hypothesized that improvements in frailty would be associated with improved disability and HRQL in adults with CF undergoing LTx.

METHODS

In a single-center prospective cohort study from 2010 to 2017, assessments of frailty, disability, and HRQL were performed before and at 3- and 6-months after LTx. We assessed frailty by the short physical performance battery (SPPB). We assessed disability with the Lung Transplant Valued Life Activities scale (LT-VLA) and HRQL by the Medical Outcomes Study Short Form Physical and Mental Component Summary scales (SF12-PCS, -MCS), the Airway Questionnaire 20-Revised (AQ20R), and the Euroqol 5D (EQ5D). We tested the association of concurrent changes in frailty and lung function on disability and HRQL by linear mixed-effects models adjusted for sex and body mass index.

RESULTS

Among 23 participants with CF, improvements in frailty and lung function were independently associated with improved disability and some HRQL measures. For example, each 1-point improvement in SPPB or 200 mL improvement in FEV1 was associated with improved LT-VLA disability by 0.14 (95%CI: 0.08-0.20) and 0.07 (95%CI: 0.05-0.09) points and improved EQ5D by 0.05 (95%CI: 0.03 to 0.07) and 0.02 (95%CI: 0.01-0.03) points, respectively.

CONCLUSION

Improvement in frailty is a novel determinant of improved disability and HRQL in adults with CF undergoing LTx.

Tacrolimus trough monitoring guided by mass spectrometry without accounting for assay differences is associated with acute kidney injury in lung transplant recipients

PURPOSE

Tacrolimus is a nephrotoxic immunosuppressant historically monitored via enzyme-based immunoassay (IA). After 2011, the 2 largest laboratory companies in the United States implemented tacrolimus quantification by liquid chromatography-mass spectrometry (LC-MS); this method excludes metabolites, potentially resulting in lower quantified drug concentrations. We sought to determine if tacrolimus therapeutic drug monitoring via LC-MS, as performed using trough targets originally derived from IA values, influences clinical outcomes.

METHODS

In a single-center retrospective cohort study of lung transplant recipients, risks of acute kidney injury, acute renal failure, and new-onset diabetes after transplantation, as well as chronic lung allograft dysfunction-free survival, were compared in 82 subjects monitored by LC-MS and 102 subjects monitored by IA using Cox proportional hazard models adjusted for age, sex, baseline renal function, and race.

RESULTS

LC-MS-based monitoring was associated with a greater risk of acute kidney injury (adjusted hazard ratio, 1.65; 95% confidence interval, 1.02-2.67). No statistically significant differences in risks of acute renal failure and new-onset diabetes after transplantation were observed.

CONCLUSION

Although LC-MS provides a more accurate representation of the blood concentration of the parent compound tacrolimus exclusive of metabolite, established cut points for tacrolimus dosing may need to be adjusted to account for the increased risk of renal injury.

Cystic fibrosis transmembrane conductance regulator dysfunction in platelets drives lung hyperinflammation

Cystic fibrosis (CF) lung disease is characterized by an inflammatory response that can lead to terminal respiratory failure. The cystic fibrosis transmembrane conductance regulator (CFTR) is mutated in CF, and we hypothesized that dysfunctional CFTR in platelets, which are key participants in immune responses, is a central determinant of CF inflammation. We found that deletion of CFTR in platelets produced exaggerated acute lung inflammation and platelet activation after intratracheal LPS or Pseudomonas aeruginosa challenge. CFTR loss of function in mouse or human platelets resulted in agonist-induced hyperactivation and increased calcium entry into platelets. Inhibition of the transient receptor potential cation channel 6 (TRPC6) reduced platelet activation and calcium flux, and reduced lung injury in CF mice after intratracheal LPS or Pseudomonas aeruginosa challenge. CF subjects receiving CFTR modulator therapy showed partial restoration of CFTR function in platelets, which may be a convenient approach to monitoring biological responses to CFTR modulators. We conclude that CFTR dysfunction in platelets produces aberrant TRPC6-dependent platelet activation, which is a major driver of CF lung inflammation and impaired bacterial clearance. Platelets and TRPC6 are what we believe to be novel therapeutic targets in the treatment of CF lung disease.

Mitochondrial DNA Stimulates TLR9-Dependent Neutrophil Extracellular Trap Formation in Primary Graft Dysfunction

The immune system is designed to robustly respond to pathogenic stimuli but to be tolerant to endogenous ligands to not trigger autoimmunity. Here, we studied an endogenous damage-associated molecular pattern, mitochondrial DNA (mtDNA), during primary graft dysfunction (PGD) after lung transplantation. We hypothesized that cell-free mtDNA released during lung ischemia-reperfusion triggers neutrophil extracellular trap (NET) formation via TLR9 signaling. We found that mtDNA increases in the BAL fluid of experimental PGD (prolonged cold ischemia followed by orthotopic lung transplantation) and not in control transplants with minimal warm ischemia. The adoptive transfer of mtDNA into the minimal warm ischemia graft immediately before lung anastomosis induces NET formation and lung injury. TLR9 deficiency in neutrophils prevents mtDNA-induced NETs, and TLR9 deficiency in either the lung donor or recipient decreases NET formation and lung injury in the PGD model. Compared with human lung transplant recipients without PGD, severe PGD was associated with high levels of BAL mtDNA and NETs, with evidence of relative deficiency in DNaseI. We conclude that mtDNA released during lung ischemia-reperfusion triggers TLR9-dependent NET formation and drives lung injury. In PGD, DNaseI therapy has a potential dual benefit of neutralizing a major NET trigger (mtDNA) in addition to dismantling pathogenic NETs.

Gene signatures common to allograft rejection are associated with lymphocytic bronchitis

Lymphocytic bronchitis (LB) precedes chronic lung allograft dysfunction. The relationships of LB (classified here as Endobronchial or E-grade rejection) to small airway (A- and B-grade) pathologies are unclear. We hypothesized that gene signatures common to allograft rejection would be present in LB. We studied LB in two partially overlapping lung transplant recipient cohorts: Cohort 1 included large airway brushes (6 LB cases and 18 post-transplant referents). Differential expression using DESeq2 was used for pathway analysis and to define an LB-associated metagene. In Cohort 2, eight biopsies for each pathology subtype were matched with pathology-free biopsies from the same subject (totaling 48 samples from 24 subjects). These biopsies were analyzed by multiplexed digital counting of immune transcripts. Metagene score differences were compared by paired t tests. Compared to referents in Cohort 1, LB demonstrated upregulation of allograft rejection pathways, and upregulated genes in these cases characterized an LB-associated metagene. We observed statistically increased expression in Cohort 2 for this LB-associated metagene and four other established allograft rejection metagenes in rejection vs paired non-rejection biopsies for both E-grade and A-grade subtypes, but not B-grade pathology. Gene expression-based categorization of allograft rejection may prove useful in monitoring lung allograft health.

Frailty trajectories in adult lung transplantation: A cohort study

BACKGROUND

Frailty is common in adults with advanced lung disease and is associated with death before and after lung transplantation. We aimed to determine whether frailty changes from before to after the lung transplant.

METHODS

In a single-center, prospective cohort study among adults undergoing lung transplantation from 2010 to 2017, we assessed frailty by the Short Physical Performance Battery (SPPB; higher scores reflect less frailty) and Fried Frailty Phenotype (FFP; higher scores reflect greater frailty) before and repeatedly up to 36 months after transplant. We tested for changes in frailty scores over time using segmented mixed effects models, adjusting for age, sex, and diagnosis. We quantified the proportion of subjects transitioning between frailty states (frail vs not frail) from before to after the transplant.

RESULTS

In 246 subjects, changes in frailty occurred within the first 6 post-operative months and remained stable thereafter. The overall change in frailty was attributable to improvements among those subjects who were frail before transplant. They experienced a 5.1-point improvement in SPPB (95% confidence interval [CI] 4.6-5.7) and a 1.8-point improvement in FFP (95% CI -2.1 to -1.6) during the early period. Frailty by SPPB and FFP did not change in those who were not frail before transplant. Approximately 84% of survivors who were frail before transplant became not frail after transplant.

CONCLUSIONS

Pre-operative frailty resolves in many patients after lung transplantation. Because a large proportion of frailty may be attributable to advanced lung disease, frailty alone should not be an absolute contraindication to transplantation.

Improvement in patient-reported outcomes after lung transplantation is not impacted by the use of extracorporeal membrane oxygenation as a bridge to transplantation

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is increasingly used as a bridge to lung transplantation. The impact of preoperative ECMO on health-related quality of life (HRQL) and depressive symptoms after lung transplantation remains unknown, however.

METHODS

In a single-center prospective cohort study, we assessed HRQL and depressive symptoms before and at 3, 6, and 12 months after lung transplantation using the Short Form 12 Physical and Mental Component Scores (SF12-PCS and SF12-MCS), Airway Questionnaire 20-Revised (AQ20R), EuroQol 5D (EQ5D), and Geriatric Depression Scale (GDS). Changes in HRQL were quantified by segmented linear mixed-effects models controlling for age, sex, diagnosis, preoperative forced expiratory volume in 1 second, 6-minute walk distance, and Lung Allocation Score. We compared changes in HRQL among subjects bridged with ECMO, subjects hospitalized but not on ECMO, and subjects called in for transplantation as outpatients.

RESULTS

Out of 189 subjects, 17 were bridged to transplantation with ECMO. In all groups, improvements in HRQL following lung transplantation exceeded the minimally clinically important difference using the SF12-PCS, AQ20R, EQ5D, and GDS. HRQL defined by SF12-MCS did not change after transplantation. Improvements were generally similar among the groups, except for EQ5D, which showed a trend toward less benefit in the outpatients, possibly due to their better HRQL before lung transplantation.

CONCLUSIONS

Subjects ill enough to require ECMO as a bridge to lung transplantation appear to achieve similar improvements in HRQL and depressive symptoms as those who do not. It is reassuring to both providers and patients that lung transplantation provides substantial improvements in HRQL, even for those patients who are critically ill in the run up to transplantation.

Effect of Lung Transplantation on Health-Related Quality of Life in the Era of the Lung Allocation Score: A U.S. Prospective Cohort Study

Under the U.S. Lung Allocation Score (LAS) system, older and sicker patients are prioritized for lung transplantation (LT). The impact of these changes on health-related quality of life (HRQL) after transplant has not been determined. In a single-center prospective cohort study from 2010 to 2016, we assessed HRQL before and repeatedly after LT for up to 3 years using the SF12-Physical and Mental Health, the respiratory-specific Airway Questionnaire 20-Revised, and the Euroqol 5D/Visual Analog Scale utility measures by multivariate linear mixed models jointly modeled with death. We also tested changes in LT-Valued Life Activities disability, BMI, allograft function, and 6-min walk test exercise capacity as predictors of HRQL change. Among 211 initial participants (92% of those eligible), LT improved HRQL by all 5 measures (p < 0.05) and all but SF12-Mental Health improved by threefold or greater than the minimally clinically important difference. Compared to younger participants, those aged ≥65 improved less in SF12-Physical and Mental Health (p < 0.01). Improvements in disability accounted for much of the HRQL improvement. In the LAS era, LT affords meaningful and durable HRQL improvements, mediated by amelioration of disability. Identifying factors limiting HRQL improvement in selected subgroups, especially those aged ≥65, are needed to maximize the net benefits of LT.

Prolonged Barium-Impaction Ileus in Two Lung Transplant Recipients With Systemic Sclerosis: Case Report

Lung transplantation can be a life-saving measure for people with end-stage lung disease from systemic sclerosis. However, outcomes of lung transplantation may be compromised by gastrointestinal manifestations of systemic sclerosis, which can involve any part of the gastrointestinal tract. Esophageal and gastric disease can be managed by enteral feeding with the use of a gastrojejunal feeding tube. In this report, we describe the clinical courses of 2 lung transplant recipients with systemic sclerosis who experienced severe and prolonged barium-impaction ileus after insertion of a percutaneous gastrojejunal feeding tube.

The feasibility of lung transplantation in HIV-seropositive patients

RATIONALE

HIV seropositivity has long been considered a contraindication to lung transplantation, primarily because of the potential risks of added immunosuppression. In the past decade, however, experience with kidney and liver transplantation in the setting of HIV infection, with achievement of satisfactory outcomes, has grown considerably. This promising development has created a need to reconsider this contraindication to lung transplantation.

OBJECTIVES

There is presently limited evidence upon which to base medical decision-making regarding lung transplantation in individuals with HIV infection. In our present study, we wished to extend the existing literature by reporting the outcomes of three individuals with HIV infection who underwent lung transplantation at two centers.

METHODS

We compiled data for a case series of three HIV-infected subjects undergoing lung transplantation at two centers.

MEASUREMENTS AND MAIN RESULTS

We reviewed medical records to investigate the effects of lung transplantation on the course of HIV infection, the development of HIV-related opportunistic infections or malignancies, the occurrence of lung transplant and HIV drug interactions, and the extent of acute rejection. Subject 1, who underwent transplantation for HIV-associated pulmonary arterial hypertension, experienced recalcitrant acute rejection requiring a lymphocyte-depleting agent with subsequent rapid development of bronchiolitis obliterans syndrome. Subjects 2 and 3, who underwent transplantation for idiopathic pulmonary fibrosis, experienced mild acute rejection but remain free from chronic rejection at 4 and 2 years after transplant, respectively.

CONCLUSIONS

Lung transplantation may be feasible for carefully selected patients in the setting of controlled HIV infection. On the basis of our experience with three patients, we caution that acute graft rejection may be more common in such patients.

Improving transition from paediatric to adult cystic fibrosis care: programme implementation and evaluation

BACKGROUND

The paradigm of cystic fibrosis (CF) care has changed as effective therapies extend the lives of patients well into adulthood. Preparing for and maintaining high quality CF care into the adult healthcare setting is critical for prolonged survival. Unfortunately, this transfer process from the paediatric to the adult CF centre is met with a variety of challenges.

OBJECTIVE AND METHODS

The objective of this quality improvement (QI) project was to develop, implement and evaluate a theory-based programme for transition from paediatric to adult CF care. In a multi-phase process, the paediatric and adult programmes developed a transition curriculum, addressed care standards and standardised patient transfer protocols. We evaluated the impact of this process through staff surveys, review of field notes from QI meetings, tracking transfers and responses of patients to the Transition Readiness Assessment Questionnaire (TRAQ) at the start of the programme and 18 months after initiation.

RESULTS

The collaboration between the paediatric and adult teams continued through quarterly meetings over the past 4 years. This has provided a forum that sustained our transition programme, harmonised care across CF centres and addressed other needs of our CF centre. Discussion of transition with families in the paediatric centre increased twofold (35% to 73% p<0.001), and resulted in a trend towards improved patient TRAQ self-advocacy scores and decreased in-hospital transfer.

CONCLUSIONS

We successfully created a curriculum and process for transition from paediatric to adult CF care at our centres. This collaboration shapes the communication between our paediatric and adult CF care teams and enables ongoing feedback among patients, families and providers. The impact of our transition programme on long-term patient morbidity will require future evaluation.

Airway microbiota and pathogen abundance in age-stratified cystic fibrosis patients

Bacterial communities in the airways of cystic fibrosis (CF) patients are, as in other ecological niches, influenced by autogenic and allogenic factors. However, our understanding of microbial colonization in younger versus older CF airways and the association with pulmonary function is rudimentary at best. Using a phylogenetic microarray, we examine the airway microbiota in age stratified CF patients ranging from neonates (9 months) to adults (72 years). From a cohort of clinically stable patients, we demonstrate that older CF patients who exhibit poorer pulmonary function possess more uneven, phylogenetically-clustered airway communities, compared to younger patients. Using longitudinal samples collected form a subset of these patients a pattern of initial bacterial community diversification was observed in younger patients compared with a progressive loss of diversity over time in older patients. We describe in detail the distinct bacterial community profiles associated with young and old CF patients with a particular focus on the differences between respective "early" and "late" colonizing organisms. Finally we assess the influence of Cystic Fibrosis Transmembrane Regulator (CFTR) mutation on bacterial abundance and identify genotype-specific communities involving members of the Pseudomonadaceae, Xanthomonadaceae, Moraxellaceae and Enterobacteriaceae amongst others. Data presented here provides insights into the CF airway microbiota, including initial diversification events in younger patients and establishment of specialized communities of pathogens associated with poor pulmonary function in older patient populations.

Lung transplantation in patients with connective tissue disorders and esophageal dysmotility

Lung and esophageal dysfunction are common in patients with connective tissue disease (CTD). Recent reports have suggested a link between pathologic gastroesophageal reflux and bronchiolitis obliterans syndrome (BOS) after lung transplant. Because patients with CTD have a high incidence of esophageal dysmotility and reflux, this group may be at increased risk of allograft dysfunction after lung transplantation. Little is known about antireflux surgery in these patients. Our aims were to describe: (i) the esophageal motility and reflux profile of patients with CTD referred for lung transplantation; and (ii) the safety and outcomes of laparoscopic fundoplication in this group. A retrospective review of 26 patients with CTD referred for lung transplantation between July 2003 and June 2007 at a single center. Esophageal studies included manometry and ambulatory 24-h pH monitoring. Twenty-three patients had esophageal manometry and ambulatory 24-h pH monitoring. Nineteen patients (83%) had pathologic distal reflux and 7 (30%) also had pathologic proximal reflux. Eighteen patients (78%) had impaired or absent peristalsis. Eleven of 26 patients underwent lung transplantation. Ten patients are alive at a median follow-up of 26 months (range 3-45) and one has bronchiolitis obliterans syndrome-1. Six patients had a laparoscopic fundoplication, 1 before transplantation and 5 after. All fundoplication patients are alive at median follow-up of 25 months (range 19-45). In conclusion, esophageal dysmotility and reflux are common in CTD patients referred for lung transplant. For this group, laparoscopic fundoplication is safe in experienced hands.

Antireflux surgery for patients with end-stage lung disease before and after lung transplantation

BACKGROUND

Gastroesophageal reflux disease (GERD) is prevalent among patients with end-stage lung disease (ESLD). This disease can lead to microaspiration and may be a risk factor for lung damage before and after transplantation. A fundoplication is the best way to stop reflux, but little is known about the safety of elective antireflux surgery for patients with ESLD. This study aimed to report the safety of laparoscopic fundoplication for patients with ESLD and GERD before or after lung transplantation.

METHODS

Between January 1997 and January 2007, 305 patients were listed for lung transplantation, and 189 patients underwent the procedure. In 2003, routine esophageal studies were added to the pretransplantation evaluation. After the authors' initial experience, gastric emptying studies were added as well.

RESULTS

A total of 35 patients with GERD or delayed gastric emptying were referred for surgical intervention. A laparoscopic fundoplication was performed for 32 patients (27 total and 5 partial). For three patients, a pyloroplasty also was performed. Two patients had a pyloroplasty without fundoplication. Of the 35 operations, 15 were performed before and 20 after transplantation. Gastric emptying of solids or liquids was delayed in 12 (92%) of 13 posttransplantation studies and 3 (60%) of 5 pretransplantation studies. All operations were completed laparoscopically, and 33 patients recovered uneventfully (94%). The median hospital length of stay was 2 days (range, 1-34 days) for the patients admitted to undergo elective operations. Hospitalization was not prolonged for the three patients who had fundoplications immediately after transplantation.

CONCLUSIONS

The results of this study show that laparoscopic antireflux surgery can be performed safely by an experienced multidisciplinary team for selected patients with ESLD before or after lung transplantation, and that gastric emptying is frequently abnormal and should be objectively measured in ESLD patients.

The diffusing capacity in adult cystic fibrosis

The value of adjusting the diffusing capacity for the lung volume has been demonstrated in a large number of patients with other lung diseases but has not been validated in patients with cystic fibrosis (CF). Pulmonary function test results on a cohort of 52 adult CF patients were analyzed to determine whether the diffusing capacity of carbon monoxide by single breath method (DLCO(SB)) when adjusted for alveolar volume (V(A)%), correlated with the severity of pulmonary dysfunction. The DLCO(SB) remained within the reference range except in those with severe lung impairment (61.88 +/- 15.48%). DLCO(SB) has a significant (P < 0.05) positive correlation (0.70, 0.67, 048, 0.69 and 0.31, respectively) with measures of airflow limitation (FVC%, FEV1%, FEV1/FVC%, MVV%, and sGaw) and negative correlation (-0.36 and -0.21, respectively) with measures of air trapping (RV% and RV/TLC%). DLCO(SB)/V(A) remained above 100% of predicted despite worsening lung disease and did not correlate with other measures of lung function. On the other hand, the DLCO(SB) and DLCO(SB)/V(A), when adjusted for V(A)%, decreased and were significantly correlated with worsening airflow limitation and, to a lesser extent, air trapping. The relatively preserved adjusted DLCO(SB) and DLCO(SB)/V(A) values in CF patients up until late in its course may be explained the predominant airway involvement, minimal loss of alveolar-capillary units, and enhanced V/Q relationship due to claustration in CF.

Chronic ventilator dependence in elderly patients

Long-term ventilator dependence is the need for mechanical ventilation for more than 6 h/d for more than 21 days. Long-term ventilator dependence complicates 9% to 20% of the episodes of mechanical ventilation treated in the intensive care units of acute care hospitals; it is associated with an average mortality rate of 40%. Unlike acute respiratory failure, the risk for which does not increase with age, long-term ventilator dependence falls disproportionately to patients aged 70 years or older. During the past 2 decades, a profusion of care sites for patients with long-term ventilator dependence has evolved, largely as the product of the prospective payment system for health services introduced by the Health Care Financing Administration in 1983. The outcome of long-term ventilator dependence in elderly patients across this health care continuum is addressed.

Paradoxical embolization in an adult patient with cystic fibrosis

To our knowledge, we describe the first reported case of paradoxical embolization via a patent foramen ovale (PFO) in an adult with moderately severe cystic fibrosis (CF) and advanced lung disease. Fluctuating neurologic symptoms and signs suggestive of cerebrovascular disease in an adult patient with advanced CF may be due to paradoxical embolization via a PFO. The possibility of a PFO should be considered before placement of a totally implantable venous access device to avert unnecessary risk of stroke in CF patients. Further study is needed to determine whether the use of a totally implantable venous access device increases the risk of paradoxical embolization in adult CF patients with a PFO.

Deformation-induced ATP release from red blood cells requires CFTR activity

Recently, it was reported that rabbit and human red blood cells (RBCs) release ATP in response to mechanical deformation. Here we investigate the hypothesis that the activity of the cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ATP binding cassette, is required for deformation-induced ATP release from RBCs. Incubation of rabbit RBCs with either of two inhibitors of CFTR activity, glibenclamide (10 microM) or niflumic acid (20 microM), resulted in inhibition of deformation-induced ATP release. To demonstrate the contribution of CFTR to deformation-induced ATP release from human RBCs, cells from healthy humans, patients with cystic fibrosis (CF), or patients with chronic obstructive lung disease (COPD) unrelated to CF were studied. RBCs of healthy humans and COPD patients released ATP in response to mechanical deformation. In contrast, deformation of RBCs from patients with CF did not result in ATP release. We conclude that deformation-induced ATP release from rabbit and human RBCs requires CFTR activity, suggesting a previously unrecognized role for CFTR in the regulation of vascular resistance.

Validity of three clinical performance assessments of internal medicine clerks

PURPOSE

To analyze the construct validity of three methods to assess the clinical performances of internal medicine clerks.

METHOD

A multitrait-multimethod (MTMM) study was conducted at the Case Western Reserve University School of Medicine to determine the convergent and divergent validity of a clinical evaluation form (CEF) completed by faculty and residents, an objective structured clinical examination (OSCE), and the medicine subject test of the National Board of Medical Examiners. Three traits were involved in the analysis: clinical skills, knowledge, and personal characteristics. A correlation matrix was computed for 410 third-year students who completed the clerkship between August 1988 and July 1991.

RESULTS

There was a significant (p < .01) convergence of the four correlations that assessed the same traits by using different methods. However, the four convergent correlations were of moderate magnitude (ranging from .29 to .47). Divergent validity was assessed by comparing the magnitudes of the convergence correlations with the magnitudes of correlations among unrelated assessments (i.e., different traits by different methods). Seven of nine possible coefficients were smaller than the convergent coefficients, suggesting evidence of divergent validity. A significant CEF method effect was identified.

CONCLUSION

There was convergent validity and some evidence of divergent validity with a significant method effect. The findings were similar for correlations corrected for attenuation. Four conclusions were reached: (1) the reliability of the OSCE must be improved, (2) the CEF ratings must be redesigned to further discriminate among the specific traits assessed, (3) additional methods to assess personal characteristics must be instituted, and (4) several assessment methods should be used to evaluate individual student performances.

Informed consent for blood transfusion as a transfusion medicine educational intervention

The aim here was to determine the effectiveness of a transfusion medicine educational intervention in a medicine core clerkship program. Third-year medical students enrolled in their medicine core clerkship rotations at tertiary care hospitals affiliated with our institution underwent a two-part educational intervention that incorporated a transfusion medicine curriculum within the context of the medicolegal, ethical and educational elements of informed consent. Part one was a 1-h didactic session on standards of practice for red blood cell transfusion. Part two was a 90-min multidisciplinary workshop on informed consent. The effectiveness of the educational intervention was analysed by an objective structured clinical evaluation. The student group receiving the educational intervention scored significantly higher than in the comparison group (65.8 +/- 9.2 vs. 54.1 +/- 10.56, P < 0.001). When student scores were used to determine changes in student response patterns over time, the largest change occurred in identifying possible other options to allogeneic blood transfusion. These results suggest that a transfusion medicine curriculum using an informed consent model can be used effectively as an educational intervention in a medicine core clerkship programme.

Psychological factors in sarcoidosis: the relationship between life stress and pulmonary function

Seventeen patients with diagnosed sarcoidosis were administered a number of psychological instruments to assess anxiety, depression, life stress, and symptoms of agoraphobia and/or panic. These patients were then followed medically for a period of nine months. Scores on the various psychological tests were then compared with results obtained from repeated pulmonary function tests. Results showed a consistent relationship between increased life stress at time one and impairment in lung function throughout the study period. In addition, no consistent set of psychiatric symptoms were associated with the disease. Sarcoid patients did, however, report many symptoms similar to patients with agoraphobia. These results are discussed in terms of the potential benefits of stress reduction treatment as an adjunctive therapy for patients with sarcoidosis.

Antigen responsiveness during tuberculosis: regulatory interactions of T cell subpopulations and adherent cells

Previous studies from this laboratory demonstrated that adherent mononuclear cells selectively decreased in vitro tuberculin responses in some anergic patients with tuberculosis; subsequently this adherent suppressor cell was characterized as a monocyte. The current study of 41 patients with active pulmonary tuberculosis examined whether T cell subpopulations also acquired antigen-specific suppressor function during Mycobacterium tuberculosis infection, contributed to monocyte-mediated suppression of tuberculin responses, or both. Alteration in the numbers of circulating T-helper (Leu 3a) and T-suppressor (Leu 2a) cells was not observed in patients with tuberculosis, nor did Leu 2a cells selectively modulate in vitro tuberculin responses. The numbers of circulating T gamma cells, a subset of T cells identified by surface receptors for the Fc portion of IgG (Fc gamma R), was increased twofold in patients with active pulmonary tuberculosis. Depletion of T gamma cells from in vitro cell culture consistently and selectively increased tuberculin responsiveness of T cells from patients with tuberculosis. In addition, in the absence of T gamma cells, monocyte-mediated suppression of tuberculin responses was demonstrated in each patient observed. These studies demonstrate that during M. tuberculosis infection T gamma cells acquire antigen-specific suppressor cell activity and suggest that T gamma cells also contribution to immunoregulation modulating the expression of tuberculin-specific suppression by monocytes.

Immunohistologic identification of antigen-presenting cells in cutaneous sarcoidosis

Considerable evidence exists to show that activated T lymphocytes preferentially accumulate at sites of disease activity in sarcoidosis. Langerhans cells, which can be recognized by reactivity with an antibody to the T6 antigen are thought to play a primary role in T-lymphocyte activation by the skin, a tissue frequently involved in sarcoidosis. This immunohistologic study examined the distribution of OKT6-positive cells and surface expression of HLA-DR antigen in cutaneous sarcoid lesions. Skin specimens stained with an anti-HLA-DR antibody demonstrated diffuse staining of the granulomas. In addition, keratinocytes, which do not normally express HLA-DR antigens, were found to stain with monoclonal antibody to HLA-DR in an intercellular pattern. Examination of specimens for OKT6-reactive Langerhans cells revealed significantly greater concentrations in the epidermis overlying sarcoidal granulomas (33 +/- 7 cells/mm) than in the epidermis of age-, sex-, and race-matched controls (11 +/- 3 cells/mm, p less than 0.001). Of greater importance was the demonstration that significant numbers of OKT6-positive cells were present within the dermal sarcoid granulomas (19-208/mm2) in a distribution that paralleled that of Leu-3a-positive T lymphocytes. These data suggest that the epidermis may participate in activation of lymphocytes in cutaneous sarcoidosis, and implicate OKT6-positive cells in granuloma formation.

Defective interleukin 2 production and responsiveness in human pulmonary tuberculosis

Patients with newly diagnosed, pulmonary tuberculosis had a tuberculin-specific defect in IL-2 production. Mean PPD-induced IL-2 activity was 81.2% lower in patients as compared with healthy tuberculin reactors. PPD-induced expression of T cell IL-2 receptors was 5.9 times less in peripheral blood mononuclear cells of patients with tuberculosis as compared with healthy tuberculin reactors. Furthermore, purified IL-2 failed to correct PPD-induced blastogenesis in patients. Suppression by adherent cells was operative in one group of patients; adherent cell depletion increased their T cell production of IL-2 7.2-fold. A second group of patients with low IL-2 production did not have suppressor adherent cells and were clinically distinct, with more extensive disease on chest x ray. The basis for low IL-2 production in such individuals is unknown. Disordered regulation of IL-2 metabolism may be a key feature in the depressed cellular immune response of tuberculosis.

Increased interleukin-1 production and monocyte suppressor cell activity associated with human tuberculosis

Interleukin-1 (IL-1) production by blood monocytes and blastogenesis produced by tuberculin purified protein derivative (PPD) in blood T lymphocytes were examined in patients with pulmonary tuberculosis. Monocytes were isolated from blood mononuclear cells by plastic adherence, and IL-1 activity was determined in the mouse thymocyte proliferation assay. Monocytes from patients with tuberculosis produced significantly higher activities of IL-1 than did those from healthy tuberculin reactors when stimulated with lipopolysaccharide (LPS) (patients, 56.1 +/- 20.0 U/ml; healthy control subjects, 7.3 +/- 1.7 U/ml; p less than 0.05) or PPD (patients, 28.1 +/- 7.2 U/ml; healthy control subjects, 9.5 +/- 2.9 U/ml; p less than 0.05). In contrast, PPD-induced blastogenic responses in peripheral blood mononuclear cells (PBMC) from the patients were lower than those from healthy subjects (patients, 4,506 +/- 1,145 cpm; healthy control subjects, 14,655 +/- 2,240 cpm; p less than 0.005), and IL-1 production by monocytes showed a positive correlation with monocyte suppressor activity for PPD-induced blastogenesis. Moreover, exogenous IL-1 was capable of suppressing antigen-induced blastogenesis of PBMC from healthy subjects. These data suggest that monocytes from patients with pulmonary tuberculosis are activated to produce or secrete increased levels of IL-1 and that IL-1 may be a mediator of suppressor cell function.

Immunoregulatory adherent cells in human tuberculosis: radiation-sensitive antigen-specific suppression by monocytes

In human tuberculosis, adherent mononuclear cells (AMC) selectively depress in vitro responses to the mycobacterial antigen tuberculin purified protein derivative (PPD). The phenotype of this antigen-specific adherent suppressor cell was characterized by examining the functional activity of adherent cells after selective depletion of sheep erythrocyte-rosetting T cells or OKM1-reactive monocytes. Adherent cell suppression was studied in the [3H]thymidine-incorporation microculture assay by using T cells rigorously depleted of T cells with surface receptors for the Fc portion of IgG (T gamma cells) as antigen-responsive cells. PPD-induced [3H]thymidine incorporation by these non gamma T cells was uniformly reduced (mean, 42% +/- 10% [SD]) when autologous AMC were added to non gamma T cells at a ratio of 1:2. Antigen-specific suppression by AMC was not altered by depletion of sheep erythrocyte-rosetting T cells or treatment with indomethacin. However, AMC treated with OKM1 and complement or gamma irradiation (1,500 rads) no longer suppressed tuberculin responses in vitro. These studies identify the antigen-specific adherent suppressor cell in tuberculosis as an OKM1-reactive, non-erythrocyte-rosetting monocyte. The radiosensitivity of this monocyte immunoregulatory function may facilitate its further definition.

Bovine aortic endothelial cells elaborate an inhibitor of the generation of lipopolysaccharide-stimulated human blood monocyte procoagulant activity

We examined the effect of bovine aortic endothelial cell culture supernatants upon the generation of procoagulant activity by human blood monocytes. Confluent endothelial monolayers were cultured for up to 96 h. At timed intervals, culture supernatants were collected and incubated for 5 h with lipopolysaccharide-stimulated human peripheral blood mononuclear cells. The procoagulant activity of mononuclear cell lysates was determined in a one-stage clotting assay. In five experiments, procoagulant activity with culture supernatant (time 0) was 2,294 +/- 761 U/ml (mean +/- SEM). Culture supernatants from endothelial cells incubated for 24-96 h strongly inhibited mononuclear cell generation of procoagulant activity. Indomethacin (10 microM) added to endothelial cells delayed the appearance of procoagulant inhibitor for 72 h. Bovine aortic smooth muscle cell culture supernatants did not inhibit procoagulant activity. The inhibitor was heat stable, effective at 1:50 dilution, soluble, and acid sensitive, with a molecular weight of less than 1,500. Further studies on subpopulations of mononuclear cells demonstrated that endothelial inhibitor selectively decreased the generation of monocyte procoagulant activity and interfered with T lymphocyte amplification of monocyte production of procoagulant activity. Thus, we have demonstrated that endothelial cells elaborate a potent inhibitor of monocyte procoagulant activity.