Effects of subcutaneous nerve stimulation with blindly inserted electrodes on ventricular rate control in a canine model of persistent atrial fibrillation

BACKGROUND

Subcutaneous nerve stimulation (ScNS) delivered directly to large subcutaneous nerves can be either antiarrhythmic or proarrhythmic, depending on the stimulus output.

OBJECTIVE

The purpose of this study was to perform a prospective randomized study in a canine model of persistent AF to test the hypothesis that high-output ScNS using blindly inserted subcutaneous electrodes can reduce ventricular rate (VR) during persistent atrial fibrillation (AF) whereas low-output ScNS would have opposite effects.

METHODS

We prospectively randomized 16 male and 15 female dogs with sustained AF (>48 hours) induced by rapid atrial pacing into 3 groups (sham, 0.25 mA, 3.5 mA) for 4 weeks of ScNS (10 Hz, alternating 20-seconds ON and 60-seconds OFF).

RESULTS

ScNS at 3.5 mA, but not 0.25 mA or sham, significantly reduced VR and stellate ganglion nerve activity (SGNA), leading to improvement of left ventricular ejection fraction (LVEF). No differences were found between the 0.25-mA and sham groups. Histologic studies showed a significant reduction of bilateral atrial fibrosis in the 3.5-mA group compared with sham controls. Only 3.5-mA ScNS had significant fibrosis in bilateral stellate ganglions. The growth-associated protein 43 (GAP43) staining of stellate ganglions indicated the suppression of GAP43 protein expression in the 3.5-mA group. There were no significant differences of nerve sprouting among all groups. There was no interaction between sex and ScNS effects on reduction of VR and SGNA, LVEF improvement, or results of histologic studies.

CONCLUSION

We conclude that 3.5-mA ScNS with blindly inserted electrodes can improve VR control, reduce atrial fibrosis, and partially improve LVEF in a canine model of persistent AF.

Recording Intrinsic Nerve Activity at the Sinoatrial Node in Normal Dogs With High-Density Mapping

BACKGROUND

It is known that autonomic nerve activity controls the sinus rate. However, the coupling between local nerve activity and electrical activation at the sinoatrial node (SAN) remains unclear. We hypothesized that we would be able to record nerve activity at the SAN to investigate if right stellate ganglion (RSG) activation can increase the local intrinsic nerve activity, accelerate sinus rate, and change the earliest activation sites.

METHODS

High-density mapping of the epicardial surface of the right atrium including the SAN was performed in 6 dogs during stimulation of the RSG and after RSG stellectomy. A radio transmitter was implanted into 3 additional dogs to record RSG and local nerve activity at the SAN.

RESULTS

Heart rate accelerated from 108±4 bpm at baseline to 125±7 bpm after RSG stimulation (P=0.001), and to 132±7 bpm after apamin injection (P<0.001). Both electrical RSG stimulation and apamin injection induced local nerve activity at the SAN with the average amplitudes of 3.60±0.72 and 3.86±0.56 μV, respectively. RSG stellectomy eliminated the local nerve activity and decreased the heart rate. In ambulatory dogs, local nerve activity at the SAN had a significantly higher average Pearson correlation to heart rate (0.72±0.02, P=0.001) than RSG nerve activity to HR (0.45±0.04, P=0.001).

CONCLUSIONS

Local intrinsic nerve activity can be recorded at the SAN. Short bursts of these local nerve activities are present before each atrial activation during heart rate acceleration induced by stimulation of the RSG.

MicroRNA-223 Regulates the Development of Cardiovascular Lesions in LCWE-Induced Murine Kawasaki Disease Vasculitis by Repressing the NLRP3 Inflammasome

Kawasaki disease (KD), an acute febrile childhood illness and systemic vasculitis of unknown etiology, is the leading cause of acquired heart disease among children. Experimental data from murine models of KD vasculitis and transcriptomics data generated from whole blood of KD patients indicate the involvement of the NLRP3 inflammasome and interleukin-1 (IL-1) signaling in KD pathogenesis. MicroRNA-223 (miR-223) is a negative regulator of NLRP3 activity and IL-1β production, and its expression has been reported to be upregulated during acute human KD; however, the specific role of miR-223 during KD vasculitis remains unknown. Here, using the Lactobacillus casei cell wall extract (LCWE) murine model of KD vasculitis, we demonstrate increased miR-223 expression in LCWE-induced cardiovascular lesions. Compared with control WT mice, LCWE-injected miR-223-deficient mice (miR223 ^-/y ) developed more severe coronary arteritis and aortitis, as well as more pronounced abdominal aorta aneurysms and dilations. The enhanced cardiovascular lesions and KD vasculitis observed in LCWE-injected miR223 ^-/y mice correlated with increased NLRP3 inflammasome activity and elevated IL-1β production, indicating that miR-223 limits cardiovascular lesion development by downmodulating NLRP3 inflammasome activity. Collectively, our data reveal a previously unappreciated role of miR-223 in regulating innate immune responses and in limiting KD vasculitis and its cardiovascular lesions by constraining the NLRP3 inflammasome and the IL-1β pathway. These data also suggest that miR-223 expression may be used as a marker for KD vasculitis pathogenesis and provide a novel therapeutic target.

Interleukin-1 Beta-Mediated Sex Differences in Kawasaki Disease Vasculitis Development and Response to Treatment

OBJECTIVE

Kawasaki disease (KD) is the leading cause of acute vasculitis and acquired heart disease in children in developed countries. Notably, KD is more prevalent in males than females. We previously established a key role for IL (interleukin)-1 signaling in KD pathogenesis, but whether this pathway underlies the sex-based difference in susceptibility is unknown. Approach and Results: The role of IL-1 signaling was investigated in the Lactobacillus casei cell wall extract-induced experimental mouse model of KD vasculitis. Five-week-old male and female mice were injected intraperitoneally with PBS, Lactobacillus caseicell wall extract, or a combination of Lactobacillus caseicell wall extract and the IL-1 receptor antagonist Anakinra. Aortitis, coronary arteritis inflammation score and abdominal aorta dilatation, and aneurysm development were assessed. mRNA-seq (messenger RNA sequencing) analysis was performed on abdominal aorta tissue. Publicly available human transcriptomics data from patients with KD was analyzed to identify sex differences and disease-associated genes. Male mice displayed enhanced aortitis and coronary arteritis as well as increased incidence and severity of abdominal aorta dilatation and aneurysm, recapitulating the increased incidence in males that is observed in human KD. Gene expression data from patients with KD and abdominal aorta tissue of Lactobacillus caseicell wall extract-injected mice showed enhanced Il1b expression and IL-1 signaling genes in males. Although the more severe IL-1β-mediated disease phenotype observed in male mice was ameliorated by Anakinra treatment, the milder disease phenotype in female mice failed to respond.

CONCLUSIONS

IL-1β may play a central role in mediating sex-based differences in KD, with important implications for the use of anti-IL-1β therapies to treat male and female patients with KD.

Subcutaneous nerve stimulation reduces sympathetic nerve activity in ambulatory dogs with myocardial infarction

BACKGROUND

Subcutaneous nerve stimulation (ScNS) remodels the stellate ganglion and reduces stellate ganglion nerve activity (SGNA) in dogs. Acute myocardial infarction (MI) increases SGNA through nerve sprouting.

OBJECTIVE

The purpose of this study was to test the hypothesis that ScNS remodels the stellate ganglion and reduces SGNA in ambulatory dogs with acute MI.

METHODS

In the experimental group, a radio transmitter was implanted during the first sterile surgery to record nerve activity and an electrocardiogram, followed by a second sterile surgery to create MI. Dogs then underwent ScNS for 2 months. The average SGNA (aSGNA) was compared with that in a historical control group (n = 9), with acute MI monitored for 2 months without ScNS.

RESULTS

In the experimental group, the baseline aSGNA and heart rate were 4.08±0.35 μV and 98±12 beats/min, respectively. They increased within 1 week after MI to 6.91±1.91 μV (P=.007) and 107±10 beats/min (P=.028), respectively. ScNS reduced aSGNA to 3.46±0.44 μV (P<.039) and 2.14±0.50 μV (P<.001) at 4 and 8 weeks, respectively, after MI. In comparison, aSGNA at 4 and 8 weeks in dogs with MI but no ScNS was 8.26±6.31 μV (P=.005) and 10.82±7.86 μV (P=0002), respectively. Immunostaining showed confluent areas of remodeling in bilateral stellate ganglia and a high percentage of tyrosine hydroxylase-negative ganglion cells. Terminal deoxynucleotidyl transferase dUTP nick end labeling was positive in 26.61%±11.54% of ganglion cells in the left stellate ganglion and 15.94%±3.62% of ganglion cells in the right stellate ganglion.

CONCLUSION

ScNS remodels the stellate ganglion, reduces SGNA, and suppresses cardiac nerve sprouting after acute MI.

Mucormycosis

Mucormycosis is an infection caused by a group of filamentous molds within the order Mucorales. Infections may result from ingestion of contaminated food, inhalation of spores into the nares or lungs, or inoculation into disrupted skin or wounds. In developed countries, mucormycosis occurs primarily in severely immunocompromised hosts (e.g., those with hematological malignancies, organ transplantation, neutropenia, autoimmune disorders, or other impairments in immunity). Only 6 to 10% of cases occur in subjects with no underlying disease. In contrast, in developing countries, most cases of mucormycosis occur in persons with poorly controlled diabetes mellitus or in immunocompetent subjects following trauma. Mucormycosis exhibits a marked propensity to invade blood vessels, leading to thrombosis, necrosis, and infarction of tissue. Mortality associated with invasive mucormycosis is high (> 30-50%), with 90% mortality associated with disseminated disease. Mortality rates are much lower, though still significant (10-30%), among patients with localized cutaneous disease.The diagnosis of mucormycosis relies upon histopathology and culture. Blood tests are of limited diagnostic value. Even with disseminated disease, blood cultures are usually negative. Mucorales have a distinct histological appearance, with irregular, nonseptate hyphae that branch at right angles. Cultures and/or polymerase chain reaction (PCR) are important to identify the genera.Based on anatomic localization, mucormycosis can be classified as one of six forms: (1) rhino-orbital-cerebral mucormycosis (ROCM), (2) pulmonary, (3) cutaneous, (4) gastrointestinal (GI), (5) disseminated, and (6) mucormycosis of uncommon sites. Among diabetics, ROCM is the most common clinical presentation, whereas lung involvement is uncommon. In contrast, among organ transplant recipients or patients with hematological malignancies (HemeM), pulmonary and disseminated diseases are most common. Mucormycosis can progress rapidly, and delay in initiation of treatment by even a few days markedly worsens outcomes.Due to the rarity of mucormycosis, randomized controlled therapeutic trials have not been performed. Lipid formulations of amphotericin B (LFAB) are the mainstay of therapy, but the newer triazoles, posaconazole (POSA) and isavuconazole (ISAV) (the active component of the prodrug isavuconazonium sulfate), may be effective in patients refractory to or intolerant of LFAB. Early surgical debridement or excision plays an important adjunctive role. Additional studies are required to assess the optimal duration of therapy as well as the specific roles of LFAB and the triazoles in the treatment of mucormycosis.

Publisher Correction: In vivo imaging of mitochondrial membrane potential in non-small-cell lung cancer

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

IL-1-dependent electrophysiological changes and cardiac neural remodeling in a mouse model of Kawasaki disease vasculitis

Kawasaki disease (KD) is the leading cause of acquired heart disease in children. In addition to coronary artery abnormalities, aneurysms and myocarditis, acute KD is also associated with echocardiogram (ECG) abnormalities in 40-80% of patients. Here, we show that these ECG changes are recapitulated in the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model. LCWE-injected mice developed elevated heart rate and decreased R wave amplitude, with significant differences in prolonged ventricular repolarization. LCWE-injected mice developed cardiac ganglion inflammation, that may affect the impulse-conducting system in the myocardium. Furthermore, serum nerve growth factor (NGF) was significantly elevated in LCWE-injected mice, similar to children with KD vasculitis, associated with increased neural remodeling of the myocardium. ECG abnormalities were prevented by blocking interleukin (IL)-1 signaling with anakinra, and the increase in serum NGF and cardiac neural remodeling were similarly blocked in Il1r1^-/- mice and in wild-type mice treated with anakinra. Thus, similar to clinical KD, the LCWE-induced KD vasculitis mouse model also exhibits electrophysiological abnormalities and cardiac neuronal remodeling, and these changes can be prevented by blocking IL-1 signaling. These data support the acceleration of anti-IL-1 therapy trials to benefit KD patients.

In vivo imaging of mitochondrial membrane potential in non-small-cell lung cancer

Mitochondria are essential regulators of cellular energy and metabolism, and have a crucial role in sustaining the growth and survival of cancer cells. A central function of mitochondria is the synthesis of ATP by oxidative phosphorylation, known as mitochondrial bioenergetics. Mitochondria maintain oxidative phosphorylation by creating a membrane potential gradient that is generated by the electron transport chain to drive the synthesis of ATP¹. Mitochondria are essential for tumour initiation and maintaining tumour cell growth in cell culture and xenografts^2,3. However, our understanding of oxidative mitochondrial metabolism in cancer is limited because most studies have been performed in vitro in cell culture models. This highlights a need for in vivo studies to better understand how oxidative metabolism supports tumour growth. Here we measure mitochondrial membrane potential in non-small-cell lung cancer in vivo using a voltage-sensitive, positron emission tomography (PET) radiotracer known as 4-[¹⁸F]fluorobenzyl-triphenylphosphonium (¹⁸F-BnTP)⁴. By using PET imaging of ¹⁸F-BnTP, we profile mitochondrial membrane potential in autochthonous mouse models of lung cancer, and find distinct functional mitochondrial heterogeneity within subtypes of lung tumours. The use of ¹⁸F-BnTP PET imaging enabled us to functionally profile mitochondrial membrane potential in live tumours.

The Immune Contexture Associates with the Genomic Landscape in Lung Adenomatous Premalignancy

Epithelial cells in the field of lung injury can give rise to distinct premalignant lesions that may bear unique genetic aberrations. A subset of these lesions may escape immune surveillance and progress to invasive cancer; however, the mutational landscape that may predict progression has not been determined. Knowledge of premalignant lesion composition and the associated microenvironment is critical for understanding tumorigenesis and the development of effective preventive and interception strategies. To identify somatic mutations and the extent of immune cell infiltration in adenomatous premalignancy and associated lung adenocarcinomas, we sequenced exomes from 41 lung cancer resection specimens, including 89 premalignant atypical adenomatous hyperplasia lesions, 15 adenocarcinomas in situ, and 55 invasive adenocarcinomas and their adjacent normal lung tissues. We defined nonsynonymous somatic mutations occurring in both premalignancy and the associated tumor as progression-associated mutations whose predicted neoantigens were highly correlated with infiltration of CD8⁺ and CD4⁺ T cells as well as upregulation of PD-L1 in premalignant lesions, suggesting the presence of an adaptive immune response to these neoantigens. Each patient had a unique repertoire of somatic mutations and associated neoantigens. Collectively, these results provide evidence for mutational heterogeneity, pathway dysregulation, and immune recognition in pulmonary premalignancy.Significance: These findings identify progression-associated somatic mutations, oncogenic pathways, and association between the mutational landscape and adaptive immune responses in adenomatous premalignancy.See related commentary by Merrick, p. 4811.

Antiarrhythmic and proarrhythmic effects of subcutaneous nerve stimulation in ambulatory dogs

BACKGROUND

High output subcutaneous nerve stimulation (ScNS) remodels the stellate ganglia and suppresses cardiac arrhythmia.

OBJECTIVE

The purpose of this study was to test the hypothesis that long duration low output ScNS causes cardiac nerve sprouting and increases plasma norepinephrine concentration and the duration of paroxysmal atrial tachycardia (PAT) in ambulatory dogs.

METHODS

We prospectively randomized 22 dogs (11 males and 11 females) into 5 different output groups for 2 months of ScNS: 0 mA (sham) (n = 6), 0.25 mA (n = 4), 1.5 mA (n = 4), 2.5 mA (n = 4), and 3.5 mA (n = 4).

RESULTS

As compared with baseline, the changes in the durations of PAT episodes per 48 hours were significantly different among different groups (sham, -5.0 ± 9.5 seconds; 0.25 mA, 95.5 ± 71.0 seconds; 1.5 mA, -99.3 ± 39.6 seconds; 2.5 mA, -155.3 ± 87.8 seconds; and 3.5 mA, -76.3 ± 44.8 seconds; P < .001). The 3.5 mA group had a greater reduction in sinus heart rate than did the sham group (-29.8 ± 15.0 beats/min vs -14.5 ± 3.0 beats/min; P = .038). Immunohistochemical studies showed that the 0.25 mA group had a significantly increased while 2.5 mA and 3.5 mA stimulation had significantly reduced growth-associated protein 43 nerve densities in both atria and ventricles. The plasma norepinephrine concentrations in the 0.25 mA group was 5063.0 ± 4366.0 pg/mL, which was significantly higher than that in the other groups of dogs (739.3 ± 946.3; P = .009). There were no significant differences in the effects of simulation between males and females.

CONCLUSION

In ambulatory dogs, low output ScNS causes cardiac nerve sprouting and increases plasma norepinephrine concentration and the duration of PAT episodes while high output ScNS is antiarrhythmic.

Pathology of the Aortic Valve: Aortic Valve Stenosis/Aortic Regurgitation

PURPOSE OF REVIEW

This discussion is intended to review the anatomy and pathology of the aortic valve and aortic root region, and to provide a basis for the understanding of and treatment of the important life-threatening diseases that affect the aortic valve.

RECENT FINDINGS

The most exciting recent finding is that less invasive methods are being developed to treat diseases of the aortic valve. There are no medical cures for aortic valve diseases. Until recently, open-heart surgery was the only effective method of treatment. Now percutaneous approaches to implant bioprosthetic valves into failed native or previously implanted bioprosthetic valves are being developed and utilized. A genetic basis for many of the diseases that affect the aortic valve is being discovered that also should lead to innovative approaches to perhaps prevent these disease. Sequencing of ribosomal RNA is assisting in identifying organisms causing endocarditis, leading to more effective antimicrobial therapy. There is exciting, expanding, therapeutic innovation in the treatment of aortic valve disease.

Specific Anatomic Considerations for Tricuspid Interventions

PURPOSE OF REVIEW

This review discusses the normal anatomy and pathology of the tricuspid valve (TV) and right side of the heart. Emphasis is on those anatomic and pathologic features relevant to interventions intended to restore normal function to the TV in disease states.

RECENT FINDINGS

TV pathology is less common than aortic and mitral valve pathology, and treatment and outcomes for interventions face considerable hurdles. New innovations and early data showing safety and efficacy in transcatheter interventions have transformed TV interventions into the next frontier in cardiac valve disease treatment. Certain features of the TV and right heart have presented themselves as potential targets, as well as impediments, for TV intervention. The causes of TV pathology and the anatomy of the TV and right heart bring unique challenges to intervention. Approaches to intervention will continue to progress and change the way we view and treat TV pathology.

Subcutaneous nerve stimulation for rate control in ambulatory dogs with persistent atrial fibrillation

BACKGROUND

Subcutaneous nerve stimulation (ScNS) damages the stellate ganglion and improves rhythm control of atrial fibrillation (AF) in ambulatory dogs.

OBJECTIVE

The purpose of this study was to test the hypothesis that thoracic ScNS can improve rate control in persistent AF.

METHODS

We created persistent AF in 13 dogs and randomly assigned them to ScNS (n = 6) and sham control (n = 7) groups. ¹⁸F-2-Fluoro-2-deoxyglucose positron emission tomography/magnetic resonance imaging of the brain stem was performed at baseline and at the end of the study.

RESULTS

The average stellate ganglion nerve activity reduced from 4.00 ± 1.68 μV after the induction of persistent AF to 1.72 ± 0.42 μV (P = .032) after ScNS. In contrast, the average stellate ganglion nerve activity increased from 3.01 ± 1.26 μV during AF to 5.52 ± 2.69 μV after sham stimulation (P = .023). The mean ventricular rate during persistent AF reduced from 149 ± 36 to 84 ± 16 beats/min (P = .011) in the ScNS group, but no changes were observed in the sham control group. The left ventricular ejection fraction remained unchanged in the ScNS group but reduced significantly in the sham control group. Immunostaining showed damaged ganglion cells in bilateral stellate ganglia and increased brain stem glial cell reaction in the ScNS group but not in the control group. The ¹⁸F-2-fluoro-2-deoxyglucose uptake in the pons and medulla was significantly (P = .011) higher in the ScNS group than the sham control group at the end of the study.

CONCLUSION

Thoracic ScNS causes neural remodeling in the brain stem and stellate ganglia, controls the ventricular rate, and preserves the left ventricular ejection fraction in ambulatory dogs with persistent AF.

Tricuspid and Pulmonic Valve Pathology

PURPOSE OF REVIEW

This review describes the normal structure and pathologic changes that affect the right-sided cardiac valves and chambers.

RECENT FINDINGS

The anatomy and pathology described have been known for many years. Knowledge of these findings has gained relevance. The pattern of endocarditis is changing. New diagnostic techniques have allowed better characterization of lesions responsible for cardiac dysfunction. Novel, less invasive interventions have made recognition of abnormalities more clinically relevant. There are many different pathologic entities that can affect the right-sided cardiac valves. These are discussed in this review.

CCR4 expression on host T cells is a driver for alloreactive responses and lung rejection

Despite current immunosuppressive strategies, long-term lung transplant outcomes remain poor due to rapid allogenic responses. Using a stringent mouse model of allo-airway transplantation, we identify the CCR4-ligand axis as a central node driving secondary lymphoid tissue homing and activation of the allogeneic T cells that prevent long-term allograft survival. CCR4 deficiency on transplant recipient T cells diminishes allograft injury and when combined with CTLA4-Ig leads to an unprecedented long-term lung allograft accommodation. Thus, we identify CCR4-ligand interactions as a central mechanism driving allogeneic transplant rejection and suggest it as a potential target to enhance long-term lung transplant survival.

Capillary Proliferation in Systemic-Sclerosis-Related Pulmonary Fibrosis: Association with Pulmonary Hypertension

Objective

We sought to determine if any histopathologic component of the pulmonary microcirculation can distinguish systemic sclerosis (SSc)‐related pulmonary fibrosis (PF) with and without pulmonary hypertension (PH).

Methods

Two pulmonary pathologists blindly evaluated 360 histologic slides from lungs of 31 SSc‐PF explants or autopsies with (n = 22) and without (n = 9) PH. The presence of abnormal small arteries, veins, and capillaries (pulmonary microcirculation) was semiquantitatively assessed in areas of preserved lung architecture. Capillary proliferation (CP) within the alveolar walls was measured by its distribution, extent (CP % involvement), and maximum number of layers (maximum CP). These measures were then evaluated to determine the strength of their association with right heart catheterization–proven PH.

Results

Using consensus measures, all measures of CP were significantly associated with PH. Maximum CP had the strongest association with PH (P = 0.013; C statistic 0.869). Maximum CP 2 or more layers and CP % involvement 10% or greater were the optimal thresholds that predicted PH, both with a sensitivity of 56% and specificity of 91%. The CP was typically multifocal rather than focal or diffuse and was associated with a background pattern of usual interstitial pneumonia. There was a significant but weaker relationship between the presence of abnormal small arteries and veins and PH.

Conclusion

In the setting of advanced SSc‐PF, the histopathologic feature of the pulmonary microcirculation best associated with PH was capillary proliferation in architecturally preserved lung areas.

Myocardial fibrosis after adrenergic stimulation as a long-term sequela in a mouse model of Kawasaki disease vasculitis

Kawasaki disease (KD), the leading cause of acquired cardiac disease among children, is often associated with myocarditis that may lead to long-term myocardial dysfunction and fibrosis. Although those myocardial changes develop during the acute phase, they may persist for decades and closely correlate with long-term myocardial sequelae. Using the Lactobacillus casei cell wall extract-induced (LCWE-induced) KD vasculitis murine model, we investigated long-term cardiovascular sequelae, such as myocardial dysfunction, fibrosis, and coronary microvascular lesions following adrenergic stimuli after established KD vasculitis. We found that adrenergic stimulation with isoproterenol following LCWE-induced KD vasculitis in mice was associated with increased risk of cardiac hypertrophy and myocardial fibrosis, diminished ejection fraction, and increased serum levels of brain natriuretic peptide. Myocardial fibrosis resulting from pharmacologic-induced exercise after KD development was IL-1 signaling dependent and was associated with a significant reduction in myocardial capillary CD31 expression, indicative of a rarefied myocardial capillary bed. These observations suggest that adrenergic stimulation after KD vasculitis may lead to cardiac hypertrophy and bridging fibrosis in the myocardium in the LCWE-induced KD vasculitis mouse model and that this process involves IL-1 signaling and diminished microvascular circulation in the myocardium.

Atrial fibrillation and electrophysiology in transgenic mice with cardiac-restricted overexpression of FKBP12

Cardiomyocyte-restricted overexpression of FK506-binding protein 12 transgenic (αMyHC-FKBP12) mice develop spontaneous atrial fibrillation (AF). The aim of the present study is to explore the mechanisms underlying the occurrence of AF in αMyHC-FKBP12 mice. Spontaneous AF was documented by telemetry in vivo and Langendorff-perfused hearts of αMyHC-FKBP12 and littermate control mice in vitro. Atrial conduction velocity was evaluated by optical mapping. The patch-clamp technique was applied to determine the potentially altered electrophysiology in atrial myocytes. Channel protein expression levels were evaluated by Western blot analyses. Spontaneous AF was recorded in four of seven αMyHC-FKBP12 mice but in none of eight nontransgenic (NTG) controls. Atrial conduction velocity was significantly reduced in αMyHC-FKBP12 hearts compared with NTG hearts. Interestingly, the mean action potential duration at 50% but not 90% was significantly prolonged in αMyHC-FKBP12 atrial myocytes compared with their NTG counterparts. Consistent with decreased conduction velocity, average peak Na+ current ( INa) density was dramatically reduced and the INa inactivation curve was shifted by approximately +7 mV in αMyHC-FKBP12 atrial myocytes, whereas the activation and recovery curves were unaltered. The Nav1.5 expression level was significantly reduced in αMyHC-FKBP12 atria. Furthermore, we found increases in atrial Cav1.2 protein levels and peak L-type Ca2+ current density and increased levels of fibrosis in αMyHC-FKBP12 atria. In summary, cardiomyocyte-restricted overexpression of FKBP12 reduces the atrial Nav1.5 expression level and mean peak INa, which is associated with increased peak L-type Ca2+ current and interstitial fibrosis in atria. The combined electrophysiological and structural changes facilitated the development of local conduction block and altered action potential duration and spontaneous AF. NEW & NOTEWORTHY This study addresses a long-standing riddle regarding the role of FK506-binding protein 12 in cardiac physiology. The work provides further evidence that FK506-binding protein 12 is a critical component for regulating voltage-gated sodium current and in so doing has an important role in arrhythmogenic physiology, such as atrial fibrillation.

Methods for registering and calibrating in vivo terahertz images of cutaneous burn wounds

A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% reflectivity), and abdomen regions within the registered THz images. Pixel populations, defined by the segmentations, informed unsupervised image calibration and contrast warping for display. The registered images revealed that the largest variation in THz tissue reflectivity occurred superior to the contact region at ~0.13%/min. Conversely the contact region showed demonstrated an ~6.5-fold decrease at ~0.02%/min. Exploration of occlusion effects suggests that window contact may affect the measured edematous response.

Augmented concentrations of CX3CL1 are associated with interstitial lung disease in systemic sclerosis

BACKGROUND

Dysregulation of Fractalkine (CX3CL1) and its receptor CX3CR1 has been linked to the pathobiology of chronic inflammatory conditions. We explored CX3CL1 in systemic sclerosis (SSc) related progressive interstitial lung disease (ILD) and pulmonary hypertension (PH) in two different but complementary sources of biomaterial.

METHODS

We collected lung tissue at the time of lung transplantation at UCLA from SSc-ILD patients (n = 12) and healthy donors (n = 12); and serum samples from the prospective Oslo University Hospital SSc cohort (n = 292) and healthy donors (n = 100). CX3CL1 was measured by ELISA. Cellular sources of CX3CL1/CX3CR1 in lung tissues were determined by immunohistochemistry and immunofluorescence. ILD progression and new onset PH endpoints were analysed.

RESULTS

CX3CL1 concentrations were increased in SSc in lung tissue as well as in sera. In the UCLA cohort, CX3CL1 was highly correlated with DLCO. In the SSc-ILD lungs, CX3CL1 was identified in reactive type II pneumocytes and airway epithelial cells. CX3CR1 stained infiltrating interstitial mononuclear cells, especially plasma cells. In the Oslo cohort, CX3CL1 correlated with anti-Topoisomerase-I-antibody and lung fibrosis. CX3CL1 was associated with ILD progression in multivariable regression analysis but not PH.

CONCLUSION

CX3CL1 is associated with progressive SSc-ILD but not SSc-PH. The CX3CR1/CX3CL1-biological axis may be involved in recruiting antibody secreting plasma cells to SSc lungs, thereby contributing to the immune-mediated pathobiology of SSc-ILD.

Abstract B20: Premalignant lung lesions demonstrate enhanced PD-L1 upregulation in response to interferon-gamma exposure

Background: Interferon-gamma (IFN-g) is known to play a pivotal role in PD-L1 expression and immune evasion in cancer cells, but there is little known regarding its interactions with premalignant lung lesions.

Methods: Immortalized human bronchial epithelial cells (HBEC-vector control), KRAS-mutated (KRASv12) HBEC cells (HBEC-KRAS), p53 knockdown HBEC cells (HBEC-p53), and p53 knockdown/KRAS mutated cells (HBEC-p53/KRAS) were used to assess mRNA expression as well as surface and total protein expression levels of PD-L1 by RT-PCR, flow cytometry, and Western blot before and after treatment with IFN-g. For STAT-1 knockdown, cells were transiently transfected using Lipofectamine RNAiMAX (Thermo Scientific). After 48 hours of transfection, cells were incubated with IFN-g (50 ng/mL) or PBS with 0.1% BSA for 48 hours, then harvested and analyzed by RT-PCR, flow cytometry, and Western blot. An FFPE tissue block from a patient with known premalignant lesions and lung adenocarcinoma was obtained from the UCLA Lung Cancer Tissue Repository and sectioned to create slides for H&E staining and to identify areas of atypical adenomatous hyperplasia. Serial sectioning was performed to create slides for multiplex staining, targeting anti-PD-L1, anti-p-STAT1-Ser747, and anti-CD8. Quantitative image analysis was performed with Visiopharm.

Results: Using RT-PCR, flow cytometry, and Western blot, exposure to IFN-g led to upregulation of PD-L1 in HBECs with various gene mutations (HBEC-vector compared to HBEC-Kras, HBEC-p53, HBEC-KRAS/p53, HBEC-EGFR-L858R) (p&lt;0.05). These experiments demonstrated that PD-L1 is elevated at the mRNA and protein levels with IFN-g exposure, with the greatest upregulation in HBECs with KRAS mutation (p&lt;0.013). To investigate potential mechanisms of PD-L1 upregulation in premalignant cell lines after IFN-g exposure, we evaluated levels of STAT1, pSTAT1, ERK, pERK, AKT, and pAKT in the paired HBEC3 vector and KRAS cell lines. On Western blot, pSTAT1 was the only signaling protein that was upregulated after IFN-g exposure. We then performed STAT-1 knockdown of HBEC3-vector and HBEC3-KRAS cell lines. With IFN-g exposure, there was significantly diminished PD-L1 upregulation in the HBEC3-KRAS with STAT-1 knockdown as compared to the HBEC3-KRAS control (p&lt;0.002). In our human staining, there was increased CD8 T cells (11% versus 2.5%) and pSTAT1 (80% versus 32%) in the vicinity of premalignant lesions as compared to normal tissues. In addition, although we identified sporadic premalignant epithelial cells with membranous PD-L1 staining, no PD-L1 staining was identified in any normal epithelial cells.

Conclusions: Premalignant lung lesions may contribute to immune evasion by responding to IFN-gamma exposure with enhanced PD-L1 upregulation via pSTAT1 signaling. Further studies are required to establish the role of IFN-gamma in the immune microenvironment of premalignant lung lesions.

Citation Format: Jane Yanagawa, Eileen Fung, Mi-Heon Lee, W. Dean Wallace, Michael C. Fishbein, Manash Paul, Kostyantyn Krysan, John D. Minna, Rong Guo, David Elashoff, Jay M. Lee, Steven M. Dubinett. Premalignant lung lesions demonstrate enhanced PD-L1 upregulation in response to interferon-gamma exposure [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B20.