Anthony M. Szema

Moderate Pulmonary Arterial Hypertension in Male Mice Lacking the Vasoactive Intestinal Peptide Gene

Background— Vasoactive intestinal peptide (VIP), a pulmonary vasodilator and inhibitor of vascular smooth muscle proliferation, has been reported absent in pulmonary arteries from patients with idiopathic pulmonary arterial hypertension (PAH). We have tested the hypothesis that targeted deletion of the VIP gene may lead to PAH with pulmonary vascular remodeling. Methods and Results— We examined VIP knockout (VIP−/−) mice for evidence of PAH, right ventricular (RV) hypertrophy, and pulmonary vascular remodeling. Relative to wild-type control mice, VIP−/− mice showed moderate RV hypertension, RV hypertrophy confirmed by increased ratio of RV to left ventricle plus septum weight, and enlarged, thickened pulmonary artery and smaller branches with increased muscularization and narrowed lumen. Lung sections also showed perivascular inflammatory cell infiltrates. No systemic hypertension and no arterial hypoxemia existed to explain the PAH. The condition was associated with increased mortality. Both the vascular remodeling and RV remodeling were attenuated after a 4-week treatment with VIP. Conclusions— Deletion of the VIP gene leads to spontaneous expression of moderately severe PAH in mice during air breathing. Although not an exact model of idiopathic PAH, the VIP−/− mouse should be useful for studying molecular mechanisms of PAH and evaluating potential therapeutic agents. VIP replacement therapy holds promise for the treatment of PAH, and mutations of the VIP gene may be a factor in the pathogenesis of idiopathic PAH.

New-onset asthma among soldiers serving in Iraq and Afghanistan.

Since June 4, 2004, asthma diagnosed and symptomatic after the age of 12 years has been an exclusion criterion for military enlistment unless exempted via medical waiver. The Department of Defense determined that 13% of U.S. Army Medic visits in Iraq are for new-onset acute respiratory illness; case reports of veterans with asthma that began in Iraq and Afghanistan War zones have surfaced. This prompted our study to determine whether new asthma is diagnosed more frequently among Iraq/Afghanistan War troops versus stateside-based troops. Retrospective review of asthma diagnoses among computerized charts for military personnel discharged from active duty and examined between March 1, 2004 and May 1, 2007, at the Veterans Affairs Medical Center (VAMC), Northport, NY, classified soldiers by (1) deployment status-whether they were stationed in Iraq/Afghanistan for a 1-year tour of duty or stationed in the United States, and (2) VA diagnosis of asthma per International Classification of Disease codes. Associations between deployment and asthma statuses were evaluated/stratified by gender/age group. Eligibility criteria entailed (1) residence in Long Island, (2) aged 18-45 years, and (3) both U.S. military service and discharge dates between March 1, 2004 and May 1, 2007. Out of 6233 patients who served between 2004 and 2007 and were followed at the Northport VAMC, 290 new-onset/prevalent asthma cases were identified. Deployment to Iraq was associated with a significantly higher risk of asthma compared with stateside soldiers (6.6% versus 4.3%; with a crude odds ratio, 1.58; 95% CI, 1.18, 2.11). These associations persist when stratified by gender and age group. Deployment to Iraq and Afghanistan is associated with new-onset asthma. Etiologic studies, surveillance, incidence, epidemiology, and assessing response to therapy are recommended.

VIP and endothelin receptor antagonist: an effective combination against experimental pulmonary arterial hypertension.

BackgroundPulmonary Arterial Hypertension (PAH) remains a therapeutic challenge, and the search continues for more effective drugs and drug combinations. We recently reported that deletion of the vasoactive intestinal peptide (VIP) gene caused the spontaneous expression of a PH phenotype that was fully corrected by VIP. The objectives of this investigation were to answer the questions: 1) Can VIP protect against PH in other experimental models? and 2) Does combining VIP with an endothelin (ET) receptor antagonist bosentan enhance its efficacy?MethodsWithin 3 weeks of a single injection of monocrotaline (MCT, s.c.) in Sprague Dawley rats, PAH developed, manifested by pulmonary vascular remodeling, lung inflammation, RV hypertrophy, and death within the next 2 weeks. MCT-injected animals were either untreated, treated with bosentan (p.o.) alone, with VIP (i.p.) alone, or with both together. We selected this particular combination upon finding that VIP down-regulates endothelin receptor expression which is further suppressed by bosentan. Therapeutic outcomes were compared as to hemodynamics, pulmonary vascular pathology, and survival.ResultsTreatment with VIP, every other day for 3 weeks, begun on the same day as MCT, almost totally prevented PAH pathology, and eliminated mortality for 45 days. Begun 3 weeks after MCT, however, VIP only partially reversed PAH pathology, though more effectively than bosentan. Combined therapy with both drugs fully reversed the pathology, while preventing mortality for at least 45 days.Conclusions1) VIP completely prevented and significantly reversed MCT-induced PAH; 2) VIP was more effective than bosentan, probably because it targets a wider range of pro-remodeling pathways; and 3) combination therapy with VIP plus bosentan was more effective than either drug alone, probably because both drugs synergistically suppressed ET-ET receptor pathway.

Clues to VIP function from knockout mice.

Abstract:  We have taken advantage of the availability of vasoactive intestinal polypeptide (VIP) knockout (KO) mice to examine the possible influence of deletion of the VIP gene on: (a) airway reactivity and airway inflammation, as indicators of bronchial asthma; (b) mortality from endotoxemia, a model of septic shock; and (c) the pulmonary circulation. VIP KO mice showed: (a) airway hyperresponsiveness to the cholinergic agonist methacholine, as well as peribronchial and perivascular inflammation; (b) a greater susceptibility to death from endotoxemia; and (c) evidence suggestive of pulmonary hypertension.

Angioedema in a child with a liver transplant, intussusception, and normal c4 levels.

Swelling is a common chief complaint among patients. Swelling and hives are not typical of hereditary angioedema. Organ transplantation drugs are associated with angiodema and may complicate diagnosis. Our objective was to manage a complex case of angioedema in a setting of rashes and liver transplantation. We present an illustrative case of angioedema, rashes, and intussusception in a setting of a liver transplant and tacrolimus use with a family history of autoimmune disease. Treatment with the kallikrein inhibitor, kalbitor, eliminated angioedema and intussusception, though not permanently. Serial C1 esterase [corrected] inhibitor levels were only suppressed during severe attacks of angioedema. C1q autoantibody was elevated. Although 95% of cases of hereditary angioedema (HAE) have low [corrected] C4 levels, those with C1q immune complexes have autoantibodies leading to low-grade inflammation and eventual consumption of C1 esterase inhibitor levels with C4 unaffected. Rashes associated with angioedema are not urticarial. Physicians should learn to recognize the signs of attacks of HAE.

Differences in physicians’ self-reported knowledge of, attitudes toward, and responses to the black box warning on long-acting β-agonists

BACKGROUND Inhaled corticosteroids and long-acting beta-agonists (LABAs) are recommended for treating moderate to severe persistent asthma. The Food and Drug Administration has issued a black box warning (BBW) for LABAs. OBJECTIVE To investigate physician knowledge of the BBW and its effect on the practice of specialists (pulmonologists and allergists) and primary care physicians (PCPs) (internists and family physicians). METHODS A total of 1,107 physicians responded to a questionnaire to determine their awareness of the BBW and whether it changed their practice. RESULTS The group comprised 429 pulmonologists (38.8%), 395 allergists (35.7%), 141 internists (12.7%), 132 family physicians (11.9%), and 10 pediatricians (0.9%). Comparing specialists with PCPs, there was approximately a 10% difference in the rate of knowledge concerning the BBW (99.0% vs 90.8%, P < .001). Approximately a quarter of specialists agreed with the BBW compared with 52.9% of family physicians and 40.3% of internists. Twice as many PCPs vs specialists agreed with the warning (45.6% vs 24.2%, P < .001). The PCPs were more likely to alter their prescribing habits than were specialists (40.1% vs 34.6%, P < .005). Specialists were more likely to discuss the warning with patients than were PCPs (87.4% vs 64.8%, P < .001). For mild persistent asthma, most respondents chose inhaled corticosteroids as the preferred first-line therapy, but 11.4% of PCPs and 2.1% of specialists identified LABA monotherapy as their first choice. For moderate to severe asthma, the pattern of response was similar. CONCLUSION Although most physicians were aware of the BBW for LABAs, there was a difference in how specialists and PCPs approached it and altered their prescribing habits.

Iraq dust is respirable, sharp, and metal-laden and induces lung inflammation with fibrosis in mice via IL-2 upregulation and depletion of regulatory T cells.

Objectives: Determine whether surface dust grab samples taken from a large military base in Iraq are toxic and respirable. Methods: X-ray diffraction for mineral content, x-ray fluorescence for elemental content, in vivo mouse dust challenges for assessment of histological changes, bronchoalveolar lavage for cytokines, polarizing light microscopy for crystals in lung tissue, and Fluorescence Activated Cell Sorting for cell surface and intracellular markers were utilized. Results: Camp Victory, Iraq dust taken during wartime contains respirable particles 2.5 microns in size, constituting particulate matter air pollution. Dust particles are angular and have sharp edges. Trace metals (including titanium) calcium and silicon are present. Mice with airway instillation of dust have polarizable crystals in lung and septate inflammation. Regulatory T cells (CD4+CD25+FOXP3+) are decreased in thymus and spleen. Interleukin-2 (IL-2) is upregulated in bronchoalveolar lavage. Conclusions: Respirable Iraq dust leads to lung inflammation in mice similar to that seen in patients with polarizable crystals, which seem to be titanium.

Titanium and iron in lung of a soldier with nonspecific interstitial pneumonitis and bronchiolitis after returning from Iraq.

To the Editor:The abnormal respiratory illnesses of soldiers after Iraq deployment reported by King et al1 are corroborated by our studies. Their discovery of crystalline material in lung tissue is enhanced by our identification of copper and hotspots of titanium and iron in lung tissue of an affect

VIP Gene Deletion in Mice Causes Cardiomyopathy Associated with Upregulation of Heart Failure Genes

Rationale Vasoactive Intestinal Peptide (VIP), a pulmonary vasodilator and inhibitor of vascular smooth muscle proliferation, is absent in pulmonary arteries of patients with idiopathic pulmonary arterial hypertension (PAH). We previously determined that targeted deletion of the VIP gene in mice leads to PAH with pulmonary vascular remodeling and right ventricular (RV) dilatation. Whether the left ventricle is also affected by VIP gene deletion is unknown. In the current study, we examined if VIP knockout mice (VIP−/−) develop both right (RV) and left ventricular (LV) cardiomyopathy, manifested by LV dilatation and systolic dysfunction, as well as overexpression of genes conducive to heart failure. Methods We examined VIP−/−and wild type (WT) mice using Magnetic Resonance Imaging (MRI) for evidence of cardiomyopathy associated with biventricular dilation and wall thickness changes. Lung tissue from VIP−/− and WT mice was subjected to whole-genome gene microarray analysis. Results Lungs from VIP−/− mice showed overexpression of cardiomyopathy genes: Myh1 was upregulated 224 times over WT, and Mylpf was increased 72 fold. Tnnt3 was increased 105 times and tnnc2 181 fold. Hearts were dilated in VIP−/− mice, with thinning of LV wall and increase in RV and LV chamber size, though RV enlargement varied. Weights of VIP−/− mice were consistently lower. Conclusions Critically-important heart failure-related genes are upregulated in VIP−/− mice associated with the spontaneous cardiomyopathy phenotype, involving both left and right ventricles, suggesting that loss of the VIP gene orchestrates a panoply of pathogenic genes which are detrimental to both left and right cardiac homeostasis.

VIP Regulates the Development & Proliferation of Treg in vivo in spleen.

BackgroundMounting evidence supports a key role for VIP as an anti-inflammatory agent and promoter of immune tolerance. It suppresses TNF-α and other inflammatory cytokines and chemokines, upregulates anti-inflammatory IL-10, and promotes immune tolerant cells called T regulatory (Treg) cells. VIP KO mice have recently been demonstrated to have spontaneous airway and pulmonary perivascular inflammatory responses, as part of asthma-like and pulmonary hypertension phenotypes, respectively. Both inflammatory responses are correctable with VIP. Focusing on this model, we have now investigated the influence of VIP not only on inflammatory cells but also on Treg cells.MethodsUsing flow cytometric analysis, we examined the relative preponderance of CD25+CD4+ cells and anti-inflammatory Treg cells, in extracts of thymus and spleen from VIP KO mice (5 VIP KO; 5 VIP KO+ VIP; 10 wild-type). This method allowed antibody-based flow cytometric identification of Treg cells using surface markers CD25 and CD4, along with the: 1) intracellular activation marker FoxP3; and 2) Helios, which distinguishes cells of thymic versus splenic derivation.ConclusionsDeletion of the VIP gene results in: 1) CD25+CD4- cell accumulation in the thymus, which is corrected by VIP treatment; 2) more Treg in thymus lacking Foxp3 expression, suggesting VIP is necessary for immune tolerance; and, 3) a tendency towards deficiency of Treg cells in the spleen, which is normalized by VIP treatment. Treg lacking Helios are induced by VIP intrasplenically rather than by migration from the thymus. These results confirm the dual role of VIP as an anti-inflammatory and immune tolerance-promoting agent.