Alveolar Septae Research Articles

Intravascular large B-cell lymphoma (IVLBCL): subtle presentation and challenging diagnosis; a case report

Intravascular large B-cell lymphoma (IVLBCL) is a rare, clinically aggressive lymphoma defined by the proliferation of atypical lymphoma cells in the lumen of all sized blood vessels, particularly capillaries. The reasons for this unusual neoplastic cell proliferation are still only partially understood. IVLBCL is considered stage IV lymphoma and manifests with a variety of nonspecific signs and symptoms. Patients with IVLBCL usually do not present with lymphadenopathy. The tumor cells invade the blood vessels of multiple organs such as the central nervous system, skin, lungs, kidneys, and bone marrow. Common presenting symptoms are based on the organ affected and include mental status changes and fever of unknown origin. Although immunochemotherapy has significantly improved the often-poor prognosis of this kind of lymphoma, a large percentage of patients’ relapse. We present a 63-year-old man who had been diagnosed with large B cell lymphoma in the bone marrow in March 2021 and was in remission state after completing six cycles of chemotherapy. There was no abnormal FDG uptake on a post-chemotherapy PET/CT scan. Patient presented to the emergency room (ER) two months later with fever and dyspnea. The entire workup was completed and showed pancytopenia and elevated ESR. While chest CT scan did not show lymphadenopathy or lesions, PET/CT scans revealed a widespread increase in FDG uptake in both the lungs and spleen. Lung biopsy revealed large, atypical cells within alveolar septae and vessels. Immunohistochemical stains demonstrated that these cells were positive for CD20 and PAX-5 and had high proliferation rate based on Ki67. IVLBCL has a low incidence rate with non-specific clinical presentation. The diagnosis can be easily missed in both clinical, radiological and the corresponding histopathological findings. Radiological finding and CT scan are not sensitive enough and may miss the lesion. Even though the PET/CT scan is more sensitive, the definitive diagnosis of IVLBCL relies mainly on histopathology and immunohistochemistry, at which point awareness of this entity by the pathologist is most necessary.

B cells in the pneumococcus-infected lung are heterogeneous and require CD4+ T cell help including CD40L to become resident memory B cells.

Recovery from respiratory pneumococcal infections generates lung-localized protection against heterotypic bacteria, mediated by resident memory lymphocytes. Optimal protection in mice requires re-exposure to pneumococcus within days of initial infection. Serial surface marker phenotyping of B cell populations in a model of pneumococcal heterotypic immunity revealed that bacterial re-exposure stimulates the immediate accumulation of dynamic and heterogeneous populations of B cells in the lung, and is essential for the establishment of lung resident memory B (BRM) cells. The B cells in the early wave were activated, proliferating locally, and associated with both CD4+ T cells and CXCL13. Antagonist- and antibody-mediated interventions were implemented during this early timeframe to demonstrate that lymphocyte recirculation, CD4+ cells, and CD40 ligand (CD40L) signaling were all needed for lung BRM cell establishment, whereas CXCL13 signaling was not. While most prominent as aggregates in the loose connective tissue of bronchovascular bundles, morphometry and live lung imaging analyses showed that lung BRM cells were equally numerous as single cells dispersed throughout the alveolar septae. We propose that CD40L signaling from antigen-stimulated CD4+ T cells in the infected lung is critical to establishment of local BRM cells, which subsequently protect the airways and parenchyma against future potential infections.

Ellagic acid alleviates pulmonary inflammation and oxidative stress in mouse model of diisononyl phthalate-induced asthma

Polyvinyl chloride is plasticized using diisononyl phthalate (DiNP), and exposure to phthalates has been linked to the emergence of asthma and allergies. The adjuvant impact of DiNP exposure results in allergic airway inflammation. In the current study, we looked into how ellagic acid (ELA) impacted asthma brought on by DiNP. Male BALB/c mice (n=40, 20-30 g) were divided into 4 groups of 10 mice each, and the following treatments were given to each group: group 1 (control) received saline orally for 30 days; group 2 (ELA) received 10 mg/kg of ELA (oral) for 30 days; group 3 (DiNP & ELA) received 10 mg/kg of ELA (oral) for 7 days prior to DiNP (50mg/kg) exposure (intraperitoneal and intranasal); group 4 (DiNP) received 50 mg/kg DiNP. After the last administration, mice were sacrificed, lungs were removed and their bronchoalveolar lavage fluid was collected which was used for biochemical and histopathological analysis. The mice given DiNP had changes in their histoarchitecture, inflammatory cells, antioxidant status, and inflammation markers. Malondialdehyde (MDA) and inflammatory biomarkers (NO, MPO) were considerably higher (p< 0.05) in the lungs of DiNP-treated mice than in the control group. In the lungs, DiNP reduced the concentration of non-enzymatic antioxidants (GSH and AA), and the activity of enzymatic antioxidants (SOD, CAT, and GST). DiNP also altered inflammatory cells (eosinophils, neutrophils, lymphocytes, monocytes, leucocytes) in the BALF. ELA administration ameliorated these changes. Histopathological analysis revealed airway inflammation characterized by inflammatory cell infiltration, oedema, hemorrhage, and constricted alveoli space. Additionally, the mice co-treated with ELA and DiNP experienced mild inflammation of the alveoli and interstitial spaces as well as mild thickening of the alveolar septae. ELA offered a protective effect against DiNP-induced allergic asthma in mice.

Intravascular large B-cell lymphoma (IVLBCL): Subtle Presentation and Challenging Diagnosis

Abstract Introduction/Objective Intravascular large B-cell lymphoma (IVLBCL) is a rare, clinically aggressive lymphoma defined by the proliferation of atypical lymphoma cells in the lumen of all sized blood vessels, particularly capillaries. The reasons for this unusual neoplastic cell proliferation are still only partially understood. IVLBCL is considered stage IV lymphoma and manifests with a variety of nonspecific signs and symptoms. Patients with IVLBCL usually do not present with lymphadenopathy. The tumor cells invade the blood vessels of multiple organs such as the central nervous system, skin, lungs, kidneys, and bone marrow. Common presenting symptoms are based on the organ affected and include mental status changes and fever of unknown origin. Although immunochemotherapy has significantly improved the often-poor prognosis of this kind of lymphoma, a large percentage of patients relapse. Methods/Case Report We present a 63-year-old man who had been diagnosed with diffuse large B cell lymphoma in the bone marrow in March 2021 and was in remission state after completing six cycles of chemotherapy. There was no abnormal FDG uptake on a post-chemotherapy PET/CT scan. Patient presented to the ER two months later with fever and dyspnea. The entire workup was completed and showed pancytopenia and elevated ESR. While chest CT scan did not show lymphadenopathy or lesions, PET/CT scans revealed a widespread increase in FDG uptake in both the lungs and spleen. Lung biopsy revealed large atypical cells within alveolar septae and vessels. Immunohistochemical stains demonstrated that these cells were positive for CD20 and PAX-5 and had high proliferation rate based on Ki67. Results (if a Case Study enter NA) NA Conclusion IVLBCL has a low incidence rate with non-specific clinical presentation. The diagnosis can be easily missed in both clinical, radiological and the corresponding histopathological findings . Radiological finding and CT scan are not sensitive enough and may miss the lesion. Even though the PET/CT scan is more sensitive, the definitive diagnosis of IVLBCL relies mainly on histopathology and immunohistochemistry, at which point awareness of this entity by the Pathologist is most necessary.

WHEN LUNG BECOMES BONE: A RARE CASE OF DENDRIFORM PULMONARY OSSIFICATION

WHEN LUNG BECOMES BONE: A RARE CASE OF DENDRIFORM PULMONARY OSSIFICATION

Pulmonary Capillary Haemangiomatosis: A Rare Cause of Pulmonary Hypertension

Pulmonary capillary haemangiomatosis (PCH) is a rare disorder of unknown aetiology, characterised by proliferating capillaries that invade the pulmonary interstitium, alveolar septae and the pulmonary vasculature. It is often mis-diagnosed as primary pulmonary hypertension and pulmonary veno-occlusive disease. Pulmonary capillary haemangiomatosis is a locally aggressive benign vascular neoplasm of the lung. We report the case of a 19-year-old female who was referred to us in the early post-partum period with severe pulmonary artery hypertension, which was diagnosed as PCH by open lung biopsy.

The common ABCA3E292V variant disrupts AT2 cell quality control and increases susceptibility to lung injury and aberrant remodeling.

ATP-binding cassette class A3 (ABCA3) is a lipid transporter that plays a critical role in pulmonary surfactant function. The substitution of valine for glutamic acid at codon 292 (E292V) produces a hypomorphic variant that accounts for a significant portion of ABCA3 mutations associated with lung disorders spanning from neonatal respiratory distress syndrome and childhood interstitial lung disease to diffuse parenchymal lung disease (DPLD) in adults including pulmonary fibrosis. The mechanisms by which this and similar ABCA3 mutations disrupt alveolar type 2 (AT2) cell homeostasis and cause DPLD are largely unclear. The present study, informed by a patient homozygous for the E292V variant, used an in vitro and a preclinical murine model to evaluate the mechanisms by which E292V expression promotes aberrant lung injury and parenchymal remodeling. Cell lines stably expressing enhanced green fluorescent protein (EGFP)-tagged ABCA3 isoforms show a functional deficiency of the ABCA3E292V variant as a lipid transporter. AT2 cells isolated from mice constitutively homozygous for ABCA3E292V demonstrate the presence of small electron-dense lamellar bodies, time-dependent alterations in macroautophagy, and induction of apoptosis. These changes in AT2 cell homeostasis are accompanied by a spontaneous lung phenotype consisting of both age-dependent inflammation and fibrillary collagen deposition in alveolar septa. Older ABCA3E292V mice exhibit increased vulnerability to exogenous lung injury by bleomycin. Collectively, these findings support the hypothesis that the ABCA3E292V variant is a susceptibility factor for lung injury through effects on surfactant deficiency and impaired AT2 cell autophagy.

Intrauterine Gardnerella vaginalis Infection Results in Fetal Growth Restriction and Alveolar Septal Hypertrophy in a Rabbit Model.

Background: Gardnerella vaginalis (GV) is most frequently associated with bacterial vaginosis and is the second most common etiology causing intrauterine infection after Ureaplasma urealyticum. Intrauterine GV infection adversely affects pregnancy outcomes, resulting in preterm birth, fetal growth restriction, and neonatal pneumonia. The knowledge of how GV exerts its effects is limited. We developed an in vivo animal model to study its effects on fetal development.Materials and Methods: A survival mini-laparotomy was conducted on New Zealand rabbits on gestational day 21 (28 weeks of human pregnancy). In each dam, fetuses in the right uterine horn received intra-amniotic 0.5 × 102 colony-forming units of GV injections each, while their littermate controls in the left horn received sterile saline injections. A second laparotomy was performed seven days later. Assessment of the fetal pups, histopathology of the placenta and histomorphometric examination of the fetal lung tissues was done.Results: Three dams with a combined total of 12 fetuses were exposed to intra-amniotic GV, and 9 fetuses were unexposed. The weights of fetuses, placenta, and fetal lung were significantly lower in the GV group than the saline-inoculated control group [mean gross weight, GV (19.8 ± 3.8 g) vs. control (27.9 ± 1.7 g), p < 0.001; mean placenta weight, GV (5.5 ± 1.0 g) vs. control (6.5 ± 0.7 g), p = 0.027; mean fetal lung weight, GV (0.59 ± 0.11 g) vs. control (0.91 ± 0.08 g), p = 0.002. There was a two-fold increase in the multinucleated syncytiotrophoblasts in the placenta of the GV group than their littermate controls (82.9 ± 14.9 vs. 41.6 ± 13.4, p < 0.001). The mean alveolar septae of GV fetuses was significantly thicker than the control (14.8 ± 2.8 μm vs. 12.4 ± 3.8 μm, p = 0.007). Correspondingly, the proliferative index in the interalveolar septum was 1.8-fold higher in the GV group than controls (24.9 ± 6.6% vs. 14.2 ± 2.9%, p = 0.011). The number of alveoli and alveolar surface area did not vary between groups.Discussion: Low-dose intra-amniotic GV injection induces fetal growth restriction, increased placental multinucleated syncytiotrophoblasts and fetal lung re-modeling characterized by alveolar septal hypertrophy with cellular proliferative changes.Conclusion: This intra-amniotic model could be utilized in future studies to elucidate the acute and chronic effects of GV intrauterine infections.

Characteristics of H7N9 avian influenza pneumonia: a retrospective analysis of 17 cases.

H7N9 avian influenza is an infection of public health concern, in part because of its high mortality rate and pandemic potential. To describe the clinical features of H7N9 avian influenza and the response to treatment. Clinical, radiological and histopathological data, and treatment-related of H7N9-infected patients hospitalised during 2014-2017 were extracted and analysed. A total of 17 H7N9 patients (three females; mean age, 58.4 ± 13.7 years) was identified; of these six died. All patients presented with fever and productive cough; four patients had haemoptysis and 13 had chest distress and/or shortness of breath. Early subnormal white blood cell count and elevation of serum liver enzymes were common. Multilobar patchy shadows, rapid progression to ground-glass opacities, air bronchograms and consolidation were the most common imaging findings. Histopathological examination of lung tissue of three patients who died showed severe alveolar epithelial cell damage, with inflammatory exudation into the alveolar space and hyaline membrane formation; widened alveolar septae, prominent inflammatory cell infiltration; and hyperplasia of pneumocytes. Viral inclusions were found in the lung tissue of two patients. All patients received antiviral drugs (oseltamivir ± peramivir). Four patients carried the rs12252-C/C interferon-induced transmembrane protein-3 (IFITM3) genotype, while the others had the C/T genotype. H7N9 virus infection causes human influenza-like symptoms, but may rapidly progress to severe pneumonia and even death. Clinicians should be alert to the possibility of H7N9 infection in high-risk patients. The presence of the IFITM3 rs12252-C genotype may predict severe illness.

Pulmonary Capillary Hemangiomatosis: A Rare Cause of Pulmonary Arterial Hypertension, Presenting as Supraventricular Tachycardia

With a prevalence of less than 1/million, Pulmonary Capillary Hemangiomatosis is a rare disorder of capillary proliferation in the alveolar septae leading to pulmonary arterial hypertension and mimics pulmonary veno-occlusive disease.

Altered Megakaryocytes Are Associated with Development of Pulmonary Fibrosis in Mice Carrying the Hypomorphic Gata1low Mutation

Several studies indicate that abnormal megakaryocytes (MK) drive bone marrow fibrosis in primary myelofibrosis (PMF). Since the lung is a site where MK lodge to release platelets (Lefrançais, Nature 2017; 544:105), we investigated whether the MK abnormalities observed in PMF also lead to fibrosis in lung. To this aim, we used Gata1low mice that express MK abnormalities similar to those observed in PMF patients and develop myelofibrosis with age (Zingariello, Blood 2013;121:3345) and compared number/morphology of MK and extent of fibrosis in lungs from Gata1low mice or from their wild-type (WT) littermates. Two age groups were considered: adult, A (5-7 months) and old, O (&gt;12 months). Pulmonary fibrosis was assessed by H&amp;E and Masson's staining and graded from 0 (absent) to 3 (severe). MK were evaluated by immunohistochemistry and immunofluorescent analysis with CD42 and their number expressed per 0.144 mm2. Statistical analysis was performed with Shapiro test for normality while chi-square test and Spearman's correlation test for comparisons. Since the mutation is carried in the CD1 background that is known to develop multisite inflammation with age (Brayton, Vet Pathol 2012; 49:85), preliminary experiments compared the pro-inflammatory signature of the mice groups by ELISA determinations of the plasma levels of CXCL1 (murine equivalent of IL-8) and its inducer lipocalin2 (LCN2). WT mice expressed a pro-inflammatory signature with high levels of LCN2 (90±45ng/mL in A; 50±49 in O) and CXCL1 (44.5±11.4pg/mL in A;31.6±4.6 in O compared to 17.0 ±5.1 in O P-Selnull/Gata1low mice which do not express inflammation, p&lt;0.01). These levels were not affected by age. Gata1low mice expressed high levels of LCN2 that increased with age (100±18 in A and 150±45 in O, p&lt;0.05) and levels of CXCL1 significantly lower than those expressed by WT (27.9±1.3 in A and 28.8 ±9.7 in O, p&lt;0.05) but still greater than those in negative controls. Mild and localized interstitial pneumonia characterized by infiltration with lymphocytes, plasma cells and macrophages in the alveolar septae and peribronchial-vascular spaces was observed in 66.6% of WT mice. However, mild interstitial pneumonia was detected in 84.6% of Gata1low mice where it was multi-focal to coalescent and extended from alveolar septae to subpleural interstitium. Lungs from 33% of WT mice had mild fibrosis with accumulation of collagen in alveolar septae (grade 1) while those from 70.8% Gata1low mice presented severe fibrosis (37.5% grade 1, 29.4% grade 2 and 17.6% grade 3) (Fig. 1A, 1B). The mild interstitial pneumonia associated to grade 1 fibrosis present both in Gata1low and WT littermates is considered a background lesion due to the pro-inflammatory cytokine profile of the strain investigated. By contrast, despite the severity of pneumonia was similar in Gata1low and WT littermates, grade 2 and 3 fibrosis was only present in Gata1low mice, indicating that it was not due to the baseline inflammatory milieu of their CD1 background. MK were observed intravascularly and within the perivascular interstitium of lungs from both WT and Gata1low mice, the same location where fibrosis was detected. The number of MK was significantly lower in Gata1low than in WT littermates (median=1, range 0.6-2.57 vs 1.8, range 0.4-8.3, respectively, p=0.02) (Fig 1C). The morphology of MK found in the two groups was significantly dissimilar (p&lt;0.01): most MK (88.8%) in WT lungs contained either a round nucleus with small amount of cytoplasm or a polylobated nucleus with well developed platelet territories (Fig.1D). The morphology of most (70%) of MK in Gata1low lungs was instead characterized by large size, polylobated nuclei but poorly developed platelet territories (Fig.1E). Therefore, the significantly higher number of Gata1low mice that exhibited moderate to severe pulmonary fibrosis compared to WT controls was associated with abnormal MK suggesting that factors released by Gata1low MK in addition to CXCL1/LPN2 are involved in establishing lung fibrosis in this model. Further studies will clarify whether these factors are similar to those responsible for fibrosis in bone marrow. In conclusion, the significantly higher number of Gata1low mice that exhibited moderate to severe pulmonary fibrosis compared to WT controls establishes Gata1low mice as a potential new animal model to study human idiopathic pulmonary fibrosis and to identify possible drug targets to treat this disease. Disclosures No relevant conflicts of interest to declare.

Novel EIF2AK4 mutations in histologically proven pulmonary capillary hemangiomatosis and hereditary pulmonary arterial hypertension

BackgroundPulmonary hypertension (PH) remains one of the rarest and deadliest diseases. Pulmonary Capillary Hemangiomatosis (PCH) is one of the sub-classes of PH. It was identified using histological and molecular tools and is characterized by the proliferation of capillaries into the alveolar septae. Mutations in the gene encoding the eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) have recently been linked to this particular subgroup of PH.MethodsIn our effort to unveil the genetic basis of idiopathic and familial cases of PH in Lebanon, we have used whole exome sequencing to document known and/or novel mutations in genes that could explain the underlying phenotype.ResultsWe showed bi-allelic mutations in EIF2AK4 in two non-consanguineous families: a novel non-sense mutation c.1672C > T (p.Q558*) and a previously documented deletion c.560_564drlAAGAA (p.K187Rfs9*). Our histological analysis coupled with the CT-scan results showed that the two patients with the p.Q558* mutation have PH. In contrast, only one of the individuals harboring the p.K187Rfs9* variant has a documented PCH while his older brother remains asymtomatic. Differential analysis of the variants in the genes of the neighboring network of EIF2AK4 between the two siblings identified a couple of interesting missense mutations that could account for this discrepancy.ConclusionThese findings represent a novel documentation of the involvement of EIF2AK4 in the different aspects of pulmonary hypertension. The absence of a molecular mechanism that relates the abrogated function of the protein to the phenotype is still a major hurdle in our understanding of the disease.

Myeloid Cell Recruitment and Activation Following Ozone Exposure in a Murine Model of Mutant Surfactant Protein‐C Pulmonary Dysfunction

The missense isoleucine to threonine substitution at position 73 [I73T] in the Surfactant Protein‐C [SP‐C] gene [SFTPC], an alveolar type‐2 cell [AT2] restricted protein, has been linked to sporadic and familial cases of idiopathic pulmonary fibrosis (IPF). We have developed a hypomorphic SP‐CI73T mouse model which expresses 20% of wild‐type SP‐C output. In this setting, AT2 cells mistraffick pro‐SP‐C on the plasma membrane and temporally acquire a late block in AT2 cell macroautophagy. This is associated with age‐dependent enlargement of alveolar septae, AT2 cell hyperplasia and minor inflammatory cell accumulation, beginning at 16 wk of age. Ozone is a ubiquitous air pollutant that causes parenchymal injury and monocyte/macrophage dominant inflammation. Clinically, acute exposure to ozone is known to exacerbate respiratory injury in susceptible population (i.e. asthma). Therefore, we tested whether SP‐CI73T dysfunction is associated with susceptibility to ozone induced injury (0.8 ppm, 3 h) in young (8–12wk) and aging (52 wk) mouse cohorts. We found that young WT mice exposed to ozone did not cause significant alterations in bronchoalveolar lavage (BAL) fluid immune cell composition or cell numbers at 24 h. Conversely, differential analysis of cytospins and flow cytometry analysis of tissue digest showed increased cell counts with significant neutrophilia and lymphocyte accumulation in SP‐CI73T mice. Analysis of aging cohorts confirmed significant deterioration of lung architecture in air‐exposed 52 wk SP‐CI73T mice. Ozone exposure was associated with histological evidence of perivascular edema and immune cells influx. BAL total protein analysis also showed increased epithelial‐vascular barrier disruption at 24 h and 48 h. Taken together, our findings support the concept that epithelial dysfunction driven by mutant SP‐CI73T expression is associated with increased susceptibility to environmental toxicant and that these effects are heightened with aging.Support or Funding InformationGrant support: P30ES013508 (MFB), VA 1I01BX001176 (MFB), ES004738 (DL), ES005022 (DL).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Smooth muscle cell-specific knockout of neuropilin-1 impairs postnatal lung development and pathological vascular smooth muscle cell accumulation.

Neuropilin 1 (NRP1) is important for neuronal and cardiovascular development due to its role in conveying class 3 semaphorin and vascular endothelial growth factor signaling, respectively. NRP1 is expressed in smooth muscle cells (SMCs) and mediates their migration and proliferation in cell culture and is implicated in pathological SMC remodeling in vivo. To address the importance of Nrp1 for SMC function during development, we generated conditional inducible Nrp1 SMC-specific knockout mice. Induction of early postnatal SMC-specific Nrp1 knockout led to pulmonary hemorrhage associated with defects in alveogenesis and revealed a specific requirement for Nrp1 in myofibroblast recruitment to the alveolar septae and PDGF-AA-induced migration in vitro. Furthermore, SMC-specific Nrp1 knockout inhibited PDGF-BB-stimulated SMC outgrowth ex vivo in aortic ring assays and reduced pathological arterial neointima formation in vivo. In contrast, we observed little significant effect of SMC-specific Nrp1 knockout on neonatal retinal vascularization. Our results point to a requirement of Nrp1 in vascular smooth muscle and myofibroblast function in vivo, which may have relevance for postnatal lung development and for pathologies characterized by excessive SMC and/or myofibroblast proliferation.

Acute and chronic bovine pulmonary edema and emphysema in Uruguay

ABSTRACT: An outbreak of pulmonary edema and emphysema with acute and chronic cases is reported in a farm in Uruguay. In a herd of 40 Hereford steers, 20 died. The deaths began four days after a change of paddock, from an old pasture of Avena sativa to a lush growing pasture of the same grass. Acutely affected animals showed severe dyspnea, sialorrhea, cough, and subcutaneous edema, and died within 72 hours. Chronically affected steers showed dyspnea, respiratory noises, weight loss, and intolerance to exercise. The deaths began four days after the change of paddock. Ten days after the first death, the steers were withdrawn from the pasture, but continued dying throughout the following 40 days. Twenty animals died and six were necropsied. Grossly, the lungs were diffusely armed and glistening, with reddish and crepitant cut surface, and presented alveolar septae sharply distended by edema and emphysema. There was subpleural emphysema with air blebs distributed across the pleural surface. Presence of Dictyocaulus viviparus was observed in three steers. In some animals, the trachea was diffusely reddish with presence of pink foam; in some others, there was bloody liquid in the tracheal lumen. Histologic examination showed severe diffuse alveolar and interstitial emphysema, hyaline membranes adhered to the alveolar wall, thickening of the interlobular septae with proliferation of type II pneumocytes, and moderate-to-severe multifocal histiocytic, neutrophilic and eosinophilic infiltrate. In the trachea, there was submucosal hemorrhage and moderate multifocal eosinophilic and lymphocytic infiltrate. The steers with chronic signs presented similar lung lesions, but multifocal pulmonary fibrosis and cardiac dilatation were also observed. The diagnosis of acute bovine pulmonary emphysema and edema (ABPE) was based on the occurrence of the disease after introduction of the herd in a lush green pasture, on the characteristic gross and histologic lesions, and on the absence of other toxic or infectious agents causing similar lesions. Cattle raisers should be alert to the risks of occurrence of this disease after the introduction of the herds into paddocks with green and lush pastures.

Novel functional role of GH/IGF-I in neonatal lung myofibroblasts and in rat lung growth after intrauterine growth restriction.

Intrauterine growth restriction (IUGR) is a risk factor for neonatal chronic lung disease (CLD) characterized by reduced alveoli and perturbed matrix remodeling. Previously, our group showed an activation of myofibroblasts and matrix remodeling in rat lungs after IUGR. Because growth hormone (GH) and insulin-like growth factor I (IGF-I) regulate development and growth, we queried 1) whether GH/IGF-I signaling is dysregulated in lungs after IUGR and 2) whether GH/IGF-I signaling is linked to neonatal lung myofibroblast function. IUGR was induced in Wistar rats by isocaloric low-protein diet during gestation. Lungs were obtained at embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Murine embryonic fibroblasts (MEF) or primary neonatal myofibroblasts from rat lungs of control (pnFCo) and IUGR (pnFIUGR) were used for cell culture studies. In the intrauterine phase (E21), we found a reduction in GH receptor (GH-R), Stat5 signaling and IGF-I expression in lungs after IUGR. In the postnatal phase (P3-P23), catchup growth after IUGR was linked to increased GH mRNA, GH-R protein, activation of proliferative Stat5/Akt signaling, cyclin D1 and PCNA in rat lungs. On P23, a thickening of the alveolar septae was related to increased vimentin and matrix deposition, indicating fibrosis. In cell culture studies, nutrient deprivation blocked GH-R/IGF-IR signaling and proliferation in MEFs; this was reversed by IGF-I. Proliferation and Stat5 activation were increased in pnFIUGR. IGF-I and GH induced proliferation and migration of pnFCo; only IGF-I had these effects on pnFIUGR. Thus, we show a novel mechanism by which the GH/IGF-I axis in lung myofibroblasts could account for structural lung changes after IUGR.

Spatial and temporal changes in extracellular elastin and laminin distribution during lung alveolar development

Lung alveolarization requires precise coordination of cell growth with extracellular matrix (ECM) synthesis and deposition. The role of extracellular matrices in alveogenesis is not fully understood, because prior knowledge is largely extrapolated from two-dimensional structural analysis. Herein, we studied temporospatial changes of two important ECM proteins, laminin and elastin that are tightly associated with alveolar capillary growth and lung elastic recoil respectively, during both mouse and human lung alveolarization. By combining protein immunofluorescence staining with two- and three-dimensional imaging, we found that the laminin network was simplified along with the thinning of septal walls during alveogenesis, and more tightly associated with alveolar endothelial cells in matured lung. In contrast, elastin fibers were initially localized to the saccular openings of nascent alveoli, forming a ring-like structure. Then, throughout alveolar growth, the number of such alveolar mouth ring-like structures increased, while the relative ring size decreased. These rings were interconnected via additional elastin fibers. The apparent patches and dots of elastin at the tips of alveolar septae found in two-dimensional images were cross sections of elastin ring fibers in the three-dimension. Thus, the previous concept that deposition of elastin at alveolar tips drives septal inward growth may potentially be conceptually challenged by our data.

Exercise Training Mitigates Water Pipe Smoke Exposure-Induced Pulmonary Impairment via Inhibiting NF-κB and Activating Nrf2 Signalling Pathways.

Water pipe smoking is a tobacco smoking method commonly used in Eastern countries and is gaining popularity in Europe and North America, in particular among adolescents and young adults. Several clinical and experimental studies have reported that exposure to water pipe smoke (WPS) induces lung inflammation and impairment of pulmonary function. However, the mechanisms of such effects are not understood, as are data on the possible palliative effect of exercise training. The present study evaluated the effects of regular aerobic exercise training (treadmill: 5 days/week, 40 min/day) on subchronic exposure to WPS (30 minutes/day, 5 days/week for 2 months). C57BL/6 mice were exposed to air or WPS with or without exercise training. Airway resistance measured using forced oscillation technique was significantly and dose-dependently increased in the WPS-exposed group when compared with the air-exposed one. Exercise training significantly prevented the effect of WPS on airway resistance. Histologically, the lungs of WPS-exposed mice had focal moderate interstitial inflammatory cell infiltration consisting of neutrophil polymorphs, plasma cells, and lymphocytes. There was a mild increase in intra-alveolar macrophages and a focal damage to alveolar septae in some foci. Exercise training significantly alleviated these effects and also decreased the WPS-induced increase of tumor necrosis factor α and interleukin 6 concentrations and attenuated the increase of 8-isoprostane in lung homogenates. Likewise, the lung DNA damage induced by WPS was significantly inhibited by exercise training. Moreover, exercise training inhibited nuclear factor kappa-B (NF-κB) expression induced by WPS and increased that of nuclear factor erythroid 2-related factor 2 (Nrf2). Our findings suggest that exercise training significantly mitigated WPS-induced increase in airway resistance, inflammation, oxidative stress, and DNA damage via mechanisms that include inhibiting NF-κB and activating Nrf2 signalling pathways.

Role of LTBP4 in alveolarization, angiogenesis, and fibrosis in lungs.

Deficiency of the extracellular matrix protein latent transforming growth factor-β (TGF-β)-binding protein-4 (LTBP4) results in lack of intact elastic fibers, which leads to disturbed pulmonary development and lack of normal alveolarization in humans and mice. Formation of alveoli and alveolar septation in pulmonary development requires the concerted interaction of extracellular matrix proteins, growth factors such as TGF-β, fibroblasts, and myofibroblasts to promote elastogenesis as well as vascular formation in the alveolar septae. To investigate the role of LTBP4 in this context, lungs of LTBP4-deficient (Ltbp4-/-) mice were analyzed in close detail. We elucidate the role of LTBP4 in pulmonary alveolarization and show that three different, interacting mechanisms might contribute to alveolar septation defects in Ltbp4-/- lungs: 1) absence of an intact elastic fiber network, 2) reduced angiogenesis, and 3) upregulation of TGF-β activity resulting in profibrotic processes in the lung.

Vasoproliferative process resembling pulmonary capillary hemangiomatosis in a cat

BackgroundPulmonary capillary hemangiomatosis is a rare, vascular obstructive disorder that uniformly causes pulmonary arterial hypertension. Clinically, pulmonary capillary hemangiomatosis is indistinguishable from primary pulmonary arterial hypertension and histology is required for definitive diagnosis. The distinctive histologic feature of pulmonary capillary hemangiomatosis is non-malignant extensive proliferation of capillaries in the alveolar septae. Vasodilator treatment of humans with primary arterial hypertension due to pulmonary capillary hemangiomatosis can result in fatal acute pulmonary edema. Computed tomography is thus critical to discern pulmonary capillary hemangiomatosis from other causes of pulmonary arterial hypertension prior to vasodilator therapy. This is the first report of a vasoproliferative process resembling pulmonary capillary hemangiomatosis in the feline species.Case presentationA 15-year-old, male castrated, domestic shorthair cat presented for persistent labored breathing presumptively due to congestive heart failure despite treatment with diuretics for 7 days. Echocardiography showed evidence of hypertrophic cardiomyopathy with severe pulmonary hypertension; however, a normal sized left atrium was not consistent with congestive heart failure. Thoracic computed tomography was performed and showed evidence of diffuse ill-defined nodular ground glass opacities, enlarged pulmonary arteries, and filling defects consistent with pulmonary thromboembolism. The cat acutely decompensated after a single dose of sildenafil and was euthanized. Histopathology of the lungs showed severe multifocal alveolar capillary proliferation with respiratory bronchiolar infiltration, marked type II pneumocyte hyperplasia and multifocal pulmonary arterial thrombosis.ConclusionThis is the first description in a cat of a vasoproliferative disorder resembling pulmonary capillary hemangiomatosis complicated by multifocal pulmonary arterial thrombosis. Inspiratory and expiratory ventilator-driven breath holds with angiography revealed lesions predominantly characterized by ground glass opacification and vascular filling defects with absence of air trapping. The results from this report suggest that, as in humans, the cat can develop a pulmonary capillary hemangiomatosis-like disease in which vasodilator therapy to address pulmonary hypertension may lead to fatal pulmonary edema.