Expression of Inflammatory Genes in Murine Lungs in a Model of Experimental Pulmonary Hypertension: Effects of an Antibody-Based Targeted Delivery of Interleukin-9.

BACKGROUND: Pathogenesis of pulmonary hypertension (PH) is a multifactorial process driven by inflammation and pulmonary vascular remodeling. To target these two aspects of PH, we recently tested a novel treatment: Interleukin-9 (IL9) fused to F8, an antibody that binds to the extra-domain A of fibronectin (EDA+ Fn). As EDA+ Fn is not found in healthy adult tissue but is expressed during PH, IL9 is delivered specifically to the tissue affected by PH. We found that F8IL9 reduced pulmonary vascular remodeling and attenuated PH compared with sham-treated mice. PURPOSE: To evaluate possible F8IL9 effects on PH-associated inflammatory processes, we analysed the expression of genes involved in pulmonary immune responses. METHODS: We applied the monocrotaline (MCT) model of PH in mice (n = 44). Animals were divided into five experimental groups: sham-induced animals without PH (control, n = 4), MCT-induced PH without treatment (PH, n = 8), dual endothelin receptor antagonist treatment (dual ERA, n = 8), F8IL9 treatment (n = 12, 2 formats with n = 6 each), or with KSFIL9 treatment (KSFIL9, n = 12, 2 formats with n = 6 each, KSF: control antibody with irrelevant antigen specificity). After 28 days, a RT-PCR gene expression analysis of inflammatory response (84 genes) was performed in the lung. RESULTS: Compared with the controls, 19 genes exhibited relevant (+2.5-fold) upregulation in the PH group without treatment. Gene expression levels in F8IL9-treated lung tissue were reduced compared to the PH group without treatment. This was the case especially for CCL20, CXCL5, C-reactive protein, pentraxin related (CRPPR), and Kininogen-1 (KNG1). CONCLUSION: In accordance with the hypothesis stated above, F8IL9 treatment diminished the upregulation of some genes associated with inflammation in a PH animal model. Therefore, we hypothesize that IL9-based immunocytokine treatment will likely modulate various inflammatory pathways.

Immune infiltration landscape and immune-marker molecular typing of pulmonary fibrosis with pulmonary hypertension.

BACKGROUND: Pulmonary arterial hypertension (PH) secondary to pulmonary fibrosis (PF) is one of the most common complications in PF patients, it causes severe disease and usually have a poor prognosis. Whether the combination of PH and PF is a unique disease phenotype is unclear. We aimed to screen the key modules associated with PH-PF immune infiltration based on WGCNA and identify the hub genes for molecular typing. METHOD: Using the gene expression profile GSE24988 of PF patients with or without PH from the Gene Expression Omnibus (GEO) database, we evaluated immune cell infiltration using Cibersortx and immune cell gene signature files. Different immune cell types were screened using the Wilcoxon test; differentially expressed genes were screened using samr. The molecular pathways implicated in these differential responses were identified using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses. A weighted co-expression network of the differential genes was constructed, relevant co-expression modules were identified, and relationships between modules and differential immune cell infiltration were calculated. The modules most relevant to this disease were identified using weighted correlation network analysis. From these, we constructed a co-expression network; using the STRING database, we integrated the values into the human protein-protein interaction network before constructing a co-expression interaction subnet, screening genes associated with immunity and unsupervised molecular typing, and analyzing the immune cell infiltration and expression of key genes in each disease type. RESULTS: Of the 22 immune cell types from the PF GEO data, 20 different immune cell types were identified. There were 1622 differentially expressed genes (295 upregulated and 1327 downregulated). The resulting weighted co-expression network identified six co-expression modules. These were screened to identify the modules most relevant to the disease phenotype (the green module). By calculating the correlations between modules and the differentially infiltrated immune cells, extracting the green module co-expression network (46 genes), extracting 25 key genes using gene significance and module-membership thresholds, and combining these with the 10 key genes in the human protein-protein interaction network, we identified five immune cell-related marker genes that might be applied as biomarkers. Using these marker genes, we evaluated these disease samples using unsupervised clustering molecular typing. CONCLUSION: Our results demonstrated that all PF combined with PH samples belonged to four categories. Studies on the five key genes are required to validate their diagnostic and prognostic value.

Heterozygous missense variant of the proteasome subunit ß-type 9 causes neonatal-onset autoinflammation and immunodeficiency.

Impaired proteasome activity due to genetic variants of certain subunits might lead to proteasome-associated autoinflammatory syndromes (PRAAS). Here we report a de novo heterozygous missense variant of the PSMB9 proteasome subunit gene in two unrelated Japanese infants resulting in amino acid substitution of the glycine (G) by aspartic acid (D) at position 156 of the encoded protein ß1i. In addition to PRAAS-like manifestations, these individuals suffer from pulmonary hypertension and immunodeficiency, which are distinct from typical PRAAS symptoms. The missense variant results in impaired immunoproteasome maturation and activity, yet ubiquitin accumulation is hardly detectable in the patients. A mouse model of the heterozygous human genetic variant (Psmb9G156D/+) recapitulates the proteasome defects and the immunodeficiency phenotype of patients. Structurally, PSMB9 G156D interferes with the ß-ring-ßring interaction of the wild type protein that is necessary for 20S proteasome formation. We propose the term, proteasome-associated autoinflammatory syndrome with immunodeficiency (PRAAS-ID), to indicate a separate category of autoinflammatory diseases, similar to, but distinct from PRAAS, that describes the patients in this study.

Research on the improvement of oxidative stress in rats with high-altitude pulmonary hypertension through the participation of irbesartan in regulating intestinal flora.

OBJECTIVE: High-altitude pulmonary hypertension (HAPH) is one of the diseases with higher occurrence among people living in plateau areas. The possible mechanism of angiotensin II receptor 1 inhibitor irbesartan in improving HAPH was explored from the perspective of intestinal bacterial flora in this study. MATERIALS AND METHODS: A HAPH rat model was established under simulated high-altitude hypobaric hypoxia. The levels of oxidative stress and vasoactive substances were detected after irbesartan intervention, and intestinal flora genomics analysis was performed. RESULTS: High-altitude hypobaric hypoxia-induced the increase in pulmonary artery pressure and left ventricular systolic dysfunction in HAPH model rats, but its effects were alleviated by irbesartan. Changes in the levels of oxidative damage in intestinal tissues, such as the increase in superoxide dismutase and glutathione peroxidase in intestinal tissues and the decrease in malondialdehyde content, were also reversed by irbesartan. The serum levels of angiotensin II, endothelin 1, interleukin-6, and C-reactive protein increased substantially whereas the level of nitric oxide decreased in HAPH model rats. The levels of these vasoconstriction and inflammatory indicators were also reversed after irbesartan intervention. The distribution of intestinal florae in rats was changed by the simulated high-altitude hypoxia environment as manifested by the increased Firmicutes-to-Bacteroidetes ratio (F/B), the increased abundance of Lactobacillaceae and Lachnospiraceae, and the decreased abundance of Prevotellaceae and Desulfovibrionaceae at the family level. However, the changes in F/B ratio and the abundance of these florae were reversed by irbesartan. CONCLUSIONS: Irbesartan can alleviate pulmonary artery pressure and left ventricular relaxation in HAPH model rats, reduce the oxidative damage caused by high-altitude hypoxia, and lower the release of vasoconstrictor factors and inflammatory mediators. These effects might be caused by the increased abundance of Lactobacillaceae and Lachnospiraceae and the decreased abundance of Prevotellaceae and Desulfovibrionaceae in the intestines.

Cell landscape atlas for patients with chronic thromboembolic pulmonary hypertension after pulmonary endarterectomy constructed using single-cell RNA sequencing.

This study aimed to construct an atlas of the cell landscape and comprehensively characterize the cellular repertoire of the pulmonary endarterectomized tissues of patients with chronic thromboembolic pulmonary hypertension (CTEPH). Five pulmonary endarterectomized tissues were collected. 10× Genomics single-cell RNA sequencing was performed, followed by the identification of cluster marker genes and cell types. Gene Ontology (GO) enrichment analysis was conducted. Seventeen cell clusters were characterized, corresponding to 10,518 marker genes, and then classified into eight cell types, including fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, cysteine rich secretory protein LCCL domain containing 2 (CRISPLD2)+ cell, cancer stem cell, and undefined. The specific marker genes of fibroblast/smooth muscle cell, endothelial cell, T cell/NK cell, macrophage, mast cell, and cancer stem cell were significantly enriched for multiple functions associated with muscle cell migration, endothelial cell migration, T cell activation, neutrophil activation, erythrocyte homeostasis, and tissue remodeling, respectively. No functions were significantly enriched for the marker gene of CRISPLD2+ cell. Our study, for the first time, provides an atlas of the cell landscape of the pulmonary endarterectomized tissues of CTEPH patients at single-cell resolution, which may serve as a valuable resource for further elucidation of disease pathophysiology.

Monocyte-released HERV-K dUTPase engages TLR4 and MCAM causing endothelial mesenchymal transition.

We previously reported heightened expression of the human endogenous retroviral protein HERV-K deoxyuridine triphosphate nucleotidohydrolase (dUTPase) in circulating monocytes and pulmonary arterial (PA) adventitial macrophages of patients with PA hypertension (PAH). Furthermore, recombinant HERV-K dUTPase increased IL-6 in PA endothelial cells (PAECs) and caused pulmonary hypertension in rats. Here we show that monocytes overexpressing HERV-K dUTPase, as opposed to GFP, can release HERV-K dUTPase in extracellular vesicles (EVs) that cause pulmonary hypertension in mice in association with endothelial mesenchymal transition (EndMT) related to induction of SNAIL/SLUG and proinflammatory molecules IL-6 as well as VCAM1. In PAECs, HERV-K dUTPase requires TLR4-myeloid differentiation primary response-88 to increase IL-6 and SNAIL/SLUG, and HERV-K dUTPase interaction with melanoma cell adhesion molecule (MCAM) is necessary to upregulate VCAM1. TLR4 engagement induces p-p38 activation of NF-κB in addition to p-pSMAD3 required for SNAIL and pSTAT1 for IL-6. HERV-K dUTPase interaction with MCAM also induces p-p38 activation of NF-κB in addition to pERK1/2-activating transcription factor-2 (ATF2) to increase VCAM1. Thus in PAH, monocytes or macrophages can release HERV-K dUTPase in EVs, and HERV-K dUTPase can engage dual receptors and signaling pathways to subvert PAEC transcriptional machinery to induce EndMT and associated proinflammatory molecules.

Therapeutic Evaluation of Antibody-Based Targeted Delivery of Interleukin 9 in Experimental Pulmonary Hypertension.

BACKGROUND AND AIMS: Pulmonary hypertension (PH) is a heterogeneous disorder associated with poor prognosis. For the majority of patients, only limited therapeutic options are available. Thus, there is great interest to develop novel treatment strategies focusing on pulmonary vascular and right ventricular remodeling. Interleukin 9 (IL9) is a pleiotropic cytokine with pro- and anti-inflammatory functions. The aim of this study was to evaluate the therapeutic activity of F8IL9F8 consisting of IL9 fused to the F8 antibody, specific to the alternatively-spliced EDA domain of fibronectin, which is abundantly expressed in pulmonary vasculature and right ventricular myocardium in PH. METHODS: The efficacy of F8IL9F8 in attenuating PH progression in the monocrotaline mouse model was evaluated in comparison to an endothelin receptor antagonist (ERA) or an IL9 based immunocytokine with irrelevant antibody specificity (KSFIL9KSF). Treatment effects were assessed by right heart catheterization, echocardiography as well as histological and immunohistochemical tissue analyses. RESULTS: Compared to controls, systolic right ventricular pressure (RVPsys) was significantly elevated and a variety of right ventricular echocardiographic parameters were significantly impaired in all MCT-induced PH groups except for the F8IL9F8 group. Both, F8IL9F8 and ERA treatments lead to a significant reduction in RVPsys and an improvement of echocardiographic parameters when compared to the MCT group not observable for the KSFIL9KSF group. Only F8IL9F8 significantly reduced lung tissue damage and displayed a significant decrease of leukocyte and macrophage accumulation in the lungs and right ventricles. CONCLUSIONS: Our study provides first pre-clinical evidence for the use of F8IL9F8 as a new therapeutic agent for PH in terms of a disease-modifying concept addressing cardiovascular remodeling.

Immunomodulation Therapy Using Tolerogenic Macrophages in a Rodent Model of Pulmonary Hypertension.

Inflammation plays a major role in the pathogenesis of pulmonary hypertension (PH). We sought to investigate the effects of a cell-based immunomodulation in a dysimmune model of PH. PH was induced in athymic nude rats using semaxinib (Su group, n = 6). Tolerogenic macrophages (toM) were generated from monocyte isolation and then injected either the day before semaxinib injection (Prevention group, n = 6) or 3 weeks after (Reversion group, n = 6). Six athymic nude rats were used as controls. In vivo trafficking of toM was investigated with bioluminescence imaging showing that toM were mainly located into the lungs until 48 h after injection. Right ventricular (RV) end-systolic pressure and RV systolic function were assessed at 4 weeks using echocardiography. Morphometric analysis and RNA sequencing of the lungs were realized at 4 weeks. Rats treated with toM (Prevention and Reversion groups) had a significantly lower RV end-systolic pressure at 4 weeks (respectively, 25 ± 8 and 30 ± 6 mmHg vs. 67 ± 9 mmHg, P < 0.001), while RV systolic dysfunction was observed in Su and Reversion groups. Mean medial wall thickness of small arterioles was lower in Prevention and Reversion groups compared with the Su group (respectively, 10.9% ± 0.8% and 16.4% ± 1.3% vs. 28.2% ± 2.1%, P < 0.001). Similarly, cardiomyocyte area was decreased in rats treated with toM (150 ± 18 and 160 ± 86 µm2 vs. 279 ± 50 µm2, P < 0.001). A trend toward upregulation of genes involved in pulmonary arterial hypertension pathobiology was found in Su rats, while KCNK3 was significantly downregulated (fold-change = 9.8, P < 0.001). Injection of toM was associated with a less severe phenotype of PH in rats exposed to angioproliferative stress. Preserved expression of KCNK3 may explain the protective effect of toM.

Fatal intracardiac and pulmonary arterial thromboembolic damage following ABO-incompatible living donor liver transplantation for autoimmune hepatitis: A case report.

RATIONALE: We present the case of a patient with autoimmune hepatitis who suffered fatal intracardiac and pulmonary arterial thromboembolic complications after ABO-incompatible living donor liver transplantation (ABOi LDLT) with splenectomy. PATIENT CONCERNS: A 46-year-old female (blood type B+) with autoimmune hepatitis and hepatitis B carrier status underwent elective ABOi LDLT. The donor liver was from a 51-year-old male living donor (blood type A+). A splenectomy was performed without bleeding complications. Intraoperatively, the patients hemodynamic condition was acceptable, with no evidence of thromboembolism on transesophageal echocardiography (TEE). DIAGNOSIS: Postoperatively, her platelet count increased from 15.0 to 263.0 (× 109/L) and thromboelastographic parameters indicated hypercoagulable state. She suffered acute circulatory collapse, respiratory distress and, eventually, a decline in mental status. The attending physicians in the intensive care unit (ICU) immediately performed resuscitation. INTERVENTIONS: The patient underwent emergency exploratory surgery. Intraoperatively, hypotension, bradycardia and arrhythmia developed, together with high central venous pressure. Assessment of cardiac structure and function using rescue TEE incidentally identified multiple, huge thromboembolic clots in the cardiac chambers; therefore, the patient underwent cardiac thromboembolectomy, including cardiopulmonary bypass with hypothermia therapy. OUTCOMES: Due to severe cardiac and respiratory distress, the patient required venoarterial extracorporeal membrane oxygenation (VAECMO) in the operating room and ICU. Despite continuous resuscitation in the ICU and maintenance of VAECMO, she suffered severe hypotension and massive bleeding that eventually led to death. LESSONS: In patients with autoimmune hepatitis, risk factors for thromboembolism should be rigorously controlled during the peak period of reactive thrombocytosis after ABOi LDLT with splenectomy.

Interleukin-6 mediates neutrophil mobilization from bone marrow in pulmonary hypertension.

Myeloid cells, such as neutrophils, are produced in the bone marrow in high quantities and are important in the pathogenesis of vascular diseases such as pulmonary hypertension (PH). Although neutrophil recruitment into sites of inflammation has been well studied, the mechanisms of neutrophil egress from the bone marrow are not well understood. Using computational flow cytometry, we observed increased neutrophils in the lungs of patients and mice with PH. Moreover, we found elevated levels of IL-6 in the blood and lungs of patients and mice with PH. We observed that transgenic mice overexpressing Il-6 in the lungs displayed elevated neutrophil egress from the bone marrow and exaggerated neutrophil recruitment to the lungs, resulting in exacerbated pulmonary vascular remodeling, and dysfunctional hemodynamics. Mechanistically, we found that IL-6-induced neutrophil egress from the bone marrow was dependent on interferon regulatory factor 4 (IRF-4)-mediated CX3CR1 expression in neutrophils. Consequently, Cx3cr1 genetic deficiency in hematopoietic cells in Il-6-transgenic mice significantly reduced neutrophil egress from bone marrow and decreased neutrophil counts in the lungs, thus ameliorating pulmonary remodeling and hemodynamics. In summary, these findings define a novel mechanism of IL-6-induced neutrophil egress from the bone marrow and reveal a new therapeutic target to curtail neutrophil-mediated inflammation in pulmonary vascular disease.

In situ Evidence of Collagen V and Interleukin-6/Interleukin-17 Activation in Vascular Remodeling of Experimental Pulmonary Hypertension.

Several studies have reported the pathophysiologic and molecular mechanisms responsible for pulmonary arterial hypertension (PAH). However, the in situ evidence of collagen V (Col V) and interleukin-17 (IL-17)/interleukin-6 (IL-6) activation in PAH has not been fully elucidated. We analyzed the effects of collagen I (Col I), Col V, IL-6, and IL-17 on vascular remodeling and hemodynamics and its possible mechanisms of action in monocrotaline (MCT)-induced PAH. Twenty male Wistar rats were randomly divided into two groups. In the PAH group, animals received MCT 60 mg/kg intraperitoneally, whereas the control group (CTRL) received saline. On day 21, the pulmonary blood pressure (PAP) and right ventricular systolic pressure (RVSP) were determined. Lung histology (smooth muscle cell proliferation [α-smooth muscle actin; α-SMA] and periadventitial fibrosis), immunofluorescence (Col I, Col V, and α-SMA), immunohistochemistry (IL-6, IL-17, and transforming growth factor-beta [TGF-ß]), and transmission electron microscopy to detect fibronexus were evaluated. The RVSP (40 ± 2 vs. 24 ± 1 mm Hg, respectively; p < 0.0001), right ventricle hypertrophy index (65 ± 9 and 25 ± 5%, respectively; p < 0.0001), vascular periadventitial Col I and Col V, smooth muscle cell α-SMA+, fibronexus, IL-6, IL-17, and TGF-ß were higher in the MCT group than in the CTRL group. In conclusion, our findings indicate in situ evidence of Col V and IL-6/IL-17 activation in vascular remodeling and suggest that increase of Col V may yield potential therapeutic targets for treating patients with PAH.

The role of macrophages in pulmonary hypertension: Pathogenesis and targeting.

Pulmonary hypertension (PH) is a pathophysiological disorder that can complicate most cardiovascular and respiratory diseases and may involve multiple clinical conditions, but its pathogenesis is poorly understood. Despite recent developments in the management of PH, there is an urgent need for new ways to effectively treat PH and reduce the risk of further complications. Recent studies have shown that dysregulated immunity underlies the development of PH. Myeloid cells, including monocytes and macrophages, participate in immune homeostasis and the adaptive immune response, but the function and production of these cells in PH is not well understood. A prominent pathological feature of pH is the accumulation of macrophages near the arterioles of the lung, indicating that pulmonary inflammation mediated by lung perivascular macrophages is a key driver of pulmonary remodelling, which leads to increased right ventricular systolic pressure. An improved understanding of the roles macrophages play in immune responses associated with PH may lead to new therapeutic targets. In this review, we highlight the relationship between macrophages and PH, the molecular mechanisms involved, and the recent advances in targeting these processes to treat PH.

DNGR1-Cre-mediated Deletion of Tnfaip3/A20 in Conventional Dendritic Cells Induces Pulmonary Hypertension in Mice.

Chronic perivascular inflammation is a prominent feature in the lungs of idiopathic pulmonary arterial hypertension. Although the proportions of conventional dendritic cells (cDCs) and plasmacytoid DCs are increased in idiopathic pulmonary arterial hypertension lungs, it remains unknown whether activated cDCs play a pathogenic role. The Tnfaip3 gene encodes the ubiquitin-binding protein A20, which is a negative regulator of NF-κB, critically involved in DC activation. Targeting of Tnfaip3/A20 in cDCs was achieved by Clec9a (DNGR1)-Cre-mediated excision of the Tnfaip3 gene in Tnfaip3DNGR1-KO mice. Mice were evaluated for signs of pulmonary hypertension (PH) using right heart catheterization, echocardiography, and measurement of the Fulton index. Inflammation was assessed by immunohistochemistry and flow cytometry. Pulmonary cDCs and monocyte-derived DCs from 31-week-old Tnfaip3DNGR1-KO mice showed modulated expression of cell surface activation markers compared with Tnfaip3DNGR1-WT mice. Tnfaip3DNGR1-KO mice developed elevated right ventricular systolic pressure and right ventricular hypertrophy. The lungs of these mice displayed increased vascular remodeling and perivascular and peribronchial immune cell infiltration resembling tertiary lymphoid organs. Proportions of activated T cells and expression of IL-1ß, IL-6, and IL-10 were enhanced in the lungs of Tnfaip3DNGR1-KO mice. Autoreactive IgA and IgG1 was detected in BAL and autoreactive IgA recognizing pulmonary endothelial antigens was present in the serum of Tnfaip3DNGR1-KO mice. All signs of PH were ameliorated in Tnfaip3DNGR1-KO mice by anti-IL-6 antibody treatment. These results indicate that activation of the NF-κB pathway in DCs, through deletion of A20/Tnfaip3, leads to experimental PH with accompanied pulmonary inflammation in an IL-6-dependent fashion.

The risk of circulating angiogenic T cells and subsets in patients with systemic sclerosis.

To ascertain the number and percentage of angiogenic T (Tang) cell subsets by flow cytometry in systemic sclerosis (SSc), and their relation with specific clinical features. Thirty SSc patients and 15 healthy controls (HCs) were included. Luminex was performed to analyze the levels of interleukin (IL)-17A, vascular endothelial growth factor (VEGF), tumor necrosis factor-α, and vascular cell adhesion molecule (VCAM). The ratio of circulating CD3 + CD31 + CXCR4 + T (CD3 + Tang) cells and CD8+ CD31 + CXCR4 + T (CD8+ Tang) cells in SSc patients was enlarger than in HCs, while CD4 + CD31 + CXCR4 + T cells (CD4 + Tang) exhibited no difference between SSc patients and HCs. The number and percentage of Tang cells were higher in SSc patients with pulmonary artery hypertension (PAH) than in non-PAH SSc patients and HCs. The ratios of Tang cell subsets in nucleolar pattern-positive SSc patients were markedly raised as compared with their negative ones and HCs. Additionally, the percentage of circulating CD3 + Tang cells was positively associated with VEGF serum levels in SSc patients. Meanwhile, the rate of CD8+ tang cells might have been emphatically corresponded to VEGF and VCAM serum levels in SSc patients. These results imply that the increase in Tang cells in peripheral blood are associated with immunoregulatory disturbances in SSc patients.

Nonclassical Monocytes Sense Hypoxia, Regulate Pulmonary Vascular Remodeling, and Promote Pulmonary Hypertension.

An increasing body of evidence suggests that bone marrow-derived myeloid cells play a critical role in the pathophysiology of pulmonary hypertension (PH). However, the true requirement for myeloid cells in PH development has not been demonstrated, and a specific disease-promoting myeloid cell population has not been identified. Using bone marrow chimeras, lineage labeling, and proliferation studies, we determined that, in murine hypoxia-induced PH, Ly6Clo nonclassical monocytes are recruited to small pulmonary arteries and differentiate into pulmonary interstitial macrophages. Accumulation of these nonclassical monocyte-derived pulmonary interstitial macrophages around pulmonary vasculature is associated with increased muscularization of small pulmonary arteries and disease severity. To determine if the sensing of hypoxia by nonclassical monocytes contributes to the development of PH, mice lacking expression of hypoxia-inducible factor-1α in the Ly6Clo monocyte lineage were exposed to hypoxia. In these mice, vascular remodeling and PH severity were significantly reduced. Transcriptome analyses suggest that the Ly6Clo monocyte lineage regulates PH through complement, phagocytosis, Ag presentation, and chemokine/cytokine pathways. Consistent with these murine findings, relative to controls, lungs from pulmonary arterial hypertension patients displayed a significant increase in the frequency of nonclassical monocytes. Taken together, these findings show that, in response to hypoxia, nonclassical monocytes in the lung sense hypoxia, infiltrate small pulmonary arteries, and promote vascular remodeling and development of PH. Our results demonstrate that myeloid cells, specifically cells of the nonclassical monocyte lineage, play a direct role in the pathogenesis of PH.

Racial differences in systemic sclerosis disease presentation: a European Scleroderma Trials and Research group study.

OBJECTIVES: Racial factors play a significant role in SSc. We evaluated differences in SSc presentations between white patients (WP), Asian patients (AP) and black patients (BP) and analysed the effects of geographical locations. METHODS: SSc characteristics of patients from the EUSTAR cohort were cross-sectionally compared across racial groups using survival and multiple logistic regression analyses. RESULTS: The study included 9162 WP, 341 AP and 181 BP. AP developed the first non-RP feature faster than WP but slower than BP. AP were less frequently anti-centromere (ACA; odds ratio (OR) = 0.4, P < 0.001) and more frequently anti-topoisomerase-I autoantibodies (ATA) positive (OR = 1.2, P = 0.068), while BP were less likely to be ACA and ATA positive than were WP [OR(ACA) = 0.3, P < 0.001; OR(ATA) = 0.5, P = 0.020]. AP had less often (OR = 0.7, P = 0.06) and BP more often (OR = 2.7, P < 0.001) diffuse skin involvement than had WP. AP and BP were more likely to have pulmonary hypertension [OR(AP) = 2.6, P < 0.001; OR(BP) = 2.7, P = 0.03 vs WP] and a reduced forced vital capacity [OR(AP) = 2.5, P < 0.001; OR(BP) = 2.4, P < 0.004] than were WP. AP more often had an impaired diffusing capacity of the lung than had BP and WP [OR(AP vs BP) = 1.9, P = 0.038; OR(AP vs WP) = 2.4, P < 0.001]. After RP onset, AP and BP had a higher hazard to die than had WP [hazard ratio (HR) (AP) = 1.6, P = 0.011; HR(BP) = 2.1, P < 0.001]. CONCLUSION: Compared with WP, and mostly independent of geographical location, AP have a faster and earlier disease onset with high prevalences of ATA, pulmonary hypertension and forced vital capacity impairment and higher mortality. BP had the fastest disease onset, a high prevalence of diffuse skin involvement and nominally the highest mortality.

Pathogenesis of HIV-Related Lung Disease: Immunity, Infection, and Inflammation.

Despite anti-retroviral therapy (ART), human immunodeficiency virus-1 (HIV)-related pulmonary disease continues to be a major cause of morbidity and mortality for people living with HIV (PLWH). The spectrum of lung diseases has changed from acute opportunistic infections resulting in death to chronic lung diseases for those with access to ART. Chronic immune activation and suppression can result in impairment of innate immunity and progressive loss of T cell and B cell functionality with aberrant cytokine and chemokine responses systemically as well as in the lung. HIV can be detected in the lungs of PLWH and has profound effects on cellular immune functions. In addition, HIV-related lung injury and disease can occur secondary to a number of mechanisms including altered pulmonary and systemic inflammatory pathways, viral persistence in the lung, oxidative stress with additive effects of smoke exposure, microbial translocation, and alterations in the lung and gut microbiome. Although ART has had profound effects on systemic viral suppression in HIV, the impact of ART on lung immunology still needs to be fully elucidated. Understanding of the mechanisms by which HIV-related lung diseases continue to occur is critical to the development of new preventive and therapeutic strategies to improve lung health in PLWH.

Immunoglobulin-driven Complement Activation Regulates Proinflammatory Remodeling in Pulmonary Hypertension.

Rationale: Pulmonary hypertension (PH) is a life-threatening cardiopulmonary disorder in which inflammation and immunity have emerged as critical early pathogenic elements. Although proinflammatory processes in PH and pulmonary arterial hypertension (PAH) are the focus of extensive investigation, the initiating mechanisms remain elusive.Objectives: We tested whether activation of the complement cascade is critical in regulating proinflammatory and pro-proliferative processes in the initiation of experimental hypoxic PH and can serve as a prognostic biomarker of outcome in human PAH.Methods: We used immunostaining of lung tissues from experimental PH models and patients with PAH, analyses of genetic murine models lacking specific complement components or circulating immunoglobulins, cultured human pulmonary adventitial fibroblasts, and network medicine analysis of a biomarker risk panel from plasma of patients with PAH.Measurements and Main Results: Pulmonary perivascular-specific activation of the complement cascade was identified as a consistent critical determinant of PH and PAH in experimental animal models and humans. In experimental hypoxic PH, proinflammatory and pro-proliferative responses were dependent on complement (alternative pathway and component 5), and immunoglobulins, particularly IgG, were critical for activation of the complement cascade. We identified Csf2/GM-CSF as a primary complement-dependent inflammatory mediator. Furthermore, using network medicine analysis of a biomarker risk panel from plasma of patients with PAH, we demonstrated that complement signaling can serve as a prognostic factor for clinical outcome in PAH.Conclusions: This study establishes immunoglobulin-driven dysregulated complement activation as a critical pathobiological mechanism regulating proinflammatory and pro-proliferative processes in the initiation of experimental hypoxic PH and demonstrates complement signaling as a critical determinant of clinical outcome in PAH.