Intrapulmonary T Cells Are Sufficient for Schistosoma-Induced Pulmonary Hypertension.

BACKGROUND: Schistosomiasis is a parasitic infection that can cause pulmonary hypertension (PH). Th2 CD4 T cells are necessary for experimental Schistosoma-PH. However, if T cells migrate to the lung to initiate, the localized inflammation that drives vascular remodeling and PH is unknown. METHODS: Mice were sensitized to Schistosoma mansoni eggs intraperitoneally and then challenged using tail vein injection. FTY720 was administered, which blocks lymphocyte egress from lymph nodes. T cells were quantified using flow cytometry, PH severity via heart catheterization, and cytokine concentration through ELISA. RESULTS: FTY720 decreased T cells in the peripheral blood, and increased T cells in the mediastinal lymph nodes. However, FTY720 treatment resulted in no change in PH or type 2 inflammation severity in mice sensitized and challenged with S. mansoni eggs, and the number of memory and effector CD4 T cells in the lung parenchyma was also unchanged. Notably, intraperitoneal Schistosoma egg sensitization alone resulted in a significant increase in intravascular lymphocytes and T cells, including memory T cells, although there was no significant change in parenchymal cell density, IL-4 or IL-13 expression, or PH. CONCLUSION: Blocking T cell migration did not suppress PH following Schistosoma egg challenge. Memory CD4 T cells, located in the lung intravascular space following egg sensitization, appear sufficient to cause type 2 inflammation and PH.

Classical dendritic cells contribute to hypoxia-induced pulmonary hypertension.

Pulmonary hypertension (PH) is a chronic and progressive disease with significant morbidity and mortality. It is characterized by remodeled pulmonary vessels associated with perivascular and intravascular accumulation of inflammatory cells. Although there is compelling evidence that bone marrow-derived cells, such as macrophages and T cells, cluster in the vicinity of pulmonary vascular lesions in humans and contribute to PH development in different animal models, the role of dendritic cells in PH is less clear. Dendritic cells' involvement in PH is likely since they are responsible for coordinating innate and adaptive immune responses. We hypothesized that dendritic cells drive hypoxic PH. We demonstrate that a classical dendritic cell (cDC) subset (cDC2) is increased and activated in wild-type mouse lungs after hypoxia exposure. We observe significant protection after the depletion of cDCs in ZBTB46 DTR chimera mice before hypoxia exposure and after established hypoxic PH. In addition, we find that cDC depletion is associated with a reduced number of two macrophage subsets in the lung (FolR2+ MHCII+ CCR2+ and FolR2+ MHCII+ CCR2-). We found that depleting cDC2s, but not cDC1s, was protective against hypoxic PH. Finally, proof-of-concept studies in human lungs show increased perivascular cDC2s in patients with Idiopathic Pulmonary Arterial Hypertension (IPAH). Our data points to an essential role of cDCs, particularly cDC2s, in the pathophysiology of experimental PH.

CCL28 modulates neutrophil responses during infection with mucosal pathogens.

The chemokine CCL28 is highly expressed in mucosal tissues, but its role during infection is not well understood. Here we show that CCL28 promotes neutrophil accumulation in the gut of mice infected with Salmonella and in the lung of mice infected with Acinetobacter. Neutrophils isolated from the infected mucosa expressed the CCL28 receptors CCR3 and, to a lesser extent, CCR10, on their surface. The functional consequences of CCL28 deficiency varied between the two infections: Ccl28-/- mice were highly susceptible to Salmonella gut infection but highly resistant to otherwise lethal Acinetobacter lung infection. In vitro, unstimulated neutrophils harbored pre-formed intracellular CCR3 that was rapidly mobilized to the cell surface following phagocytosis or inflammatory stimuli. Moreover, CCL28 stimulation enhanced neutrophil antimicrobial activity, production of reactive oxygen species, and formation of extracellular traps, all processes largely dependent on CCR3. Consistent with the different outcomes in the two infection models, neutrophil stimulation with CCL28 boosted the killing of Salmonella but not Acinetobacter. CCL28 thus plays a critical role in the immune response to mucosal pathogens by increasing neutrophil accumulation and activation, which can enhance pathogen clearance but also exacerbate disease depending on the mucosal site and the infectious agent.

Pathogenic Bacteroides fragilis strains can emerge from gut-resident commensals.

Bacteroides fragilis is a prominent member of the human gut microbiota, playing crucial roles in maintaining gut homeostasis and host health. Although it primarily functions as a beneficial commensal, B. fragilis can become pathogenic. To determine the genetic basis of its duality, we conducted a comparative genomic analysis of 813 B. fragilis strains, representing both commensal and pathogenic origins. Our findings reveal that pathogenic strains emerge across diverse phylogenetic lineages, due in part to rapid gene exchange and the adaptability of the accessory genome. We identified 16 phylogenetic groups, differentiated by genes associated with capsule composition, interspecies competition, and host interactions. A microbial genome-wide association study identified 44 genes linked to extra-intestinal survival and pathogenicity. These findings reveal how genomic diversity within commensal species can lead to the emergence of pathogenic traits, broadening our understanding of microbial evolution in the gut.

How bile acids and the microbiota interact to shape host immunity.

Bile acids are increasingly appearing in the spotlight owing to their novel impacts on various host processes. Similarly, there is growing attention on members of the microbiota that are responsible for bile acid modifications. With recent advances in technology enabling the discovery and continued identification of microbially conjugated bile acids, the chemical complexity of the bile acid landscape in the body is increasing at a rapid pace. In this Review, we summarize our current understanding of how bile acids and the gut microbiota interact to modulate immune responses during homeostasis and disease, with a particular focus on the gut.

Fluorinated Dialkyl Chloronium Salts: Synthesis and Reactivity for Fluoroalkylation and Hydride Abstraction.

A new concept for the synthesis of dialkyl chloronium cations [R‒Cl‒R]+ is described (R = CH3, CH2CF3), that allows the formation of fluorinated derivatives. By utilizing the xenonium salt [XeOTeF5][M(OTeF5)n] (M = Sb, n = 6; M = Al, n = 4) chlorine atoms of chloroalkanes or the deactivated chlorofluoroalkane CH2ClCF3 are oxidized and removed as ClOTeF5 leading to the isolation of the corresponding chloronium salt. Since the resulting highly electrophilic cation [Cl(CH2CF3)2]+ is able to alkylate weak nucleophiles, this compound can be utilized for the introduction of a fluorinated alkyl group to those. In addition, the fluorinated alkyl chloronium cation displays a high hydride ion affinity, enabling the activation of linear hydrocarbons by hydride abstraction even at low temperatures ultimately leading to the formation of branched carbocations.

Interstitial macrophage phenotypes in Schistosoma-induced pulmonary hypertension.

Background: Schistosomiasis is a common cause of pulmonary hypertension (PH) worldwide. Type 2 inflammation contributes to the development of Schistosoma-induced PH. Specifically, interstitial macrophages (IMs) derived from monocytes play a pivotal role by producing thrombospondin-1 (TSP-1), which in turn activates TGF-ß, thereby driving the pathology of PH. Resident and recruited IM subpopulations have recently been identified. We hypothesized that in Schistosoma-PH, one IM subpopulation expresses monocyte recruitment factors, whereas recruited monocytes become a separate IM subpopulation that expresses TSP-1. Methods: Mice were intraperitoneally sensitized and then intravenously challenged with S. mansoni eggs. Flow cytometry on lungs and blood was performed on wildtype and reporter mice to identify IM subpopulations and protein expression. Single-cell RNA sequencing (scRNAseq) was performed on flow-sorted IMs from unexposed and at day 1, 3 and 7 following Schistosoma exposure to complement flow cytometry based IM characterization and identify gene expression. Results: Flow cytometry and scRNAseq both identified 3 IM subpopulations, characterized by CCR2, MHCII, and FOLR2 expression. Following Schistosoma exposure, the CCR2+ IM subpopulation expanded, suggestive of circulating monocyte recruitment. Schistosoma exposure caused increased monocyte-recruitment ligand CCL2 expression in the resident FOLR2+ IM subpopulation. In contrast, the vascular pathology-driving protein TSP-1 was greatest in the CCR2+ IM subpopulation. Conclusion: Schistosoma-induced PH involves crosstalk between IM subpopulations, with increased expression of monocyte recruitment ligands by resident FOLR2+ IMs, and the recruitment of CCR2+ IMs which express TSP-1 that activates TGF-ß and causes PH.

Experimental Schistosoma haematobium pulmonary hypertension.

Whether all Schistosoma species cause pulmonary hypertension (PH) is unclear. Experimentally exposing mice to Schistosoma haematobium eggs caused PH, which was less severe than that induced by S. mansoni exposure. These findings align with the relatively uncommon reports of pulmonary arterial hypertension associated with S. haematobium.

Is pulmonary arterial hypertension associated with schistosomiasis distinct from pulmonary arterial hypertension associated with portal hypertension?

Pulmonary arterial hypertension associated with schistosomiasis (SchPAH) and pulmonary arterial hypertension associated with portal hypertension (PoPAH) are lung diseases that develop in the presence of liver diseases. However, mechanistic pathways by which the underlying liver conditions and other drivers contribute to the development and progression of pulmonary arterial hypertension (PAH) are unclear for both etiologies. In turn, these unknowns limit certainty of strategies to prevent, diagnose, and reverse the resultant PAH. Here we consider specific mechanisms that contribute to SchPAH and PoPAH, identifying those that may be shared and those that appear to be unique to each etiology, in the hope that this exploration will both highlight known causal drivers and identify knowledge gaps appropriate for future research. Overall, the key pathophysiologic differences that we identify between SchPAH and PoPAH suggest that they are not variants of a single condition.

Dexamethasone prophylaxis protects from acute high-altitude illness by modifying the peripheral blood mononuclear cell inflammatory transcriptome.

Acute high-altitude (HA) exposure can induce several pathologies. Dexamethasone (DEX) can be taken prophylactically to prevent HA disease, but the mechanism by which it acts in this setting is unclear. We studied the transcriptome of peripheral blood mononuclear cells (PBMCs) from 16 subjects at low altitude (LA, 225 m) and then 3 days after acute travel to HA (3500 m) during the India-Leh-Dexamethasone-Expedition-2020 (INDEX2020). Half of the participants received oral DEX prophylaxis 4 mg twice daily in an unblinded manner, starting 1 day prior to travel to HA, and 12 h prior to the first PBMC collection. PBMC transcriptome data were obtained from 16 subjects, half of whom received DEX. The principal component analysis demonstrated a clear separation of the groups by altitude and treatment. HA exposure resulted in a large number of gene expression changes, particularly in pathways of inflammation or the regulation of cell division, translation, or transcription. DEX prophylaxis resulted in changes in fewer genes, particularly in immune pathways. The gene sets modulated by HA and DEX were distinct. Deconvolution analysis to assess PBMC subpopulations suggested changes in B-cell, T-cell, dendritic cell, and myeloid cell numbers with HA and DEX exposures. Acute HA travel and DEX prophylaxis induce significant changes in the PBMC transcriptome. The observed benefit of DEX prophylaxis against HA disease may be mediated by suppression of inflammatory pathways and changing leukocyte population distributions.

Repetitive schistosoma exposure causes perivascular lung fibrosis and persistent pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) can occur as a complication of schistosomiasis. In humans, schistosomiasis-PH persists despite antihelminthic therapy and parasite eradication. We hypothesized that persistent disease arises as a consequence of exposure repetition. METHODS: Following intraperitoneal sensitization, mice were experimentally exposed to Schistosoma eggs by intravenous injection, either once or three times repeatedly. The phenotype was characterized by right heart catheterization and tissue analysis. RESULTS: Following intraperitoneal sensitization, a single intravenous Schistosoma egg exposure resulted in a PH phenotype that peaked at 7-14 days, followed by spontaneous resolution. Three sequential exposures resulted in a persistent PH phenotype. Inflammatory cytokines were not significantly different between mice exposed to one or three egg doses, but there was an increase in perivascular fibrosis in those who received three egg doses. Significant perivascular fibrosis was also observed in autopsy specimens from patients who died of this condition. CONCLUSIONS: Repeatedly exposing mice to schistosomiasis causes a persistent PH phenotype, accompanied by perivascular fibrosis. Perivascular fibrosis may contribute to the persistent schistosomiasis-PH observed in humans with this disease.

Exercise metabolomics in pulmonary arterial hypertension: Where pulmonary vascular metabolism meets exercise physiology.

Pulmonary arterial hypertension is an incurable disease marked by dysregulated metabolism, both at the cellular level in the pulmonary vasculature, and at the whole-body level characterized by impaired exercise oxygen consumption. Though both altered pulmonary vascular metabolism and abnormal exercise physiology are key markers of disease severity and pulmonary arterial remodeling, their precise interactions are relatively unknown. Herein we review normal pulmonary vascular physiology and the current understanding of pulmonary vascular cell metabolism and cardiopulmonary response to exercise in Pulmonary arterial hypertension. We additionally introduce a newly developed international collaborative effort aimed at quantifying exercise-induced changes in pulmonary vascular metabolism, which will inform about underlying pathophysiology and clinical management. We support our investigative approach by presenting preliminary data and discuss potential future applications of our research platform.

The role of brachytherapy in treatment of stage I esophageal cancer: A systematic review.

PURPOSE: Despite advancements in the early detection of esophageal cancer, optimal radiotherapy methods for treatment of early disease have not yet been determined. Moreover, the benefit of intraluminal brachytherapy on local control or survival remains controversial. We performed a systematic review to establish the role of brachytherapy as boost therapy in stage I esophageal squamous cell carcinoma, and to evaluate associated survival outcomes. METHODS AND MATERIALS: A systematic search of three bibliographic databases from January 1950 to January 2019 was conducted. All studies investigating brachytherapy for curative intent were included and palliative treatment was excluded. Primary outcomes included overall survival and disease-free survival (DFS). Secondary outcomes included loco-regional control (LRC) and toxicity grades and/or complications. Two reviewers independently abstracted data and evaluated study quality using grading of recommendations assessment, development, and evaluation, pooled results were presented through risk ratios. RESULTS: A total of 12 retrospective studies met inclusion criteria. The overall quality of evidence yielded a Grade 1C rating (strong recommendation, low quality evidence). Of 525 included patients, 325 patients received both external beam radiation (EBRT), and brachytherapy, 132 underwent EBRT only, and 68 received brachytherapy with and/or without chemoradiation. For patient group treated with EBRT and brachytherapy, 5-year mortality, DFS and LRC were: 43% (27-59%), 63% (49-76%) and 72% (63-80%) respectively. Rates of complications reported included 82.1% Grade 1 esophagitis for a combined external beam radiation and brachytherapy cohort, 12.3% ulcerations, and 3.3% fistulae. CONCLUSIONS: Brachytherapy as a combined modality is encouraging, given its relative safety and effectiveness. Further prospective analysis using higher quality evidence is warranted to evaluate oncologic outcomes and survival advantage.

The role of macrophages in right ventricular remodeling in experimental pulmonary hypertension.

Right ventricular (RV) failure is the primary cause of death in pulmonary hypertension (PH), but the mechanisms of RV failure are not well understood. We hypothesized macrophages in the RV contribute to the RV response in PH. We induced PH in mice with hypoxia (FiO2 10%) and Schistosoma mansoni exposure, and in rats with SU5416-hypoxia. We quantified cardiac macrophages in mice using flow cytometry. Parabiosis between congenic CD45.1/.2 mice or Cx3cr1-green fluorescent protein and wild-type mice was used to quantify circulation-derived macrophages in experimental PH conditions. We administered clodronate liposomes to Sugen hypoxia (SU-Hx) exposed rats to deplete macrophages and evaluated the effect on the extracellular matrix (ECM) and capillary network in the RV. In hypoxia exposed mice, the overall number of macrophages did not significantly change but two macrophage subpopulations increased. Parabiosis identified populations of RV macrophages that at steady state is derived from the circulation, with one subpopulation that significantly increased with PH stimuli. Clodronate treatment of SU-Hx rats resulted in a change in the RV ECM, without altering the RV vasculature, and correlated with improved RV function. Populations of RV macrophages increase and contribute to RV remodeling in PH, including through regulation of the RV ECM.

Contribution of fatty acid oxidation to the pathogenesis of pulmonary hypertension.

Dysregulated metabolism characterizes both animal and human forms of pulmonary hypertension (PH). Enzymes involved in fatty acid metabolism have previously not been assessed in human pulmonary arteries affected by pulmonary arterial hypertension (PAH), and how inhibition of fatty acid oxidation (FAO) may attenuate PH remains unclear. Fatty acid metabolism gene transcription was quantified in laser-dissected pulmonary arteries from 10 explanted lungs with advanced PAH (5 idiopathic, 5 associated with systemic sclerosis), and 5 donors without lung diseases. Effects of oxfenicine, a FAO inhibitor, on female Sugen 5416-chronic hypoxia (SuHx) rats were studied in vivo using right heart catheterization, and ex vivo using perfused lungs and pulmonary artery ring segments. The impact of pharmacologic (oxfenicine) and genetic (carnitine palmitoyltransferase 1a heterozygosity) FAO suppression was additionally probed in mouse models of Schistosoma and hypoxia-induced PH. Potential mechanisms underlying FAO-induced PH pathogenesis were examined by quantifying ATP and mitochondrial mass in oxfenicine-treated SuHx pulmonary arterial cells, and by assessing pulmonary arterial macrophage infiltration with immunohistochemistry. We found upregulated pulmonary arterial transcription of 26 and 13 FAO genes in idiopathic and systemic sclerosis-associated PAH, respectively. In addition to promoting de-remodeling of pulmonary arteries in SuHx rats, oxfenicine attenuated endothelin-1-induced vasoconstriction. FAO inhibition also conferred modest benefit in the two mouse models of PH. Oxfenicine increased mitochondrial mass in cultured rat pulmonary arterial cells, and decreased the density of perivascular macrophage infiltration in pulmonary arteries of treated SuHx rats. In summary, FAO inhibition attenuated experimental PH, and may be beneficial in human PAH.

Rationale and design of a screening study to detect schistosomiasis-associated pulmonary hypertension in Ethiopia and Zambia.

Schistosomiasis is a major cause of pulmonary arterial hypertension (PAH) worldwide, but the prevalence and risk factors for schistosomiasis-associated PAH (SchPAH) development are not well understood. Schistosomiasis-associated hepatosplenic disease (SchHSD) is thought to be a major risk factor for PAH development. Herein, we describe our plans for prospectively screening SchHSD subjects for clinical evidence of PAH at two major academic medical centers and national referral hospitals in Addis Ababa, Ethiopia and Lusaka, Zambia. The screening study will primarily be conducted by echocardiography, in addition to clinical assessments. Plasma samples will be drawn and banked for subsequent analysis based on preclinical animal model rationale. If successful, this study will demonstrate feasibility of conducting prospective cohort studies of SchPAH screening in schistosomiasis-endemic regions of Africa, and provide initial data on clinic-based disease prevalence and potential mechanistic biomarkers underlying disease pathogenesis.