Schistosomiasis-associated pulmonary hypertension unveils disrupted murine gut-lung microbiome and reduced endoprotective Caveolin-1/BMPR2 expression

Liver bypass in the development of pathogen-associated pulmonary vascular disease: contribution of mesocaval and portosystemic shunts

Portosystemic and mesocaval shunts are aberrant vascular connections that bypass hepatic detoxification process, directly linking the portal to the systemic circulation. These shunts, whether congenital or acquired, might play a pivotal role in the pathogenesis of systemic inflammatory diseases, such as schistosomiasis-associated pulmonary hypertension (Sch-PH) by facilitating the dissemination of pathogen-derived eggs and antigens from the gut and mesentery into the lungs. Beyond the translocation of Schistosoma mansoni eggs, emerging evidence implicates that gut-lung microbiome dysbiosis contributes to the development of pulmonary hypertension (PH) in the preclinical animal model of Sch-PH. Sch-PH emerges as a chronic complication of schistosomiasis and evolves silently, progressively increasing the mean pulmonary arterial pressure and vascular resistance, leading to right heart hypertrophy, failure, and significant morbidity and mortality. Chronic schistosomiasis is often linked to the development of portal hypertension, which significantly contributes to the formation of the porto/mesocaval shunt as a compensatory response that can have far-reaching implications on pulmonary vascular physiology. In addition, portal hypertension compromises the integrity of the intestinal barrier, exacerbating peritoneal and mesenteric inflammation, potentially facilitating microbial and metabolite entrance into the systemic circulation. This article briefly discusses the mechanisms by which porto/mesocaval shunts contribute to PH, especially Group I PH, focusing on the interplay between portosystemic shunting, microbial translocation, and systemic dissemination of proinflammatory metabolites.

Global Landscape of Infection-Induced Pulmonary Hypertension

Introduction: Infectious diseases significantly impact pulmonary vascular disorders, particularly in developing countries where parasitic infections remain prevalent. These infections constitute a substantial yet frequently overlooked contributor to pulmonary hypertension. Discussion: This review examines the prevalence of parasitic lung diseases in regions where communicable infections are endemic and highlights their pathophysiological links to pulmonary hypertension. Schistosomiasis and HIV notably increase pulmonary hypertension risk in these areas. While other infectious diseases may also cause pulmonary vascular lesions, most remain insufficiently studied. The review addresses global epidemiological trends, diagnostic challenges, and recent advancements in understanding the multifaceted origins of pulmonary hypertension. Conclusion: The association between parasitic infections and pulmonary hypertension is significant, necessitating a high index of suspicion for pulmonary hypertension in patients with a history of parasitic diseases, especially in endemic regions. More research is needed to understand infection-related pulmonary hypertension mechanisms and reduce its global impact.

Precision Medicine for Pulmonary Vascular Disease: The Future Is Now (2023 Grover Conference Series)

Pulmonary vascular disease is not a single condition; rather it can accompany a variety of pathologies that impact the pulmonary vasculature. Applying precision medicine strategies to better phenotype, diagnose, monitor, and treat pulmonary vascular disease is increasingly possible with the growing accessibility of powerful clinical and research tools. Nevertheless, challenges exist in implementing these tools to optimal effect. The 2023 Grover Conference Series reviewed the research landscape to summarize the current state of the art and provide a better understanding of the application of precision medicine to managing pulmonary vascular disease. In particular, the following aspects were discussed: (1) Clinical phenotypes, (2) genetics, (3) epigenetics, (4) biomarker discovery, (5) application of precision biology to clinical trials, (6) the right ventricle (RV), and (7) integrating precision medicine to clinical care. The present review summarizes the content of these discussions and the prospects for the future.

Altered purinergic P2X7 and A2B receptors signaling limits macrophage-mediated host defense in schistosomiasis

BACKGROUND

The occurrence of co-infections during schistosomiasis, a neglected tropical disease, with other parasites have been reported suggesting an impaired host immune defense. Macrophage purinergic P2X7 receptor (P2X7R) plays an important role against intracellular pathogens. Therefore, we investigated the P2X7R-mediated phagocytosis and killing capacity of Leishmania amazonensis by macrophages during schistosomiasis in vitro and in vivo.

METHODS

Swiss and C57BL/6 (Wild type) and P2X7R-/- were randomized in two groups: control (uninfected) and Schistosoma mansoni-infected. Alternatively, control Swiss and S. mansoni-infected mice were also infected with L. amazonensis.

RESULTS

The pre-treatment of control macrophages with the P2X7R antagonist (A74003) or TGF-β reduced the phagocytosis index, mimicking the phenotype of cells from S. mansoni-infected mice and P2X7R-/- mice. Apyrase also reduced the phagocytosis index in the control group corroborating the role of ATP to macrophage activation. Moreover, l-arginine-nitric oxide pathway was compromised during schistosomiasis, which could explain the reduced killing capacity in response to ATP in vitro and in vivo. We found an increased extracellular nucleotide (ATP, ADP and AMP) hydrolysis along with an increased frequency of F4/80+ CD39+ macrophages from the S. mansoni-infected group. Moreover, the content of adenosine in the cell supernatant was higher in the S. mansoni-infected group in relation to controls. Schistosomiasis also increased the expression of macrophage adenosine A2BR. In good accordance, both ADA and the selective A2BR antagonist restored the phagocytosis index of macrophages from S. mansoni-infected group.

CONCLUSIONS

Altogether, the altered P2X7R and A2BR signaling limits the role of macrophages to host defense against L. amazonensis during schistosomiasis, potentially contributing to the pathophysiology and clinically relevant co-infections.

Mechanisms of lung endothelial cell injury and survival in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive, chronic, and incurable inflammatory pulmonary vascular disease characterized by significant sex bias and largely unexplored microbial-associated molecular mechanisms that may influence its development and sex prevalence across various subgroups. PAH can be subclassified as idiopathic, heritable, or associated with conditions such as connective tissue diseases, congenital heart defects, liver disease, infections, and chronic exposure to drugs or toxins. During PAH progression, lung vascular endothelial cells (ECs) undergo dramatic morphofunctional transformations in response to acute and chronic inflammation. These transformations include the appearance and expansion of abnormal vascular cell phenotypes such as those derived from apoptosis-resistant cell growth and endothelial-to-mesenchymal transition (EndoMT). Compelling evidence indicates that these endothelial phenotypes seem to be triggered by chronic lung vascular injury and dysfunction, often characterized by reduced secretion of vasoactive molecules like nitric oxide (NO) and exacerbated response to vasoconstrictors such as Endothelin-1 (ET-1), both long-term known contributors of PAH pathogenesis. This review sheds light on the mechanisms of EC dysfunction, apoptosis, and EndoMT in PAH, aiming to unravel the intricate interactions between ECs, pathogens, and other cell types that drive the onset and progression of this devastating disease. Ultimately, we hope to provide an overview of the complex functions of lung vascular ECs in PAH, inspiring novel therapeutic strategies that target these dysfunctional cells to improve the treatment landscape for PAH, particularly in the face of current and emerging global pathogenic threats.

Schistosoma antigens: A future clinical magic bullet for autoimmune diseases?

Autoimmune diseases are characterized by dysregulated immunity against self-antigens. Current treatment of autoimmune diseases largely relies on suppressing host immunity to prevent excessive inflammation. Other immunotherapy options, such as cytokine or cell-targeted therapies, have also been used. However, most patients do not benefit from these therapies as recurrence of the disease usually occurs. Therefore, more effort is needed to find alternative immune therapeutics. Schistosoma infection has been a significant public health problem in most developing countries. Schistosoma parasites produce eggs that continuously secrete soluble egg antigen (SEA), which is a known modulator of host immune responses by enhancing Th2 immunity and alleviating outcomes of Th1 and Th17 responses. Recently, SEA has shown promise in treating autoimmune disorders due to their substantial immune-regulatory effects. Despite this interest, how these antigens modulate human immunity demonstrates only limited pieces of evidence, and whether there is potential for Schistosoma antigens in other diseases in the future remains an unsolved question. This review discusses how SEA modulates human immune responses and its potential for development as a novel immunotherapeutic for autoimmune diseases. We also discuss the immune modulatory effects of other non-SEA schistosome antigens at different stages of the parasite's life cycle.

Breast cancer-derived CAV1 promotes lung metastasis by regulating integrin α6β4 and the recruitment and polarization of tumor-associated neutrophils

Lung metastasis in breast cancer (BC) patients is one of the main reasons for their high mortality rate. The most prevalent BC small extracellular vesicles (sEVs receptor, integrin α6β4, has been found to interact with surfactant-associated protein (SFTPC) in lung epithelial cells, making BC more likely to metastasize to the lung. Tumor-associated neutrophils (TANs) play an essential role in BC lung metastasis as a component of the lung pre-metastatic niche (PMN) with two sides. It has been demonstrated that Toll-like Receptor4 (TLR4) can participate in signaling, such as NF-B and NLRP3, to facilitate tumor metastasis. A cellular membrane structural protein called caveolin-1 (CAV1) is associated with BC's proliferation, metastasis, and immunological control. According to our previous research, CAV1 on BC-derived sEVs facilitates the formation of the lung PMN by enhancing tenascin-C (TnC) secretion in lung fibroblasts to promote the deposition of ECM, by increasing the expression of PMN marker genes and inflammatory chemokines in lung epithelial cells, and by supporting N2-type polarization of lung macrophages via inhibiting the PTEN/CCL2/VEGF-A axis. More research is needed to determine how sEVs-mediated CAV1 facilitates BC-targeted metastasis to the lungs. By creating a stable-translocating cell line that stably interfered with CAV1 and a mouse model of BC lung metastasis, we investigated how sEVs-mediated CAV1 promotes BC lung metastasis and TAN recruitment and polarization in vivo and in vitro. In this study, we showed that CAV1 increases the likelihood that BC lung metastasis would occur by controlling the expression of integrin α6β4 and via boosting TANs recruitment and polarization through activating the TLR4-NF-B-IL-6/CCL2 and TLR4/NF-B/NLRP3 signaling pathways. According to our findings, CAV1 regulates integrin α6β4 and modulates TLR4 signaling, both of which are critical for BC lung metastasis. This finding may open new avenues for BC lung metastasis prevention and treatment.

Infection and pulmonary vascular diseases consortium: United against a global health challenge

Leveraging the potential of virtual platforms in the post-COVID-19 era, the Infection and Pulmonary Vascular Diseases Consortium (iPVDc), with the support of the Pulmonary Vascular Research Institute (PVRI), launched a globally accessible educational program to highlight top-notch research on inflammation and infectious diseases affecting the lung vasculature. This innovative virtual series has already successfully brought together distinguished investigators across five continents - Asia, Europe, South and North America, and Africa. Moreover, these open global forums have contributed to a comprehensive understanding of the complex interplay among immunology, inflammation, infection, and cardiopulmonary health, especially concerning pulmonary hypertension and related pulmonary disorders. These enlightening discussions have not only heightened awareness about the impact of various pathogenic microorganisms, including fungi, parasites, and viruses, on the onset and development of pulmonary vascular diseases but have also cast a spotlight on co-infections and neglected illnesses like schistosomiasis - a disease that continues to impose a heavy socioeconomic burden in numerous regions worldwide. Thus, the overall goal of this review article is to present the most recent breakthroughs from infectious PVDs as well as bring to light the scientific and educational insights from the 2023 iPVDc/PVRI virtual symposium series, shaping our understanding of these crucial health issues in this more than ever interconnected world.

P2Y2-P2X7 receptors cross-talk in primed mesenteric endothelial cells upregulates NF-κB signaling favoring mononuclear cell adhesion in schistosomiasis

Schistosomiasis is an intravascular infectious disease that impacts over 200 million people globally. In its chronic stage, it leads to mesenteric inflammation with significant involvement of monocytes/macrophages. Endothelial cells lining the vessel lumens play a crucial role, and mount of evidence links this disease to a downregulation of endoprotective cell signaling favoring a primed and proinflammatory endothelial cell phenotype and therefore the loss of immunovascular homeostasis. One hallmark of infectious and inflammatory conditions is the release of nucleotides into the extracellular milieu, which, in turn, act as innate messengers, activating purinergic receptors and triggering cell-to-cell communication. ATP influences the progression of various diseases through P2X and P2Y purinergic receptor subtypes. Among these receptors, P2Y2 (P2Y2R) and P2X7 (P2X7R) receptors stand out, known for their roles in inflammation. However, their specific role in schistosomiasis has remained largely unexplored. Therefore, we hypothesized that endothelial P2Y2R and P2X7R could contribute to monocyte adhesion to mesenteric endothelial cells in schistosomiasis. Using a preclinical murine model of schistosomiasis associated with endothelial dysfunction and age-matched control mice, we showed that endothelial P2Y2R and P2X7R activation increased monocyte adhesion to cultured primary endothelial cells in both groups. However, a distinct upregulation of endothelial P2Y2R-driven canonical Ca2+ signaling was observed in the infected group, amplifying adhesion. In the control group, the coactivation of endothelial P2Y2R and P2X7R did not alter the maximal monocyte adhesion induced by each receptor individually. However, in the infected group, this coactivation induced a distinct upregulation of P2Y2R-P2X7R-driven canonical signaling, IL-1β release, and VCAM-1 expression, with underlying mechanisms involving inflammasome and NF-κB signaling. Therefore, current data suggest that schistosomiasis alters endothelial cell P2Y2R/P2X7R signaling during inflammation. These discoveries advance our understanding of schistosomiasis. This intricate interplay, driven by PAMP-triggered endothelial P2Y2R/P2X7R cross-talk, emerges as a potential key player in the mesenteric inflammation during schistosomiasis.