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

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.

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.

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.