Glutathione-S-transferase omega 1 and nurse cell formation during experimental Trichinella infection

Murine skeletal muscle satellite cells isolation and preliminary study on regulation in immune microenvironment during nurse cells formation of Trichinella spiralis infection

As an intracellular parasitic nematode, Trichinella spiralis (T. spiralis) can induce the formation of nurse cells (NC) in host muscles and keep it to survive within the NC for an extended period. The formation of NC is similar to muscle cell injury and repair which lead to the arrest of satellite cells in the G2/M phase and build a suitable parasitic environment for the muscle larvae of T. spiralis. However, the molecular mechanisms involved in skeletal muscle repair through skeletal muscle satellite cells (SMSC) and the host immune response during T. spiralis infection have not been fully elucidated. In this study, histopathological examination revealed that the severity of damage increased as the infection progressed in the soleus muscle. SMSCs were isolated from BALB/c mice infected with T. spiralis at 4, 21 and 35 days post-infection (dpi). The immunological characteristics of these cells were analyzed by real-time PCR and flow cytometry (FCM). FCM analysis revealed a notable increase in the expression of B7 homolog 1 (B7-H1) in SMSCs following T. spiralis infection, while conversely, the expression of inducible costimulatory ligand (ICOSL) significantly decreased. Furthermore, real-time PCR results showed that toll like receptor 3 (TLR3) expression in SMSCs of the infected mice was upregulated at 21 dpi. The expression levels of three subtypes (PPARα, PPARβ and PPARγ) of peroxisome proliferator-activated receptors (PPARs) also increased in the cells. This study highlights the immunological regulation significance of SMSCs host during T. spiralis infection and suggests that SMSCs actively participant in the local immune response to T. spiralis by regulating the interaction between the parasite and the host.

Anti-glutathione S-transferase omega 1-1 (GSTO1-1) antibodies are increased during acute and chronic inflammation in humans

Glutathione S-transferase omega-1 (GSTO1-1) is a cytosolic enzyme involved in the modulation of critical inflammatory pathways as well as in cancer progression. Auto-antibodies against GSTO1-1 were detected in the serum of patients with esophageal squamous cell carcinoma and were proposed as potential biomarkers in the early detection of the disease. Our findings show that anti-GSTO1-1 antibodies can be found in a variety of inflammatory diseases, including autoimmune rheumatoid arthritis, infectious SARS-CoV-2, and trichinellosis. Our findings strongly suggest that anti-GSTO1-1 antibodies may be a marker of tissue damage/inflammation rather than a specific tumor-associated biomarker.

Trichinella-induced immunomodulation: Another tale of helminth success

Trichinella spiralis is a unique parasite in that both the adults and larvae survive in two different intracellular niches in the same host. The immune response, albeit intense, is highly modulated to ensure the survival of both the host and the parasite. It is skewed to T helper 2 and regulatory arms. Diverse cells from both the innate and adaptive compartments of immunity, including dendritic cells, T regulatory cells, and alternatively activated macrophages are thought to mediate such immunomodulation. The parasite has also an outstanding ability to evade the immune system by several elaborate processes. The molecules derived from the parasites including Trichinella, particularly the components of the excretory-secretory products, are being continually identified and explored for the potential of ameliorating the immunopathology in animal models of diverse inflammatory and autoimmune human diseases. Herein we discuss the various aspects of Trichinella-induced immunomodulation with a special reference to the practical implications of the immune system manipulation in alleviating or possibly curing human diseases.

Purinergic P2X7 Receptor Mediates the Elimination of Trichinella spiralis by Activating NF-κB/NLRP3/IL-1β Pathway in Macrophages

Trichinellosis is one of most neglected foodborne zoonoses worldwide. During Trichinella spiralis infection, the intestinal immune response is the first line of defense and plays a vital role in the host's resistance. Previous studies indicate that purinergic P2X7 receptor (P2X7R) and pyrin domain-containing protein 3 (NLRP3) inflammasome are involved in the intestinal immune response in T. spiralis infection. However, the precise role of P2X7R and its effect on NLRP3 remains largely underdetermined. In this study, we aimed to investigate the role of P2X7R in the activation of NLRP3 in macrophages during the intestinal immune response against T. spiralis We found that T. spiralis infection upregulated expression of P2X7R and activation of NLRP3 in macrophages in mice. In vivo, P2X7R deficiency resulted in increased intestinal adult and muscle larval burdens, along with decreased expression of NLRP3/interleukin-1β (IL-1β) in macrophages from the infected mice with T. spiralis In In vitro experiments, P2X7R blockade inhibited activation of NLRP3/IL-1β via NF-κB and thus reduced the capacity of macrophages to kill newborn larvae of T. spiralis These results indicate that P2X7R mediates the elimination of T. spiralis by activating the NF-κB/NLRP3/IL-1β pathway in macrophages. Our findings contribute to the understanding of the intestinal immune mechanism of T. spiralis infection.

Vaccination with novel low-molecular weight proteins secreted from Trichinella spiralis inhibits establishment of infection

Trichinella spiralis muscle stage larvae (mL1) produce excretory-secreted products (ESPs), a complex mixture of protein, which are believed to be important for establishing or maintaining an infection niche within skeletal muscle and the intestine. Studies of both whole ESPs and individual cloned proteins have shown that some ESPs are potent immunogens capable of eliciting protective immune responses. Here we describe two novel proteins, Secreted from Muscle stage Larvae SML-4 and SML-5 which are 15 kDa and 12 kDa respectively. The genes encoding these proteins are highly conserved within the Trichinellids, are constituents of mL1 ESP and localized in the parasite stichosome. While SML-5 is only expressed in mL1 and early stages of adult nematode development, SML-4 is a tyvosylated glycoprotein also produced by adult nematodes, indicating it may have a function in the enteral phase of the infection. Vaccination with these proteins resulted in an impaired establishment of adult stages and consequently a reduction in the burden of mL1 in BALB/c mice. This suggests that both proteins may be important for establishment of parasite infection of the intestine and are prophylactic vaccine candidates.