NLRP3, NLRC4 and NLRC5 Gene Polymorphisms Associate with Susceptibility of Pulmonary Aspergillosis in Non-Neutropenic Patients

Integrating genetic and immune factors to uncover pathogenetic mechanisms of viral-associated pulmonary aspergillosis

Invasive pulmonary aspergillosis is a severe fungal infection primarily affecting immunocompromised patients. Individuals with severe viral infections have recently been identified as vulnerable to developing invasive fungal infections. Both influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are linked to high mortality rates, emphasizing the urgent need for an improved understanding of disease pathogenesis to unveil new molecular targets with diagnostic and therapeutic potential. The recent establishment of animal models replicating the co-infection context has offered crucial insights into the mechanisms that underlie susceptibility to disease. However, the development and progression of human viral-fungal co-infections exhibit a significant degree of interindividual variability, even among patients with similar clinical conditions. This observation implies a significant role for host genetics, but information regarding the genetic basis for viral-fungal co-infections is currently limited. In this review, we discuss how genetic factors known to affect either antiviral or antifungal immunity could potentially reveal pathogenetic mechanisms that predispose to IAPA or CAPA and influence the overall disease course. These insights are anticipated to foster further research in both pre-clinical models and human patients, aiming to elucidate the complex pathophysiology of viral-associated pulmonary aspergillosis and contributing to the identification of new diagnostic and therapeutic targets to improve the management of these co-infections.

The NLR gene family: from discovery to present day

The mammalian NLR gene family was first reported over 20 years ago, although several genes that were later grouped into the family were already known at that time. Although it is widely known that NLRs include inflammasome receptors and/or sensors that promote the maturation of caspase 1, IL-1β, IL-18 and gasdermin D to drive inflammation and cell death, the other functions of NLR family members are less well appreciated by the scientific community. Examples include MHC class II transactivator (CIITA), a master transcriptional activator of MHC class II genes, which was the first mammalian NBD-LRR-containing protein to be identified, and NLRC5, which regulates the expression of MHC class I genes. Other NLRs govern key inflammatory signalling pathways or interferon responses, and several NLR family members serve as negative regulators of innate immune responses. Multiple NLRs regulate the balance of cell death, cell survival, autophagy, mitophagy and even cellular metabolism. Perhaps the least discussed group of NLRs are those with functions in the mammalian reproductive system. The focus of this Review is to provide a synopsis of the NLR family, including both the intensively studied and the underappreciated members. We focus on the function, structure and disease relevance of NLRs and highlight issues that have received less attention in the NLR field. We hope this may serve as an impetus for future research on the conventional and non-conventional roles of NLRs within and beyond the immune system.

Pyroptosis and Inflammasome-Related Genes-NLRP3, NLRC4 and NLRP7 Polymorphisms Were Associated with Risk of Lung Cancer

Background

Cancer development and tumor immune microenvironment remodeling are closely linked to pyroptosis and inflammasome activation. However, little information is available in single nucleotide polymorphisms (SNPs) in pyroptosis and inflammasome-related genes in patients with lung cancer. This study aims to evaluate the associations between pyroptosis-related gene (NLRP3, NLRC4, and NLRP7) polymorphisms and the risk of lung cancer.

Methods

The MassARRAY platform was used to genotype six SNPs of the NLRP3, NLRC4, and NLRP7 genes in 660 lung cancer cases and 660 controls.

Results

Individuals with rs35829419-A, rs385076-C, and rs775882-T alleles exhibited a higher risk of lung cancer (p < 0.01), while rs212704-T appears protective (p = 0.006). The rs35829419-AA, rs385076-TC/CC, and rs775882-CT/TT genotypes were associated with various degrees of elevated risk of lung cancer (p<0.02), whereas rs212704-TT was associated with a reduced risk of the disease (p=0.014). Genetic models analysis showed that rs35829419, rs385076, and rs775882 was associated with an increased risk of lung cancer, while rs212704 was related to a reduced risk in all three models (p < 0.05). The four SNPs remained significant in smoker and nonsmoker subgroups (p < 0.05). However, rs35829419 was correlated with risk of adenocarcinoma and small cell lung cancer, and rs212704 was only protective for squamous cell carcinoma. The rs385076 and rs775882 were associated with all three pathological types (p < 0.01).

Conclusion

Besides providing candidate markers for identification of high-risk populations and early prevention of the disease, our research also provided new insight into anti-tumor strategies targeting inflammasomes and pyroptosis.

Innate Immune Responses to Sporothrix schenckii: Recognition and Elimination

Sporothrix schenckii (S. schenckii), a ubiquitous thermally dimorphic fungus, is the etiological agent of sporotrichosis, affecting immunocompromised and immunocompetent individuals. Despite current antifungal regimens, sporotrichosis results in prolonged treatment and significant mortality rates in the immunosuppressed population. The innate immune system forms the host's first and primary line of defense against S. schenckii, which has a bi-layered cell wall structure. Many components act as pathogen-associated molecular patterns (PAMPs) in pathogen-host interactions. PAMPs are recognized by pattern recognition receptors (PRRs) such as toll-like receptors, C-type lectin receptors, and complement receptors, triggering innate immune cells such as neutrophils, macrophages, and dendritic cells to phagocytize or produce mediators, contributing to S. schenckii elimination. The ultrastructure of S. schenckii and pathogen-host interactions, including PRRs and innate immune cells, are summarized in this review, promoting a better understanding of the innate immune response to S. schenckii and aiding in the development of protective and therapeutic strategies to combat sporotrichosis.

NOD1, NOD2, and NLRC5 Receptors in Antiviral and Antimycobacterial Immunity

The innate immune system recognizes pathogen-associated molecular motifs through pattern recognition receptors (PRRs) that induce inflammasome assembly in macrophages and trigger signal transduction pathways, thereby leading to the transcription of inflammatory cytokine genes. Nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) represent a family of cytosolic PRRs involved in the detection of intracellular pathogens such as mycobacteria or viruses. In this review, we discuss the role of NOD1, NOD2, and NLRC5 receptors in regulating antiviral and antimycobacterial immune responses by providing insight into molecular mechanisms as well as their potential health and disease implications.