Research progress on Mincle as a multifunctional receptor

Optimization, Immunological Evaluation, and Combination Study of Mincle-Dependent Self-Adjuvanted Anti-Tn Cancer Vaccines with an External Adjuvant

Nine Tn-based cancer vaccines were designed and synthesized using Mincle agonists as a carrier to elucidate the structure-immunogenicity relationships of Mincle-dependent vaccines. The Immunological evaluation showed that the immune response levels were significantly influenced by the acyl chains of trehalose, coupling site of antigen and carriers, antigen copy number, and coupling mode of acyl chains and trehalose. Notably, installing the antigen onto the lipid chains of the carrier could also effectively improve the immunogenicity. Among them, conjugate 9 showed the highest activity. In the presence of EcMPLA (TLR4 agonist) and aluminum hydroxide (Al), the immunological activity of conjugate 9 could further be improved and significantly inhibit tumor growth, prolonging the survival time of tumor-challenged mice. Survived mice also successfully rejected subsequent tumor attacks without any additional treatment. This work provides guidance for developing and applying self-adjuvanted cancer vaccines using Mincle agonists as both the carrier and "build-in" adjuvant.

Innate immune cells in acute and chronic kidney disease

Acute kidney injury (AKI) and chronic kidney disease (CKD) are inter-related clinical and pathophysiological disorders. Cells of the innate immune system, such as granulocytes and macrophages, can induce AKI through the secretion of pro-inflammatory mediators such as cytokines, chemokines and enzymes, and the release of extracellular traps. In addition, macrophages and dendritic cells can drive the progression of CKD through a wide range of pro-inflammatory and pro-fibrotic mechanisms, and by regulation of the adaptive immune response. However, innate immune cells can also promote kidney repair after acute injury. These actions highlight the multifaceted nature of the way by which innate immune cells respond to signals within the kidney microenvironment, including interaction with the complement and coagulation cascades, cells of the adaptive immune system, intrinsic renal cells and infiltrating mesenchymal cells. The factors and mechanisms that underpin the ability of innate immune cells to contribute to renal injury or repair and to drive the progression of CKD are of great interest for understanding disease processes and for developing new therapeutic approaches to limit AKI and the AKI-to-CKD transition.

SARS-CoV-2 nucleocapsid protein induces a Mincle-dependent macrophage inflammatory response in acute kidney injury

BACKGROUND

Although the COVID-19 pandemic has receded, the SARS-CoV-2 virus still poses a significant threat to individuals with pre-existing renal conditions, leading to severe acute kidney injury (AKI). However, the underlying mechanisms remain poorly understood.

METHODS

In this study, we used ultrasound microbubble technology to transfect and overexpress the SARS-CoV-2 nucleocapsid (N) protein in the kidneys of IRI (ischemia-reperfusion injury) and Cis (cisplatin) induced AKI mice. Additionally, we generated macrophage-specific Mincle knockout mice to investigate the amplifying effects of the SARS-CoV-2 N protein on AKI renal injury and the critical regulatory role of macrophage inducible C-type lectin (Mincle). Finally, we employed Mincle-neutralizing antibodies to intervene in the SARS-CoV-2 N-induced exacerbation of kidney injury in AKI.

RESULTS

We found that the specific overexpression of the SARS-CoV-2 N protein significantly aggravates kidney injury in the context of AKI. Mechanistically, we found that the exacerbation of acute kidney injury by the SARS-CoV-2 N protein is dependent on Mincle, as the SARS-CoV-2 N protein activates Mincle to enhance the Syk/NF-κB signaling pathway, leading to damage and inflammation of renal tubular epithelial cells. This was confirmed in Mincle knockout mice and cells, where Mincle knockout alleviated the renal tubular injury and inflammation caused by SARS-CoV-2 N transfection. Importantly, the use of anti-Mincle neutralizing antibodies could effectively mitigate the acute kidney injury exacerbated by the SARS-CoV-2 N protein.

CONCLUSIONS

In summary, we identified the SARS-CoV-2 N protein as a key mediator of kidney injury in AKI and demonstrated that it exacerbates the injury through a Mincle-dependent mechanism. Targeting Mincle may represent a novel therapeutic strategy for treating COVID-19-related acute kidney injury.

Periodic mesoporous organosilica-loaded mincle agonists enhance the immunogenicity of COVID-19 subunit vaccines by dual activation of B cells and dendritic cells

Effective vaccination is crucial for intervening in the COVID-19 pandemic. However, with the continuous mutation of the SARS-CoV-2, existing vaccines including subunit vaccines cannot effectively prevent virus infections. Hence, there is an urgent need to enhance the immunogenicity of existing vaccines to induce a more potent and durable immune response. We previously found that periodic mesoporous organosilica (PMO) could act as a potential nanoadjuvant for subunit vaccines, eliciting potent antigen-specific germinal center (GC) responses by activating naïve B cells. In this study, we describe the design of PMO decorated with TDB, a potent Macrophage-induced C-type lectin (Mincle) agonist, to improve the adjuvanticity of PMO for COVID-19 vaccines. We found that the TDB@PMO adjuvant can effectively deliver antigens to lymph nodes and promote antigen uptake by immune cells. More importantly, the TDB@PMO adjuvant vaccine could activate the innate immune of both naïve B cells and dendritic cells via the Mincle signaling pathway, and further enhance the GC responses and resulting in potent SARS-CoV-2 specific humoral and cellular immune responses. Overall, we have developed an effective and safe nanoadjuvant platform, laying the foundation for the design and development of subunit vaccines against pathogens such as SARS-CoV-2. STATEMENT OF SIGNIFICANCE: Adjuvants play a crucial role in enhancing the effectiveness of vaccines by boosting the immune response. The emergence of highly mutated viruses, such as coronaviruses, has presented new requirements for adjuvant design. This work designed a nanoadjuvant platform, TDB@PMO, to enhance the immune response of the COVID-19 subunit vaccine. The result demonstrated that TDB@PMO nanoadjuvant can simultaneously boost the activation effects of B cells and DC cells through the Mincle signaling pathway. Furthermore, immunization with TDB@PMO-RBD nanoadjuvanted vaccine in mice significantly enhanced germinal center responses and antibody production, while also eliciting a robust antigen-specific T cell immune response in spleen. This design provided a reference for the development of next-generation virus subunit vaccines.

Systematic Evaluation of Regiochemistry and Lipidation of Aryl Trehalose Mincle Agonists

The Macrophage-Inducible C-type Lectin receptor (Mincle) plays a critical role in innate immune recognition and pathology, and therefore represents a promising target for vaccine adjuvants. Innovative trehalose-based Mincle agonists with improved pharmacology and potency may prove useful in the development of Th17-mediated adaptive immune responses. Herein, we report on in vitro and in silico investigations of specific Mincle ligand-receptor interactions required for the effective receptor engagement and activation of Th17-polarizing cytokines. Specifically, we employed a library of trehalose benzoate scaffolds, varying the degree of aryl lipidation and regiochemistry that produce inflammatory cytokines in a Mincle-dependent fashion. In vitro interleukin-6 (IL-6) cytokine production by human peripheral blood mononuclear cells (hPBMCs) indicated that the lipid regiochemistry is key to potency and maximum cytokine output, with the tri-substituted compounds inducing higher levels of IL-6 in hPBMCs than the di-substituted derivatives. Additionally, IL-6 production trended higher after stimulation with compounds that contained lipids ranging from five to eight carbons long, compared to shorter (below five) or longer (above eight) carbon chains, across all the substitution patterns. An analysis of the additional cytokines produced by hPBMCs revealed that compound 4d, tri-substituted and five carbons long, induced significantly greater levels of interleukin-1β (IL-1β), tumor necrosis factor- α (TNF-α), interleukin-23 (IL-23), and interferon- γ (IFN-γ) than the other compounds tested in this study. An in silico assessment of 4d highlighted the capability of this analogue to bind to the human Mincle carbohydrate recognition domain (CRD) efficiently. Together, these data highlight important structure-activity findings regarding Mincle-specific cytokine induction, generating a lead adjuvant candidate for future formulations and immunological evaluations.

The genomic landscape of the immune system in lung cancer: present insights and continuing investigations

Lung cancer is one of the most prevalent malignancies worldwide, contributing to over a million cancer-related deaths annually. Despite extensive research investigating the genetic factors associated with lung cancer susceptibility and prognosis, few studies have explored genetic predispositions regarding the immune system. This review discusses the most recent genomic findings related to the susceptibility to or protection against lung cancer, patient survival, and therapeutic responses. The results demonstrated the effect of immunogenetic variations in immune system-related genes associated with innate and adaptive immune responses, cytokine, and chemokine secretions, and signaling pathways. These genetic diversities may affect the crosstalk between tumor and immune cells within the tumor microenvironment, influencing cancer progression, invasion, and prognosis. Given the considerable variability in the individual immunegenomics profiles, future studies should prioritize large-scale analyses to identify potential genetic variations associated with lung cancer using highthroughput technologies across different populations. This approach will provide further information for predicting response to targeted therapy and promotes the development of new measures for individualized cancer treatment.

Mincle receptor in macrophage and neutrophil contributes to the unresolved inflammation during the transition from acute kidney injury to chronic kidney disease

Background

Recent studies have demonstrated a strong association between acute kidney injury (AKI) and chronic kidney disease (CKD), while the unresolved inflammation is believed to be a driving force for this chronic transition process. As a transmembrane pattern recognition receptor, Mincle (macrophage-inducible C-type lectin, Clec4e) was identified to participate in the early immune response after AKI. However, the impact of Mincle on the chronic transition of AKI remains largely unclear.

Methods

We performed single-cell RNA sequencing (scRNA-seq) with the unilateral ischemia-reperfusion (UIR) murine model of AKI at days 1, 3, 14 and 28 after injury. Potential effects and mechanism of Mincle on renal inflammation and fibrosis were further validated in vivo utilizing Mincle knockout mice.

Results

The dynamic expression of Mincle in macrophages and neutrophils throughout the transition from AKI to CKD was observed. For both cell types, Mincle expression was significantly up-regulated on day 1 following AKI, with a second rise observed on day 14. Notably, we identified distinct subclusters of Minclehigh neutrophils and Minclehigh macrophages that exhibited time-dependent influx with dual peaks characterized with remarkable pro-inflammatory and pro-fibrotic functions. Moreover, we identified that Minclehigh neutrophils represented an "aged" mature neutrophil subset derived from the "fresh" mature neutrophil cluster in kidney. Additionally, we observed a synergistic mechanism whereby Mincle-expressing macrophages and neutrophils sustained renal inflammation by tumor necrosis factor (TNF) production. Mincle-deficient mice exhibited reduced renal injury and fibrosis following AKI.

Conclusion

The present findings have unveiled combined persistence of Minclehigh neutrophils and macrophages during AKI-to-CKD transition, contributing to unresolved inflammation followed by fibrosis via TNF-α as a central pro-inflammatory cytokine. Targeting Mincle may offer a novel therapeutic strategy for preventing the transition from AKI to CKD.

Punicalagin promotes mincle-mediated phagocytosis of macrophages via the NF-κB and MAPK signaling pathways

Punicalagin (PUN) is a polyphenol derived from the pomegranate peel. It has been reported to have many beneficial effects, including anti-inflammatory, anti-oxidant, and anti-proliferation. However, the role of PUN in macrophage phagocytosis is currently unknown. In this study, we found that pre-treatment with PUN significantly enhanced phagocytosis by macrophages in a time- and dose-dependent manner in vitro. Moreover, KEGG enrichment analysis by RNA-sequencing showed that differentially expressed genes following PUN treatment were significantly enriched in phagocyte-related receptors, such as the C-type lectin receptor signaling pathway. Among the C-type lectin receptor family, Mincle (Clec4e) significantly increased at the mRNA and protein level after PUN treatment, as shown by qRT-PCR and western blotting. Small interfering RNA (siRNA) mediated knockdown of Mincle in macrophages resulted in down regulation of phagocytosis. Furthermore, western blotting showed that PUN treatment enhanced the phosphorylation of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) in macrophages at the early stage. Mincle-mediated phagocytosis by PUN was inhibited by PDTC (a NF-κB inhibitor) and SB203580 (a p38 MAPK inhibitor). In addition, PUN pre-treatment enhanced phagocytosis by peritoneal and alveolar macrophages in vivo. After intraperitoneal injection of Escherichia coli (E.coli), the bacterial load of peritoneal lavage fluid and peripheral blood in PUN pre-treated mice decreased significantly. Similarly, the number of bacteria in the lung tissue significantly reduced after intranasal administration of Pseudomonas aeruginosa (PAO1). Taken together, our results reveal that PUN enhances bacterial clearance in mice by activating the NF-κB and MAPK pathways and upregulating C-type lectin receptor expression to enhance phagocytosis by macrophages.

Intestinal epithelial cells of Japanese flounder (Paralichthys olivaceus) as an in vitro model for studying intestine immune function based on transcriptome analysis

Japanese flounder (Paralichthys olivaceus) is an economically crucial marine species, but diseases like hemorrhagic septicemia caused by Edwardsiella tarda have resulted in significant economic losses. E. tarda infects various hosts, and its pathogenicity in fish is not fully understood. Lipopolysaccharides (LPS) are components of the outer membrane of Gram-negative bacteria and are representative of typical PAMP molecules that cause activation of the immune system. The PoIEC cell line is a newly established intestinal epithelial cell line from P. olivaceus. In order to investigate whether it can be used as an in vitro model for studying the pathogenesis of E. tarda and LPS stimulation, we conducted RNA-seq experiments for the PoIECs model of E. tarda infection and LPS stimulation. In this study, transcriptome sequencing was carried out in the PoIEC cell line after treatment with LPS and E. tarda. A total of 62.52G of high-quality data from transcriptome sequencing results were obtained in nine libraries, of which an average of 87.96% data could be aligned to the P. olivaceus genome. Data analysis showed that 283 and 414 differentially expressed genes (DEGs) in the LPS versus Control (LPS-vs-Con) and E. tarda versus Control groups (Et-vs-Con), respectively, of which 60 DEGs were shared in two comparation groups. The GO terms were predominantly enriched in the extracellular space, inflammatory response, and cytokine activity in the LPS-vs-Con group, whereas GO terms were predominantly enriched in nucleus and positive regulation of transcription by RNA polymerase II in the Et-vs-Con group. KEGG analysis revealed that three immune-related pathways were co-enriched in both comparison groups, including the Toll-like receptor signaling pathway, C-type lectin receptor signaling pathway, and Cytokine-cytokine receptor interaction. Five genes were randomly screened to confirm the validity and accuracy of the transcriptome data. These results suggest that PoIEC cell line can be an ideal in vitro model for studies of marine fish gut immunity and pathogenesis of Edwardsiellosis.

Ligand-Controlled Stereoselective Synthesis and Biological Activity of 2-Exomethylene Pseudo-glycoconjugates: Discovery of Mincle-Selective Ligands

Glycoconjugate analogues in which the sp3 -hybridized C2 position of the carbohydrate structure (normally bearing a hydroxy group) is converted into a compact sp2 -hybridized exomethylene group are expected to have unique biological activities. We established ligand-controlled Tsuji-Trost-type glycosylation methodology to directly prepare a variety of these 2-exomethylene pseudo-glycoconjugates, including glucosylceramide analogues, in an α- or β-selective manner. Glucocerebrosidase GBA1 cleaves these synthetic pseudo-β-glucosylceramides similarly to native glucosylceramides. The pseudo-glucosylceramides exhibit selective ligand activity towards macrophage-inducible C-type lectin (Mincle), but unlike native glucosylceramides, are inactive towards CD1d.

Ligand‐Controlled Stereoselective Synthesis and Biological Activity of 2‐Exomethylene Pseudo‐glycoconjugates: Discovery of Mincle‐Selective Ligands

Glycoconjugate analogues in which the sp3‐hybridized C2 position of the carbohydrate structure (normally bearing a hydroxy group) is converted into a compact sp2‐hybridized exomethylene group are expected to have unique biological activities. We established ligand‐controlled Tsuji–Trost‐type glycosylation methodology to directly prepare a variety of these 2‐exomethylene pseudo‐glycoconjugates, including glucosylceramide analogues, in an α‐ or β‐selective manner. Glucocerebrosidase GBA1 cleaves these synthetic pseudo‐β‐glucosylceramides similarly to native glucosylceramides. The pseudo‐glucosylceramides exhibit selective ligand activity towards macrophage‐inducible C‐type lectin (Mincle), but unlike native glucosylceramides, are inactive towards CD1d.