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Dectin‐1 is a well‐characterized C‐type lectin receptor involved in anti‐fungal immunity through the recognition of polysaccharides; however, molecular mechanisms and outcomes initiated through self‐recognition have not been fully understood. Here, we purified a water‐soluble fraction from mouse liver that acts as a Dectin‐1 agonist. To address the physiological relevance of this recognition, we utilized sterile liver inflammation models. The CCl4‐induced hepatitis model showed that Dectin‐1 deficiency led to reduced inflammation through decreased inflammatory cell infiltration and lower pro‐inflammatory cytokine levels. Moreover, in a NASH model induced by streptozotocin and a high‐fat diet, hepatic inflammation and fibrosis were ameliorated in Dectin‐1‐deficient mice. The Dectin‐1 agonist activity was increased in the water‐soluble fraction from NASH mice, suggesting a potential pathogenic cycle between Dectin‐1 activation and hepatitis progression. In vivo administration of the fraction into mice induced hepatic inflammation. These results highlight a role of self‐recognition through Dectin‐1 that triggers hepatic innate immune responses and contributes to the exacerbation of inflammation in pathogenic settings. Thus, the blockade of this axis may provide a therapeutic option for liver inflammatory diseases. [ABSTRACT FROM AUTHOR]

Our bodies are continuously assaulted by infection and tissue damage; most of these injurious insults are primarily sensed by immune receptors to maintain tissue homeostasis. Although immune recognition of proteins or nucleic acids has been well characterized, the molecular mechanisms by which immune receptors discriminate lipids to elicit suitable immune responses remain elusive. Recent studies have demonstrated that the C-type lectin receptor family functions as immune sensors for adjuvant lipids derived from pathogens and damaged tissues, thereby promoting innate/acquired immunity. In this review, we will discuss how these receptors recognize lipid components to initiate appropriate, but sometimes deleterious, immune responses against environmental stimuli. We will also discuss an aspect of inhibitory C-type lectin receptors; their ligands might reflect normal self which silences the immune response regarded as "silence"-associated molecular patterns or may be associated with escape strategies of pathogens as "evasion"-associated molecular patterns. [ABSTRACT FROM AUTHOR]

Summary Phosphatidyl-inositol mannosides (PIM) are glycolipids unique to mycobacteria and other related bacteria that stimulate host immune responses and are implicated in mycobacteria pathogenicity. Here, we found that the FcRγ-coupled C-type lectin receptor DCAR (dendritic cell immunoactivating receptor; gene symbol Clec4b1 ) is a direct receptor for PIM. Mycobacteria activated reporter cells expressing DCAR, and delipidation of mycobacteria abolished this activity. Acylated PIMs purified from mycobacteria were identified as ligands for DCAR. DCAR was predominantly expressed in small peritoneal macrophages and monocyte-derived inflammatory cells in lungs and spleen. These cells produced monocyte chemoattractant protein-1 (MCP-1) upon PIM treatment, and absence of DCAR or FcRγ abrogated MCP-1 production. Upon mycobacterial infection, Clec4b1 -deficient mice showed reduced numbers of monocyte-derived inflammatory cells at the infection site, impaired IFNγ production by T cells, and an increased bacterial load. Thus, DCAR is a critical receptor for PIM that functions to promote T cell responses against mycobacteria. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis H37Ra produces a range of immunogenic β-gentiobiosyl diacylglycerides. We report the total synthesis of several candidate structures and show that these compounds signal weakly through mouse, but not human, Mincle. Structure–activity relationships reveal a striking dependence upon acyl chain length for gentiobiosyl diacylglyceride signalling through Mincle. Significantly, a truncated β-glucosyl diglyceride was shown to provide potent signalling through both human and mouse Mincle and could activate murine bone marrow derived dendritic cells. [ABSTRACT FROM AUTHOR]

An enantioselective synthesis of (+)-corynomycolic acid, and its elaboration to esters of trehalose, glucose and glycerol, is described. Trehalose dicorynomycolate and trehalose monocorynomycolate activate human and mouse Mincle as effectively as trehalose dicorynomycolate (cord factor). Glucose monomycolate is revealed to be a potent activator of both mouse and human Mincle. Glycerol monocorynomycolate signals through human Mincle, with the activity predominantly residing in the 2′S-isomer. [ABSTRACT FROM AUTHOR]

(1) Background: This work presents a high-efficiency, high sensitivity, compact rectifier based on a dual-band impedance matching network that employs a simple and straightforward T-matching circuit, for sub-1 GHz license-free applications. The development of a low-cost RF energy harvester dedicated to the ISM bands is introduced. The proposed rectifier design is optimized to operate at the sub-GHz frequency bands (0.9 to 2.4 GHz), specifically those at the ISM 900 and 2400 MHz. The motivation for this band is due to the low attenuation, well-known fundamental electromagnetic theories and background, and several wireless communications are emitting at those bands, such as RFID (2). Methods: The rectifier design is based on a simple, balanced single-series diode connected with a T-matching circuit. The dual-band performance is achieved by deploying reactive elements in each branch. The full mathematical analysis and simulation results are discussed in the manuscript. (3) Results: The rectifier can achieve a 80 MHz bandwidth around 920 MHz frequency and 200 MHz around the higher band 2.4 GHz. The resultant conversion efficiency level is maintained above 45% at both bands with a peak efficiency reaches up to 70% at the higher band. The optimum terminal load attached to the circuit at which the peak efficiency is achieved, is given as 4.7 k Ω. (4) Conclusion: Due to the compactness and small footprint, simple design, and simple integration with microwave circuits, the proposed rectifier architecture might find several potential applications in wireless RF energy harvesting. [ABSTRACT FROM AUTHOR]