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University of Tokyo Researchers Explore Role of TLR7/8 Stress Responses in Histiocytosis
The SLC29A3 gene in humans plays a critical role in lysosomal function, ensuring the effective recycling of waste in macrophages. It facilitates the transport of nucleosides, the breakdown products of RNA and DNA, from lysosomes to the cell's cytoplasm. Mutations that lead to the loss of function in this gene cause unusual nucleoside storage and a range of resulting conditions known as SLC29A3 disorders. Symptoms may include distinct skin patches, enlarged liver or spleen, hearing loss, or even type 1 diabetes. Among these, histiocytosis, marked by the build-up of mononuclear phagocytes (histiocytes) in various organs, has been particularly baffling to researchers.
In a recent article in the Journal of Experimental Medicine, a research team from Japan offers clarity on the molecular mechanics of SLC29A3 disorders. They have identified that the malfunctions of the toll-like receptor (TLR) 7 and TLR8 in macrophages play a significant role in causing histiocytosis when SLC29A3 is not functioning. “We have now uncovered how TLR signaling, a key innate immune response pathway, contributes to histiocytosis in SLC29A3 disorders,” stated Prof. Kensuke Miyake of The Institute of Medical Science, University of Tokyo.
When macrophages consume pathogens, the subsequent degradation of pathogenic RNA produces nucleosides, which are detected by TLR7 and TLR8. With mutations in SLC29A3 causing unusual nucleoside storage, the research team posited that the constant activation of TLR7 and TLR8 by these nucleosides might be a contributing factor to SLC29A3 disorders. Experiments with mice supported this theory. Prof. Takuma Shibata, the study's primary author, described the situation succinctly: “To put it simply, mutations in SLC29A3 lead to nucleoside accumulation in macrophages. These nucleosides activate TLR7 and TLR8, and this excessive TLR response leads to excess macrophage proliferation and accumulation.” Prof. Miyake added that this indicates SLC29A3's role in moderating the TLR7/8 response in the innate immune system's cells.
This comprehensive study by Prof. Miyake and Associate Prof. Shibata provides valuable knowledge in innate immunology. With the identification of TLR7 and TLR8 as potential treatment targets for SLC29A3 disorders, the path to innovative therapeutic solutions seems promising. Prof. Miyake emphasizes that these findings can also enhance the understanding of other disorders tied to macrophage proliferation and build-up.
The SLC29A3 gene in humans plays a critical role in lysosomal function, ensuring the effective recycling of waste in macrophages. It facilitates the transport of nucleosides, the breakdown products of RNA and DNA, from lysosomes to the cell's cytoplasm. Mutations that lead to the loss of function in this gene cause unusual nucleoside storage and a range of resulting conditions known as SLC29A3 disorders. Symptoms may include distinct skin patches, enlarged liver or spleen, hearing loss, or even type 1 diabetes. Among these, histiocytosis, marked by the build-up of mononuclear phagocytes (histiocytes) in various organs, has been particularly baffling to researchers.
In a recent article in the Journal of Experimental Medicine, a research team from Japan offers clarity on the molecular mechanics of SLC29A3 disorders. They have identified that the malfunctions of the toll-like receptor (TLR) 7 and TLR8 in macrophages play a significant role in causing histiocytosis when SLC29A3 is not functioning. “We have now uncovered how TLR signaling, a key innate immune response pathway, contributes to histiocytosis in SLC29A3 disorders,” stated Prof. Kensuke Miyake of The Institute of Medical Science, University of Tokyo.
When macrophages consume pathogens, the subsequent degradation of pathogenic RNA produces nucleosides, which are detected by TLR7 and TLR8. With mutations in SLC29A3 causing unusual nucleoside storage, the research team posited that the constant activation of TLR7 and TLR8 by these nucleosides might be a contributing factor to SLC29A3 disorders. Experiments with mice supported this theory. Prof. Takuma Shibata, the study's primary author, described the situation succinctly: “To put it simply, mutations in SLC29A3 lead to nucleoside accumulation in macrophages. These nucleosides activate TLR7 and TLR8, and this excessive TLR response leads to excess macrophage proliferation and accumulation.” Prof. Miyake added that this indicates SLC29A3's role in moderating the TLR7/8 response in the innate immune system's cells.
This comprehensive study by Prof. Miyake and Associate Prof. Shibata provides valuable knowledge in innate immunology. With the identification of TLR7 and TLR8 as potential treatment targets for SLC29A3 disorders, the path to innovative therapeutic solutions seems promising. Prof. Miyake emphasizes that these findings can also enhance the understanding of other disorders tied to macrophage proliferation and build-up.