Toll-like Receptors In Pathogenesis Research Articles

Toll-like receptors in pathogenesis of neurodegenerative diseases and their therapeutic potential.

Toll-like receptors (TLRs) are a family of pattern-recognition receptorstriggered by pathogen-derived and tissue-damage-related ligands. TLRs were previously believed to only be expressed in immune cells. However, it is now confirmed that they are ubiquitously expressed in cells within the body including neurons, astrocytes, and microglia of the central nervous system (CNS). Activation of TLRs is capable of inducing immunologic and inflammatory responses to injury or infection of CNS. This response is self-limiting that usually resolves once the infection has been eradicated or the tissue damage has been repaired. However, the persistence of inflammation-inducing insults or a failure in normal resolution mechanisms may result in overwhelming inflammation which may induce neurodegeneration. This implies that TLRs may play a role in mediating the link between inflammation and neurodegenerative diseases namely Alzheimer's disease, Parkinson's disease, Huntington's disease, stroke, and amyotrophic lateral sclerosis. So, new therapeutic approaches that specifically target TLRs may be developed by better understanding TLR expression mechanisms in the CNS and their connections to particular neurodegenerative disorders. Therefore, this review paper discussed the role of TLRs in neurodegenerative diseases.

SARS-CoV-2 Infected Pediatric Cerebral Cortical Neurons: Transcriptomic Analysis and Potential Role of Toll-like Receptors in Pathogenesis.

Different mechanisms were proposed as responsible for COVID-19 neurological symptoms but a clear one has not been established yet. In this work we aimed to study SARS-CoV-2 capacity to infect pediatric human cortical neuronal HCN-2 cells, studying the changes in the transcriptomic profile by next generation sequencing. SARS-CoV-2 was able to replicate in HCN-2 cells, that did not express ACE2, confirmed also with Western blot, and TMPRSS2. Looking for pattern recognition receptor expression, we found the deregulation of scavenger receptors, such as SR-B1, and the downregulation of genes encoding for Nod-like receptors. On the other hand, TLR1, TLR4 and TLR6 encoding for Toll-like receptors (TLRs) were upregulated. We also found the upregulation of genes encoding for ERK, JNK, NF-κB and Caspase 8 in our transcriptomic analysis. Regarding the expression of known receptors for viral RNA, only RIG-1 showed an increased expression; downstream RIG-1, the genes encoding for TRAF3, IKKε and IRF3 were downregulated. We also found the upregulation of genes encoding for chemokines and accordingly we found an increase in cytokine/chemokine levels in the medium. According to our results, it is possible to speculate that additionally to ACE2 and TMPRSS2, also other receptors may interact with SARS-CoV-2 proteins and mediate its entry or pathogenesis in pediatric cortical neurons infected with SARS-CoV-2. In particular, TLRs signaling could be crucial for the neurological involvement related to SARS-CoV-2 infection.

The role of Toll-like receptors in the pathogenesis of allergic diseases – where is the truth?

Toll-like receptors (TLRs) are pattern recognition receptors crucial for the innate and adaptive immune response to pathogen-associated molecular patterns (PAMPs). TLR stimulation via microbial products activates antigen-presenting cells, influences the function of T regulatory cells (Treg), determines the Th1/Th2 balance and Th17 cell differentiation, and controls cytokine production in mast cells and activation of eosinophils. The role of TLR receptors in pathogenesis of allergic diseases results from the biological function that they play in activation and regulation of the immune response. However, the exact role still remains a controversial area. Whereas numerous epidemiological studies mainly indicate a protective effect of microbial exposure, experiments show that innate immune stimulation via TLRs may be involved in both development of and protection against allergic diseases. Timing, dose, site and intensity of exposure to environmental factors and host genetic predisposition are clearly crucial to understanding the interaction between innate immune stimulation and allergy development.Furthermore, extensive clinical trials suggest that ligands for TLRs provide new therapeutic targets for protection against and treatment of asthma and allergic rhinitis. The aim of this review is to summarize the current knowledge about the role of TLRs in pathogenesis of allergic diseases. We will further discuss how we can reconcile inconsistencies in the results of existing studies and review information on the potential use of ligands for TLRs in allergy prevention and therapy.

Role of Toll-like receptors in pathogenesis of rheumatoid arthritis

Toll-like receptors(TLRs), as the family members of type Ⅰ transmembrane receptors, play a pivotal role in both innate and adaptive immune responses. Recently, TLRs are believed to be the cntical receptors in innate immunity . Innate immunity activated by the recognition of exogenous or endogenous by TLRs induces multiple cytokines that is the key factor to affect differentiation of naive T cells. Abnormal activation of TLIRs may cause the functional imbalance of Th1, Th2, Th17 and Treg, resulting in the occurence of autoimmune disease. Key words: Toll-like receptors; Rheumatoid arthritis; Signal transduction

Role of Toll-like receptors in pathogenesis of asthma

Toll样受体可识别多种病原微生物及其产物,并且是联系天然免疫与获得性免疫的重要分子,结合脂多糖等配体后,通过激活天然免疫,产生γ干扰素等辅助T细胞(Th)1型细胞因子;诱导幼稚树突细胞发育成熟,并呈递抗原,促进Th1型免疫反应,抑制Th2型免疫反应;树突细胞上的Toll样受体与病原菌的病原相关分子模式结合,可能通过抑制性共刺激分子或分泌白介素-10、转化生长因子-β等调节性因子,促进Th0向具有调节功能的调节性T细胞转化.从而调节哮喘的Th1/Th2失衡。