Innate immunity against Legionella pneumophila during pulmonary infections in mice

박봉규,박가영,김지영,임선아,이경미 대한약학회 2017 Archives of Pharmacal Research Vol.40 No.2

Legionella pneumophila is an etiological agentof the severe pneumonia known as Legionnaires’ disease(LD). This gram-negative bacterium is thought toreplicate naturally in various freshwater amoebae, but alsoreplicates in human alveolar macrophages. Inside hostcells, legionella induce the production of non-endosomalreplicative phagosomes by injecting effector proteins intothe cytosol. Innate immune responses are first line defensesagainst legionella during early phases of infection, anddistinguish between legionella and host cells using germline-encoded pattern recognition receptors such as Toll-likereceptors , NOD-like receptors, and RIG-I-like receptors,which sense pathogen-associated molecular patterns thatare absent in host cells. During pulmonary legionellainfections, various inflammatory cells such as macrophages,neutrophils, natural killer (NK) cells, largemononuclear cells, B cells, and CD4? and CD8? T cellsare recruited into infected lungs, and predominantly occupyinterstitial areas to control legionella. During pulmonarylegionella infections, the interplay between distinctcytokines and chemokines also modulates innate hostresponses to clear legionella from the lungs. Recognitionby NK cell receptors triggers effector functions includingsecretion of cytokines and chemokines, and leads to lysis oftarget cells. Crosstalk between NK cells and dendritic cells,monocytes, and macrophages provides a major first-linedefense against legionella infection, whereas activation ofT and B cells resolves the infection and mounts legionellaspecificmemory in the host.

Colonic Gene Expression and Fecal Microbiota in Diarrhea-predominant Irritable Bowel Syndrome: Increased Toll-like Receptor 4 but Minimal Inflammation and no Response to Mesalazine

( Jonna Jalanka ),( Ching Lam ),( Andrew Bennett ),( Anna Hartikainen ),( Fiona Crispie ),( Laura A Finnegan ),( Paul D Cotter ),( Robin Spiller ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2021 Journal of Neurogastroenterology and Motility (JNM Vol.27 No.2

Background/Aims Diarrhea-predominant irritable bowel syndrome (IBS-D) has been previously associated with evidence of immune activation and altered microbiota. Our aim is to assess the effect of the anti-inflammatory agent, mesalazine, on inflammatory gene expression and microbiota composition in IBS-D. Methods We studied a subset of patients (n = 43) from a previously published 12-week radomized placebo-controlled trial of mesalazine. Mucosal biopsies were assessed by immunohistochemistry and reverse transcription-polymerase chain reaction for a range of markers of inflammation, altered permeability, and sensory receptors including Toll-like receptors (TLRs) at randomization after treatment. All biopsy data were compared to 21 healthy controls. Patient’s stool microbiota composition was analysed through 16S ribosomal RNA sequencing. Results We found no evidence of increased immune activation compared to healthy controls. However, we did find increased expression of receptors in both sensory pathways and innate immune response including TLR4. Higher TLR4 expression was associated with greater urgency. TLR4 expression correlated strongly with the expression of the receptors bradykinin receptor B2, chemerin chemokine-like receptor 1, and transient receptor potential cation channel, subfamily A, member 1 as well as TLR4’s downstream adaptor myeloid differentiation factor 88. Mesalazine had minimal effect on either gene expression or microbiota composition. Conclusions Biopsies from a well-characterized IBS-D cohort showed no substantial inflammation. Mesalazine has little effect on gene expression and its previous reported effect on fecal microbiota associated with much greater inflammation found in inflammatory bowel diseases is likely secondary to reduced inflammation. Increased expression of TLR4 and correlated receptors in IBS may mediate a general increase in sensitivity to external stimuli, particularly those that signal via the TLR system. (J Neurogastroenterol Motil 2021;27:279-291)

Toll-like Receptors and NOD-like Receptors in Innate Immune Defense during Pathogenic Infection

Jin, Hyo Sun,Park, Jeong-Kyu,Jo, Eun-Kyeong The Korean Society for Microbiology 2014 Journal of Bacteriology and Virology Vol.44 No.3

In response to invading pathogens, the body immune system develops an immediate defense mechanism, i.e., innate immune response, which is detected in almost all living organisms including mammals, plants, insects, etc. Recent studies have identified numerous innate immune receptors that are able to recognize pathogen-associated molecular patterns and transduce the essential intracellular signaling cascades to mount early and successful host defenses against infectious challenge. Among innate immune receptors, we will focus on two important receptors, toll-like receptors (TLRs) and nucleotide binding oligomerization domain (Nod)-like receptors, and their major intracellular signaling pathways that culminate to activate innate immune effectors and inflammatory mediators during pathogen infection. In this review, we address the recent advances of understanding intracellular signaling mechanisms by which TLRs and NLRs activate host immune defense and inflammation. The role and regulatory mechanisms by which a subet of NLRs-associated inflammasome activation induce interleukin-$1{\beta}$ secretion and their relevance with host defense will be also discussed. Both TLR- and NLR-mediated intracellular signaling networks serve crucial roles in mounting resistance to bacterial and viral infection through synthesis of immune mediators and antimicrobial chemicals during infection.

Toll-like Receptors and NOD-like Receptors in Innate Immune Defense during Pathogenic Infection

진효선,박정규,조은경 대한미생물학회 2014 Journal of Bacteriology and Virology Vol.44 No.3

In response to invading pathogens, the body immune system develops an immediate defense mechanism, i.e., innateimmune response, which is detected in almost all living organisms including mammals, plants, insects, etc. Recent studieshave identified numerous innate immune receptors that are able to recognize pathogen-associated molecular patternsand transduce the essential intracellular signaling cascades to mount early and successful host defenses against infectiouschallenge. Among innate immune receptors, we will focus on two important receptors, toll-like receptors (TLRs) andnucleotide binding oligomerization domain (Nod)-like receptors, and their major intracellular signaling pathways thatculminate to activate innate immune effectors and inflammatory mediators during pathogen infection. In this review, weaddress the recent advances of understanding intracellular signaling mechanisms by which TLRs and NLRs activatehost immune defense and inflammation. The role and regulatory mechanisms by which a subet of NLRs-associatedinflammasome activation induce interleukin-1β secretion and their relevance with host defense will be also discussed. Both TLR- and NLR-mediated intracellular signaling networks serve crucial roles in mounting resistance to bacterial andviral infection through synthesis of immune mediators and antimicrobial chemicals during infection.

중이 진주종에서 Toll Like Receptor 2와 4의 발현

변재용,차창일,여승근,이선규,조중생 대한이비인후과학회 2006 대한이비인후과학회지 두경부외과학 Vol.49 No.5

Background and Objectives:One of the hallmarks of aural cholesteatoma is chronic and recurrent infection. Initiation and perpetuationof the inflammatory response of cholesteatoma may result from an exaggerated host defense reaction of the cholesteatomaepithelium. However, the role of innate immune system in cholesteatoma has not been fully elucidated. Toll-likereceptors (TLRs) are a part of the innate immune system involved in the response to microbial pathogen. TLRs appear torespond to pathogens and induce NF-κB activation. TLR 2 and TLR 4 seem to be related to the initiation of immune responsesagainst gram negative and positive bacteria. We have investigated the expression of TLR 2, and 4 in the normal external auditorycanal skin and cholesteatoma. Subjects and Method:A real time RT-PCR was performed to determine and quantify the expressionof TLR 2 and 4 mRNA. Immunohistochemical staining was performed for 17 cases of cholesteatoma and 8 cases of normalauditory canal skin to demonstrate the distribution of TLR 2 and 4. Results:All cholestatoma and normal external auditory canalskin expressed both TLR 2 and 4 mRNA. The mRNA of TLR 2 and 4 were expressed significantly higher in cholesteatoma thanin the normal external auditory canal skin (p<0.05). Immunohistochemistry using anti-TLR2 and anti-TLR4 antibody revealedthe expression of TLR 2 and 4 in the epithelial cells of the cholesteatoma. Conclusion:These findings suggest that distinctivepatterns of the innate immune related receptors, TLR 2 and 4 system, constitute a part of the innate immune system in the cholesteatoma.(Korean J Otolaryngol 2006;49:482-7)

Cooperative Interactions between Toll-Like Receptor 2 and Toll-Like Receptor 4 in Murine Klebsiella pneumoniae Infections

( Hee-yeon Jeon ),( Jong-hyung Park ),( Jin-il Park ),( Jun-young Kim ),( Sun-min Seo ),( Seung-hoon Ham ),( Eui-suk Jeong ),( Yang-kyu Choi ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.8

Klebsiella pneumoniae is an opportunistic and clinically significant emerging pathogen. We investigated the relative roles of Toll-like receptor (TLR) 2 and TLR4 in initiating host defenses against K. pneumoniae. TLR2 knockout (KO), TLR4 KO, TLR2/4 double KO (DKO), and wildtype (WT) mice were inoculated with K. pneumoniae. Mice in each group were sacrificed after either 12 or 24h, and the lungs, liver, and blood were harvested to enumerate bacterial colonyforming units (CFU). Cytokine and chemokine levels were analyzed using enzyme-linked immunosorbent assay and real-time PCR, and pneumonia severity was determined by histopathological analysis. Survival was significantly shortened in TLR4 KO and TLR2/4 DKO mice compared with that of WT mice after infection with 5 × 103 CFU. TLR2 KO mice were more susceptible to infection than WT mice after exposure to a higher infectious dose. Bacterial burdens in the lungs and liver were significantly higher in TLR2/4 DKO mice than in WT mice. Serum TNF-α, MCP-1, MIP-2, and nitric oxide levels were significantly decreased in TLR2/4 DKO mice relative to those in WT mice, and TLR2/4 DKO mice showed significantly decreased levels of TNF-α, IL-6, MCP-1, and inducible nitric oxide synthase mRNA in the lung compared with those in WT mice. Collectively, these data indicate that TLR2/4 DKO mice were more susceptible to K. pneumoniae infection than single TLR2 KO and TLR4 KO mice. These results suggest that TLR2 and TLR4 play cooperative roles in lung innate immune responses and bacterial dissemination, resulting in systemic inflammation during K. pneumoniae infection.

Basic and Translational Understandings of Microbial Recognition by Toll-Like Receptors in the Intestine

( Sang Hoon Rhee ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2011 Journal of Neurogastroenterology and Motility (JNM Vol.17 No.1

Microbial recognition by multicellular organisms is initially accomplished by a group of pattern recognition receptors which are specialized to recognize microbe-associated molecular patterns (MAMPs) such as lipopolysaccharide, bacterial lipoprotein, CpG DNA motif, double strand RNA and flagellin. Toll-like receptors (TLRs) are the representative pattern recognition receptors, and microbial recognition by TLRs elicits innate and inflammatory responses. Ten TLR family members have been presently identified in human genome, and numerous studies discovered that intracellular responses from MAMPs-TLR engagements are mediated by a participation of at least 4 immediate adaptor molecules such as myeloid differentiation primary response gene-88 (MyD88), MyD88 adaptor-like (Mal) (also known as Toll/IL-1 receptor domain-containing adaptor protein [TIRAP]), Toll/IL-1 receptor domain-containing adaptor-inducing interferon-β (TRIF) and TRIF-related adaptor molecule (TRAM) leading to activate transcription factors including nuclear factor κB, activator protein-1 and interferon-regulatory factors. Given that large amounts of commensal microbiota constantly reside in the intestinal lumen, enteric microbial recognition by TLRs at the intestinal epithelium provides a critical impact on regulating intestinal homeostasis. Indeed, aberrant TLR4 and TLR5 activations are etiologically associated with the development and progress of intestinal inflammatory diseases including inflammatory bowel disease and necrotizing enterocolitis. In this review article, we present the molecular mechanism by which TLRs elicit intracellular signal transduction, and summarize the physiological relevance of TLRs related to the gastrointestinal tract. (J Neurogastroenterol Motil 2011;17:28-34)

Molecular Characterization of Chicken Toll-like Receptor 7

Chai, Han-Ha,Suk, Jae Eun,Lim, Dajeong,Lee, Kyung-Tai,Choe, Changyong,Cho, Yong-Min The Korean Society of Animal Reproduction 2015 Reproductive & developmental biology Vol.39 No.4

Toll-like receptor 7 (TLR7) is critical for the triggering of innate immune response by recognizing the conserved molecular patterns of single-stranded RNA (ssRNA) viruses and mediated antigenic adaptive immunity. To understand how TLR7 distinguish pathogen-derived molecular patterns from the host self, it is essential to be able to identify TLR7 receptor interaction interfaces, such as active sites or R848-agonist binding sites. The functional interfaces of TLR7 can serve as targets for structure-based drug design in studying the TLR7 receptor's structure-function relationship. In contrast to mammalian TLR7, chicken TLR7 (chTLR7) is unknown for its important biological function. Therefore, it has been targeted to mediate contrasting evolutionary patterns of positive selection into non-synonymous SNPs across eleven species using TLR7 conservation patterns (evolutionary conserved and class-specific trace residues), where protein sequence differences to the TLR7 receptors of interest record mutation that have passed positive section across the species. In this study, we characterized the Lys609 residue on chTLR7-ECD homodimer interfaces to reflect the current tendency of evolving positive selection to be transfer into a stabilization direction of the R848-agonist/chTLR7-ECDs complex under the phylogenetically variable position across species and we suggest a potential indicator for contrasting evolutionary patterns of both the species TLR-ECDs.

세균 초항원에 의해 활성화된 대식세포에서 Toll-like receptor의 발현양상

김효열,조현철,김수기,신계철 대한감염학회 2004 감염과 화학요법 Vol.36 No.5

목적 : 대표적인 세균 초항원인 포도알균 창자독소B(SEB)에 의한 면역세포 활성에 Toll-like receptor(TLR)의 관련성을 알아보고, 지질다당질(LPS)에 의한 TLR의 발현양상과 비교하여 보았다. 재료 및 방법 : 세균 초항원인 SEB를 dye ligand affinity chromatography법으로 순수분리정제한 뒤 사람 말초혈액 단핵구와 사람 대식세포주인 THP-l을 자극하여 이들 세포에서 TLR1-9의 mRNA의 발현을 역전사중합효소반응법으로 확인하였고, 또한 LPS 자극에 의한 발현양상과 비교하여 보았다. 결과 : SEB로 사람 말초혈액 단핵구세포를 자극하였을 때 TLRl과 TLR5 mRNA 발현의 상승이 관찰되었고, TLR4 mRNA의 발현은 SEB 처리 후 1, 2시간째는 발현이 억제되다가 3시간 이후에 상승되는 양상을 보였다. 이런 TLR4 mRNA 발현의 변화는 말초혈액 단핵구를 LPS로 자극하였을 때도 유사하게 관찰되었고, SEB와 LPS를 동시에 자극하였을 때 더 현저한 변화를 보였다. 사람 대식세포주인 THP-l을 SEB 및 LPS로 자극하였을 때TLR2 보다는 TLR4의 mRNA 발현에 현저한 변화를 관찰할 수 있었다. 결론 : 이상의 결과로 SEB에 의한 사람 말초혈액 단핵구세포와 대식세포의 활성에 TLR의 연관성을 확인할 수 있었으며, 적어도 TLR4가 SEB에 대식세포 활성에 관여되었다. 또한 SEB와 LPS는 동시에 병용하여 단핵구세포를 자극하였을 때 상승적으로 TLR4 발현을 촉진할 것으로 추정된다. 향후 SEB 자극에 의한 대식세포 활성에 TLR의 관여 여부를 더 상세히 밝히는 것이 초항원에 의해 유발되는 질환들을 해결하는 중요한 열쇠가 될 수 있을 것으로 생각된다. Background : Staphylococcal enterotoxin B (SEB) as a prototype superantigen is known to play a pivotal role in toxic shock syndrome and severe sepsis. However, the precise mechanism initiating the activation of innate effector cells by SEB is unclear. Recently, Toll-like receptors (TLRs), the sensor of pathogen associated molecular pattern (PAMP), have been reported to be expressed abundantly in monocytic lineage-cells. The purpose of this study is to investigate whether TLRs are involved in the SEB-induced immune cell activation and to prove the differential TLRs expression in response to SEB and/or lipopolysaccharide (LPS). Materials and Methods : SEB was purified by dye ligand affinity chromatography. The mRNA expression of TLR1-9 in human peripheral blood mononuclear cells (PBMC) and human monocyte- like THP-1 cell line stimulated by SEB and/or LPS was detected by RT-PCR. Results : The treatment of PBMC with SEB elicited significant changes in the expression of several TLRs. Interestingly, the mRNAs of TLR1 and TLR5 were clearly up-regulated in PBMC, whereas mRNA of TLR4 was down-regulated in the very early period of stimulation within 1-2 hours, and subsequently up-regulated 3 hours later after the stimulation. The up-regulation of mRNA of TLR4 was detected in PBMC stimulated by LPS. The up-regulation was more prominent in the cells exposed concomitantly to SEB and LPS. The mRNA expression pattern of TLR4 in THP-1 cell line stimulated by SEB or LPS was comparable to those of PBMC. Conclusion : This study indicates that SEB triggers inflammatory signals on macrophages and PBMC by engaging TLRs, particularly TLR4. The combination of LPS and SEB synergistically modulates TLR4 signaling.

Ligand Recognition by the Toll-like Receptor Family

진미선,이지오 한국통합생물학회 2009 Animal cells and systems Vol.13 No.1

Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation. Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation.