Pattern Recognition Receptors Genes Research Articles

Immune response gene coexpression network analysis of Arachis hypogaea infected with Aspergillus flavus

Aspergillus flavus (A. flavus) infection and aflatoxin contamination is a major bottleneck for peanut cultivation and value chain industry. In this study, a transcriptomic network study was conducted by retrieving publically available RNA-seq datasets of resistant and susceptible peanut varieties infected by A. flavus separately to understand the peanut defense mechanism against A. flavus. The gene expression analysis revealed differentially expressed genes (DEGs) in response to the different levels of infection and coexpression network of DEGs deciphered hub genes involved in the immune process in resistant and susceptible varieties. The interplay of resistance conferring genes and cell wall related genes was observed through functional enrichment analysis in response to pathogen infection and identified few key genes such as Protein P21, R genes, Pattern Recognition Receptor genes, Pectinesterases, Laccase and Thaumatin-like protein 1b as candidate genes in imparting immune response against A. flavus.

Skin-brain axis signaling mediates behavioral changes after skin wounding

Patients with chronic wounds often have associated cognitive dysfunction and depression with an as yet unknown mechanism for this association. To address the possible causality of skin wounding inducing these changes, behavior and cognitive functions of female C57BL/6 mice with an excisional skin wound were compared to unwounded animals. At six days post wounding, animals exhibited anxiety-like behaviors, impaired recognition memory, and impaired coping behavior. Wounded animals also had concomitant increased hippocampal expression of Tnfa, the pattern recognition receptor (PRR) Nod2, the glucocorticoid receptors GR/Nr3c1 and Nr3c2. Prefrontal cortex serotonin and dopamine turnover were increased on day six post-wounding. In contrast to the central nervous system (CNS) findings, day six post -wounding serum catecholamines did not differ between wounded and unwounded animals, nor did levels of the stress hormone corticosterone, TNFα, or TGFβ. Serum IL6 levels were, however elevated in the wounded animals. These findings provide evidence of skin-to-brain signaling, mediated either by elevated serum IL6 or a direct neuronal signaling from the periphery to the CNS, independent of systemic mediators. Wounding in the periphery is associated with an altered expression of inflammatory mediators and PRR genes in the hippocampus, which may be responsible for the observed behavioral deficits.

Extremes of age are associated with differences in the expression of selected pattern recognition receptor genes and ACE2, the receptor for SARS-CoV-2: implications for the epidemiology of COVID-19 disease

BackgroundOlder aged adults and those with pre-existing conditions are at highest risk for severe COVID-19 associated outcomes.MethodsUsing a large dataset of genome-wide RNA-seq profiles derived from human dermal fibroblasts (GSE113957) we investigated whether age affects the expression of pattern recognition receptor (PRR) genes and ACE2, the receptor for SARS-CoV-2.ResultsExtremes of age are associated with increased expression of selected PRR genes, ACE2 and four genes that encode proteins that have been shown to interact with SAR2-CoV-2 proteins.ConclusionsAssessment of PRR expression might provide a strategy for stratifying the risk of severe COVID-19 disease at both the individual and population levels.

In Vivo Efficacy of Lacticaseibacillus rhamnosus L8020 in a Mouse Model of Oral Candidiasis.

Oral candidiasis presents with multiple clinical manifestations. Among known pathogenic Candida species, Candida albicans is the most virulent and acts as the main causative fungus of oral candidiasis. Novel treatment modalities are needed because of emergent drug resistance and frequent candidiasis recurrence. Here, we evaluated the ability of Lacticaseibacillus rhamnosus L8020, isolated from healthy and caries-free volunteers, to prevent against the onset of oral candidiasis in a mouse model. Mice were infected with C. albicans, in the presence or absence of L. rhamnosus L8020. The mice were treated with antibiotics and corticosteroid to disrupt the oral microbiota and induce immunosuppression. We demonstrated that oral consumption of L. rhamnosus L8020 by C. albicans-infected mice abolished the pseudomembranous region of the mouse tongue; it also suppressed changes in the expression levels of pattern recognition receptor and chemokine genes. Our results suggest that L. rhamnosus L8020 has protective or therapeutic potential against oral candidiasis, which supports the potential use of this probiotic strain for oral health management.

GM-1111 reduces radiation-induced oral mucositis in mice by targeting pattern recognition receptor-mediated inflammatory signaling.

PurposeOral mucositis (OM) is a common, painful side effect of radiation therapy used for the treatment of head and neck cancer (HNC). Activation of the innate immune system upon irradiation has been identified as a key precipitating event of OM. To better understand OM’s pathogenesis, we studied pattern recognition receptors (PRRs) and their downstream pro-inflammatory cytokines in a mouse model of radiation-induced OM. We also tested therapeutic efficacy of GM-1111 that targets innate immune system to reduce radiation-induced OM.Methods and materialsThe pathogenesis of OM was studied in a single X-ray induced mouse model. The severity of OM was measured by visual and microscopical examinations. The irradiation-induced changes of PRRs and their downstream effector cytokine gene expression levels were determined. The efficacy of GM-1111 to reduce OM was tested in single and fractionated irradiation mouse models. The impact of the drug on tumor response to radiation therapy was also tested in a mouse model of human HNC.ResultsRadiation-induced tissue ulcerations were radiation-dosage and -time dependent. The lesions showed selective increases in PRR and pro-inflammatory cytokine gene expression levels. Once daily administration of GM-1111 (≥30 mg/kg, s.c.) significantly reduced the severity and the incidence of OM. The drug had little effect on PRRs but significantly inhibited downstream pro-inflammatory cytokine genes. GM-1111 did not interfere radiation therapy to induce HNC SCC-25 tumor regression. Instead, we observed significant drug-induced tumor regression.ConclusionsRadiation induces tissue damages. The increased expression levels of PRRs and their downstream pro-inflammatory cytokine genes in the damaged tissues suggest their important contribution to the pathogenesis of OM. Drug GM-1111 that targets these innate immune molecules may be a potential drug candidate as an intervention for OM.

PTX3 gene polymorphism associated with cryptococcosis in HIV-uninfected Chinese patients.

For Chinese Han populations, cryptococcosis are more likely to occur in HIV-uninfected patients instead of HIV-infected patients compared with other countries and regions, implying that there may be genetic predisposing factors for cryptococcosis in the Chinese Han populations. However, the retail mechanism has not been clarified. We aimed to conduct an association analysis between the single nucleotide polymorphisms (SNPs) of pattern recognition receptors (PRR) genes and the susceptibility to cryptococcosis in HIV-uninfected Chinese patients, which may provide new genetic predisposing factors for early-risk predictionof disease, individualised treatment and prognosis monitoring. Using the SNaPshot SNP typing technique, eight SNPs of PRR genes (Dectin-2, Dectin-1, PTX3, CXCL8, IL12B, IFIH1, TLR1 and CD209) were typed on 97 HIV-uninfected cryptococcosis patients and 120 healthy controls who admitted to West China Hospital, Sichuan University, China, from 1 March 2018 to 30 December 2018. The results were analysed by the SHEsis software and SPSS 20.0 software. It was found that that PTX3 rs2305619 polymorphism was associated with cryptococcosis in HIV-uninfected patients. Compared with the GG genotype, AA genotype increased the risk of cryptococcosis in HIV-uninfected patients (p=.015, OR, 2.579; 95% CI, 1.202-5.535). In the immunocompetent patients, the AA genotype had a higher risk (p=.002, OR, 4.399; 95% CI, 1.745-11.088). Further verification found that the plasma PTX3 level of the AA genotype was significantly higher than the GA or GG genotype (60.28±16.12 vs 7.32±0.79, p<.001). PTX3 rs2305619 polymorphism was associated with cryptococcosis in HIV-uninfected Chinese patients. The AA genotype increased the risk of cryptococcosis, and its plasma PTX3 level was significantly higher than that of GA or GG genotype.

Divergence in Coding Sequence and Expression of Different Functional Categories of Immune Genes between Two Wild Rodent Species.

Differences in immune function between species could be a result of interspecific divergence in coding sequence and/or expression of immune genes. Here, we investigate how the degree of divergence in coding sequence and expression differs between functional categories of immune genes, and if differences between categories occur independently of other factors (expression level, pleiotropy). To this end, we compared spleen transcriptomes of wild-caught yellow-necked mice and bank voles. Immune genes expressed in the spleen were divided into four categories depending on the function of the encoded protein: pattern recognition receptors (PRR); signal transduction proteins; transcription factors; and cyto- and chemokines and their receptors. Genes encoding PRR and cyto-/chemokines had higher sequence divergence than genes encoding signal transduction proteins and transcription factors, even when controlling for potentially confounding factors. Genes encoding PRR also had higher expression divergence than genes encoding signal transduction proteins and transcription factors. There was a positive correlation between expression divergence and coding sequence divergence, in particular for PRR genes. We propose that this is a result of that divergence in PRR coding sequence leads to divergence in PRR expression through positive feedback of PRR ligand binding on PRR expression. When controlling for sequence divergence, expression divergence of PRR genes did not differ from other categories. Taken together, the results indicate that coding sequence divergence of PRR genes is a major cause of differences in immune function between species.

Single-Blinded Study Highlighting the Differences between the Small Intestines of Neonatal and Weaned Piglets.

Simple SummaryThe gut mucosa of pigs, which contains intestinal epithelium and subepithelial immune cells, forms a barrier against microorganisms. Nonetheless, infectious diseases of the digestive tract remain the most frequent and recurrent conditions in the swine industry. Changes in intestinal morphology and structure primarily occur at birth and during weaning. However, the difference in the intestinal structures between neonatal and weaned piglets remains unclear. In this study, for the first time, we evaluated the differences in the small intestine between neonatal (0-day-old) and weaned piglets (21-day-old) and analyzed the morphology and immunological components of the small intestines of 0- and 21-day-old piglets, thereby providing preliminary data for future mechanistic studies.The gut is one of the body’s major immune structures, and the gut mucosa, which contains intestinal epithelium and subepithelial immune cells, is the primary site for eliciting local immune responses to foreign antigens. Intestinal immune system development in pigs is a transitional period during birth and weaning. This study compares the morphological and immunological differences in the small intestine of neonatal and weaned piglets to potentially prevent intestinal infectious diseases in neonatal piglets. Histological analyses of weaned piglet intestines showed increased crypt depth, higher IEL count, and larger ileal Peyer’s patches compared with those of neonates. Additionally, the ileal villi of weaned piglets were longer than those of neonatal piglets, and claudin-3 protein expression was significantly higher in weaned than in neonatal piglets. The numbers of CD3+ T, goblet, and secretory cells were also higher in the small intestines of weaned piglets than in those of neonates. No significant differences were observed in the secretory IgA-positive cell number in the jejunum of weaned and neonatal piglets. The mRNA expression of most pattern recognition receptors genes in the duodenum and jejunum was higher in the weaned than neonatal piglets; however, the opposite was true in the ileum. The mRNA levels of IL-1β and TNF-α in the jejunal and ileal mucosa were higher in weaned piglets than in neonatal piglets. There were significantly fewer CD3+, CD4+, and CD8+ T cells from peripheral blood-mononuclear cells in neonatal piglets. Our study provides insights regarding the different immune mechanisms within the small intestines of 0- and 21-day-old piglets. Studies on the additional developmental stages and how differences in the small intestines affect the response of pigs to pathogens remain warranted.

Conserved exitrons of FLAGELLIN-SENSING 2 (FLS2) across dicot plants and their functions

The alternative splicing of pattern recognition receptor genes regulates immune signalling in mammals, but in plants its role is still unknown. Here, we detected alternatively spliced introns (exitrons) in the first annotated exons of FLAGELLIN-SENSING 2 (FLS2) genes in all the examined dicot plants across nine families. The 5′ splice site (SS) regions were conserved and with rare synonymous substitutions. Point mutations and gene swaps indicated that the position and efficiency of exitron splicing primarily depended on the nucleotide sequences of FLS2 genes. Single-nucleotide mutations in the invariable codon carrying 5′ SS dramatically altered the accumulation of poplar and tomato FLS2 transcripts, indicating the 5′-proximal exitrons of FLS2 function as stimulatory introns on gene expression. The 3′ SSs of exitrons are diverse and can be changed by 1–2 nucleotide mutations in Salicaceae FLS2. The alternative transcripts (ATs) of poplar and tobacco FLS2, which encode small secreted proteins, were specifically induced by flg22, and one such AT from tobacco FLS2 suppressed flg22-induced response. Our results indicated that the exitrons of FLS2 genes regulate the accumulation of transcripts by an intron mediated enhancement (IME) mechanism and some ATs have the potential to encode suppressors for FLS2 pathway.

Locust can detect β-1, 3-glucan of the fungal pathogen before penetration and defend infection via the Toll signaling pathway

The timing and mechanism by which a host insect initiates an immune response are critical to successful defense against infection. Pathogen recognition, a prerequisite for host defense, has long been recognized to take place during the insect epidermis invasion by fungus. Here we report that insect can sense the fungal pathogen before host cuticle is penetrated by fungus. We discovered the upstream pattern recognition receptor (PRR) genes of the Toll pathway were upregulated in both the integument and fat body early during fungal germination on the epicuticle of Locusta migratoria manilensis. The Toll signaling pathway was strongly activated in the fat body at the penetration stage. RNAi of Myd88 increased the susceptibility of locusts to fungal infection, but that of Cactus showed the opposite effect. In addition, β-1, 3-glucan (laminarin), the main component of the cell wall of the pathogenic fungus Metarhizium acridum, was capable of activating the Toll signaling pathway (Spaetzle and Cactus) when it was applied on the host cuticle. These results demonstrate that host epidemis can effectively defend fungal infection by detecting β-1, 3-glucan on the fungal cell wall and activate the Toll signaling pathway even before fungal penetration.

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Transcriptomics of Cherax quadricarinatus hepatopancreas during infection with Decapod iridescent virus 1 (DIV1)

Cherax quadricarinatus is a large-sized, highly fecund, and fast-growing species of freshwater crayfish, and has become one of the world's most intensely studied crustaceans. Decapod iridescent virus 1 (DIV1), a newly described species in the family Iridoviridae, is known to infect various crustaceans, including C. quadricarinatus, and may pose a new threat in the shrimp-farming industry. The present study performed de novo transcriptome sequencing of C. quadricarinatus hepatopancreas during DIV1 infection. A total of 114,784 transcripts and 56,418 genes were obtained; 1070 genes were upregulated and 775 genes were downregulated when compared with the uninfected samples (controls). Three pattern recognition receptor genes (fibrinogen-related protein, C-type lectin, and beta-1,3-glucan-binding protein) were upregulated during DIV1 infection. Among the top-30 upregulated unigenes, 9 unigenes were identified as vitellogenin (Vg) genes, and the top-3 upregulated unigenes were identified as involved in Vg lipid transport, lipid localization, and lipid transporter activity, which were all significantly over-representative GO terms in the GO enrichment analysis of total and upregulated differentially expressed genes (DEGs). Many genes associated with Jak-STAT signaling pathway, Endocytosis, Phagosome, MAPK signaling pathway, Apoptosis and Lysosome were positively modified after DIV1 infection. The predicted protein–protein interaction (PPI) analysis showed NF1 and TUBA, CRM1 and TUBB were involved in protein interactions. This research showed that DIV1 infection has a significant impact on the transcriptome profile of C. quadricarinatus hepatopancreas, and the results enhance our understanding of virus–host interactions. Furthermore, the high number of transcripts generated in the present study will provide information for identifying novel genes in the absence of a full C. quadricarinatus genome sequence.

Genetic polymorphisms in toll-like receptors 1, 2, and 4 in feline upper respiratory tract aspergillosis

Fungal species in the genus Aspergillus are environmental saprophytes that can act as opportunistic pathogens of the nasal cavity and paranasal sinuses in humans, cats and other species. Upper respiratory tract aspergillosis (URTA) presents as non-invasive and invasive forms with the latter occurring almost exclusively in immunocompromised hosts. However, in domestic cats, invasive URTA affects apparently immunocompetent patients. A defect in innate immunity has been proposed as a predisposing factor in invasive feline URTA. Single nucleotide polymorphisms (SNPs) in pattern recognition receptor genes have been implicated in the pathogenesis of aspergillosis in humans. The aims of this study were to identify non-synonymous SNPs in the coding regions of toll-like receptors involved in the immune response to Aspergillus spp. and to compare the frequency of these SNPs between affected and control cats. The coding and flanking regions of TLR1, TLR2 and TLR4 were sequenced in 14 cats with URTA and the sequences were compared with those in 20 control cats without aspergillosis. In total, 23 non-synonymous SNPs were identified in TLR1 (n = 11), TLR2 (n = 3) and TLR4 (n = 10). Differences in allelic frequency of non-synonymous SNPs between affected and controls were not identified either within breeds or overall or between non-invasive and invasive disease phenotypes. Although allelic frequency differed between cat breeds that are overrepresented for URTA and underrepresented breeds there was no association differences identified between affected cats and underrepresented breeds. The difference in allelic frequency of an INDEL point mutation identified in intron 1 of TLR4, between cats with non-invasive versus invasive aspergillosis approached significance (p = 0.054). While results from this study do not support a role for non-synonymous SNPs in the pathogenesis of feline URTA they do provide evidence that investigation for polymorphisms in non-coding regions of these genes and in other pattern recognition receptors are warranted.

Polymorphisms in pattern recognition receptor genes of indigenous and White Leghorn breeds of chicken.

Functional polymorphisms in pattern recognition receptors (PRRs) modulate innate immunity and play a crucial role in resistance or susceptibility to diseases. The present study was carried out to explore polymorphic patterns in the coding sequences of PRR genes TLR3, TLR1LA (TLRs), MDA5, LGP2 (RLRs) and NOD1 (NLR) in chicken breeds of India, namely Ghagus (GH), Nicobari (NB) and the exotic White Leghorn (WLH) breed. Out of 209 SNPs observed in five genes among three breeds, 117 were synonymous (Syn) and 92 were non-synonymous (NS) SNPs. In TLR genes the highest polymorphism was observed in NB (16, 28) compared to GH (14, 16) and WLH (13, 19) breeds. In the MDA5 gene the highest polymorphism was observed in GH (12) compared to NB (eight) and WLH (four) breeds. However, an almost similar level of polymorphism was observed in the LGP2 gene among the three breeds. In the NOD1 gene, the highest polymorphism was observed in NB (27), followed by WLH (11) and GH (10) breeds. The overall highest number of SNPs was observed in NB (90), followed by GH (62) and the WLH (57) breed. With regard to variation in polymorphism among different classes of PRRs, the study revealed the highest polymorphism in TLRs compared to NOD1 and the RLR class of PRRs. Further, the domain locations of various Syn and NS SNPs in each PRR among the three breeds were identified. In silico analysis of NS SNPs revealed that most of them had a neutral effect on protein function. However, two each in TLR1LA and LGP2 and one in the MDA5 gene were predicted to be deleterious to protein function. The present study unravelled extensive polymorphism in the coding sequences of the TLR and NLR class of PRR genes, and the polymorphism was higher in indigenous chicken breeds.

Intracellular and extracellular effector activity of mouse neutrophils in response to cutaneous and visceral Leishmania parasites

Neutrophils are short-lived phagocytic cells equipped with several receptors for pathogen recognition and phagocytosis and have intracellular and extracellular effector mechanisms that can inactivate pathogens. Leishmaniases are diseases caused by different species of Leishmania that mainly afflicts poorer populations of tropical and subtropical regions and immunocompromised individuals. Thus, the present study aims to investigate the effector response of murine neutrophils to species of Leishmania causing American cutaneous leishmaniasis and zoonotic visceral leishmaniasis by evaluating pattern recognition receptors (PRR) and intracellular and extracellular effector microbicide activity. When exposed to Leishmania parasites, mouse neutrophils produced superoxide, released enzymes in the extracellular space and generated neutrophil extracellular traps, although PRR gene expression is negatively regulated. L. infantum, L. guyanensis, and L. shawi inhibited enzymatic activity, whereas L. amazonensis reduced the emission of extracellular structures. These findings indicate that although neutrophils trigger several microbicide mechanisms, Leishmania parasites can manipulate extracellular effector mechanisms. The present study also provides evidence that neutrophils can internalize parasites by coiling phagocytosis.

The transcriptomic expression of pattern recognition receptors: Insight into molecular recognition of various invading pathogens in Oyster Crassostrea gigas

Pattern recognition receptors (PRRs) are essential in recognizing specific pathogen-associated molecular patterns (PAMPs) on microbes and triggering responses to eliminate the invading pathogens. Previous genomic studies have revealed a great number of PRR genes in the Pacific oyster Crassostrea gigas, a sessile and filter-feeder marine bivalve belonging to the phylum Mollusca. On the survey of PRRs in the assembly oyster reference genome version 9, a total of 1084 PRRs were identified, which were composed of at least 12 gene families. Some of the gene families were significantly expanded, including C-type lectins (CTLs), fibrinogen-related proteins (FREPs), scavenger receptor cysteine-rich repeat protein (SRCRs), leucine-rich repeat (LRR)-only proteins (LRRops), and especially C1q domain-containing proteins (C1qDCs). The transcriptomic profiles of these abundant PRRs in response to PAMP treatments were investigated by RNA-Seq using the SOLiD EZ BeadTM system. Compared to the control library, there were 6,655, 7,273, 7,593, 6,830, 6687 and 8250 differentially expressed genes in the haemocytes of oysters in response to lipopolysaccharide (LPS) stimulation for 6 h, 12 h and 24 h, and peptidoglycan (PGN), glucan (GLU) and poly I:C (IC) stimulation for 12 h, respectively. After stimulation for 12 h, there were 134, 97, 114 and 159 genes up-regulated in the LPS, PGN, GLU and IC library, respectively. Most of the gene families involved in immune response towards PAMPs were C1qDCs, CTLs and FREPs, while only a few members of LRR and immunoglobin-containing proteins (LRRIGs), retinoic acid-inducible gene I [RIG-I]-like receptors (RLRs) and Toll like receptors (TLRs) were up-regulated. After LPS stimulation, the expression level of 258 non-redundant PRR genes in oyster haemocytes increased significantly with different expression pattern, and most of them were C1qDCs, CTLs, LRRops and FREPs. The transcriptomic analyses indicated that there was a dynamic and orchestrated specific expression regulation of numerous PRR genes in response to pathogen invasion. The expanded PRR gene family members were differentiated with more specific functional responses to certain PAMPs rather than the versatile ones. Based on the different expression pattern during the LPS stimulation, the oyster PRRs could be assigned into three consecutive steps in the response against pathogen invading. All the results would provide useful information for future studies of oyster PRRs and deep insight into the researches on invertebrate innate immunity.

Immunomodulatory effect of 1, 25 dihydroxy vitamin D3 on the expression of RNA sensing pattern recognition receptor genes and cytokine response in dengue virus infected U937-DC-SIGN cells and THP-1 macrophages

Dengue virus (DENV) infections are straining public health systems worldwide. Vitamin D, a secosteroid hormone, is currently being investigated for its immunomodulatory effects in DENV infections. The objectives of the present study was to study the effect of 1, 25 dihydroxy vitamin D3 (1,25(OH)2D3) on the expression of genes coding for RNA sensing pattern recognition receptors, downstream signaling components including oligoadenylate synthetases (OAS) and interferon stimulated gene 15 (ISG15) and T helper (Th)1, Th2 and Th17 cytokine response in DENV infected U937-DC-SIGN cells and THP-1 macrophages. U937-DC-SIGN RNA was investigated for the expression of TLR3, DDX58, IFIH1, OAS1, OAS2, OAS3, CAMP and ISG15 genes using gene expression assays. Interleukin (IL)-12p70, IL-10, IL-4 and IL-17A levels were assessed in the THP-1 macrophage culture supernatants. The results revealed that 1,25(OH)2D3 increased the expression of DDX58, OAS1, OAS2 and OAS3 at 0.1 μM while higher concentration had diminishing effect. 1,25(OH)2D3 enhanced the expression of ISG15 and CAMP genes. 1,25(OH)2D3 suppressed the levels of IL-4 and IL-17A. Lower concentration of 1,25(OH)2D3 suppressed IL-12p70 and IL-10 levels while a higher concentration enhanced the levels. The results suggest that 1,25(OH)2D3 may have concentration dependent immunomodulatory effects. Higher dose of 1,25(OH)2D3 might have an immunoregulatory role in ameliorating inflammation during dengue infections. Further studies are needed to evaluate the efficacy of different doses of 1,25(OH)2D3 in preventing severe dengue.

Enhanced expression of IFI16 and RIG-I in human third-trimester placentas following HSV-1 infection.

The innate immune response in the placenta depends on the ability of maternal immune cells and fetal trophoblast cells to detect and eliminate invading pathogens through germline-encoded pattern recognition receptors (PRRs). In the present study, we analysed the transcripts and protein expression of interferon (IFN)-inducible protein (IFI)16, melanoma differentiation-associated protein 5 (MDA5), RIG-I-like receptor (RIG-I) and Toll-like receptor (TLR)-3 in third-trimester human placentas and investigated cytokine profiles generated during herpes simplex type 1 (HSV-1) infection. Decidual and chorionic villous biopsies (38-42 weeks of gestation) were obtained from healthy women immediately after a caesarean section. The expression of the DDX58 (RIG-I), IFIH1 (MDA5), IFI16 and TLR3 transcripts was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Extracellular cytokine and PRRs levels were then quantified by enzyme-linked immunosorbent assays (ELISAs). All examined PRRs genes, including DDX58, IFIH1, IFI16 and TLR3, were expressed constitutively at the mRNA and protein levels in the placental biopsies. The concentration of the IFI16 protein was increased in HSV-1-infected decidual and chorionic villous explants compared to those of mock-infected tissues (P=0·029). Higher protein expression levels of RIG-I in both the maternal and fetal parts of the placenta were found (P=0·009 and P=0·004, respectively). In addition, increased production of IFN-β by HSV-1-infected tissues was noticed (P=0·004 for decidua, P=0·032 for chorionic villi). No significant differences in the IFN-α, interleukin (IL)-6 and IL-8 levels were found. These results showed that HSV-1 infection can enhance the expression of IFI16 and RIG-I proteins in the human term placenta.

The respiratory syncytial virus fusion protein formulated with a polymer-based adjuvant induces multiple signaling pathways in macrophages

Respiratory syncytial virus (RSV) causes acute respiratory tract infections in infants, the elderly and immunocompromised individuals. No licensed vaccine is available against RSV. We previously reported that intranasal immunization of rodents and lambs with a RSV vaccine candidate (ΔF/TriAdj) induces protective immunity with a good safety profile. ΔF/TriAdj promoted innate immune responses in respiratory mucosal tissues in vivo, by local chemokine and cytokine production, as well as infiltration and activation of immune cells including macrophages. The macrophage is an important cell type in context of both innate and adaptive immune responses against RSV. Therefore, we characterized the effects of ΔF/TriAdj on a murine macrophage cell line, RAW264.7, and bone marrow-derived macrophages (BMMs). A gene expression study of pattern recognition receptors (PRRs) revealed induction of endosomal and cytosolic receptors in RAW264.7 cells and BMMs by ΔF/TriAdj, but no up-regulation by ΔF in PBS. As a secondary response to the PRR gene expression, induction of several chemokines and pro-inflammatory cytokines, as well as up-regulation of MHC-II and co-stimulatory immune markers, was observed. To further investigate the mechanisms involved in ΔF/TriAdj-mediated secondary responses, we used relevant signal transduction pathway inhibitors. Based on inhibition studies at both transcript and protein levels, JNK, ERK1/2, CaMKII, PI3K and JAK pathways were clearly responsible for ΔF/TriAdj-mediated chemokine and pro-inflammatory cytokine responses, while the p38 and NF-κB pathways appeared to be not or minimally involved. ΔF/TriAdj induced IFN-β, which may participate in the JAK-STAT pathway to further amplify CXCL-10 production, which was strongly up-regulated. Blocking this pathway by a JAK inhibitor almost completely abrogated CXCL-10 production and caused a significant reduction in the cell surface expression of MHC-II and co-stimulatory immune markers. These data demonstrate that ΔF/TriAdj induces multiple signaling pathways in macrophages.

Divergent Selection of Pattern Recognition Receptors in Mammals with Different Ecological Characteristics.

Pattern recognition receptors (PRRs) are specialized receptors that represent a key component of the host innate immune system. Whether molecular evolutionary history of different PRR classes have involved different genetic mechanisms underlying diverse pathogen environment in mammals, and whether distinct ecology of mammals may have imposed divergent selective pressures on the evolution of the PRRs, remained unknown. To test these hypotheses, we investigated the characterization of 20 genes belonging to four PRR classes in mammals. Evidence of positive selection was found in most (17 of 20) PRR genes examined, and most positively selected sites (84%) undergoing radical changes were found to fall in important functional regions, consistent with the co-evolutionary dynamics between the hosts and their microbial counterparts. We found different evolutionary patterns in different PRR classes, with the highest level of positive selection in C-type lectin receptor (CLR) family, suggesting that the capability of CLRs in response to a wide variety of ligands might explain their malleability to selection pressures. Tests using branch models that partitioned the data along habitat and social behavior found significant evidence of divergent selective pressures of PRRs among mammalian groups. Interestingly, species-specific evolution was detected on RIG-I-like helicase genes (RLRs) in cetaceans, suggesting that RLRs might play a critical role in the defense against widespread marine RNA viruses during their divergence and radiation into marine habitats. This study provides a comprehensive look at the evolutionary patterns and implications of mammalian PRRs, and highlights the importance of ecological influences in molecular adaptation.