Changes In Toll-like Receptors Expression Research Articles

Distinctive Toll-like Receptors Gene Expression and Glial Response in Different Brain Regions of Natural Scrapie.

Prion diseases are chronic and fatal neurodegenerative diseases characterized by the accumulation of disease-specific prion protein (PrPSc), spongiform changes, neuronal loss, and gliosis. Growing evidence shows that the neuroinflammatory response is a key component of prion diseases and contributes to neurodegeneration. Toll-like receptors (TLRs) have been proposed as important mediators of innate immune responses triggered in the central nervous system in other human neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. However, little is known about the role of TLRs in prion diseases, and their involvement in the neuropathology of natural scrapie has not been studied. We assessed the gene expression of ovine TLRs in four anatomically distinct brain regions in natural scrapie-infected sheep and evaluated the possible correlations between gene expression and the pathological hallmarks of prion disease. We observed significant changes in TLR expression in scrapie-infected sheep that correlate with the degree of spongiosis, PrPSc deposition, and gliosis in each of the regions studied. Remarkably, TLR4 was the only gene upregulated in all regions, regardless of the severity of neuropathology. In the hippocampus, we observed milder neuropathology associated with a distinct TLR gene expression profile and the presence of a peculiar microglial morphology, called rod microglia, described here for the first time in the brain of scrapie-infected sheep. The concurrence of these features suggests partial neuroprotection of the hippocampus. Finally, a comparison of the findings in naturallyinfected sheep versus an ovinized mouse model (tg338 mice) revealed distinct patterns of TLRgene expression.

Contribution of Aberrant Toll Like Receptor Signaling to the Pathogenesis of Myelodysplastic Syndromes.

Toll like receptors (TLRs) are a family of pattern recognition receptors that play a central role in the innate immune response. These receptors are expressed on a wide variety of immune and non-immune cells, and they help shape the immune response to infection and injury through the recognition of pathogen-associated molecular patterns (PAMPs) as well as endogenous damage-associated molecular patterns (DAMPs). Accumulating evidence suggests that, in addition to regulating mature effector immune cells, TLRs can influence the immune response from the level of the hematopoietic stem cell (HSC). HSCs express TLRs, and exposure to TLR ligands influences the cycling, differentiation, and function of HSCs, with chronic TLR stimulation leading to impairment of normal HSC repopulating activity. Moreover, enhanced TLR expression and signaling is associated with myelodysplastic syndromes (MDS), a heterogenous group of HSC disorders characterized by ineffective hematopoiesis and a high risk of transformation to acute leukemias. In this review, we will discuss the role of TLR signaling in the pathogenesis of MDS, focusing on the known direct and indirect effects of this type of signaling on HSCs, the mechanisms of TLR signaling upregulation in MDS, the changes in TLR expression with disease progression, and the therapeutic implications for modulating TLR signaling in the treatment of MDS.

Expression patterns of Toll-like receptors in the ovine corpus luteum during the early pregnancy and prostaglandin F2α-induced luteolysis

The aim of this study was to elucidate the expression profiles of Toll-like receptors (TLRs) in the ovine corpus luteum (CL) during early pregnancy and prostaglandin F2α (PGF2α)-induced luteolysis. For this purpose, multiparous Anatolian Merino ewes were selected and randomly allotted into cyclic (including those in the induced luteolysis group, n = 20) and pregnant (n = 12) groups. All of the ewes were scheduled to be slaughtered for predetermined days/hour during the estrous cycle, early pregnancy, and PGF2α induced luteolysis. The CLs were collected from both cyclic and pregnant ewes on days 12 (C12 and P12; n = 8) and 16 (C16 and P16; n = 8) and pregnant ewes on day 22 (P22; n = 4). For the induced luteolysis model, ewes were injected with PGF2α on day 12 of the estrous cycle and CLs were collected at 1 h (PG1h; n = 4), 4 h (PG4h; n = 4), and 16 h (PG16h, n = 4) after injection. Quantitative polymerase chain reaction (qPCR) was used to evaluate the expression profiles of TLR2, TLR4, TLR6, TLR8, and TLR10, while free-floating in situ hybridization and immunohistochemistry were used to define the spatial localization of TLR2, TLR4, and TLR7 in the CL. Data were then analyzed by one-way ANOVA and were considered statistically significant when P values were lower than 0.05. Expression of TLR2 was upregulated in both early and late stages of luteolysis (P < .05). An upregulation of TLR4 was detected at PG16h, while TLR6 was decreased at PG4h (P < .05). Expression of TLR7 and TLR8 was significantly increased during early pregnancy, at both PG16h and regressed groups (C16, P < .05). In contrast, TLR10 was downregulated during PGF2α-induced luteolysis and on P16 (P < .05). TLR4 and TLR7 proteins were particularly localized in endothelial cells on C12/PG0h, but prominent signals corresponding to TLR4 and TLR7 were detected in luteal cells at PG16h. The results suggest an involvement of TLRs in the luteolytic mechanism in ovine CL, as indicated by differential expression levels of TLRs during PGF2α-induced luteolysis. Moreover, the present study indicates that early pregnancy-mediated changes in TLR expression in the CL may contribute to the establishment and maintenance of ovine pregnancy.

Time-course of striatal Toll-like receptor expression in neurotoxic, environmental and inflammatory rat models of Parkinson's disease

Because Toll-like receptors (TLRs) are emerging as potential targets for anti-inflammatory intervention in neurodegenerative diseases, the aim of this study was to characterise the time-course of TLR expression in neurotoxic, environmental and inflammatory Parkinson's disease models. Male Sprague Dawley rats were given intra-striatal injections of 6-hydroxydopamine (10μg), rotenone (1.25μg), LPS (10μg) or Poly I:C (20μg) and were sacrificed on Days 1, 4, 14 and 28 post surgery. Changes in the expression of several inflammatory markers, including TLR3, TLR4 and selected cytokines, were examined using qRT-PCR. We found pronounced changes in the bacterial responsive TLR4 and the viral responsive TLR3 receptors in the inflamed striatum in all models, regardless of whether the challenge was neurotoxic, environmental or inflammatory in nature. However, the magnitude and time-course of changes in expression was different between the different models. This study highlights the pattern of changes in TLR expression in models of Parkinson's disease, and further strengthens the rationale for targeting TLRs for anti-inflammatory intervention in this neurodegenerative disease.

Differential Expression of Toll-Like Receptors in Dendritic Cells of Patients with Dengue During Early and Late Acute Phases of the Disease

Background: Dengue hemorrhagic fever (DHF) is observed in individuals that have pre-existing heterotypic dengue antibodies and is associated with increased viral load and high levels of pro-inflammatory cytokines early in infection. Interestingly, a recent study showed that dengue virus infection in the presence of antibodies resulted in poor stimulation of Toll-like receptors (TLRs), thereby facilitating virus particle production, and also suggesting that TLRs may contribute to disease pathogenesis. Methodology/Principal Findings: We evaluated the expression levels of TLR2, 3, 4 and 9 and the co-stimulatory molecules CD80 and CD86 by flow cytometry. This was evaluated in monocytes, in myeloid and plasmacytoid dendritic cells (mDCs and pDCs) from 30 dengue patients with different clinical outcomes and in 20 healthy controls. Increased expression of TLR3 and TLR9 in DCs of patients with dengue fever (DF) early in infection was detected. In DCs from patients with severe manifestations, poor stimulation of TLR3 and TLR9 was observed. In addition, we found a lower expression of TLR2 in patients with DF compared to DHF. Expression levels of TLR4 were not affected. Furthermore, the expression of CD80 and CD86 was altered in mDCs and CD86 in pDCs of severe dengue cases. We show that interferon alpha production decreased in the presence of dengue virus after stimulation of PBMCs with the TLR9 agonist (CpG A). This suggests that the virus can affect the interferon response through this signaling pathway. Conclusions/Significance: These results show that during dengue disease progression, the expression profile of TLRs changes depending on the severity of the disease. Changes in TLRs expression could play a central role in DC activation, thereby influencing the innate immune response.

Early pregnancy-related changes in toll-like receptors expression in ovine trophoblasts and peripheral blood leukocytes

In the present study, we aimed to 1) demonstrate the presence of all 10 toll-like receptors (TLRs) in ovine trophoblasts, and 2) investigate the expression profiles of TLR1–10 mRNAs in peripheral blood leukocytes (PBLs) in ewes during early pregnancy. For those purposes, ovine trophoblasts (n = 6) were collected from pregnant ewes on day 13. PBLs were collected from non-pregnant (n = 6) and pregnant ewes (n = 17) on days of mating (d) 0 and 18. TLR mRNAs in ovine trophoblasts were visualized by free-floating in situ hybridization (ISH). To assess the expression profiles of TLR1–10 in PBLs, total RNA was isolated and transcribed to cDNA. TLR1–10 mRNA levels were determined by real-time PCR in triplicate. The Relative Expression Software Tool (REST 2009) was used for statistical analysis. We detected mRNAs for TLR2, TLR4, TLR5, TLR6, TLR7, TLR8, and TLR10 but not for TLR1, TLR3, and TLR9 in trophoblasts. TLR2, TLR5, TLR6, TLR7, TLR8, and TLR10 mRNAs were expressed by all trophoblasts, whereas TLR4 mRNA and protein in trophoblasts were more limited. In PBLs, TLR expression did not differ between day 0 and day 18 in non-pregnant ewes; however, ewes in early pregnancy exhibited significantly upregulated expression of TLR2 (2.3-fold), TLR4 (3.1-fold), TLR6 (1.7-fold), and TLR8 (2.2-fold) on day 18 compared with day 0. In contrast, TLR10 was downregulated (2-fold) on day 18 by pregnancy. Similar results were also obtained for TLR2, TLR4, TLR6, TLR8 and TLR10 from the comparison between day 18 non –pregnant and day 18 pregnant groups. According to these results, the presence of TLRs in early ovine trophoblasts suggests that these cells play an immunological role at the maternal–fetal interface. The results also suggest that tight regulation of some components of TLRs in PBLs due to embryo- and/or pregnancy-related factors is necessary for successful establishment of early pregnancy in ewes.

Longitudinal expression of Toll-like receptors on dendritic cells in uncomplicated pregnancy and postpartum

Toll-like receptors (TLRs) are integral parts of the innate immune system and have been implicated in complications of pregnancy. The longitudinal expression of TLRs on dendritic cells in the maternal circulation during uncomplicated pregnancies is unknown. The objective of this study was to prospectively evaluate TLRs 1-9 as expressed on dendritic cells in the maternal circulation at defined intervals throughout pregnancy and postpartum. This was a prospective cohort of 30 pregnant women with uncomplicated pregnancies and 30 nonpregnant controls. TLRs and cytokine expression was measured in unstimulated dendritic cells at 4 defined intervals during pregnancy and postpartum. Basal expression of TLRs and cytokines was measured by multicolor flow cytometry. The percent-positive dendritic cells for each TLRs were compared with both nonpregnant and postpartum levels with multivariate linear regression. TLRs 1, 7, and 9 were elevated compared with nonpregnant controls with persistent elevation of TLR 1 and interleukin-12 (IL-12) into the postpartum period. Concordantly, levels of IL-6, IL-12, interferon alpha, and tumor necrosis factor alpha increased during pregnancy and returned to levels similar to nonpregnant controls during the postpartum period. The elevated levels of TLR 1 and IL-12 were persistent postpartum, challenging notions that immunologic changes during pregnancy resolve after the prototypical postpartum period. Normal pregnancy is associated with time-dependent changes in TLR expression compared with nonpregnant controls; these findings may help elucidate immunologic dysfunction in complicated pregnancies.

Differential Expression of Toll-like Receptors in Dendritic Cells of Patients with Dengue during Early and Late Acute Phases of the Disease

BackgroundDengue hemorrhagic fever (DHF) is observed in individuals that have pre-existing heterotypic dengue antibodies and is associated with increased viral load and high levels of pro-inflammatory cytokines early in infection. Interestingly, a recent study showed that dengue virus infection in the presence of antibodies resulted in poor stimulation of Toll-like receptors (TLRs), thereby facilitating virus particle production, and also suggesting that TLRs may contribute to disease pathogenesis.Methodology/Principal FindingsWe evaluated the expression levels of TLR2, 3, 4 and 9 and the co-stimulatory molecules CD80 and CD86 by flow cytometry. This was evaluated in monocytes, in myeloid and plasmacytoid dendritic cells (mDCs and pDCs) from 30 dengue patients with different clinical outcomes and in 20 healthy controls. Increased expression of TLR3 and TLR9 in DCs of patients with dengue fever (DF) early in infection was detected. In DCs from patients with severe manifestations, poor stimulation of TLR3 and TLR9 was observed. In addition, we found a lower expression of TLR2 in patients with DF compared to DHF. Expression levels of TLR4 were not affected. Furthermore, the expression of CD80 and CD86 was altered in mDCs and CD86 in pDCs of severe dengue cases. We show that interferon alpha production decreased in the presence of dengue virus after stimulation of PBMCs with the TLR9 agonist (CpG A). This suggests that the virus can affect the interferon response through this signaling pathway.Conclusions/SignificanceThese results show that during dengue disease progression, the expression profile of TLRs changes depending on the severity of the disease. Changes in TLRs expression could play a central role in DC activation, thereby influencing the innate immune response.

The Expression of Toll-Like Receptors (TLRs) in Cultured Human Skin Fibroblast is Modulated by Histamine

Fibroblasts are responsible for the synthesis and degradation of various connective tissue components and soluble mediators of extracellular matrix metabolism. Few studies have been conducted concerning the expression of toll-like receptors (TLRs) in fibroblasts until now. This study aimed first to determine the quantitative expression of TLRs 1 to 10 in human skin fibroblasts and secondarily to explore any influence of expression by histamine, which is a well-known factor engaged in dermal inflammation. It was found that all 10 TLRs were expressed in fibroblasts. Interestingly, the expression of TLRs 4, 5, and 10 was increased after 2 and 6 hours of histamine treatment during culture. However, the expression of TLRs 2, 3, 6, 7, 8, and 9 was decreased after 6 hours of histamine treatment. Among the TLRs with a decreasing expression pattern, TLRs 7 and 8 showed a persistent tendency to decrease. All of these changes in TLR expression with histamine treatment were antagonized by treatment with diphenhydramine, a well-known antihistamine. Thus, these results suggest a role of histamine in the early phase of the dermal inflammatory reaction mediated by TLRs.

Colitis development during the suckling-weaning transition in mucin Muc2-deficient mice

The mucin Muc2 is the structural component of the colonic mucus layer. Adult Muc2 knockout (Muc2(-/-)) mice suffer from severe colitis. We hypothesized that Muc2 deficiency induces inflammation before weaning of mother's milk [postnatal day (P) 14] with aggravation of colitis after weaning (P28). Muc2(-/-) and wild-type mice were killed at embryonic day 18.5 and P1.5, P7.5, P14, P21, and P28. Colonic morphology, influx of T cells, and goblet cell-specific protein expression was investigated by (immuno)histochemistry. Cytokine and Toll-like receptor (TLR) profiles in the colon were analyzed by quantitative RT-PCR. Muc2(-/-) mice showed an increased and persistent influx of Cd3ε-positive T cells in the colonic mucosa as of P1.5. This was accompanied by mucosal damage at P28 in the distal colon but not in the proximal colon. At P14, the proinflammatory immune response [i.e., increased interleukin (IL)-12 p35, IL-12 p40, and tumor necrosis factor-α, expression] in the distal colon of Muc2(-/-) mice presented with an immune suppressive response [i.e., increased Foxp3, transforming growth factor (TGF)-β1, IL-10, and Ebi3 expression]. In contrast, at P28, a proinflammatory response remained in the distal colon, whereas the immune suppressive response (i.e., Foxp3 and TGF-β1 expression) declined. The proximal colon of Muc2(-/-) mice did not show morphological damage and was dominated by an immune suppressive response at P14 and P28. Interestingly, changes in expression of TLRs and TLR-related molecules were observed in the distal colon at P14 and P28 and in the proximal colon only at P28. Colitis in Muc2(-/-) mice is limited before weaning by immune suppressive responses and exacerbates in the distal colon after weaning because of the decline in the immune suppressive response.

Changes in expression of Toll-like receptor 4 and its downstream cytokines in spinal cord in a rat model of bone cancer pain

Objective To investigate the changes in the expression of Toll-like receptor 4(TLR4)and its downstream cytokines TNF-α and IL-1β in the spinal cord in a rat model of bone cancer pain.Methods Seventy-two female SD rats weighing 150-180 g were randomly divided into 3 groups(n = 24 each): group Ⅰ normal control(group C);group Ⅱ sham operation(group S)and group Ⅲ bone cancer pain(group BP).Bone cancer was induced by intra-tibial inoculation of 1× 10~5 Walker 256 breast cancer cells.Bone cancer and bone destruction were shown by X-ray.Paw withdrawal threshold (PWT) to mechanical stimulation was measured with von Frey filaments and spontaneous pain was evaluated by ambulatory score.The expression of TLR4,TNF-α and IL-1βmRNA in the spinal cord was determined by RT-PCR and the expression of TLR4 protein by immuno-histochemistry and TLR4 positive cell count was determined.Results In group BP the ambulatory score started increasing and PWT to mechanical stimulation started decreasing at 6 days after inoculation.The ambulatory score was significantly higher,PWT significantly lower and the expression of TLR4 mRNA and protein and TNF-α and IL-1β mRNA in the spinal cord and TLR4 positive cell count were significantly higher in group BP than in group C and S.Conclusion Intra-tibial inoculation of Walker 256 breast cancer cells activates TLR4 in the spinal cord,leading to the increased release of its downstream cytokines and mechanical hyperalgesia.TLR4 might be a potential target for the treatment of bone cancer pain. Key words: Bone neoplasms; Pain; Toll-like receptor 4; Tumor necrosis factor-alpha; Interleukin-1beta

Up-regulation of cell surface Toll-like receptors on circulating γδ T-cells following burn injury

Burn injury is associated with profound inflammation and activation of the innate immune system involving γδ T-cells. Similarly, Toll-like receptors (TLR) are associated with activation of the innate immune response; however, it is unclear whether TLR expression is altered in γδ T-cells after major burn injury. To study this, male C57BL/6 mice were subjected to burn injury (25% TBSA) and 1 or 7 days thereafter, blood and spleen cells were isolated and subjected to FACs analysis for TLRs and other phenotypic markers (γδ TCR, αβ TCR, CD69, CD120b). A marked increase in the number of circulating γδ T-cells was observed at 24 h post-burn (14% vs. 4%) and a higher percentage of these cells expressed TLR-2. TLR-4 expression was also increased post-burn, but to a lesser degree. These changes in TLR expression were not associated with altered CD69 or CD120b expression in γδ T-cells. The mobilization of, and increased TLR expression in, γδ T-cells was transient, as phenotypic changes were not evident at 7 days post-burn or in γδ T-cells from the circulation or spleen. The increases in TLR expression were not observed in αβ T-cells after burn injury. In conclusion, 24 h after burn injury mobilization of γδ T-cells with increased TLR expression was observed. This finding suggests that this unique T-cell population is critical in the innate immune response to injury, possibly through the recognition of danger signals by TLRs.

The expression and function of enterocyte toll like receptor-4 are enhanced by lipopolysaccharide in vitro and during systemic endotoxemia

Introduction: Necrotizing enterocolitis (NEC) is characterized by increased circulating lipopolysaccharide (LPS) and systemic inflammation, potentially through the activation of toll like receptors (TLRs) on the intestinal epithelium. However, the expression of TLRs on enterocytes and their regulation by LPS remain undefined. We therefore tested the hypothesis that LPS alters TLR expression on enterocytes in vitro and in vivo, and sought to define whether changes in TLR expression by LPS correlated with changes in receptor signaling.