GraphPad Prism version 5·0 software was used for statistical analyses. Results are expressed as mean ± standard deviation (s.d.). Relationships between different values were examined by Pearson’s correlation coefficient. A proportion of cell subsets were compared using Student’s t-test for normally or non-normally distributed subsets as appropriate. Statistical significance LY2157299 was expressed by a P-value of < 0·05. MSCs isolated from

SSc patients were characterized by expressing the surface molecules CD90, CD105 and CD73. They did not express CD45, CD34 and CD14, as assessed by flow cytometry analysis. Moreover, MSCs showed normal ability in differentiating into osteoblast, adipocytes and chondroblast LY2606368 solubility dmso in vitro (data not shown). The cumulative population doublings for MSCs isolated from SSc patients, as markers of the replication

rate, was consistently lower than that of HC cells (HC–MSCs 3·07 ± 0·38 versus SSc–MSCs 2·42 ± 0·16, P < 0·0070; Fig. 1a). In order to assess whether this reduced proliferation of SSc–MSCs was due to a growth-arrested status and the different cell cycle distributions with respect to HC cells, both SSc and HC–MSCs were analysed by flow cytometry after DNA staining with PI. Of note, no significant differences were observed between HC– and SSc–MSC, as cell cycle analysis revealed that the large percentage of MSCs obtained from both HC and SSc were in G0/G1 phases [HC–MSCs 80·23 ± 1·79 versus SSc–MSCs 83·00 ± 3·33%, P = not significant (n.s.)]; on the contrary, only a small population of cells were engaged in active proliferation (S+G2/M phases: HC–MSCs 18·75 ± 2·09 versus SSc–MSCs 15·65 ± 3·41%, Chlormezanone P = n.s., Fig. 1b), although not significantly. Because the above method does not distinguish between actively growing (G1) and growth-arrested (G0) cells, to distinguish more effectively between proliferative and resting

cells we assessed Ki67 gene expression by qPCR analysis. We found that MSCs isolated from SSc patients showed a lower expression of Ki67 gene when compared to HC cells (HC–MSCs 3·44 ± 0·20 versus SSc–MSCs 1·57 ± 0·53 mRNA levels, P = 0·019), confirming that the majority of cells was in G0 phase (Fig. 1c). No differences were observed in the proliferative ability of SSc–MSCs between the two disease subsets. Given the functional implications of the in-vitro senescence of MSCs, we employed β-Gal as a senescence marker. We observed that the percentage of β-Gal-positive stained cells was significantly higher in SSc when compared to HC (HC–MSCs 7·67 ± 4·41% versus SSc–MSCs 26·00 ± 4·34%, P = 0·03, Fig. 2a). Furthermore, we cultured both HC and SSc cells for 24 h in the presence of 5 μg/ml of doxorubicin, which represents a well-accepted in-vitro model to recreate the premature ageing of stem cells [29].

Values with a P-value < 0·05 were considered significant and are designated by an asterisk or diamond in the figures. Eosinophils are predominant in thyroids of IFN-γ−/− recipients of splenocytes from IFN-γ−/− donors 20 days after cell transfer, whereas thyroids of WT recipients of WT donor cells have extensive infiltration by neutrophils.6–8 IL-5 regulates eosinophil production,9 and

neutralization or gene knockout of IL-5 decreases eosinophil infiltration in models of allergy and other inflammatory diseases.9,24–28 To determine if the presence of eosinophils in IFN-γ−/− thyroids plays a role in determining the severity or outcome of G-EAT, anti-IL-5 was used to inhibit migration of eosinophils to thyroids of IFN-γ−/− mice. Very few eosinophils with typical pink granule staining were present in thyroids of WT mice (Fig. 1a), whereas many eosinophils were present in thyroids of IFN-γ−/− mice with G-EAT (Fig. 1b). Thyroids Cilomilast of IFN-γ−/− recipients given anti-IL-5 had many fewer eosinophils (Fig. 1c), indicating that the amount of anti-IL-5 was sufficient to inhibit infiltration of most eosinophils into thyroids of IFN-γ−/− mice. Thyroids of IFN-γ−/− mice given anti-IL-5 (Fig. 1f,i) had more neutrophils than thyroids of IFN-γ−/− mice

given IgG (Fig. 1e,h), but the extent of neutrophil infiltration was always much less than in thyroids of WT mice (Fig. 1d,g). Numbers of eosinophils (Fig. 1j, click here pink column) and neutrophils (Fig. 1j, brown column) in five or six randomly selected high-power fields for three individual mice per group (magnification: ×1000) were manually counted and results are summarized (Fig. 1j). Consistent with the extensive infiltration by neutrophils, thyroids of WT recipients

had extensive necrosis at day 20, whereas there was little necrosis in thyroids of IFN-γ−/− mice given anti-IL-5 (Table 1). Eosinophils and neutrophils had largely Fludarabine mw disappeared in all thyroids by day 40–50 (Table 1). These results indicate that administration of anti-IL-5 leads to less eosinophil infiltration and more neutrophil infiltration into thyroids of IFN-γ−/− mice. Protein expression of IL-5 at day 20 (Fig. 1k–m) was increased in thyroids of IFN-γ−/− mice given control IgG compared with that in thyroids of WT (Fig. 1l,k) or IFN-γ−/− mice given anti-IL-5 (Fig. 1l,m). As IL-5 neutralization correlates with reduced eosinophil infiltration and increased neutrophil infiltration into thyroids of IFN-γ−/− mice, this provides an excellent opportunity to address the role of eosinophils versus neutrophils in G-EAT resolution. Because anti-IL-5 markedly reduced eosinophil infiltration and resulted in increased neutrophil infiltration in thyroids of IFN-γ−/− mice (Fig. 1 and Table 1), we hypothesized that inhibiting infiltration of eosinophils into thyroids using anti-IL-5 might influence the severity and/or rate of resolution of G-EAT.

The CD80/CD86:CD28/CTLA-4 (cytotoxic T lymphocyte-associated antigen 4) pathway is the best-characterized inhibitory pathway for T-cell activation [58, 59]. CD28 is constitutively expressed on naïve and activated T cells. CD80 is expressed at low levels on resting

antigen-presenting cells (APCs) and is upregulated with prolonged interaction with T cells, whereas CD86 is constitutively expressed and rapidly upregulated on APCs. Thus, CD86 is likely to be mainly involved in mediating initial T-cell activation, while CD80 may play an important role in propagating the immune responses. After activation, T cells express CTLA-4 (CD152). Engagement of CTLA-4 delivers BTK inhibitor negative signal into T cells, resulting in inhibition and/or termination of T-cell responses. Taking advantage of the fact that CTLA-4

binds CD80 and CD86 with much higher affinity than CD28 does, a fusion protein consisting of the extracellular domain of Vemurafenib research buy CTLA-4 and the constant region of IgG (CTLA-Ig) has been developed to block the interaction between CD80-CD86 and CD28 and thereby inhibit T-cell activation [39]. Such a fusion protein would preferentially inhibit lymphocytes that are in the process of responding to self-antigens without affecting resting T cells that recognize other antigens. After the encouraging results of in vivo studies in animal models, including PBC models [60], the efficacy of the CTLA-4 Ig (Abatacept) has been examined in patients with autoimmune diseases. Abatacept has shown efficacy in a broad spectrum of RA patients from early stage to refractory

diseases that are resistant to TNF blockers [61, 62] and in patients with psoriasis in a phase I trial [63]. Blockade of costimulation between T cells and APCs through CD80 could represent an important therapeutic FER approach for the treatment of refractory PBC. TNF-α is an activating factor for a number of intracellular pathways that determine the fate of hepatocytes, and thus plays a key role in liver homeostasis [64]. Interactions between specific members of the TNF pathway lead to the induction of apoptosis as well as the activation of NF-κB signaling, which is antiapoptotic and proinflammatory [65]. GWAS in PBC identified three loci containing genes in TNF-α signaling pathways: TNFRSF1A, DENND1B [21], and TNFAIP2 [21, 22]. TNFRSF1A is one of two receptors for TNF-α; TNFRSF1A−/− mice show attenuated liver fibrosis when compared with wild-type mice after administration of a potent hepatotoxin [66]. DENND1B interacts directly with TNFRSF1A [67] and has previously been associated with asthma [68]. TNF-α signaling also directly induces TNFAIP2 expression [69]. Macrophages from PBC patients, when stimulated with apoptotic bodies from cholangiocytes, produce high levels of TNF-α [70]. Furthermore, serum levels of TNF-α reflect the severity of morphological liver changes in PBC [71].

Previous studies have shown that the frequency and absolute numbers of NK cells are decreased in chronic HIV infection and the function of remaining NK cells is impaired.32,33 In the current study, increased numbers of NK cells correlated Metformin solubility dmso with increased NK cell function, and we found greater numbers of CD107+ NK cells in HSV-2 co-infected subjects. Of greatest interest is that the number of NK cells expressing the receptors NKp30, NKp46 and low-level KIR3D was strongly and inversely correlated with viral load in HIV-1-infected subjects. This suggests that increased numbers

of functional NK cells negatively impact HIV-1 viral load, and that NK cells might mediate some level of control of HIV-1, although this will require further study to determine causality and potential mechanisms. Conversely, in the context of HSV-2 co-infection, there are greater numbers of functional NK cells, yet this increase in NK cell functional capacity has no impact on HIV-1 viral load, as the correlation with the numbers of NK cells expressing activating receptors is lost. These data suggest a model whereby HSV-2 co-infection results in an increased number of functional check details NK cells, but this increased function is possibly directed towards HSV-2 at the expense of HIV-1 recognition and control. In this model, prophylactic control of HSV-2 infection may allow

NK cells to resume effective control of HIV-1 viraemia, resulting in reduced HIV-1 viral load. Importantly, however, we have not formally demonstrated either HIV-1 or HSV-2 specificity of NK cell function, leaving our results open to other interpretations. In previous studies selleck of HSV-2 co-infection in HIV-1-positive subjects, reactivation of HSV-2 was associated with increased HIV-1 viral load, and was more common in subjects with lower CD4+ T-cell counts.21,34 Conversely, no significant correlation was observed between HIV-1 viral load and HSV-2 infection

in the absence of HSV-2 lesions. Subjects infected with HSV-2 are at greater risk for HIV-1 acquisition,35 providing the impetus for the study of HSV-2 prophylaxis in preventing HIV-1 infection. However, treatment with acyclovir has not been demonstrated to be effective in preventing HIV-1 acquisition in HSV-2-positive subjects,36 but was effective in reducing HIV-1 viral load in co-infected women.37 More recent evidence has shown that acyclovir itself strongly inhibits HIV-1 reverse transcriptase, and may account for the reduced HIV-1 viral load observed in response to HSV-2 prophylaxis.38 In the previous study evaluating CD4+ T-cell numbers in co-infected subjects by Barbour et al.,20 it was noted that subjects who had acquired HSV-2 prior to HIV-1 infection had elevated numbers of CD4+ T cells; however, this was not the case in subjects who acquired HSV-2 subsequent to HIV-1 infection.

However, such

mutant cells are unable to display activation-dependent TCR clustering, IS formation, expression of CD25/CD69 activation markers, or produce/secrete cytokine, effects also seen in the corresponding APCs. We are the first to show a direct TCR-actin linkage, providing Selleck EPZ-6438 the missing gap linking between TCR-mediated Ag recognition, specific cytoskeleton orientation toward the T-cell–APC interacting pole and long-lived IS maintenance. Upon TCR-mediated Ag-MHC recognition, polarized reorganization of TCRs together with additional cell surface receptors and intracellular signaling molecules is initiated toward the T-cell–antigen-presenting cell (APC) interface, segregating into receptor

microclusters and eventually to a defined immune synapse (IS) [1-3]. The exact mechanism that controls the dynamics TCR rearrangement in the IS is as yet unknown. However, it is well established that TCR-mediated signaling controls synapse formation, since disruption of TCR signaling molecules such as LCK and VAV prevents this process [4, 5]. In addition, many studies have indicated that polymerization and remodeling of the actin-based cytoskeleton creates a scaffold critical to IS formation and stabilization [6]. Actin reorganization at the IS also plays a role in advanced stages of activation, enabling directed secretion of cytokines and execution of PD184352 (CI-1040) T-cell effector functions NVP-LDE225 price [7]. Disruption of the actin-based cytoskeleton or deficiency in key actin-regulatory proteins causes severe alterations of TCR-mediated activation progression [7]. Various studies including ours demonstrated that ∼30% of the total TCRs are found in the detergent-insoluble cell fraction (dicf)-TCRs and were suggested as being linked

to actin-based cytoskeleton via ζ. dicf-TCRs were shown to be expressed on the cell surface of both nonactivated and activated T cells [8, 9]. Although the unique features of dicf-TCRs, such as conformation and phosphorylation pattern [10] suggest a distinct role in T-cell function compared with that of detergent-soluble cell fraction (dscf)-TCRs, the mode of association with the cytoskeleton and their functional significance remain unclear. It was previously published that upon TCR-mediated activation, although the majority of the receptors are internalized and degraded within 1–4 h, T-cell–APC interactions and TCR-mediated signaling are still evident for up to 10 h, and cytokine secretion persists for even longer (10–24 h) [11].

010, respectively. In addition, at the endpoint of rejection (40 hours post-transplantation), the xenogeneic group/syngeneic control group ratio of miR-146a, miR-155, PD0332991 purchase and miR-451 measured by QRT-PCR assay was 2.869 ± 0.464, 1.808 ± 0.432, and 0.079 ± 0.006, respectively (P < 0.05 vs. syngeneic controls, n = 8 per group), whereas the ratios of those miRNAs detected by the microarray assay were

3.284, 1.667, and 0.021, respectively. This was accordant with the data from the QRT-PCR assay (Fig. 2). Recently, significant progress has been made in studying the role of miRNA in regulating the nervous and hematopoietic system, as well as in the immune response in diseases like cancer.[4] However, the profiles of miRNA expression in organ transplantation, especially in xenotransplantation, have yet to be

fully understood. In this study, a well-established heterotopic cardiac xenotransplantation model was used to determine the profiles of miRNA expression in xenograft rejection. As the mean survival time of heart xenografts is 40.17 ± 3.76 hours, 40 hours was chosen as the study endpoint for this xenotransplant model. The intragraft miRNA expressions between the xenogeneic group and the syngeneic group were then compared at uniform time points. At both the 24-hour time point as well as the endpoint of rejection after xenografting, a total of 31 miRNAs LY2835219 cell line were found to be differentially expressed in xenografts when compared with syngeneic heart grafts; of these, 17 miRNAs were upregulated and 14 miRNAs were

downregulated, indicating that these miRNAs may play important roles in the regulation of xenograft rejection. Furthermore, because of significant differential expression, miR-146a, miR-155, and miR-451 were selected Glutathione peroxidase as representative miRNAs to be used in the relative quantitative test that verified miRNA microarray results. It was determined that xenografts showed significantly increased levels of miR-146a and miR-155 and significantly decreased levels of miR-451. In addition, the changes of xenogeneic group/syngeneic control group ratios detected by QRT-PCR were consistent with those of the miRNA microarray data. By using TargetScan, 21 of 31 differentially expressed miRNAs were found for their predicted target genes in heart xenografts. Using this information, a functional annotation for the miRNAs was made by David analysis to determine the impact factor in the xenograft rejection (data not shown); this analysis may provide very important information for future in further studies. The differential expression of miRNAs in allografts has been studied in a mouse heart transplantation model.[11] However, reports regarding the profiles of miRNA in xenograft rejection are presently lacking. By comparing the data obtained from the allogeneic study by Wei et al.[11] with our xenogeneic study, it was demonstrated that miR-146a, miR-155, and miR-150 were upregulated in both allografts and xenografts—this shows the same trend in miRNA expression.

In summary, we have investigated the evolutionary development of the myeloid gene cluster within the NK gene complex and analysed sequence characteristics, phylogenetic relationship and expression pattern of several encoded genes. This work was supported by a grant from the European Commission (MRTN-CT-2005-019248). We are grateful to the midwifes of the hospitals Hietzing and Wilheminenspital (Vienna) for collecting umbilical cords and Maria Witkowsky for isolation and culturing of HUVEC. We further thank Dr. Frank Kalthoff (Novartis) for providing CBDC and all the members of the molecular vascular biology laboratory for help and

discussions. “
“OTHER THEMES PUBLISHED IN THIS IMMUNOLOGY IN THE CLINIC REVIEW SERIES Allergy, Host Responses, Cancer, Autoinflammatory Diseases, Type 1 diabetes and viruses. Historically, the development of

type 2 diabetes has check details been considered not to have an autoimmune component, in contrast to the autoimmune pathogenesis of type 1 diabetes. In this review we will discuss the accumulating data supporting the concept that islet autoreactivity and inflammation is present in type 2 diabetes pathogenesis, and the islet autoimmunity appears to be one of the factors associated with the progressive nature of the type 2 diabetes disease process. The immune system is a collection of highly regulated processes designed to promote Daporinad clinical trial protective immunity against insults from pathogenic organisms and neoplasias. These highly regulated processes (adaptive and innate immune systems) encompass both stimulatory and regulatory pathways aimed at turning on and off appropriate responses designed to rid the host of the assailant without producing long-term damage to the host. To accomplish the eradication of pathogenic organisms, the host mounts an inflammatory insult. The developing inflammation serves to protect a defined region of infected or damaged tissue by recruiting cells necessary to resolve the insult while isolating the area to prevent the spread of inflection. Regulatory mechanisms have evolved in the host

to down-regulate and control the immune response and tissue inflammation [1]. However, Parvulin inflammation sometimes fails to subside and this unresolved inflammation may become chronic. Chronic inflammation has been attributed to the development of inflammatory diseases such as atherosclerosis [2]. Moreover, intriguing evidence is accumulating which indicates that unresolved chronic inflammation may play a role in the initiation, promotion, malignant conversion and metastasis of several human cancers [3,4]. Allowing inflammatory responses to assist in eradicating pathogenic mechanisms while forbidding establishment of chronic inflammatory conditions and subsequent development of inflammatory disease is one of the multiple facets of the normally functioning immune system. Another facet of the normal immune system is the recognition of self versus altered self.

gingivalis see more [64]. Notably, P. gingivalis does not rely on immunological mechanisms for C5aR activation, since it can activate this complement receptor through C5a generated locally by its Arg-specific gingipains (HRgpA, RgpB) that have C5 convertase-like activity [64, 65]. Porphyromonas gingivalis also expresses a number of potent TLR2 ligands including serine lipids and lipoproteins [66, 67]. At the molecular level, the P. gingivalis-induced C5aR-TLR2 cross-talk in macrophages leads to synergistic activation of cAMP-dependent protein kinase A for inhibition of glycogen synthase kinase-3β and of iNOS-dependent

intracellular bacterial killing [64] (Fig. 3). In the murine periodontal tissue, C5aR signaling synergizes with TLR2 to induce secretion of cytokines that promote periodontal inflammation and bone loss (TNF, IL-1β, IL-6, and IL-17A). This is likely to enhance the fitness of P. gingivalis and other periodontitis-associated bacteria that require an inflammatory environment to secure critical nutrients, i.e. tissue breakdown products including peptides and hemin-derived iron. In stark contrast to the upregulation of bone-resorptive inflammatory cytokines, P. gingivalis-induced C5aR signaling in macrophages downregulates TLR2-induced Ribociclib order IL-12 and hence inhibits IFN-γ production and cell-mediated immunity against the bacteria [63, 65]. The selective inhibition

of

bioactive IL-12 (IL-12p35/IL-12p40) associated with C5aR-TLR2 cross-talk involves ERK1/2 signaling-dependent suppression of the IFN regulatory factor-1 (IRF-1), a transcription Montelukast Sodium factor that is crucial for the regulation of IL-12 p35 and p40 mRNA expression [65, 68]. Importantly, genetic ablation of C5aR or TLR2 promotes the killing of P. gingivalis in vivo [64, 69]. The inhibitory ERK1/2 pathway that regulates TLR2-induced IL-12 is also activated when P. gingivalis binds complement receptor 3 (CR3) on macrophages [70, 71] (Fig. 3). CR3 is a β2 integrin (CD11b/CD18) that can bind ligands when its high-affinity conformation is transactivated via inside-out signaling by other receptors such as chemokine receptors. Porphyromonas gingivalis induces TLR2-mediated transactivation of CR3 through an inside-out pathway that involves RAC1, PI3K, and cytohesin-1 [72, 73] (see Fig. 3). Upon binding CR3, P. gingivalis not only downregulates IL-12 but also enters macrophages in a relatively safe way [74], perhaps because CR3 is not linked to strong microbicidal mechanisms such as those activated by FcγR-mediated phagocytosis [75]. Indeed, P. gingivalis can persist intracellularly in WT macrophages for longer times than in CR3-deficient macrophages [74]. As alluded to above, P. gingivalis can activate C5aR signaling independently of the canonical activation of complement [64, 65]. In fact, P.

The role of STAT3

for normal signalling of the IL-6 receptor has important consequences for normal host defence. Together with other cytokines such as IL-1β and IL-23, the IL-6/STAT3 pathway is crucial for the normal development of CD4+–T helper type 17 (Th17) cells [6,7]. Because IL-17 has an important role in the activation of neutrophil-dependent immunity [8], defective Th17 generation as a result of STAT3 mutation may play an important role in the pathogenesis of HIES. In a recent paper, Milner et al. have demonstrated that T lymphocytes from patients with HIES are unable to differentiate into Th17 after mitogenic stimulation [9]. These data were supported by two reports that also showed defective generation of Th17 when anti-CD3/anti-CD28/IL-2

or cytokine cocktails were used [10,11]. These studies reported the defective generation of Th17 using mitogenic cocktails in patients with established Selleck Everolimus Selleck LGK974 mutations in the SH2 and DNA-binding domains of STAT3. In contrast, patients with atopic dermatitis and high IgE, but without skin and respiratory infections and without STAT3 mutations, had normal Th17 responses [9,12]. In the present paper, we aimed to extend these initial findings by investigating the generation of Th17 cells and IL-17 production by relevant microbial stimuli for HIES. In addition, we assessed Th17 profiles in three distinct groups of patients: ‘classical’ HIES patients with STAT3 mutations in the SH2/DNA-binding domains, ‘classical’ HIES without STAT3 mutations and a family with ‘variant’ HIES that we described as having a milder clinical phenotype [13], with deletion of a triplet in the linker domain. The differences in the degree of IL-17 production defects after stimulation with Staphylococcus aureus or Candida albicans determined the severity of the clinical phenotype. Eight patients with a clinical diagnosis of HIES at the out-patient clinic for infectious diseases and immunodeficiencies of the Department of General Internal Medicine Rebamipide of Radboud University Nijmegen Medical Centre were enrolled into the study. Three of these patients were family members. After

informed consent, blood was collected from eight healthy, non-smoking volunteers who were free of infectious or inflammatory disease and the enrolled HIES patients by venipuncture into 10 ml ethylenediamine tetraacetic acid (EDTA) syringes (Monoject; BD Vacutainer, Plymouth, UK). STAT3 mutation analysis was kindly performed in the Laboratory of Human Molecular Biology and Genetics, Catholic University of the Sacred Heart, Milan, Italy (head Professor Roberto Colombo). C. albicans American Type Culture Collection (ATCC) MYA-3573 (UC820), a strain well described elsewhere [14], was used. C. albicans was grown overnight in Sabouraud broth at 37°C, cells were harvested by centrifugation, washed twice and resuspended in culture medium (RPMI-1640 Dutch modification; ICN Biomedicals, Aurora, OH, USA) [15]. C.

The unique regulation and patterning of B7 family molecules

in the placenta, together SCH772984 nmr with emerging empirical data, suggests that these proteins may play an important role in shaping the milieu of the local maternal–fetal environment. In addition, the nature of the costimulatory and co-inhibitory signals B7 family members provide will also influence the outcome of the interaction of maternal lymphocytes with fetal antigen in lymphoid tissues. From the experimental data in humans, we can infer that B7 family proteins could function in at least three distinct capacities (Fig. 4). First, the B7 expressing cells in pregnancy that could function as APCs, i.e., those that express both B7 molecules and MHC, may directly influence T-cell activation and effector functions by delivering a positive or negative costimulatory signal in conjunction with TCR stimulation. Second, trophoblast cells that repress MHC might affect lymphocytes through B7/CD28 family molecules

in trans. Finally, B7 molecules on either decidual APCs or trophoblast cells may backsignal toward the B7-expressing cell and influence the local immune environment through induced expression of immunosuppressive RXDX-106 molecular weight factors independently of their effects on T cells. Thus, in determining the functions of these key regulators of the immune system, there is a need to think ‘outside the box’ when considering B7 family molecules during pregnancy. The authors thank Sarika Kshirsagar and Joseph

Juscius for their technical contributions and Stanton Fernald (University of Kansas Interdisciplinary Center for Male Contraceptive Research & Drug Development Imaging Core) for assistance with images. A.L.P. is supported by NIH training grant T32HD007455. This work is supported by NIH grants R01 HD045611, P01 HD049480, and P20 RR16475. “
“Toll-like receptors (TLRs) play a central role in the innate immune response, recognizing a variety of molecular structures characteristic of pathogens. Although TLR4, together with its co-receptor MD-2, recognize bacterial lipopolysaccharide (LPS) and therefore Gram-negative bacterial infections, it also plays a key role Thiamet G in many other pathophysiological processes, including sterile inflammation and viral infection. Specifically, numerous endogenous agonists of TLR4 of notably diverse nature, ranging from proteins to metal ions, have been reported. Direct activation of a single receptor by such a range of molecular signals is very difficult to explain from a structural and mechanistic point of view. It is likely that only a subset of these directly activate the TLR4-MD2 complex. We propose three postulates aimed at distinguishing the direct agonists of TLR4 from indirect activators.