Targeting toll‐like receptors for drug development: a summary of commercial approaches

Immunization with recombinant HPV16-E7d in fusion with Flagellin as a cancer vaccine: Effect of antigen-adjuvant orientation on the immune response pattern

Human papillomavirus (HPV) is the leading cause of cervical cancer worldwide. The pathogenesis of HPV is mainly dependent on its E7 and E6 proteins. Up to now, different adjuvants have been used to enhance the efficacy of the immune response against these two proteins. In this study, Flagellin (FLA) was used as adjuvant to test adjuvant activity and also see whether its orientation of attachment can affect the immune response pattern. The E7d-FLA and FLA-E7d in pET28a vector were constructed and then the recombinant proteins were expressed in E. coli BL21 (DE3) bacteria under IPTG induction. The expression of recombinant E7d-FLA and FLA-E7d proteins is confirmed by SDS-PAGE and western blot. Then, recombinant fusion proteins were purified using a nickel-nitrilotriacetic acid (Ni-NTA) column. The recombinant proteins were checked for endotoxin contamination and then quantified by Bradford. Eight-to-ten-week-old male Balb/C mice were immunized subcutaneously with 10 µg recombinant E7d-FLA, FLA-E7d and HPV16E7d vaccine on days 0, 14 and 28. In addition, PBS and FLA groups were considered as control group. Then, spleen cells were harvested to assess lymphocyte proliferation and IFN-γ, IL-4 and IL-17 cytokines. In addition, mice sera were used for specific total IgG and IgG1, IgG2a, IgG2b and IgM antibodies assessment by ELISA. The results show that E7d-FLA is more potent in the induction of lymphocyte proliferation, CTL response and specific total IgG, IgG2a and IgG2b response, while the FLA-E7d vaccine was associated with more IFN-γ, and IL-17 cytokine response. The results of this study proved the ability of FLA as an adjuvant in fusion with E7d in the induction of cellular and humoral immune responses. In addition, it also emphasizes that antigen-adjuvant orientation can affect the immune response strength and polarization against HPV E7d vaccine candidate. HIGHLIGHTS: Flagellin is attached to HPV-16 E7d at the C- or N-terminus to create E7d-FLA and FLA-E7d candidate vaccines. The E7d-FLA vaccine showed a significant increase in lymphocyte proliferation, CTL response and IgG response versus FLA-E7d vaccine. The FLA-E7d vaccine is associated with a significant increase in IFN-γ and IL-17 cytokines response versus E7d-FLA vaccine. It seems that that antigen-adjuvant orientation is an important parameter in the strength and polarization of immune response in HPV E7d vaccine candidate.

Optimizing rWTC-MBTA Vaccine Formulations, Dosing Regimens, and Cryopreservation Techniques to Enhance Anti-Metastatic Immunotherapy

Metastatic cancer poses significant clinical challenges, necessitating effective immunotherapies with minimal systemic toxicity. Building on prior research demonstrating the rWTC-MBTA vaccine's ability to inhibit tumor metastasis and growth, this study focuses on its clinical translation by optimizing vaccine composition, dosing regimens, and freezing techniques. The vaccine formula components included three TLR ligands (LTA, Poly I:C, and Resiquimod) and an anti-CD40 antibody, which were tested in melanoma and triple-negative breast cancer (TNBC) models. The formulations were categorized as rWTC-MBT (Mannan-BAM with LTA, Poly I:C, Resiquimod), rWTC-MBL (LTA), rWTC-MBP (Mannan-BAM with Poly I:C), and rWTC-MBR (Resiquimod). In the melanoma models, all the formulations exhibited efficacy that was comparable to that of the full vaccine, while in the "colder" TNBC models, the formulations with multiple TLR ligands or Resiquimod alone performed the best. Vaccine-induced activation of dendritic cell (DC) subsets, including conventional DCs (cDCs), myeloid DCs (mDCs), and plasmacytoid DCs (pDCs), was accompanied by significant CD80+CD86+ population induction, suggesting robust innate immune stimulation. An initial three-dose schedule followed by booster doses (3-1-1-1 or 3-3-3-3) reduced the metastatic burden effectively. Gradual freezing (DMSO-based preservation) maintained vaccine efficacy, underscoring the importance of intact cell structure. These findings highlight the potential of simplified formulations, optimized dosing, and freezing techniques in developing practical, scalable immunotherapies for metastatic cancers.

B cells mediate lung ischemia/reperfusion injury by recruiting classical monocytes via synergistic B cell receptor/TLR4 signaling

Ischemia/reperfusion injury-mediated (IRI-mediated) primary graft dysfunction (PGD) adversely affects both short- and long-term outcomes after lung transplantation, a procedure that remains the only treatment option for patients suffering from end-stage respiratory failure. While B cells are known to regulate adaptive immune responses, their role in lung IRI is not well understood. Here, we demonstrated by intravital imaging that B cells are rapidly recruited to injured lungs, where they extravasate into the parenchyma. Using hilar clamping and transplant models, we observed that lung-infiltrating B cells produce the monocyte chemokine CCL7 in a TLR4-TRIF-dependent fashion, a critical step contributing to classical monocyte (CM) recruitment and subsequent neutrophil extravasation, resulting in worse lung function. We found that synergistic BCR-TLR4 activation on B cells is required for the recruitment of CMs to the injured lung. Finally, we corroborated our findings in reperfused human lungs, in which we observed a correlation between B cell infiltration and CM recruitment after transplantation. This study describes a role for B cells as critical orchestrators of lung IRI. As B cells can be depleted with currently available agents, our study provides a rationale for clinical trials investigating B cell-targeting therapies.

Acute Kidney Injury: Definition, Management, and Promising Therapeutic Target

Acute kidney injury (AKI) is caused by a sudden loss of renal function, resulting in the build-up of waste products and a significant increase in mortality and morbidity. It is commonly diagnosed in critically ill patients, with its occurrence estimated at up to 50% in patients hospitalized in the intensive critical unit. Despite ongoing efforts, the death rate associated with AKI has remained high over the past half-century. Thus, it is critical to investigate novel therapy options for preventing the epidemic. Many studies have found that inflammation and Toll-like receptor-4 (TLR-4) activation have a significant role in the pathogenesis of AKI. Noteworthy, challenges in the search for efficient pharmacological therapy for AKI have arisen due to the multifaceted origin and complexity of the clinical history of people with the disease. This article focuses on kidney injury's epidemiology, risk factors, and pathophysiological processes. Specifically, it focuses on the role of TLRs especially type 4 in disease development.

Application of toll-like receptors (TLRs) and their agonists in cancer vaccines and immunotherapy

Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) expressed in various immune cell types and perform multiple purposes and duties involved in the induction of innate and adaptive immunity. Their capability to propagate immunity makes them attractive targets for the expansion of numerous immunotherapeutic approaches targeting cancer. These immunotherapeutic strategies include using TLR ligands/agonists as monotherapy or combined therapeutic strategies. Several TLR agonists have demonstrated significant efficacy in advanced clinical trials. In recent years, multiple reports established the applicability of TLR agonists as adjuvants to chemotherapeutic drugs, radiation, and immunotherapies, including cancer vaccines. Cancer vaccines are a relatively novel approach in the field of cancer immunotherapy and are currently under extensive evaluation for treating different cancers. In the present review, we tried to deliver an inclusive discussion of the significant TLR agonists and discussed their application and challenges to their incorporation into cancer immunotherapy approaches, particularly highlighting the usage of TLR agonists as functional adjuvants to cancer vaccines. Finally, we present the translational potential of rWTC-MBTA vaccination [irradiated whole tumor cells (rWTC) pulsed with phagocytic agonists Mannan-BAM, TLR ligands, and anti-CD40 agonisticAntibody], an autologous cancer vaccine leveraging membrane-bound Mannan-BAM, and the immune-inducing prowess of TLR agonists as a probable immunotherapy in multiple cancer types.

The effect of inflammatory factors and their inhibitors on the hematopoietic stem cells fate

Inflammatory cytokines exert different effects on hematopoietic stem cells (HSCs), lead to the development of various cell lineages in bone marrow (BM) and are thus a differentiation axis for HSCs. The content used in this article has been obtained by searching PubMed database and Google Scholar search engine of English-language articles (1995-2020) using "Hematopoietic stem cell," "Inflammatory cytokine," "Homeostasis," and "Myelopoiesis." Inflammatory cytokines are involved in the differentiation and proliferation of hematopoietic progenitors to compensate for cellular death due to inflammation. Since each of these cytokines differentiates HSCs into a specific cell line, the difference in the effect of these cytokines on the fate of HSC progenitors can be predicted. Inhibitors of these cytokines can also control the inflammatory process as well as the cells involved in leukemic conditions. In general, inflammatory signaling can specify the dominant cell line in BM to counteract inflammation and leukemic condition via stimulating or inhibiting hematopoietic progenitors. Therefore, detection of the effects of inflammatory cytokines on the differentiation of HSCs can be an appropriate approach to check inflammatory and leukemic conditions and the suppression of these cytokines by their inhibitors allows for control of homeostasis in stressful conditions.

Toll-like receptors (TLRs) in cancer; with an extensive focus on TLR agonists and antagonists

At the forefront of the battle against pathogens or any endogenously released molecules, toll-like receptors (TLRs) play an important role as the most noble pattern recognition receptors. The ability of these receptors in distinguishing "self" and "non-self" antigens is a cornerstone in the innate immunity system; however, misregulation links inflammatory responses to the development of human cancers. It has been known for some time that aberrant expression and regulation of TLRs not only endows cancer cells an opportunity to escape from the immune system but also supports them through enhancing proliferation and angiogenesis. Over the past decades, cancer research studies have witnessed a number of preclinical and clinical breakthroughs in the field of TLR modulators and some of the agents have exceptionally performed well in advanced clinical trials. In the present review, we have provided a comprehensive review of different TLR agonists and antagonists and discuss their limitations, toxicities, and challenges to outline their future incorporation in cancer treatment strategies.

Toll-like receptors: promising therapeutic targets for inflammatory diseases

The health of living organisms is constantly challenged by bacterial and viral threats. The recognition of pathogenic microorganisms by diverse receptors triggers a variety of host defense mechanisms, leading to their eradication. Toll-like receptors (TLRs), which are type I transmembrane proteins, recognize specific signatures of the invading microbes and activate a cascade of downstream signals inducing the secretion of inflammatory cytokines, chemokines, and type I interferons. The TLR response not only counteracts the pathogens but also initiates and shapes the adaptive immune response. Under normal conditions, inflammation is downregulated after the removal of the pathogen and cellular debris. However, a dysfunctional TLR-mediated response maintains a chronic inflammatory state and leads to local and systemic deleterious effects in host cells and tissues. Such inappropriate TLR response has been attributed to the development and progression of multiple diseases such as cancer, autoimmune, and inflammatory diseases. In this review, we discuss the emerging role of TLRs in the pathogenesis of inflammatory diseases and how targeting of TLRs offers a promising therapeutic strategy for the prevention and treatment of various inflammatory diseases. Additionally, we highlight a number of TLR-targeting agents that are in the developmental stage or in clinical trials.

TRIF-dependent TLR signaling, its functions in host defense and inflammation, and its potential as a therapeutic target

Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF)-dependent signaling is required for TLR-mediated production of type-I IFN and several other proinflammatory mediators. Various pathogens target the signaling molecules and transcriptional regulators acting in the TRIF pathway, thus demonstrating the importance of this pathway in host defense. Indeed, the TRIF pathway contributes to control of both viral and bacterial pathogens through promotion of inflammatory mediators and activation of antimicrobial responses. TRIF signaling also has both protective and pathologic roles in several chronic inflammatory disease conditions, as well as an essential function in wound-repair processes. Here, we review our current understanding of the regulatory mechanisms that control TRIF-dependent TLR signaling, the role of the TRIF pathway in different infectious and noninfectious pathologic states, and the potential for manipulating TRIF-dependent TLR signaling for therapeutic benefit.

Convergent Transcription of Interferon-stimulated Genes by TNF-α and IFN-α Augments Antiviral Activity against HCV and HEV

IFN-α has been used for decades to treat chronic hepatitis B and C, and as an off-label treatment for some cases of hepatitis E virus (HEV) infection. TNF-α is another important cytokine involved in inflammatory disease, which can interact with interferon signaling. Because interferon-stimulated genes (ISGs) are the ultimate antiviral effectors of the interferon signaling, this study aimed to understand the regulation of ISG transcription and the antiviral activity by IFN-α and TNF-α. In this study, treatment of TNF-α inhibited replication of HCV by 71 ± 2.4% and HEV by 41 ± 4.9%. Interestingly, TNF-α induced the expression of a panel of antiviral ISGs (2-11 fold). Blocking the TNF-α signaling by Humira abrogated ISG induction and its antiviral activity. Chip-seq data analysis and mutagenesis assay further revealed that the NF-κB protein complex, a key downstream element of TNF-α signaling, directly binds to the ISRE motif in the ISG promoters and thereby drives their transcription. This process is independent of interferons and JAK-STAT cascade. Importantly, when combined with IFN-α, TNF-α works cooperatively on ISG induction, explaining their additive antiviral effects. Thus, our study reveals a novel mechanism of convergent transcription of ISGs by TNF-α and IFN-α, which augments their antiviral activity against HCV and HEV.

New TLR7 agonists with improved humoral and cellular immune responses

Toll-like receptor 7 (TLR7) agonists are of interest as vaccine adjuvants and cancer therapeutics. Therefore, development of new TLR7 agonists that can efficiently promote host immune responses without evoking side effects is of great importance. Here, we describe two new compounds, J4 and F4, which elicit intracellular signaling exclusively via TLR7. Interestingly, both J4 and F4 induced less cytokine secretion (IL-1β, IL-6, IL-10, IL-12p40, TNFα, and IL-12p70) from myeloid dendritic cells (mDCs) and monocytes than CL075 and R848; however, they all generated similar levels of phenotype maturation of antigen presenting cells (APCs), including plasmacytoid DCs. We further found that J4- and F4-induced APC activation was largely dependent on the activation of NF-κB and p38. Lastly, J4 and F4 could efficiently promote B cell proliferation and plasmablast differentiation as well as antigen-specific CD8(+) T cell responses in human in vitro. Therefore, these new TLR7 agonists could be employed to facilitate the development of new therapeutics and vaccine adjuvants against cancers and microbial infections.

Activation of TLR2 and TLR6 by Dengue NS1 Protein and Its Implications in the Immunopathogenesis of Dengue Virus Infection

Dengue virus (DV) infection is the most prevalent mosquito-borne viral disease and its manifestation has been shown to be contributed in part by the host immune responses. In this study, pathogen recognition receptors, Toll-like receptor (TLR) 2 and TLR6 were found to be up-regulated in DV-infected human PBMC using immunofluorescence staining, flow cytometry and Western blot analyses. Using ELISA, IL-6 and TNF-α, cytokines downstream of TLR2 and TLR6 signaling pathways were also found to be up-regulated in DV-infected PBMC. IL-6 and TNF-α production by PBMC were reduced when TLR2 and TLR6 were blocked using TLR2 and TLR6 neutralizing antibodies during DV infection. These results suggested that signaling pathways of TLR2 and TLR6 were activated during DV infection and its activation contributed to IL-6 and TNF-α production. DV NS1 protein was found to significantly increase the production of IL-6 and TNF-α when added to PBMC. The amount of IL-6 and TNF-α stimulated by DV NS1 protein was reduced when TLR2 and TLR6 were blocked, suggesting that DV NS1 protein is the viral protein responsible for the activation of TLR2 and TLR6 during DV infection. Secreted alkaline phosphatase (SEAP) reporter assay was used to further confirm activation of TLR2 and TLR6 by DV NS1 protein. In addition, DV-infected and DV NS1 protein-treated TLR6^-/- mice have higher survivability compared to DV-infected and DV NS1 protein-treated wild-type mice. Hence, activation of TLR6 via DV NS1 protein could potentially play an important role in the immunopathogenesis of DV infection.

Despite the prevalence of dengue virus infection and the heavy economic burden it puts on the endemic countries, the immunopathogenesis of dengue virus infection remains unclear. Plasma leakage in dengue hemorrhagic fever (DHF) develops not when the viremia is at its peak in infected patients but when viremia has been significantly reduced or cleared. This suggests that host immune response is responsible for the development DHF. The interactions of the viral factors with host factors which trigger the host immune responses are likely to play a significant role in the development of dengue diseases, thus are of great interests. In this study, we found that dengue NS1 protein activates TLR2 and TLR6, leading to increase proinflammatory cytokine production. In addition, the interaction of viral factor with TLR6 was found to play an important role in the manifestation of dengue virus infection. Our study provides new insights into the involvement of TLR6 in dengue virus infection and the potential of using TLR6 anatagonist in therapeutic treatment for DV infection.

Characterization of Toll-like receptor transcriptome in squamous cell carcinoma of cervix: A case-control study

OBJECTIVE

Human papillomavirus (HPV) is a proven etiological agent for cervical cancer However, not all HPV infections result in cervical cancer. The mechanisms of host immune system to prevent/control HPV infection remain poorly understood. Toll-like receptors (TLRs) are a system of innate immune defense. HPV has been demonstrated to modulate TLR expression and interfere in TLR signaling pathways, leading to persistent viral infection and carcinogenesis. The aim was to study the relative gene expression of TLRs in cervical squamous cell carcinoma (SCC).

METHODS

Gene expression profile of TLRs 1 to 9 was examined in 30 cervical SCCs and an equal number of normal cervical tissue samples using a PCR array platform. Gene expression studies for TLRs 3 and 7 were validated by western blotting.

RESULTS

HPV was detected in all cases and in none of the controls (p<0.0001). HPV16 was the preponderant (83.3%) subtype. A significant downregulation in the relative gene expression of TLR3 (p<0.0001), TLR4 (p<0.0005) and TLR5 (p<0.0001) was observed in cases. A significant upregulation for TLR1 was observed (p=0.006). Although TLRs 2, 7, 8 and 9 were upregulated and TLR6 was downregulated, it was not significant. The western blot performed with antibodies against TLRs 3 and 7 confirmed the findings of the gene expression studies.

CONCLUSIONS

A significant downregulation in the gene expression of TLRs 3, 4 and 5 and upregulation of TLR1 was observed in cervical SCC as compared to controls. Study results evoke the proposition for investigating TLRs 3, 4 and 5 agonists for therapeutic exploration.

Discovery and hit-to-lead optimization of 2,6-diaminopyrimidine inhibitors of interleukin-1 receptor-associated kinase 4

Interleukin receptor-associated kinase 4 (IRAK4) is a critical element of the Toll-like/interleukin-1 receptor inflammation signaling pathway. A screening campaign identified a novel diaminopyrimidine hit that exhibits weak IRAK4 inhibitory activity and a ligand efficiency of 0.25. Hit-to-lead activities were conducted through independent SAR studies of each of the four pyrimidine substituents. Optimal activity was observed upon removal of the pyrimidine C-4 chloro substituent. The intact C-6 carboribose is required for IRAK4 inhibition. Numerous heteroaryls were tolerated at the C-5 position, with azabenzothiazoles conferring the best activities. Aminoheteroaryls were preferred at the C-2 position. These studies led to the discovery of inhibitors 35, 36, and 38 that exhibit nanomolar inhibition of IRAK4, improved ligand efficiencies, and modest kinase selectivities.

Toll gates: An emerging therapeutic target

Innate immune system forms the first line of defense against microbial infections, as it exerts an immediate response. Innate immunity works through Toll-like receptors (TLRs) which functions as primary sensors of pathogens. TLR activates multiple signaling cascades leading to the induction of genes responsible for the release of inflammatory cytokines and type I interferon. Thus, they induce antimicrobial responses and also have an instructive role in adaptive immunity. However, TLR-mediated inflammation is said to be responsible for many of the destructive host responses in inflammatory diseases like periodontitis. Hence, therapeutics targeting TLRs are being used to treat disease such as HIV, Hepatitis B, asthma etc. Recently, synthetic TLR agonists are tried as novel vaccine adjuvant in treating periodontal diseases. This paper reviews the scope of TLR-based therapeutics in treating periodontitis.

Toll-like receptor agonist imiquimod facilitates antigen-specific CD8+ T-cell accumulation in the genital tract leading to tumor control through IFNγ

PURPOSE

Imiquimod is a Toll-like receptor 7 agonist used topically to treat external genital warts and basal cell carcinoma. We examined the combination of topical imiquimod with intramuscular administration of CRT/E7, a therapeutic human papillomavirus (HPV) vaccine comprised of a naked DNA vector expressing calreticulin fused to HPV16 E7.

EXPERIMENTAL DESIGN

Using an orthotopic HPV16 E6/E7(+) syngeneic tumor, TC-1, as a model of high-grade cervical/vaginal/vulvar intraepithelial neoplasia, we assessed if combining CRT/E7 vaccination with cervicovaginal deposition of imiquimod could result in synergistic activities promoting immune-mediated tumor clearance.

RESULTS

Imiquimod induced cervicovaginal accumulation of activated E7-specific CD8(+) T cells elicited by CRT/E7 vaccination. Recruitment was not dependent upon the specificity of the activated CD8(+) T cells, but was significantly reduced in mice lacking the IFNγ receptor. Intravaginal imiquimod deposition induced upregulation of CXCL9 and CXCL10 mRNA expression in the genital tract, which are produced in response to IFNγ receptor signaling and attract cells expressing their ligand, CXCR3. The T cells attracted by imiquimod to the cervicovaginal tract expressed CXCR3 as well as CD49a, an integrin involved in homing and retention of CD8(+) T cells at mucosal sites. Our results indicate that intramuscular CRT/E7 vaccination in conjunction with intravaginal imiquimod deposition recruits antigen-specific CXCR3(+) CD8(+) T cells to the genital tract.

CONCLUSIONS

Several therapeutic HPV vaccination clinical trials using a spectrum of DNA vaccines, including vaccination in concert with cervical imiquimod, are ongoing. Our study identifies a mechanism by which these strategies could provide therapeutic benefit. Our findings support accumulating evidence that manipulation of the tumor microenvironment can enhance the therapeutic efficacy of strategies that induce tumor-specific T cells.

A purified recombinant lipopeptide as adjuvant for cancer immunotherapy

Synthetic lipopeptides have been widely used as vaccine adjuvants to enhance immune responses. The present study demonstrated that the tryptic N-terminal fragment of the lipoprotein rlipo-D1E3 (lipo-Nter) induces superior antitumor effects compared to a synthetic lipopeptide. The lipo-Nter was purified and formulated with protein or peptide vaccines to determine if lipo-Nter could be used as a novel adjuvant and could induce antitumor immunity in a cervical cancer model. Purified lipo-Nter activated the maturation of bone marrow-derived dendritic cells (BM-DCs), leading to the secretion of TNF-α through TLR2/6 but not TLR1/2. A recombinant mutant HPV16 E7 (rE7m) protein was mixed with lipo-Nter to immunize the mice; the anti-E7 antibody titers were increased, and the T helper cells were skewed toward the Th1 fate (increased IL-2 and decreased IL-5 secretion). Single-dose injection of rE7m and lipo-Nter inhibited tumor growth, but the injection of rE7m alone did not. Accordingly, lipo-Nter also enhanced the antitumor immunity of the E7-derived peptide but not the synthetic lipopeptide (Pam3CSK4). We demonstrated that the lipo-Nter of a bacterial-derived recombinant lipoprotein is a novel adjuvant that could be used for the development of a new generation of vaccines.

Inflammation in intracerebral hemorrhage: from mechanisms to clinical translation

Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and is associated with high mortality and morbidity. Currently, no effective medical treatment is available to improve functional outcomes in patients with ICH. Potential therapies targeting secondary brain injury are arousing a great deal of interest in translational studies. Increasing evidence has shown that inflammation is the key contributor of ICH-induced secondary brain injury. Inflammation progresses in response to various stimuli produced after ICH. Hematoma components initiate inflammatory signaling via activation of microglia, subsequently releasing proinflammatory cytokines and chemokines to attract peripheral inflammatory infiltration. Hemoglobin (Hb), heme, and iron released after red blood cell lysis aggravate ICH-induced inflammatory injury. Danger associated molecular patterns such as high mobility group box 1 protein, released from damaged or dead cells, trigger inflammation in the late stage of ICH. Preclinical studies have identified inflammatory signaling pathways that are involved in microglial activation, leukocyte infiltration, toll-like receptor (TLR) activation, and danger associated molecular pattern regulation in ICH. Recent advances in understanding the pathogenesis of ICH-induced inflammatory injury have facilitated the identification of several novel therapeutic targets for the treatment of ICH. This review summarizes recent progress concerning the mechanisms underlying ICH-induced inflammation. We focus on the inflammatory signaling pathways involved in microglial activation and TLR signaling, and explore potential therapeutic interventions by targeting the removal of hematoma components and inhibition of TLR signaling.

Toll-like receptor 4 signaling in intracerebral hemorrhage-induced inflammation and injury

Intracerebral hemorrhage (ICH) is a common type of fatal stroke, accounting for about 15% to 20% of all strokes. Hemorrhagic strokes are associated with high mortality and morbidity, and increasing evidence shows that innate immune responses and inflammatory injury play a critical role in ICH-induced neurological deficits. However, the signaling pathways involved in ICH-induced inflammatory responses remain elusive. Toll-like receptor 4 (TLR4) belongs to a large family of pattern recognition receptors that play a key role in innate immunity and inflammatory responses. In this review, we summarize recent findings concerning the involvement of TLR4 signaling in ICH-induced inflammation and brain injury. We discuss the key mechanisms associated with TLR4 signaling in ICH and explore the potential for therapeutic intervention by targeting TLR4 signaling.

Dual character of Toll-like receptor signaling: pro-tumorigenic effects and anti-tumor functions

As a major class of pattern-recognition receptors, Toll-like receptors (TLRs) play a critical role in defense against invading pathogens. Increasing evidence demonstrates that, in addition to infection, TLRs are involved in other important pathological processes, such as tumorigenesis. Activation of TLRs results in opposing outcomes, pro-tumorigenic effects and anti-tumor functions. TLR signaling can inhibit apoptosis and promote chronic inflammation-induced tumorigenesis. TLR activation in tumor cells and immune cells can induce production of cytokines, increase tumor cell proliferation and apoptosis resistance, promote invasion and metastasis, and inhibit immune cell activity resulting in tumor immune escape. In contrast, the engagement of other TLRs directly induces growth inhibition and apoptosis of tumor cells and triggers activation of immune cells enhancing anti-tumor immune responses. Thus, the interpretation of the precise function of each TLR in tumors is very important for targeting TLRs and using TLR agonists in tumor therapy. We review the role of TLR signaling in tumors and discuss the factors that affect outcomes of TLR activation.

Interactions between sulfated polysaccharides from sea brown algae and Toll-like receptors on HEK293 eukaryotic cells in vitro

We studied the interactions between sulfated polysaccharides, fucoidans from sea brown algae Laminaria japonica, Laminaria cichorioides, and Fucus evanescens, with human Toll-like receptors (TLR) expressed on membranes of cultured human embryonic kidney cells (HEK293-null, HEK293-TLR2/CD14, HEK293-hTLR4/CD14-MD2, and HEK293-hTLR5). Fucoidans interacted with TLR-2 and TLR-4, but not with TLR-5, and were nontoxic for the cell cultures. L. japonica fucoidan (1 mg/ml), L. cichorioides fucoidan (100 μg/ml and 1 mg/ml), and F. evanescens fucoidan (10 μg/ml-1 mg/ml) activated transcription nuclear factor NF-ϰB by binding specifically to TLR-2. L. japonica fucoidan (100 μg/ml and 1 mg/ml), L. cichorioides fucoidan (10 μg/ml-1 mg/ml), and F. evanescens fucoidan (1 μg/ml-1 mg/ml) activated NF-ϰB via binding to TLR-4. These results indicated that fucoidans could induce in vivo defense from pathogenic microorganisms of various classes.

Toll-like receptors in autoimmunity with special reference to systemic lupus erythematosus

The Toll-like receptor (TLR) family plays a fundamental role in host innate immunity by mounting a rapid and potent inflammatory response to pathogen infection. TLRs recognize distinct microbial components and activate intracellular signaling pathways that induce expression of host inflammatory genes. Several studies have indicated that TLRs are implicated in many inflammatory and immune disorders. Extensive research in the past decade to understand TLR-mediated mechanisms of innate immunity has enabled pharmaceutical companies to begin to develop novel therapeutics for the purpose of controlling an inflammatory disease. The roles of TLRs in the development of autoimmune diseases have been studied. TLR7 and TLR9 have key roles in production of autoantibodies and/or in development of systemic autoimmune disease. It remains to be determined their role in apoptosis, in the pathogenesis of RNA containing immune complexes, differential expression of TLRs by T regulatory cells.

A unique host defense pathway: TRIF mediates both antiviral and antibacterial immune responses

Both anti-viral and anti-bacterial host defense mechanisms involve TRIF signaling. TRIF provides early clearance of pathogens and coordination of a local inflammatory ensemble through an interferon cascade, while it may trigger organ damage. The multipotentiality of TRIF-mediated immune machinery may direct the fate of our continuous battle with microbes.

Type II heat-labile enterotoxins: structure, function, and immunomodulatory properties

The heat-labile enterotoxins (HLTs) of Escherichia coli and Vibrio cholerae are classified into two major types on the basis of genetic, biochemical, and immunological properties. Type I and Type II HLT have been intensively studied for their exceptionally strong adjuvant activities. Despite general structural similarities, these molecules, in intact or derivative (non-toxic) forms, display notable differences in their mode of immunomodulatory action. The molecular basis of these differences has remained largely uncharacterized until recently. This review focuses on the Type II HLTs and their immunomodulatory properties which depend largely on interactions with unique gangliosides and Toll-like receptors that are not utilized by the Type I HLTs.

Effects of P-MAPA Immunomodulator on Toll-Like Receptors and p53: Potential Therapeutic Strategies for Infectious Diseases and Cancer

Background

Compounds that can act as agonists for toll-like receptors (TLRs) may be promising candidates for the development of drugs against infectious diseases and cancer. The present study aimed to characterize the immunomodulatory effects of P-MAPA on TLRs in vitro and in vivo, as well as to investigate its potential as adjuvant therapy in infectious diseases and cancer.

Methods

For these purposes, the activity of P-MAPA on TLRs was assayed in vitro through NF-κB activation in HEK293 cells expressing a given TLR, and using an in vivo animal model for bladder cancer (BC). The antimicrobial activity of P-MAPA was tested against Mycobacterium tuberculosis (TB) in vitro in an MIC assay, and in vivo using an aerosol infection model of murine tuberculosis. Antitumor effects of P-MAPA were tested in an animal model with experimentally induced BC. Moxifloxacin (MXF) and Bacillus Calmette-Guerin (BCG) were used as positive controls in the animal models.

Results

The results showed that P-MAPA, administered alone or in combination with MXF, induced significant responses in vivo against TB. In contrast, the compound did not show antimicrobial activity in vitro. P-MAPA showed a significant stimulatory effect on human TLR2 and TLR4 in vitro. In BC, TLR2, TLR4 and p53 protein levels were significantly higher in the P-MAPA group than in the BCG group. The most common histopathological changes in each group were papillary carcinoma in BC group, low-grade intraepithelial neoplasia in BCG group and simple hyperplasia in P-MAPA group. Concerning the toxicological analysis performed during BC treatment, P-MAPA did not show evidence for hepatotoxicity and nephrotoxicity.

Conclusions

In conclusion, P-MAPA acted as TLR ligand in vitro and improved the immunological status in BC, increasing TLR2 and TLR4 protein levels. P-MAPA immunotherapy was more effective in restoring p53 and TLRs reactivities and showed significantly greater antitumor activity than BCG. The activation of TLRs and p53 may provide a hypothetical mechanism for the therapeutic effects in both cancer and infectious diseases. Taken together data obtained will encourage the further investigation of P-MAPA as a potential candidate for the treatment of cancer and infectious diseases.

Trauma alarmins as activators of damage-induced inflammation

BACKGROUND

A systemic inflammatory response syndrome (SIRS) is frequently observed after traumatic injury. The response is sterile and the activating stimulus is tissue damage. Endogenous molecules, called alarmins, are reputed to be released by injured tissues but the precise identity of these mediators is unclear. This review summarizes current preclinical and clinical evidence for trauma alarmins and their role in innate immune activation.

METHODS

A comprehensive literature review of putative alarmins in tissue damage after traumatic injury was conducted.

RESULTS

The presence of SIRS at admission is an independent predictor of mortality after trauma. The primary initiators of the human immune response are unclear. Several endogenous substances display alarmin characteristics in vitro. Preclinical studies demonstrate that blockade of certain endogenous substances can reduce adverse clinical sequelae after traumatic injury. Human evidence for trauma alarmins is extremely limited.

CONCLUSION

The magnitude of acute inflammation is predictive of outcome after trauma, suggesting that an early opportunity for immune modulation may exist. An understanding of the mechanisms of innate immune activation following trauma may lead to new therapeutic agents and improved patient survival.

[Sulfated polysaccharides of brown seaweeds--ligands of toll-like receptors]

The interaction of sulfated polysaccharides--fucoidans from brown seaweeds Laminaria japonica, Laminaria cichorioides and Fucus evanescens with Toll-like receptors (TLRs) expressed on membranes of embryonic human kidney epithelial cells (HEK293-null, HEK293-TLR2/CD14, HEK293-hTLR4/CD14-MD2 and HEK293-hTLR2/6) was investigated. In vitro fucoidans specifically interacted with TLR-2, TLR-4, and the heterodimer TLR-2/6 resultated in activation of transcription nuclear factor NF-kappaB. Analysis of composition the hydrolyzed fucoidan from F. evanescens was carried out by gas-liquid chromatography and chromatography-mass spectrometry. Results indicated the absence of 3-3-hydroxytetradecanoic acid (3-OHC14), the basic component of lipopolysaccharides in the preparation. Thus, the obtained results suggested that fucoidans from brown seaweeds possessing immunotropic activity are independent ligands for TLRs, and are able to induce genetically determined biochemical processes of protection organisms against pathogenic microorganisms.

IL-6-inducing whole yeast-based immunotherapy directly controls IL-12-dependent CD8 T-cell responses

In current clinical trails, whole yeast-based immunotherapy expressing hepatitis C viral antigens demonstrated statistically significant improvement in end of treatment responses when combined with type I interferon based standard of care, even in standard of care resistant patients. Although preclinical data suggest yeast vaccination, such as type I interferon, facilitates CD8 T-cell immunity, the capacity of yeast to generate immunity in patients resistant to type I interferon calls into question the mechanism(s) underpinning the efficacy of this approach. We show yeast and a Toll-like receptor exclusive agonist, Pam3Cys, differ in CD8 T-cell generation when combined with an agonistic CD40 antibody. Although both yeast and PamCys were largely Toll-like receptor dependent, the primary CD8 response generated by yeast was significantly less than Pam3Cys in wild-type hosts even in a CD4 T-cell-deficient setting. In addition, immunization of IL6 mice with yeast produced a 3-fold to 6-fold increased CD8 response while the Pam3Cys response was unaffected. The yeast but not Pam3Cys-driven CD8 response was inhibited in both wild-type and IL-6 hosts by blocking interleukin (IL)-12. In addition, IL6 mice had increased CD86 expression on their dendritic cells after yeast immunization also inhibited by IL-12 blockade. Collectively, our results indicate the CD8 T-cell response to yeast but not Pam3Cys is influenced by IL-6-mediated control of IL-12 critical for dendritic cell activation. To our knowledge this is the first demonstration that yeast directly influence IL-12-associated CD8 T-cell immunity providing an additional route whereby recombinant yeast may provide efficacy independent of type I interferon.

Modulation of toll-like receptors by insulin

Toll-like receptors (TLRs) are first-line molecules for initiating the innate immune responses and mediating functional activation in immune effector cells. A family of 10 functional human TLRs altogether can recognize the ligands that do not exist in the host and initiate the inflammatory cascades. This triggers the production of inflammatory cytokines, chemokines, and interferons. Overactivation of innate immunity might lead to immune-mediated inflammatory disorders. Besides that, TLRs are currently viewed as active participants in the cross-communication between immunity and metabolic health. Recent data directly implicate the activation of inflammatory pathways in the pathogenesis of type 1 and type 2 diabetes, atherosclerosis, obesity, and also cancer. The following approaches to develop new TLR drugs have been undertaken: generating TLR agonists/antagonists, creating monoclonal antibody to TLRs, blocking the key molecules in the signaling pathways, down-modulating TLR signaling. In this article, we briefly review the involvement of TLRs in diseases associated with metabolic alterations, underscoring the modulation of TLRs by insulin.

TLRs as pharmacological targets for plant-derived compounds in infectious and inflammatory diseases

Toll-like receptors (TLRs) are generally involved in host immune responses against microbial invasions. Dysfunction of TLRs is closely related to infectious and inflammatory diseases, for which therapeutic manipulation with TLRs agonists and antagonists represent a promising drug strategy. Medicinal plants were used traditionally for the prevention and treatment of infectious and inflammatory diseases. Active compounds derived from these plants were also found with unique features as TLRs agonists and antagonists. These findings bring about new hopes for the application of these naturally existed TLRs modulators. They also provide evidences encouraging further research work of continued characterization for these compounds, which will become promising drug candidates in TLRs-based therapy in the future.

Toll-like receptor modulators: a patent review (2006-2010)

INTRODUCTION

The immune response is mediated via two parallel immune components, innate and adaptive, whose effector functions are highly integrated and coordinated for the protection of the human body against invading pathogens and transformed cells. The discovery of pathogen recognition receptors (PRRs), most notably toll-like receptors (TLRs), in innate immunity has evoked increased interest in the therapeutic handling of the innate immune system. TLRs are germ line-encoded receptors that play a potent role in the recognition of a diverse variety of ligands ranging from hydrophilic nucleic acids to lipopolysaccharide (LPS) or peptidoglycan (PGN) structures in pathogens.

AREAS COVERED

This review discusses recent updates (2006-2010) in completed, ongoing and planned clinical trials of TLR immunomodulator-based therapies for the treatment of infectious diseases, inflammatory disorders and cancer.

EXPERT OPINION

Since the discovery of human TLRs, modulating immune responses using TLR agonists or antagonists for therapeutic purposes has provoked intense activity in the pharmaceutical industry. The ability of TLRs to initiate and propagate inflammation makes them attractive therapeutic targets. We are now at the stage of evaluating such molecules in human diseases. Additionally, there is also extensive literature available on TLRs in diseased states. These data provide a basis for the identification of novel immunomodulators (agonists and antagonists) for the therapeutic targeting of TLRs.

Immune adjuvants in early life: targeting the innate immune system to overcome impaired adaptive response

The neonatal phase is a transitory period characterized by an absence of memory cells, favoring a slow adaptive response prone to tolerance effects and the development of Th2-type responses. However, when appropriately stimulated, neonates may achieve an immune response comparable with adult counterparts. One strategy to stimulate the immunological response of neonates or children in early infancy has been to explore natural or synthetic ligands of cell receptors to stimulate innate immunity. The use of adjuvants for activating different cell receptors may be the key to enhancing neonatal adaptive immunity. This review highlights recent advances in the emerging field of molecular adjuvants of innate immune response and their implications for the development of immunotherapies, with particular focus on the neonatal period.

Association of Toll-like receptor signaling and reactive oxygen species: a potential therapeutic target for posttrauma acute lung injury

Acute lung injury (ALI) frequently occurs in traumatic patients and serves as an important component of systemic inflammatory response syndrome (SIRS). Hemorrhagic shock (HS) that results from major trauma promotes the development of SIRS and ALI by priming the innate immune system for an exaggerated inflammatory response. Recent studies have reported that the mechanism underlying the priming of pulmonary inflammation involves the complicated cross-talk between Toll-like receptors (TLRs) and interactions between neutrophils (PMNs) and alveolar macrophages (AMvarphi) as well as endothelial cells (ECs), in which reactive oxygen species (ROS) are the key mediator. This paper summarizes some novel mechanisms underlying HS-primed lung inflammation focusing on the role of TLRs and ROS, and therefore suggests a new therapeutic target for posttrauma ALI.

Targeting TLR/IL-1R signalling in human diseases

The members of Toll-like receptor/Interleukin (IL)-1 receptor (TLR/IL-1R) superfamily play a fundamental role in the immune response. These receptors detect microbial components and trigger complex signalling pathways that result in increased expression of multiple inflammatory genes. On the other hand, an aberrant activation of TLR/IL-1R signalling can promote the onset of inflammatory and autoimmune diseases, raising the interest in the development of therapeutic strategies for the control of their function. In this review, we illustrate the structural and functional features of TLR/IL-1R proteins and discuss some recent advances in the approaches undertaken to develop anti-inflammatory therapeutic drugs. In particular, we will focus on inhibitors, such as decoy peptides and synthetic mimetics, that interfere with protein-protein interactions between signalling molecules of the TLR/IL-1R superfamily. Given their central role in innate and adaptive immune responses, it is foreseen that pharmaceutical modulation of TLR/IL-1R signalling pathways by these drugs might yield clinical benefits in the treatment of inflammatory and autoimmune diseases.

Patented small molecules against psoriasis

BACKGROUND

It is hypothesized that psoriasis is an autoimmune disease. The most recent therapeutic approach that proved to be more effective than earlier methods of treatment is the use of mAb/fusion proteins. Efforts nowadays are focused on investigating the antipsoriatic affect of small molecules that can be administered orally, some of which are capable of entering cells, and being selective in targeting intracellular pathways.

OBJECTIVE

Preclinical patented small molecules that are recommended for the treatment of psoriasis are reviewed. Emphasis is placed on their mechanism of action.

METHODS

http://ep.espacenet.com/ , Pubmed, Scopus and Google websites were the main sources used for the patented small molecule search. A number of patents were poorly described and difficulties were faced in trying to figure out the patentee(s) explanation. Moreover, most patents were recommended for the treatment of a number of autoimmune diseases and cancer, and not only for psoriasis.

RESULTS/CONCLUSIONS

Small molecules that inhibit the activation of T lymphocytes, leukocyte trafficking, leukotriene activity/production and angiogenesis, and promote apoptosis have been patented. Small molecules that have been patented for the treatment of other autoimmune diseases and could be used for treating psoriasis are described. Moreover, other possible mechanistic approaches using small molecules are discussed.

Pattern recognition receptor-dependent mechanisms of acute lung injury

Acute lung injury (ALI) that clinically manifests as acute respiratory distress syndrome is caused by an uncontrolled systemic inflammatory response resulting from clinical events including sepsis, major surgery and trauma. Innate immunity activation plays a central role in the development of ALI. Innate immunity is activated through families of related pattern recognition receptors (PRRs), which recognize conserved microbial motifs or pathogen-associated molecular patterns (PAMPs). Toll-like receptors were the first major family of PRRs discovered in mammals. Recently, NACHT-leucine-rich repeat (LRR) receptors and retinoic acid-inducible gene-like receptors have been added to the list. It is now understood that in addition to recognizing infectious stimuli, both Toll-like receptors and NACHT-LRR receptors can also respond to endogenous molecules released in response to stress, trauma and cell damage. These molecules have been termed damage-associated molecular patterns (DAMPs). It has been clinically observed for a long time that infectious and noninfectious insults initiate inflammation, so confirmation of overlapping receptor-signal pathways of activation between PAMPs and DAMPs is no surprise. This review provides an overview of the PRR-dependent mechanisms of ALI and clinical implication. Modification of PRR pathways is likely to be a logical therapeutic target for ALI/acute respiratory distress syndrome.

IRAK-4 inhibitors for inflammation

Interleukin-1 receptor-associated kinases (IRAKs) are key components in the signal transduction pathways utilized by interleukin-1 receptor (IL-1R), interleukin-18 receptor (IL-18R), and Toll-like receptors (TLRs). Out of four members in the mammalian IRAK family, IRAK-4 is considered to be the “master IRAK”, the only family member indispensable for IL-1R/TLR signaling. In humans, mutations resulting in IRAK-4 deficiency have been linked to susceptibility to bacterial infections, especially recurrent pyogenic bacterial infections. Furthermore, knock-in experiments by several groups have clearly demonstrated that IRAK-4 requires its kinase activity for its function. Given the critical role of IRAK-4 in inflammatory processes, modulation of IRAK-4 kinase activity presents an attractive therapeutic approach for the treatment of immune and inflammatory diseases. The recent success in the determination of the 3-dimensional structure of the IRAK-4 kinase domain in complex with inhibitors has facilitated the understanding of the mechanistic role of IRAK-4 in immunity and inflammation as well as the development of specific IRAK-4 kinase inhibitors. In this article, we review the biological function of IRAK-4, the structural characteristics of the kinase domain, and the development of small molecule inhibitors targeting the kinase activity. We also review the key pharmacophores required for several classes of inhibitors as well as important features for optimal protein/inhibitor interactions. Lastly, we summarize how these insights can be translated into strategies to develop potent IRAK-4 inhibitors with desired properties as new anti-inflammatory therapeutic agents.

Identification of critical residues of the MyD88 death domain involved in the recruitment of downstream kinases

MyD88 couples the activation of the Toll-like receptors and interleukin-1 receptor superfamily with intracellular signaling pathways. Upon ligand binding, activated receptors recruit MyD88 via its Toll-interleukin-1 receptor domain. MyD88 then allows the recruitment of the interleukin-1 receptor-associated kinases (IRAKs). We performed a site-directed mutagenesis of MyD88 residues, conserved in death domains of the homologous FADD and Pelle proteins, and analyzed the effect of the mutations on MyD88 signaling. Our studies revealed that mutation of residues 52 (MyD88(E52A)) and 58 (MyD88(Y58A)) impaired recruitment of both IRAK1 and IRAK4, whereas mutation of residue 95 (MyD88(K95A)) only affected IRAK4 recruitment. Since all MyD88 mutants were defective in signaling, recruitment of both IRAKs appeared necessary for activation of the pathway. Moreover, overexpression of a green fluorescent protein (GFP)-tagged mini-MyD88 protein (GFP-MyD88-(27-72)), comprising the Glu(52) and Tyr(58) residues, interfered with recruitment of both IRAK1 and IRAK4 by MyD88 and suppressed NF-kappaB activation by the interleukin-1 receptor but not by the MyD88-independent TLR3. GFP-MyD88-(27-72) exerted its effect by titrating IRAK1 and suppressing IRAK1-dependent NF-kappaB activation. These experiments identify novel residues of MyD88 that are crucially involved in the recruitment of IRAK1 and IRAK4 and in downstream propagation of MyD88 signaling.

Toll-like receptor modulation: a novel therapeutic strategy in cardiovascular disease?

BACKGROUND

Toll-like receptors (TLRs) have been recently recognised as primary receptors in the innate immune system. Apart from initiating a prompt immune response against invading pathogens, TLRs are also considered to be an important link between innate immunity, inflammation and a variety of clinical disorders, including cardiovascular diseases. TLR signalling manipulation with novel drugs could offer important opportunities for cardiovascular disease modification.

OBJECTIVE

To present the latest knowledge supporting the involvement of TLRs in the pathogenesis and progress of cardiovascular diseases and explore the role of TLRs as potential targets for therapeutic intervention in cardiovascular territory.

METHODS

A review of the literature documenting implication of TLR signalling in cardiovascular disorders. Current progress in TLR-targeting drug development and the potential role of such a treatment strategy in cardiovascular disorders are discussed.

CONCLUSIONS

A growing body of evidence supports a role for TLRs in cardiovascular disease initiation and progression. Altering TLR signalling with novel drugs could be a beneficial therapeutic strategy for patients with cardiovascular disorders.

Toll gates to periodontal host modulation and vaccine therapy

Toll-like receptors (TLRs) are central mediators of innate antimicrobial and inflammatory responses and play instructive roles in the development of the adaptive immune response. Thus when stimulated by certain agonists, TLRs serve as adjuvant receptors that link innate and adaptive immunity. However, when excessively activated or inadequately controlled during an infection, TLRs may contribute to immunopathology associated with inflammatory diseases, such as periodontitis. Moreover, certain microbial pathogens appear to exploit aspects of TLR signalling in ways that enhance their adaptive fitness. The diverse and important roles played by TLRs suggest that therapeutic manipulation of TLR signalling may have implications in the control of infection, attenuation of inflammation, and the development of vaccine adjuvants for the treatment of periodontitis. Successful application of TLR-based therapeutic modalities in periodontitis would require highly selective and precisely targeted intervention. This would in turn necessitate precise characterization of TLR signalling pathways in response to periodontal pathogens, as well as development of effective and specific agonists or antagonists of TLR function and signalling. This review summarizes the current status of TLR biology as it relates to periodontitis, and evaluates the potential of TLR-based approaches for host-modulation therapy in this oral disease.

Toll-like receptors: new therapeutic targets for the treatment of atherosclerosis, acute coronary syndromes, and myocardial failure

The toll-like receptors (TLRs) are a class of transmembrane molecules that have important functions in both innate and acquired immunity. As part of the body's normal immune defense against microbial pathogens, stimulation of these receptors will trigger the inflammatory response cascade and the release of cytokines. Activation of these receptors also plays a role in a variety of systemic inflammatory diseases such as asthma, sepsis, atherosclerosis, acute coronary artery disease, and left ventricular remodeling. Pharmacologic approaches to modify the actions of TLRs are now under consideration as potential treatments for inflammatory systemic diseases that include atherosclerosis. At the same time, it is essential to characterize the benefits and risks of modifying such an important part of the body's innate immune system.

Design, synthesis, and in vitro activity of peptidomimetic inhibitors of myeloid differentiation factor 88

We describe the design and synthesis of a peptidomimetic library derived from the heptapeptide Ac-RDVLPGT-NH 2, belonging to the Toll/IL-1 receptor (TIR) domain of the adaptor protein MyD88 and effective in inhibiting its homodimerization. The ability of the peptidomimetics to inhibit protein-protein interaction was assessed by yeast 2-hybrid assay and further validated in a mammalian cell system by evaluating the inhibition of NF-kappaB activation, a transcription factor downstream of MyD88 signaling pathway that allows production of essential effector molecules for immune and inflammatory responses.