The recognition of invading pathogens and endogenous molecules from damaged tissues by toll-like receptors (TLRs) triggers protective self-defense mechanisms. However, excessive TLR activation disrupts the immune homeostasis by sustained pro-inflammatory cytokines and chemokines production and consequently contributes to the development of many inflammatory and autoimmune diseases, such as systemic lupus erythematosus (SLE), infection-associated sepsis, atherosclerosis, and asthma. Therefore, inhibitors/antagonists targeting TLR signals may be beneficial to treat these disorders. In this article, we first briefly summarize the pathophysiological role of TLRs in the inflammatory diseases. We then focus on reviewing the current knowledge in both preclinical and clinical studies of various TLR antagonists/inhibitors for the prevention and treatment of inflammatory diseases. These compounds range from conventional small molecules to therapeutic biologics and nanodevices. In particular, nanodevices are emerging as a new class of potent TLR inhibitors for their unique properties in desired bio-distribution, sustained circulation, and preferred pharmacodynamic and pharmacokinetic profiles. More interestingly, the inhibitory activity of these nanodevices can be regulated through precise nano-functionalization, making them the next generation therapeutics or “nano-drugs.” Although, significant efforts have been made in developing different kinds of new TLR inhibitors/antagonists, only limited numbers of them have undergone clinical trials, and none have been approved for clinical uses to date. Nevertheless, these findings and continuous studies of TLR inhibition highlight the pharmacological regulation of TLR signaling, especially on multiple TLR pathways, as future promising therapeutic strategy for various inflammatory and autoimmune diseases.

Campylobacter jejuni is a major source of foodborne illness in the developed world, and a common cause of clinical gastroenteritis. Exactly how C. jejuni colonizes its host's intestines and causes disease is poorly understood. Although it causes severe diarrhea and gastroenteritis in humans, C. jejuni typically dwells as a commensal microbe within the intestines of most animals, including birds, where its colonization is asymptomatic. Pretreatment of C57BL/6 mice with the antibiotic vancomycin facilitated intestinal C. jejuni colonization, albeit with minimal pathology. In contrast, vancomycin pretreatment of mice deficient in SIGIRR (Sigirr−/−), a negative regulator of MyD88-dependent signaling led to heavy and widespread C. jejuni colonization, accompanied by severe gastroenteritis involving strongly elevated transcription of Th1/Th17 cytokines. C. jejuni heavily colonized the cecal and colonic crypts of Sigirr−/− mice, adhering to, as well as invading intestinal epithelial cells. This infectivity was dependent on established C. jejuni pathogenicity factors, capsular polysaccharides (kpsM) and motility/flagella (flaA). We also explored the basis for the inflammatory response elicited by C. jejuni in Sigirr−/− mice, focusing on the roles played by Toll-like receptors (TLR) 2 and 4, as these innate receptors were strongly stimulated by C. jejuni. Despite heavy colonization, Tlr4−/−/Sigirr−/− mice were largely unresponsive to infection by C. jejuni, whereas Tlr2−/−/Sigirr−/− mice developed exaggerated inflammation and pathology. This indicates that TLR4 signaling underlies the majority of the enteritis seen in this model, whereas TLR2 signaling had a protective role, acting to promote mucosal integrity. Furthermore, we found that loss of the C. jejuni capsule led to increased TLR4 activation and exaggerated inflammation and gastroenteritis. Together, these results validate the use of Sigirr−/− mice as an exciting and relevant animal model for studying the pathogenesis and innate immune responses to C. jejuni.

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The self‐assembling peptide EAK16‐II is capable of stabilizing hydrophobic compounds to form microcrystal suspensions in aqueous solution. Here, the ability of this peptide to stabilize the hydrophobic anticancer agent ellipticine is investigated. The formation of peptide‐ellipticine suspensions is monitored with time until equilibrium is reached. The equilibration time is found to be dependent on the peptide concentration. When the peptide concentration is close to its critical aggregation concentration, the equilibration time is minimal at 5 h. With different combinations of EAK16‐II and ellipticine concentrations, two molecular states (protonated or cyrstalline) of ellipticine could be stabilized. These different states of ellipticine significantly affect the release kinetics of ellipticine from the peptide‐ellipticine complex into the egg phosphatidylcholine vesicles, which are used to mimic cell membranes. The transfer rate of protonated ellipticine from the complex to the vesicles is much faster than that of crystalline ellipticine. This observation may also be related to the size of the resulting complexes as revealed from the scanning electron micrographs. In addition, the complexes with protonated ellipticine are found to have a better anticancer activity against two cancer cell lines, A549 and MCF‐7. This work forms the basis for studies of the peptide‐ellipticine suspensions in vitro and in vivo leading to future development of self‐assembling peptide‐based delivery of hydrophobic anticancer drugs.

Purpose: Tumor fibroblasts (TF) have been suggested to play an essential role in the complex process of tumor-stroma interactions and tumorigenesis. The aim of the present study was to investigate the specific role of TF in the esophageal cancer microenvironment. Experimental Design: An Affymetrix expression microarray was used to compare gene expression profiles between six pairs of TFs and normal fibroblasts from esophageal squamous cell carcinoma (ESCC). Differentially expressed genes were identified, and a subset was evaluated by quantitative real-time PCR and immunohistochemistry. Results: About 43% (126 of 292) of known deregulated genes in TFs were associated with cell proliferation, extracellular matrix remodeling, and immune response. Up-regulation of fibroblast growth factor receptor 2 (FGFR2), which showed the most significant change, was detected in all six tested TFs compared with their paired normal fibroblasts. A further study found that FGFR2-positive fibroblasts were only observed inside the tumor tissues and not in tumor-surrounding stromal tissues, suggesting that FGFR2 could be used as a TF-specific marker in ESCC. Moreover, the conditioned medium from TFs was found to be able to promote ESCC tumor cell growth, migration, and invasion in vitro. Conclusions: Our study provides new candidate genes for the esophageal cancer microenvironment. Based on our results, we hypothesize that FGFR2(+)-TFs might provide cancer cells with a suitable microenvironment via secretion of proteins that could promote cancer development and progression through stimulation of cancer cell proliferation, induction of angiogenesis, inhibition of cell adhesion, enhancement of cell mobility, and promotion of the epithelial-mesenchymal transition.

Ionic-complementary peptides are novel nano-biomaterials with a variety of biomedical applications including potential biosurface engineering. This study presents evidence that a model ionic-complementary peptide EAK16-II is capable of assembling/coating on hydrophilic mica as well as hydrophobic highly ordered pyrolytic graphite (HOPG) surfaces with different nano-patterns. EAK16-II forms randomly oriented nanofibers or nanofiber networks on mica, while ordered nanofibers parallel or oriented 60° or 120° to each other on HOPG, reflecting the crystallographic symmetry of graphite (0001). The density of coated nanofibers on both surfaces can be controlled by adjusting the peptide concentration and the contact time of the peptide solution with the surface. The coated EAK16-II nanofibers alter the wettability of the two surfaces differently: the water contact angle of bare mica surface is measured to be <10°, while it increases to 20.3±2.9° upon 2 h modification of the surface using a 29 µM EAK16-II solution. In contrast, the water contact angle decreases significantly from 71.2±11.1° to 39.4±4.3° after the HOPG surface is coated with a 29 µM peptide solution for 2 h. The stability of the EAK16-II nanofibers on both surfaces is further evaluated by immersing the surface into acidic and basic solutions and analyzing the changes in the nanofiber surface coverage. The EAK16-II nanofibers on mica remain stable in acidic solution but not in alkaline solution, while they are stable on the HOPG surface regardless of the solution pH. This work demonstrates the possibility of using self-assembling peptides for surface modification applications.

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Background: Macrophage polarization and reprogramming in the lung play a critical role in the initiation, development and progression of acute lung injury (ALI). Regulating the activation and differentiation of pulmonary macrophages may provide a potential therapeutic strategy to treat ALI. We previously developed a novel class of antiinflammatory nanoparticles (P12) that can potently inhibit Toll-like receptor (TLR) signaling in macrophages. These bioactive nanodevices were made of gold nanoparticles (GNPs) coated with hexapeptides to not only ensure their physiological stability but also enable GNPs with TLR inhibitory activity.Results: In this study, using a lipopolysaccharide (LPS) induced ALI mouse model, we showed that P12 was able to alleviate lung inflammation and damage through reducing the infiltration of inflammatory cells and increasing the anti-inflammatory cytokine (IL-10) in the lung. These results prompted us to investigate possible macrophage polarization by P12. We first confirmed that P12 primarily targeted macrophages in the lung to exert anti-inflammatory activity. We then showed that P12 could drive the polarization of mouse bone marrow-derived macrophages (BMDMs) toward anti-inflammatory M2 phenotype. Interestingly, in the ALI mouse model, P12 was able to increase the alveolar M2 macrophages and reduce both the alveolar and interstitial M1 macrophages in the bronchoalveolar lavage fluid (BALF) and lung tissues. Conclusion:This study demonstrated that peptide-coated GNPs could induce M2 macrophage polarization in vitro and in vivo to effectively regulate lung inflammation, protect lung from injuries and promote inflammation resolution. The ability of regulating macrophage polarization together with TLR inhibition made such a bioactive nanodevice a new generation of potent therapeutics to treat ALI.