Amino Acid-Dependent Attenuation of Toll-like Receptor Signaling by Peptide-Gold Nanoparticle Hybrids.

Manipulation of immune responsiveness using nanodevices provides a potential approach to treat human diseases. Toll-like receptor (TLR) signaling plays a central role in the pathophysiology of many acute and chronic human inflammatory diseases, and pharmacological regulation of TLR responses is anticipated to be beneficial in many of these inflammatory conditions. Here we describe the discovery of a unique class of peptide-gold nanoparticle hybrids that exhibit a broad inhibitory activity on TLR signaling, inhibiting signaling through TLRs 2, 3, 4, and 5. As exemplified using TLR4, the nanoparticles were found to inhibit both arms of TLR4 signaling cascade triggered by the prototypical ligand, lipopolysaccharide (LPS). Through structure-activity relationship studies, we identified the key chemical components of the hybrids that contribute to their immunomodulatory activity. Specifically, the hydrophobicity and aromatic ring structure of the amino acids on the peptides were essential for modulating TLR4 responses. This work enhances our fundamental understanding of the role of nanoparticle surface chemistry in regulating innate immune signaling, and identifies specific nanoparticle hybrids that may represent a unique class of anti-inflammatory therapeutics for human inflammatory diseases.

Recurrent subacute post-viral onset of ataxia associated with a PRF1 mutation.

Inflammation is an important contributor to pediatric and adult neurodegeneration. Understanding the genetic determinants of neuroinflammation provides valuable insight into disease mechanism. We characterize a disorder of recurrent immune-mediated neurodegeneration. We report two sisters who presented with neurodegeneration triggered by infections. The proband, a previously healthy girl, presented at 22.5 months with ataxia and dysarthria following mild gastroenteritis. MRI at onset showed a symmetric signal abnormality of the cerebellar and peritrigonal white matter. Following a progressive course of partial remissions and relapses, she died at 5 years of age. Her older sister had a similar course following varicella infection, she died within 13 months. Both sisters had unremarkable routine laboratory testing, with exception of a transient mild cytopenia in the proband 19 months after presentation. Exome sequencing identified a biallelic perforin1 mutation (PRF1; p.R225W) previously associated with familial hemophagocytic lymphohistiocytosis (FHL). In contrast to FHL, these girls did not have hematopathology or cytokine overproduction. However, 3 years after disease onset, the proband had markedly deficient interleukin-1 beta (IL-1ß) production. These observations extend the spectrum of disease associated with perforin mutations to immune-mediated neurodegeneration triggered by infection and possibly due to primary immunodeficiency.

Ontogeny of Toll-like receptor mediated cytokine responses of human blood mononuclear cells.

Newborns and young infants suffer increased infectious morbidity and mortality as compared to older children and adults. Morbidity and mortality due to infection are highest during the first weeks of life, decreasing over several years. Furthermore, most vaccines are not administered around birth, but over the first few years of life. A more complete understanding of the ontogeny of the immune system over the first years of life is thus urgently needed. Here, we applied the most comprehensive analysis focused on the innate immune response following TLR stimulation over the first 2 years of life in the largest such longitudinal cohort studied to-date (35 subjects). We found that innate TLR responses (i) known to support Th17 adaptive immune responses (IL-23, IL-6) peaked around birth and declined over the following 2 years only to increase again by adulthood; (ii) potentially supporting antiviral defense (IFN-α) reached adult level function by 1 year of age; (iii) known to support Th1 type immunity (IL-12p70, IFN-γ) slowly rose from a low at birth but remained far below adult responses even at 2 years of age; (iv) inducing IL-10 production steadily declined from a high around birth to adult levels by 1 or 2 years of age, and; (v) leading to production of TNF-α or IL-1ß varied by stimuli. Our data contradict the notion of a linear progression from an 'immature' neonatal to a 'mature' adult pattern, but instead indicate the existence of qualitative and quantitative age-specific changes in innate immune reactivity in response to TLR stimulation.

Carbogen breathing after irradiation enhances the effectiveness of tirapazamine in SiHa tumors but not SCCVII tumors in mice.

The penetration of anticancer agents into tumor tissue has recently attracted considerable attention. This study examines the effect of carbogen breathing on the antitumor activity of tirapazamine combined with radiation. Our hypothesis is based on the observation that the diffusion of tirapazamine through tissue is dependent on oxygen tension. We postulated that carbogen breathing might enhance the ability of tirapazamine to diffuse to hypoxic cells located distal to functional blood vessels in tumors. We first determined that carbogen breathing caused no significant change in the pharmacokinetics of tirapazamine, suggesting that any effect of carbogen breathing on the activity of tirapazamine is not attributable to modulation of pharmacokinetics. Cell survival in SCCVII and SiHa tumors after 10 Gy X rays alone was similar. However, when tirapazamine was administered 30 min after radiation treatment under air-breathing conditions, cell killing was greater in SCCVII tumors compared to SiHa tumors. Carbogen breathing during the exposure to tirapazamine did not change the cell survival in SCCVII tumors, but it enhanced cell killing in the SiHa tumors. Interestingly, carbogen breathing during radiation treatment produced greater cell killing in the SiHa tumors than in the SCCVII tumors. The vascular architecture and type of hypoxia in the two tumors probably underlie the differences in the responses of the two tumors. These findings suggest that the effectiveness of tirapazamine and other hypoxic cytotoxins may be dependent on tumor type.