Author Correction: Transcriptional profiling and therapeutic targeting of oxidative stress in neuroinflammation

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Transcriptional profiling and therapeutic targeting of oxidative stress in neuroinflammation

Oxidative stress is a central part of innate-immune induced neurodegeneration. However, the transcriptomic landscape of the central nervous system (CNS) innate immune cells contributing to oxidative stress is unknown, and therapies to target their neurotoxic functions are not widely available. Here, we provide the oxidative stress innate immune cell atlas in neuroinflammatory disease, and report the discovery of new druggable pathways. Transcriptional profiling of oxidative stress-producing CNS innate immune cells (Tox-seq) identified a core oxidative stress gene signature coupled to coagulation and glutathione pathway genes shared between a microglia cluster and infiltrating macrophages. Tox-seq followed by a microglia high-throughput screen (HTS) and oxidative stress gene network analysis, identified the glutathione regulating compound acivicin with potent therapeutic effects decreasing oxidative stress and axonal damage in chronic and relapsing multiple sclerosis (MS) models. Thus, oxidative stress transcriptomics identified neurotoxic CNS innate immune populations and may enable the discovery of selective neuroprotective strategies.

Fibrin-targeting immunotherapy protects against neuroinflammation and neurodegeneration

Activation of innate immunity and deposition of blood-derived fibrin in the central nervous system (CNS) occur in autoimmune and neurodegenerative diseases, including multiple sclerosis (MS) and Alzheimer’s disease (AD). However, mechanisms linking blood-brain barrier (BBB) disruption with neurodegeneration are poorly understood, and exploration of fibrin as a therapeutic target has been limited by its beneficial clotting functions. Here we report the generation of monoclonal antibody 5B8 targeted against the cryptic fibrin epitope γ_377–395 to selectively inhibit fibrin-induced inflammation and oxidative stress without interfering with clotting. 5B8 suppressed fibrin-induced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and proinflammatory gene expression. In animal models of MS and AD, 5B8 entered the CNS and bound to parenchymal fibrin, and its therapeutic administration reduced innate immune activation and neurodegeneration. Thus, fibrin-targeting immunotherapy inhibits autoimmune- and amyloid-driven neurotoxicity and may have clinical benefit without globally suppressing innate immunity or interfering with coagulation in diverse neurological diseases.

A Hydrogel-Microsphere Drug Delivery System That Supports Once-Monthly Administration of a GLP-1 Receptor Agonist

We have developed a chemically controlled very long-acting delivery system to support once-monthly administration of a peptidic GLP-1R agonist. Initially, the prototypical GLP-1R agonist exenatide was covalently attached to hydrogel microspheres by a self-cleaving β-eliminative linker; after subcutaneous injection in rats, the peptide was slowly released into the systemic circulation. However, the short serum exenatide half-life suggested its degradation in the subcutaneous depot. We found that exenatide undergoes deamidation at Asn²⁸ with an in vitro and in vivo half-life of approximately 2 weeks. The [Gln²⁸]exenatide variant and exenatide showed indistinguishable GLP-1R agonist activities as well as pharmacokinetic and pharmacodynamic effects in rodents; however, unlike exenatide, [Gln²⁸]exenatide is stable for long periods. Two different hydrogel-[Gln²⁸]exenatide conjugates were prepared using β-eliminative linkers with different cleavage rates. After subcutaneous injection in rodents, the serum half-lives for the released [Gln²⁸]exenatide from the two conjugates were about 2 weeks and one month. Two monthly injections of the latter in the Zucker diabetic fatty rat showed pharmacodynamic effects indistinguishable from two months of continuously infused exenatide. Pharmacokinetic simulations indicate that the delivery system should serve well as a once-monthly GLP-1R agonist for treatment of type 2 diabetes in humans.

Biophysical methods for identifying fragment-based inhibitors of protein-protein interactions

Fragment-based lead discovery complements high-throughput screening and computer-aided drug design for the discovery of small-molecule inhibitors of protein-protein interactions. Fragments are molecules with molecular masses ca 280 Da or smaller, and are generally screened using structural or biophysical approaches. Several methods of fragment-based screening are feasible for any soluble protein that can be expressed and purified; specific techniques also have size limitations and/or require multiple milligrams of protein. This chapter describes some of the most common fragment-discovery methods, including surface plasmon resonance, nuclear magnetic resonance, differential scanning fluorimetry, and X-ray crystallography.

Hormone binding and co-regulator binding to the glucocorticoid receptor are allosterically coupled

The glucocorticoid receptor initiates the cellular response to glucocorticoid steroid hormones in vertebrates. Co-regulator proteins dock to the receptor in response to hormone binding and potentiate the transcriptional activity of the receptor by modifying DNA and recruiting essential transcription factors like RNA polymerase II. Hormones and co-regulators bind at distinct sites in the ligand binding domain yet function cooperatively to mediate transcriptional control. This study reveals and quantifies energetic coupling between two binding sites using purified components. Using a library of peptides taken from co-regulator proteins, we determine the pattern of co-regulator binding to the glucocorticoid receptor ligand binding domain. We show that peptides from co-regulators differ in their effects on hormone binding and kinetics. Peptides from DAX1 and SRC1 bind with similar affinity, but DAX1 binding is coupled to hormone binding, and SRC1 is not. Mechanistic details of co-regulator binding and coupling to the hormone binding pocket are uncovered by analysis of properties endowed by mutation of a key residue in the allosteric network connecting the sites.

Recognition and accommodation at the androgen receptor coactivator binding interface

Prostate cancer is a leading killer of men in the industrialized world. Underlying this disease is the aberrant action of the androgen receptor (AR). AR is distinguished from other nuclear receptors in that after hormone binding, it preferentially responds to a specialized set of coactivators bearing aromatic-rich motifs, while responding poorly to coactivators bearing the leucine-rich "NR box" motifs favored by other nuclear receptors. Under normal conditions, interactions with these AR-specific coactivators through aromatic-rich motifs underlie targeted gene transcription. However, during prostate cancer, abnormal association with such coactivators, as well as with coactivators containing canonical leucine-rich motifs, promotes disease progression. To understand the paradox of this unusual selectivity, we have derived a complete set of peptide motifs that interact with AR using phage display. Binding affinities were measured for a selected set of these peptides and their interactions with AR determined by X-ray crystallography. Structures of AR in complex with FxxLF, LxxLL, FxxLW, WxxLF, WxxVW, FxxFF, and FxxYF motifs reveal a changing surface of the AR coactivator binding interface that permits accommodation of both AR-specific aromatic-rich motifs and canonical leucine-rich motifs. Induced fit provides perfect mating of the motifs representing the known family of AR coactivators and suggests a framework for the design of AR coactivator antagonists.

Mediastinitis complicating cardiac operations: evidence of postoperative causation

An excess rate of mediastinitis complicating cardiac operations occurred in one of two hospitals served by the same surgeons. The rates were 4% at hospital A and 0.48% at hospital B for the same period (P = .002). At hospital A five patients who underwent a thoracic reoperation experienced postoperative pneumonia or bacteremia prior to onset of mediastinitis; these infections were caused by the same bacterial species. This circumstance provided a unique opportunity for comparing infection control practices, in which one hospital served as a control for interventional changes. At hospital A regular and temporary critical care nursing personnel, who took care of both infected and uninfected patients, did not antisepticize their hands before manipulation of percutaneous catheters. After cohorts of nurses were formed and antisepsis of the hands with alcohol was strictly enforced (no diminution in the number of temporary personnel was instituted), the frequency of mediastinitis decreased significantly among patients who underwent reoperations at hospital A (P = .002), but no concurrent change was noted at hospital B. Preventable postoperative remote-site infection may lead to mediastinitis.

Infections complicating low-risk cesarean sections in community hospitals: efficacy of antimicrobial prophylaxis

A prospective study of women with low-risk cesarean sections was conducted in four community hospitals to determine the frequency of postoperative infections and identify factors predisposing to endometritis and wound infection. Low-risk cesarean section was defined as a scheduled procedure without an urgent indication, with any duration of ruptured membranes being less than or equal to 12 hours. In a cohort of 1863 patients, 26 (1.4%) developed endometritis and 21 (1.1%) had wound infections. Primary cesarean section was associated with endometritis in the cohort (p less than 0.01) and in a retrospective study with the same cases as in the cohort (p = 0.01). Absence of antibiotic prophylaxis was associated with endometritis (p less than or equal to 0.013) or endometritis with wound infection (p less than 0.01) in both studies. Without prophylaxis 37 such infections occurred in 957 (3.7%) women; with prophylaxis eight infections occurred in 906 (0.9%) women. Routine timely antibiotic prophylaxis in low-risk cesarean sections could lead to an annual national savings of approximately $9 million.

How infection control can meet standards

Important aspects and interpretations of JCAH standards on infection control are explained, and approaches to ensuring compliance are discussed.