Pharmacokinetics/pharmacodynamics by race: Analysis of a peginterferon ß-1a phase 1 study.

BACKGROUND: Black/African American participants are underrepresented in clinical trials for multiple sclerosis but can experience a greater burden of disease than other racial groups in the United States. A phase 1, open-label, crossover study that demonstrated bioequivalence of subcutaneous and intramuscular injection of peginterferon ß-1a in healthy volunteers enrolled similar proportions of Black and White participants, enabling a post hoc subgroup analysis comparing these groups. METHODS: Peginterferon ß-1a (125 µg) was administered by subcutaneous or intramuscular injection, followed by a washout period before a second injection using the alternative method. The primary pharmacokinetic and pharmacodynamic endpoints were maximum observed concentration (Cmax) and area under the concentration-time curve from hour 0 to infinity (AUCinf) of study drug and serum concentration of neop-terin, respectively. Safety and tolerability were included as secondary endpoints. FINDINGS: This analysis included 70 (51.5%) Black and 59 (43.3%) White participants. Peginterferon ß-1a Cmax was 29.8% higher in Black than in White participants following subcutaneous administration but was similar following intramuscular administration. Mean AUCinf was 31.0% and 11.8% greater in Black than in White participants with subcutaneous and intramuscular administration, respectively. Pharmacodynamics and safety signals were similar between groups, although Black participants reported numerically fewer adverse events. CONCLUSIONS: No clinically meaningful differences were identified between Black and White participants related to peginterferon ß-1a administration, supporting the approved dose of 125 µg/mL peginterferon ß-1a. Future clinical studies should include sufficiently diverse populations to ensure accurate assessments of treatment response. FUNDING: Funding for medical writing support was provided by Biogen (Cambridge, MA, USA).

Peginterferon beta-1a concentrations in breast milk of lactating multiple sclerosis patients.

BACKGROUND: Peginterferon beta-1a is an interferon beta-1a formulation that has been pegylated, resulting in a longer half-life than other interferon beta formulations. We examined concentrations of peginterferon beta-1a in breast milk of lactating patients with multiple sclerosis (MS) receiving peginterferon beta-1a as their postpartum disease-modifying therapy. METHODS: After completion of titration to a full dose of peginterferon beta-1a and following a single full dose peginterferon beta-1a injection (125 µg), breast milk samples (≥10 mL) were collected by 5 women on days 1-14 post injection. Peginterferon beta-1a concentrations in breast milk samples were measured by a qualified enzyme-linked immunosorbent assay (detection threshold: 15 pg/mL). Mean and median daily concentrations and median maximum concentration (Cmax), time of Cmax (Tmax), time of last measurable concentration (Tlast), area under the concentration-time curve (AUClast), and relative infant dose (RID) were determined. RESULTS: After receiving a single full dose peginterferon beta-1a injection, the maximum breast milk concentration recorded in an individual patient was 126.2 pg/mL (0.00013 µg/mL) on day 6. The remaining patients all had maximum breast milk concentrations <72 pg/mL. The geometric mean of Cmax was 48.9 pg/mL and the median Tmax and Tlast were 4 and 7 days, respectively. The median AUClast was 210.9 day*pg/mL. Among the 5 study patients, the mean breast milk concentration across all study days was 35.95 pg/mL, with an estimated RID of 0.0054% of the maternal dose. CONCLUSION: Minimal concentrations of peginterferon beta-1a were detected in the breast milk samples. These findings may be useful for clinicians considering postpartum MS treatment options.

Peptidoglycan-Sensing Receptors Trigger the Formation of Functional Amyloids of the Adaptor Protein Imd to Initiate Drosophila NF-κB Signaling.

In the Drosophila immune response, bacterial derived diaminopimelic acid-type peptidoglycan binds the receptors PGRP-LC and PGRP-LE, which through interaction with the adaptor protein Imd leads to activation of the NF-κB homolog Relish and robust antimicrobial peptide gene expression. PGRP-LC, PGRP-LE, and Imd each contain a motif with some resemblance to the RIP Homotypic Interaction Motif (RHIM), a domain found in mammalian RIPK proteins forming functional amyloids during necroptosis. Here we found that despite sequence divergence, these Drosophila cryptic RHIMs formed amyloid fibrils in vitro and in cells. Amyloid formation was required for signaling downstream of Imd, and in contrast to the mammalian RHIMs, was not associated with cell death. Furthermore, amyloid formation constituted a regulatable step and could be inhibited by Pirk, an endogenous feedback regulator of this pathway. Thus, diverse sequence motifs are capable of forming amyloidal signaling platforms, and the formation of these platforms may present a regulatory point in multiple biological processes.

Essential structural and functional roles of the Cmr4 subunit in RNA cleavage by the Cmr CRISPR-Cas complex.

The Cmr complex is the multisubunit effector complex of the type III-B clustered regularly interspaced short palindromic repeats (CRISPR)-Cas immune system. The Cmr complex recognizes a target RNA through base pairing with the integral CRISPR RNA (crRNA) and cleaves the target at multiple regularly spaced locations within the complementary region. To understand the molecular basis of the function of this complex, we have assembled information from electron microscopic and X-ray crystallographic structural studies and mutagenesis of a complete Pyrococcus furiosus Cmr complex. Our findings reveal that four helically packed Cmr4 subunits, which make up the backbone of the Cmr complex, act as a platform to support crRNA binding and target RNA cleavage. Interestingly, we found a hook-like structural feature associated with Cmr4 that is likely the site of target RNA binding and cleavage. Our results also elucidate analogies in the mechanisms of crRNA and target molecule binding by the distinct Cmr type III-A and Cascade type I-E complexes.

Staphylococcus epidermidis Csm1 is a 3'-5' exonuclease.

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) offer an adaptive immune system that protects bacteria and archaea from nucleic acid invaders through an RNA-mediated nucleic acid cleavage mechanism. Our knowledge of nucleic acid cleavage mechanisms is limited to three examples of widely different ribonucleoprotein particles that target either DNA or RNA. Staphylococcus epidermidis belongs to the Type III-A CRISPR system and has been shown to interfere with invading DNA in vivo. The Type III-A CRISPR system is characterized by the presence of Csm1, a member of Cas10 family of proteins, that has a permuted histidine-aspartate domain and a nucleotidyl cyclase-like domain, both of which contain sequence features characteristic of nucleases. In this work, we show in vitro that a recombinant S. epidermidis Csm1 cleaves single-stranded DNA and RNA exonucleolytically in the 3'-5' direction. We further showed that both cleavage activities are divalent-metal-dependent and reside in the GGDD motif of the cyclase-like domain. Our data suggest that Csm1 may work in the context of an effector complex to degrade invading DNA and participate in CRISPR RNA maturation.

Structure of the Cmr2-Cmr3 subcomplex of the Cmr RNA silencing complex.

The Cmr complex is an RNA-guided effector complex that cleaves invader RNA in the prokaryotic immune response mediated by the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)-Cas system. Here, we report the crystal structure of a Cmr subcomplex containing Cmr2 (Cas10) and Cmr3 subunits at 2.8 Å resolution. The structure revealed a dual ferredoxin fold and glycine-rich loops characteristic of previously known repeat-associated mysterious proteins and two unique insertion elements in Cmr3 that mediate its interaction with Cmr2. Surprisingly, while mutation of both insertion elements significantly weakened Cmr3-Cmr2 interaction, they exhibit differential effects on Cmr-mediated RNA cleavage by the Cmr complex, suggesting stabilization of Cmr2-Cmr3 interactions by other subunits. Further mutational analysis of the two conserved (but non-Cmr2-binding) glycine-rich loops of Cmr3 identified a region that is likely involved in assembly or the RNA cleavage function of the Cmr complex.

Structure of the Cmr2 subunit of the CRISPR-Cas RNA silencing complex.

Cmr2 is the largest and an essential subunit of a CRISPR RNA-Cas protein complex (the Cmr complex) that cleaves foreign RNA to protect prokaryotes from invading genetic elements. Cmr2 is thought to be the catalytic subunit of the effector complex because of its N-terminal HD nuclease domain. Here, however, we report that the HD domain of Cmr2 is not required for cleavage by the complex in vitro. The 2.3Å crystal structure of Pyrococcus furiosus Cmr2 (lacking the HD domain) reveals two adenylyl cyclase-like and two α-helical domains. The adenylyl cyclase-like domains are arranged as in homodimeric adenylyl cyclases and bind ADP and divalent metals. However, mutagenesis studies show that the metal- and ADP-coordinating residues of Cmr2 are also not critical for cleavage by the complex. Our findings suggest that another component provides the catalytic function and that the essential role by Cmr2 does not require the identified ADP- or metal-binding or HD domains in vitro.