Metagenomic analysis of gut microbiome illuminates the mechanisms and evolution of lignocellulose degradation in mangrove herbivorous crabs.

BACKGROUND: Sesarmid crabs dominate mangrove habitats as the major primary consumers, which facilitates the trophic link and nutrient recycling in the ecosystem. Therefore, the adaptations and mechanisms of sesarmid crabs to herbivory are not only crucial to terrestrialization and its evolutionary success, but also to the healthy functioning of mangrove ecosystems. Although endogenous cellulase expressions were reported in crabs, it remains unknown if endogenous enzymes alone can complete the whole lignocellulolytic pathway, or if they also depend on the contribution from the intestinal microbiome. We attempt to investigate the role of gut symbiotic microbes of mangrove-feeding sesarmid crabs in plant digestion using a comparative metagenomic approach. RESULTS: Metagenomics analyses on 43 crab gut samples from 23 species of mangrove crabs with different dietary preferences revealed a wide coverage of 127 CAZy families and nine KOs targeting lignocellulose and their derivatives in all species analyzed, including predominantly carnivorous species, suggesting the crab gut microbiomes have lignocellulolytic capacity regardless of dietary preference. Microbial cellulase, hemicellulase and pectinase genes in herbivorous and detritivorous crabs were differentially more abundant when compared to omnivorous and carnivorous crabs, indicating the importance of gut symbionts in lignocellulose degradation and the enrichment of lignocellulolytic microbes in response to diet with higher lignocellulose content. Herbivorous and detritivorous crabs showed highly similar CAZyme composition despite dissimilarities in taxonomic profiles observed in both groups, suggesting a stronger selection force on gut microbiota by functional capacity than by taxonomy. The gut microbiota in herbivorous sesarmid crabs were also enriched with nitrogen reduction and fixation genes, implying possible roles of gut microbiota in supplementing nitrogen that is deficient in plant diet. CONCLUSIONS: Endosymbiotic microbes play an important role in lignocellulose degradation in most crab species. Their abundance is strongly correlated with dietary preference, and they are highly enriched in herbivorous sesarmids, thus enhancing their capacity in digesting mangrove leaves. Dietary preference is a stronger driver in determining the microbial CAZyme composition and taxonomic profile in the crab microbiome, resulting in functional redundancy of endosymbiotic microbes. Our results showed that crabs implement a mixed mode of digestion utilizing both endogenous and microbial enzymes in lignocellulose degradation, as observed in most of the more advanced herbivorous invertebrates.

Comparative analysis of gut microbiome of mangrove brachyuran crabs revealed patterns of phylosymbiosis and codiversification.

The acquisition of microbial symbionts enables animals to rapidly adapt to and exploit novel ecological niches, thus significantly enhancing the evolutionary fitness and success of their hosts. However, the dynamics of host-microbe interactions and their evolutionary implications remain largely underexplored in marine invertebrates. Crabs of the family Sesarmidae (Crustacea: Brachyura) are dominant inhabitants of mangrove forests and are considered keystone species there. Their rapid diversification, particularly after adopting a plant-feeding lifestyle, is believed to have been facilitated by symbiotic gut microbes, enabling successful colonization of intertidal and terrestrial environments. To investigate the patterns and mechanisms shaping the microbial communities and the role of microbes in the evolution of Sesarmidae, we characterized and compared the gut microbiome compositions across 43 crab species from Sesarmidae and other mangrove-associated families using 16S metabarcoding. We found that the gut microbiome assemblages in crabs are primarily determined by host identity, with a secondary influence from environmental factors such as microhabitat and sampling location, and to a lesser extent influenced by biological factors such as sex and gut region. While patterns of phylosymbiosis (i.e. when microbial community relationships recapitulate the phylogeny of their hosts) were consistently observed in all beta-diversity metrics analysed, the strength of phylosymbiosis varied across crab families. This suggests that the bacterial assemblages in each family were differentially shaped by different degrees of host filtering and/or other evolutionary processes. Notably, Sesarmidae displayed signals of cophylogeny with its core gut bacterial genera, which likely play crucial functional roles in their hosts by providing lignocellulolytic enzymes, essential amino acids, and fatty acids supplementation. Our results support the hypothesis of microbial contribution to herbivory and terrestrialization in mangrove crabs, highlighting the tight association and codiversification of the crab holobiont.

Effects of Strong Inhibition of Cytochrome P450 3A and UDP glucuronosyltransferase 1A9 and Strong Induction of Cytochrome P450 3A on the Pharmacokinetics, Safety, and Tolerability of Soticlestat: Two Drug-Drug Interaction Studies in Healthy Volunteers.

Two open-label, phase 1 studies (NCT05064449, NCT05098041) investigated the effects of cytochrome P450 (CYP) 3A inhibition (via itraconazole), UDP glucuronosyltransferase (UGT) 1A9 inhibition (via mefenamic acid), and CYP3A induction (via rifampin) on the pharmacokinetics of soticlestat and its metabolites M-I and M3. In period 1 of both studies, participants received a single dose of soticlestat 300 mg. In period 2, participants received itraconazole on days 1-11 and soticlestat 300 mg on day 5 (itraconazole/mefenamic acid study; part 1); mefenamic acid on days 1-7 and soticlestat 300 mg on day 2 (itraconazole/mefenamic acid study; part 2); or rifampin on days 1-13 and soticlestat 300 mg on day 11 (rifampin study). Twenty-eight healthy adults participated in the itraconazole/mefenamic acid study (14 per part) and 15 participated in the rifampin study (mean age, 38.1-40.7 years; male, 79-93%). For maximum observed concentration, the geometric mean ratios (GMRs) of soticlestat + itraconazole, mefenamic acid, or rifampin to soticlestat alone were 116.6%, 107.3%, and 13.2%, respectively, for soticlestat; 10.7%, 118.0%, and 266.1%, respectively, for M-I, and 104.6%, 88.2%, and 66.6%, respectively, for M3. For area under the curve from time 0 to infinity, the corresponding GMRs were 124.0%, 100.6%, and 16.4% for soticlestat; 13.3%, 117.0%, and 180.8% for M-I; and 120.3%, 92.6%, and 58.4% for M3. Soticlestat can be administered with strong CYP3A and UGT1A9 inhibitors, but not strong CYP3A inducers (except for antiseizure medications, which will be further evaluated in ongoing phase 3 studies). In both studies, all treatment-emergent adverse events were mild or moderate. SIGNIFICANCE STATEMENT: These drug-drug interaction studies improve our understanding of the potential changes that may arise in soticlestat exposure in patients being treated with CYP3A inhibitors, UGT1A9 inhibitors, or CYP3A inducers. The results build on findings from previously published soticlestat studies and provide important information to help guide clinical practice. Soticlestat has shown positive phase 2 results and is currently in phase 3 development for the treatment of seizures in patients with Dravet syndrome and Lennox-Gastaut syndrome.

Investigation of the absolute bioavailability, mass balance, metabolism, and excretion of the cholesterol 24-hydroxylase inhibitor soticlestat in healthy volunteers.

AIMS: Our aim was to determine the absolute bioavailability, mass balance, metabolism and excretion of soticlestat (TAK-935). METHODS: An open-label, two-period, single-site, phase 1 study was conducted in six healthy men. In Period 1, a single 300 mg dose of soticlestat was administered orally, followed by a 15-min intravenous infusion of [14 C]soticlestat 50 µg (~1 µCi) 10 min later. In Period 2, a single 300 mg dose (~100 µCi) of [14 C]soticlestat in solution was administered orally. Samples were collected, analysed for radioactivity or unchanged soticlestat, and profiled for metabolites. RESULTS: In Period 1, soticlestat had an absolute bioavailability of 12.6% (90% confidence interval, 7.81-20.23%). In Period 2, there was near-complete recovery of total radioactivity (TRA) following a 300 mg dose of [14 C]soticlestat: urine, 94.8% (standard deviation [SD], 1.35%); faeces, 2.7% (SD, 1.67%). Of TRA, 0.1% (SD, 0.09%) and 0.6% (SD, 0.21%) were recovered as soticlestat and metabolite M-I in urine, respectively. In plasma, soticlestat and M-I reached geometric mean maximum observed concentrations of 1352 ng/mL (geometric percent coefficient of variation [gCV%], 61.3) and 253.2 ng/mL (gCV%, 44.1) after 25 min and declined with mean terminal half-lives (SD) of 5.7 (2.90) and 2.0 (0.15) h, respectively. Soticlestat represented 4.9% of TRA in plasma. Soticlestat was rapidly eliminated primarily via O-glucuronidation to metabolite M3, which was the dominant species in plasma (92.6%) and urine (86%). CONCLUSIONS: This study indicates that soticlestat and its metabolites are rapidly cleared and eliminated, lowering the risk of dose accumulation from repeated dosing and supporting further investigation of soticlestat.

Phase 1 pharmacokinetic and safety study of soticlestat in participants with mild or moderate hepatic impairment or normal hepatic function.

This phase 1, open-label, three-arm study (NCT05098054) compared the pharmacokinetics and safety of soticlestat (TAK-935) in participants with hepatic impairment. Participants aged ≥18 to <75 years had moderate (Child-Pugh B) or mild (Child-Pugh A) hepatic impairment or normal hepatic function (matched to hepatic-impaired participants by sex, age, and body mass index). Soticlestat was administered as a single oral 300 mg dose. Pharmacokinetic parameters of soticlestat and its metabolites TAK-935-G (M3) and M-I were assessed and compared by group. The incidence of treatment-emergent adverse events (TEAEs) and other safety parameters were also monitored. The pharmacokinetic analyses comprised 35 participants. Participants with moderate hepatic impairment had lower proportions of bound and higher proportions of unbound soticlestat than participants with mild hepatic impairment and normal hepatic function. Total plasma soticlestat pharmacokinetic parameters (maximum observed concentration [Cmax], area under the concentration-time curve from time 0 to time of last quantifiable concentration [AUClast], and AUC from time 0 to infinity [AUC∞]) were approximately 115%, 216%, and 199% higher with moderate and approximately 45%, 35%, and 30% higher with mild hepatic impairment, respectively, than healthy matched participants. Moderate hepatic impairment decreased the liver's ability to metabolize soticlestat to M-I; glucuronidation to M3 was also affected. Mild hepatic impairment resulted in a lower total plasma M-I exposure, but glucuronidation was unaffected. TEAEs were similar across study arms, mild, and no new safety findings were observed. A soticlestat dose reduction is required for individuals with moderate but not mild hepatic impairment.

Integrating Regulatory Drug Label Information to Facilitate Evaluation of Adverse Events in Pharmacovigilance.

BACKGROUND: Efficiency and accuracy for signal detection and evaluation activities are integral components of routine Pharmacovigilance (PV) practices. However, an Individual Case Safety Report (ICSR) may consist of a variety of confounders such as Concomitant Medications (CM), Past Medical History (PMH), and concurrent medical conditions that influence a safety officer's evaluation of a potential Adverse Event (AE). Limited pharmacovigilance systems are currently available as a tool designed to enhance the efficiency and accuracy of signal detection and management. OBJECTIVE: To introduce a systemic approach to make critical safety information readily available for users in order to discern possible interferences from CM and make informed decisions on the signal evaluation process - saving time while improving quality. METHODS: Oracle Empirica Signal software was utilized to extract cases with CM that are Known Implicating Medications (KIM) for each AE according to public regulatory information from drug labels - FDA Structured Product Labeling (SPL) or EMA Summary of Product Characteristics (SPC). SAS Enterprise Guide was used to further process the data generated from Oracle Empirica Signal software. RESULTS: For any target drug being evaluated for safety purposes, a KIM reference table can be generated, which summarizes all potential causality contributions from CMs. CONCLUSION: In addition to providing standalone KIM table as reference, adoption of this concept and automation may also be fully integrated into commercial signal detection and management software packages for easy use and accessibility and may even lead to reduced False Positive rate in signal detection within the PV space.

Melanoma in children and the use of sentinel lymph node biopsy.

BACKGROUND: The rarity of pediatric melanoma prompted our review of sentinel lymph node biopsy (SLNB) and associated prognosis. METHODS: A chart review from 1989 to 2004 revealed 12 cases of cutaneous melanoma. Variables analyzed included demographics, site, histology, tumor characteristics, nodal status, and distant metastasis (TMN status), SLNB and/or therapeutic lymph node dissection (TLND), adjuvant treatment, disease-free survival, and overall survival. RESULTS: Mean age at diagnosis was 8.5 years with 7 of 12 patients younger than 10 years (range, 0.3-17.9 years). Site distribution was the extremity (7), trunk (4), and head and neck (1). All patients had wide local excision and primary closure or skin graft. Breslow's thickness averaged 3.5 mm (range, 0.8-6 mm). Only patients diagnosed after 2000 with melanomas thicker than 1 mm were offered SLNB (extremity = 2, trunk = 1, head and neck = 1). Two patients had positive sentinel lymph node: one received TLND and interferon and one is followed closely (unclear pathology). Disease-free survival and overall survival by stage were stage I (n = 2, 3.9 years, 100%), stage II (n = 6, 7.7 years, 83%), stage III (n = 4, 2.6 years, 75%), and stage IV (n = 0). A stage II patient with negative SLNB, adjuvant chemotherapy, and interferon died 26 months after diagnosis, and a stage III patient with clinically and pathologically positive nodes after TLND died 15 months after diagnosis. CONCLUSION: Although a negative SLNB does not guarantee a favorable prognosis, its increasing use will further define its role in pediatric melanoma.