Short-chain fatty acid producers in the gut are associated with pediatric multiple sclerosis onset

OBJECTIVE

The relationship between multiple sclerosis and the gut microbiome has been supported by animal models in which commensal microbes are required for the development of experimental autoimmune encephalomyelitis. However, observational study findings in humans have only occasionally converged when comparing multiple sclerosis cases and controls which may in part reflect confounding by comorbidities and disease duration. The study of microbiome in pediatric-onset multiple sclerosis offers unique opportunities as it is closer to biological disease onset and minimizes confounding by comorbidities and environmental exposures.

METHODS

A multicenter case-control study in which 35 pediatric-onset multiple sclerosis cases were 1:1 matched to healthy controls on age, sex, self-reported race, ethnicity, and recruiting site. Linear mixed effects models, weighted correlation network analyses, and PICRUSt2 were used to identify microbial co-occurrence networks and for predicting functional abundances based on marker gene sequences.

RESULTS

Two microbial co-occurrence networks (one reaching significance after adjustment for multiple comparisons; q < 0.2) were identified, suggesting interdependent bacterial taxa that exhibited association with disease status. Both networks indicated a potentially protective effect of higher relative abundance of bacteria observed in these clusters. Functional predictions from the significant network suggested a contribution of short-chain fatty acid producers through anaerobic fermentation pathways in healthy controls. Consistent family-level findings from an independent Canadian-US study (19 case/control pairs) included Ruminococaccaeae and Lachnospiraceae (p < 0.05). Macronutrient intake was not significantly different between cases and controls, minimizing the potential for dietary confounding.

INTERPRETATION

Our results suggest that short-chain fatty acid producers may be important contributors to multiple sclerosis onset.

Adverse childhood experiences in early life increase the odds of depression among adults with multiple sclerosis

Background

Adverse childhood experiences are demonstrated risk factors for depression, a common co-morbidity of multiple sclerosis, but are understudied among people with multiple sclerosis.

Objective

Estimate the association between adverse childhood experiences and depression among 1,990 adults with multiple sclerosis.

Methods

Participants were members of Kaiser Permanente Northern California from two studies between 2006 and 2021 and were diagnosed with multiple sclerosis by a neurologist. Adverse childhood experiences were assessed using two instruments, including the Behavioral Risk Factor Surveillance System. Participants self-reported ever experiencing a major depressive episode. Meta-analysis random effects models and logistic regression were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) to assess the relationship between adverse childhood experiences and a history of depression across study samples. Adverse childhood experiences were expressed as any/none, individual events, and counts. Models adjusted for sex, birth year, race, and ethnicity.

Results

Exposure to any adverse childhood experiences increased the odds of depression in people with multiple sclerosis (OR: 1.71, 95% CI: 1.21-2.42). Several individual adverse childhood experiences were also strongly associated with depression, including "significant abuse or neglect" (OR: 2.79, 95% CI: 2.11-3.68).

Conclusion

Findings suggest that adverse childhood experiences are associated with depression among people with multiple sclerosis. Screening for depression should be done regularly, especially among people with multiple sclerosis with a history of adverse childhood experiences.

Rare and low-frequency coding genetic variants contribute to pediatric-onset multiple sclerosis

BACKGROUND

Rare genetic variants are emerging as important contributors to the heritability of multiple sclerosis (MS). Whether rare variants also contribute to pediatric-onset multiple sclerosis (POMS) is unknown.

OBJECTIVE

To test whether genes harboring rare variants associated with adult-onset MS risk (PRF1, PRKRA, NLRP8, and HDAC7) and 52 major histocompatibility complex (MHC) genes are associated with POMS.

METHODS

We analyzed DNA samples from 330 POMS cases and 306 controls from the US Network of Pediatric MS Centers and Kaiser Permanente Northern California for which Illumina ExomeChip genotypes were available. Using the gene-based method "SKAT-O," we tested the association between candidate genes and POMS risk.

RESULTS

After correction for multiple comparisons, one adult-onset MS gene (PRF1, p = 2.70 × 10^-3) and two MHC genes (BRD2, p = 5.89 × 10^-5 and AGER, p = 7.96 × 10^-5) were significantly associated with POMS. Results suggest these are independent of HLA-DRB1*1501.

CONCLUSION

Findings support a role for rare coding variants in POMS susceptibility. In particular, rare minor alleles within PRF1 were more common among individuals with POMS compared to controls while the opposite was true for rare variants within significant MHC genes, BRD2 and AGER. These genes would not have been identified by common variant studies, emphasizing the merits of investigating rare genetic variation in complex diseases.

A Cross-Trait, Mendelian Randomization Study to Investigate Whether Migraine Is a Risk Factor for Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Migraine is common among people with multiple sclerosis (MS), but the reasons for this are unknown. We tested three hypothesized mechanisms for this observed comorbidity, including migraine is a risk factor for MS, genetic variants are shared between the conditions, and migraine is a result of MS.

METHODS

Data were from two sources: publicly available summary statistics from genome-wide association studies of MS (N=115,748) and migraine (N=375,752 and N=361,141), and a case-control study of MS recruited from the Kaiser Permanente Northern California Health Plan (N=1,991). For the latter participants, migraine status was ascertained using a validated electronic health record migraine probability algorithm or self-report. Using the public summary statistics, we used two-sample Mendelian randomization to test whether a migraine genetic instrumental variable was associated with MS. We used linkage disequilibrium score regression and LOGODetect to ascertain whether MS and migraine shared genetic variants across the genome and regionally. Using the Northern California MS cohort, we used logistic regression to identify whether people with both MS and migraine had different odds of clinical characteristics (e.g., age at MS onset, Perceived Deficits Questionnaire, depression) or MS-specific risk factors (e.g., body mass index, smoking status, infectious mononucleosis status) compared to people with MS without migraine.¬¬ RESULTS: We did not find evidence supporting migraine as a causal risk factor for MS (p=0.29). We did, however, identify four major histocompatibility complex (MHC) loci shared between MS and migraine. Among the Northern California MS cohort, 774 (39%) experienced a migraine. People with both MS and migraine from this cohort were more likely to ever smoke (odds ratio (OR)=1.30, 95% confidence interval (CI): 1.08, 1.57), have worse self-reported cognitive deficits (OR=1.04, 95% CI: 1.02, 1.06), and ever experience depression (OR=1.48, 95% CI: 1.22, 1.80).

DISCUSSION

Our findings do not support migraine as a causal risk factor for MS. Several genetic variants, particularly in the MHC, may account for some of the overlap. It seems likely that migraine within the context of MS is a result of MS. Identifying what increases risk of migraine within MS might lead to improved treatment and quality of life.

Case-control study of adverse childhood experiences and multiple sclerosis risk and clinical outcomes

Background

Adverse childhood experiences (ACEs) are linked to numerous health conditions but understudied in multiple sclerosis (MS). This study’s objective was to test for the association between ACEs and MS risk and several clinical outcomes.

Methods

We used a sample of adult, non-Hispanic MS cases (n = 1422) and controls (n = 1185) from Northern California. Eighteen ACEs were assessed including parent divorce, parent death, and abuse. Outcomes included MS risk, age of MS onset, Multiple Sclerosis Severity Scale score, and use of a walking aid. Logistic and linear regression estimated odds ratios (ORs) (and beta coefficients) and 95% confidence intervals (CIs) for ACEs operationalized as any/none, counts, individual events, and latent factors/patterns.

Results

Overall, more MS cases experienced ≥1 ACE compared to controls (54.5% and 53.8%, respectively). After adjusting for sex, birthyear, and race, this small difference was attenuated (OR = 1.01, 95% CI: 0.87, 1.18). There were no trends of increasing or decreasing odds of MS across ACE count categories. Consistent associations between individual ACEs between ages 0–10 and 11–20 years and MS risk were not detected. Factor analysis identified five latent ACE factors, but their associations with MS risk were approximately null. Age of MS onset and other clinical outcomes were not associated with ACEs after multiple testing correction.

Conclusion

Despite rich data and multiple approaches to operationalizing ACEs, no consistent and statistically significant effects were observed between ACEs with MS. This highlights the challenges of studying sensitive, retrospective events among adults that occurred decades before data collection.

Gut microbiome is associated with multiple sclerosis activity in children

OBJECTIVE

To identify features of the gut microbiome associated with multiple sclerosis activity over time.

METHODS

We used 16S ribosomal RNA sequencing from stool of 55 recently diagnosed pediatric-onset multiple sclerosis patients. Microbiome features included the abundance of individual microbes and networks identified from weighted genetic correlation network analyses. Prentice-Williams-Peterson Cox proportional hazards models estimated the associations between features and three disease activity outcomes: clinical relapses and both new/enlarging T2 lesions and new gadolinium-enhancing lesions on brain MRI. Analyses were adjusted for age, sex, and disease-modifying therapies.

RESULTS

Participants were followed, on average, 2.1 years. Five microbes were nominally associated with all three disease activity outcomes after multiple testing correction. These included butyrate producers Odoribacter (relapse hazard ratio = 0.46, 95% confidence interval: 0.24, 0.88) and Butyricicoccus (relapse hazard ratio = 0.49, 95% confidence interval: 0.28, 0.88). Two networks of co-occurring gut microbes were significantly associated with a higher hazard of both MRI outcomes (gadolinium-enhancing lesion hazard ratios (95% confidence intervals) for Modules 32 and 33 were 1.29 (1.08, 1.54) and 1.42 (1.18, 1.71), respectively; T2 lesion hazard ratios (95% confidence intervals) for Modules 32 and 33 were 1.34 (1.15, 1.56) and 1.41 (1.21, 1.64), respectively). Metagenomic predictions of these networks demonstrated enrichment for amino acid biosynthesis pathways.

INTERPRETATION

Both individual and networks of gut microbes were associated with longitudinal multiple sclerosis activity. Known functions and metagenomic predictions of these microbes suggest the important role of butyrate and amino acid biosynthesis pathways. This provides strong support for future development of personalized microbiome interventions to modify multiple sclerosis disease activity.

Mg doping affects dislocation core structures in GaN

Aberration-corrected scanning transmission electron microscopy was used to investigate the core structures of threading dislocations in undoped GaN films with both high and low dislocation densities, and in a comparable high dislocation density Mg-doped GaN film. All a-type dislocations in all samples have a 5/7-atom core structure. In contrast, most (a+c)-type dislocations in undoped GaN dissociate due to local strain variations from nearby dislocations. In contrast, Mg doping prevents (a+c)-type dislocation dissociation. Our data indicate that Mg affects dislocation cores in GaN significantly.

The incidence of necrotizing enterocolitis after introducing standardized feeding schedules for infants between 1250 and 2500 grams and less than 35 weeks of gestation

OBJECTIVE

To evaluate the incidence of necrotizing enterocolitis (NEC) after implementing standardized feeding schedules.

METHOD

This was a cohort study, which retrospectively reviewed the incidence of NEC for a 3-year period before implementing feeding schedules and prospectively evaluated the incidence of NEC for a 3-year period after implementing feeding schedules in infants with birth weights between 1250 and 2500 g and <35 weeks' gestation. The feeding schedules were comprised of 3 parts. First, no group was fed within the first 24 hours of life. Feeds were started between 24 to 72 hours of life based on birth weight. Second, the initial feed was full-strength breast milk or half-strength formula. Half-strength formula was changed to full-strength formula on the fourth day for all groups. Third, the daily feeding volume increase was no greater than 20 mL/kg for all groups.

RESULTS

In the 477 infants before the feeding schedules, there were 23 (4.8%) cases of definite NEC defined as pneumatosis on abdominal film or NEC confirmed at the time of surgery, and in the 466 infants after the feeding schedules, there were 5 (1.1%) cases of NEC. Before the feeding schedules, those who developed NEC started feeds sooner 1.5 +/- 1.5 (+/- standard deviation [SD]) days versus 3.0 +/-.7 (+/-SD) days, reached full feeds sooner 4.0 +/- 1.8 (+/- SD) days versus 9.8 +/-.5 (+/-SD) days and were more likely to have been started on formula than those who developed NEC after implementing the feeding schedules. The mean time for NEC to occur after the feeding schedules increased from 5.9 +/- 4.1 (+/-SD) days to 19.4 +/- 16.3 (+/- SD) days, although not statistically significant. The number of mothers who received prenatal steroids increased after the feeding schedules. The number of infants with NEC, however, significantly decreased whether their mothers were pretreated with steroids. The risk of NEC was reduced 84% after the introduction of feeding schedules as determined by multiple logistic regression analysis and adjusting for confounding by birth weight, white race, prenatal steroid exposure, day of life of first feed, day of life to reach full feeds, and breast milk.

CONCLUSION

The incidence of NEC was significantly decreased after the implementation of standardized feeding schedules, which was independent of birth weight, prenatal steroid exposure, breast milk, day of life of first feed, and the number of days to reach full feeds.