Long COVID-19 and Peripheral Serotonin: A Commentary and Reconsideration

George M Anderson,1,2 Edwin H Cook,3 Randy D Blakely,4 James S Sutcliffe,5,6 Jeremy Veenstra-VanderWeele7,8 1Yale Child Study Center, Yale University School of Medicine, New Haven, CT, USA; 2Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA; 3Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA; 4FAU Stiles-Nicholson Brain Institute, Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA; 5Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN, USA; 6Department of Psychiatry & Behavioral Sciences, Vanderbilt University, Nashville, TN, USA; 7Department of Psychiatry, College of Medicine, Columbia University, New York, NY, USA; 8New York State Psychiatric Institute, Columbia University, New York, NY, USACorrespondence: George M Anderson, Yale Child Study Center, 230 S. Frontage Road, New Haven, CT, USA, Email [email protected]: We believe there are serious problems with a recently published and highly publicized paper entitled “Serotonin reduction in post-acute sequelae of viral infection.” The blood centrifugation procedure reportedly used by Wong et al would produce plasma that is substantially (over 95%) depleted of platelets. Given this, their published mean plasma serotonin values of 1.2 uM and 2.4 uM for the control/contrast groups appear to be at least 30 to 60 times too high and should be disregarded. The plasma serotonin values reported for the long COVID and viremia patients also should be disregarded, as should any comparisons to the control/contrast groups. We also note that the plasma serotonin means for the two control/contrast groups are not in good agreement. In the “Discussion” section, Wong et al state that their results tend to support the use of selective serotonin reuptake inhibitors (SSRIs) for the treatment of COVID-19, and they encourage further clinical trials of SSRIs. While they state that, “Our animal models demonstrate that serotonin levels can be restored and memory impairment reversed by precursor supplementation or SSRI treatment”, it should be noted that no data are presented showing an increase or restoration in circulating serotonin with SSRI administration. In fact, one would expect a marked decline in platelet serotonin due to SSRIs’ effective inhibition of the platelet serotonin transporter. Wong et al hypothesize that problems of long COVID arise from too little peripheral serotonin. However, given the frequent presence of a hyperaggregation state in long COVID, and the known augmenting effects of platelet serotonin on platelet aggregation, it is plausible to suggest that reductions in platelet serotonin might be associated with a lessening of the cardiovascular sequelae of COVID-19.Keywords: serotonin, COVID-19, plasma, platelets, long COVID, viral infectio

TPH2 polymorphisms and expression in Prader-Willi syndrome subjects with differing genetic subtypes

Prader-Willi syndrome (PWS) is a genetic imprinting disease that causes developmental and behavioral disturbances resulting from loss of expression of genes from the paternal chromosome 15q11-q13 region. In about 70% of subjects, this portion of the paternal chromosome is deleted, while 25% have two copies of the maternal chromosome 15, or uniparental maternal disomy (UPD; the remaining subjects have imprinting center defects. There are several documented physical and behavioral differences between the two major PWS genetic subtypes (deletion and UPD) indicating the genetic subtype plays a role in clinical presentation. Serotonin is known to be disturbed in PWS and affects both eating behavior and compulsion, which are reported to be abnormal in PWS. We investigated the tryptophan hydroxylase gene (TPH2), the rate-limiting enzyme in the production of brain serotonin, by analyzing three different TPH2 gene polymorphisms, transcript expression, and correlation with PWS genetic subtype. DNA and RNA from lymphoblastoid cell lines derived from 12 PWS and 12 comparison subjects were used for the determination of genetic subtype, TPH2 polymorphisms and quantitative RT-PCR analysis. A similar frequency of TPH2 polymorphisms was seen in the PWS and comparison subjects with PWS deletion subjects showing increased expression with one or more TPH2 polymorphism. Both PWS deletion and PWS UPD subjects had significantly lower TPH2 expression than control subjects and PWS deletion subjects had significantly lower TPH2 expression compared with PWS UPD subjects. PWS subjects with 15q11-q13 deletions had lower TPH2 expression compared with PWS UPD or control subjects, requiring replication and further studies to identify the cause including identification of disturbed gene interactions resulting from the deletion process

Associations between nutrient intake and gastrointestinal symptoms in autism spectrum disorder

Many children and adolescents with autism spectrum disorder (ASD) have significant gastrointestinal (GI) symptoms, but the etiology is not well understood. Studies have shown conflicting evidence on whether there are nutritional deficiencies in the various diets of individuals with ASD. However, little is known about the relationship between dietary intake and GI symptomatology in ASD. The goal of the present study was to assess for potential relationships between GI symptoms and nutrient intake from diet in the same sample of individuals from the previous study, and to determine whether dietary differences might have contributed to our previously observed findings of a relationship between stress responses and GI functioning in ASD

Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder

PosterAutism spectrum disorder (ASD) is characterized by impairments in social communication and abnormal repetitive behavior patterns. Recent studies have shown a strong association between ASD and gastrointestinal (GI) symptomatology. Some individuals with ASD show altered reactivity to stress, as well as altered immune markers, particularly stress responsive cytokines including TNF-alpha and IL-6. To assess potential relationships between GI symptoms and stress response, we examined whether GI symptoms are associated with increases in stress-associated endocrine markers and cytokines in ASD. We also conducted exploratory analyses the examine the relationship between IL-6, TNF-alpha, cortisol, and intelligence, as well as the effects of the presence or absence of co-occurring medical conditions on the relationship between IL-6, TNF-alpha, cortisol, and GI symptoms. Given the aforementioned findings, we expected to find positive relationships between GI symptoms and biomarkers of stress, including cortisol levels, IL-6, and TNF-alpha

Genome-wide and Ordered-Subset linkage analyses provide support for autism loci on 17q and 19p with evidence of phenotypic and interlocus genetic correlates

BACKGROUND: Autism is a neurobehavioral spectrum of phenotypes characterized by deficits in the development of language and social relationships and patterns of repetitive, rigid and compulsive behaviors. Twin and family studies point to a significant genetic etiology, and several groups have performed genomic linkage screens to identify susceptibility loci. METHODS: We performed a genome-wide linkage screen in 158 combined Tufts, Vanderbilt and AGRE (Autism Genetics Research Exchange) multiplex autism families using parametric and nonparametric methods with a categorical autism diagnosis to identify loci of main effect. Hypothesizing interdependence of genetic risk factors prompted us to perform exploratory studies applying the Ordered-Subset Analysis (OSA) approach using LOD scores as the trait covariate for ranking families. We employed OSA to test for interlocus correlations between loci with LOD scores ≥1.5, and empirically determined significance of linkage in optimal OSA subsets using permutation testing. Exploring phenotypic correlates as the basis for linkage increases involved comparison of mean scores for quantitative trait-based subsets of autism between optimal subsets and the remaining families. RESULTS: A genome-wide screen for autism loci identified the best evidence for linkage to 17q11.2 and 19p13, with maximum multipoint heterogeneity LOD scores of 2.9 and 2.6, respectively. Suggestive linkage (LOD scores ≥1.5) at other loci included 3p, 6q, 7q, 12p, and 16p. OSA revealed positive correlations of linkage between the 19p locus and 17q, between 19p and 6q, and between 7q and 5p. While potential phenotypic correlates for these findings were not identified for the chromosome 7/5 combination, differences indicating more rapid achievement of "developmental milestones" was apparent in the chromosome 19 OSA-defined subsets for 17q and 6q. OSA was used to test the hypothesis that 19p linkage involved more rapid achievement of these milestones and it revealed significantly increased LOD* scores at 19p13. CONCLUSIONS: Our results further support 19p13 as harboring an autism susceptibility locus, confirm other linkage findings at 17q11.2, and demonstrate the need to analyze more discreet trait-based subsets of complex phenotypes to improve ability to detect genetic effects

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

Polymorphism screening and haplotype analysis of the tryptophan hydroxylase gene (TPH1) and association with bipolar affective disorder in Taiwan

BACKGROUND: Disturbances in serotonin neurotransmission are implicated in the etiology of many psychiatric disorders, including bipolar affective disorder (BPD). The tryptophan hydroxylase gene (TPH), which codes for the enzyme catalyzing the rate-limiting step in serotonin biosynthetic pathway, is one of the leading candidate genes for psychiatric and behavioral disorders. In a preliminary study, we found that TPH1 intron7 A218C polymorphism was associated with BPD. This study was designed to investigate sequence variants of the TPH1 gene in Taiwanese and to test whether the TPH1 gene is a susceptibility factor for the BPD. METHODS: Using a systematic approach, we have searched the exons and promoter region of the TPH1 gene for sequence variants in Taiwanese Han and have identified five variants, A-1067G, G-347T, T3804A, C27224T, and A27237G. These five variants plus another five taken from the literature and a public database were examined for an association in 108 BPD patients and 103 controls; no association was detected for any of the 10 variants. RESULTS: Haplotype constructions using these 10 SNPs showed that the 3 most common haplotypes in both patients and controls were identical. One of the fourth common haplotype in the patient group (i.e. GGGAGACCCA) was unique and showed a trend of significance with the disease (P = 0.028). However, the significance was abolished after Bonferroni correction thus suggesting the association is weak. In addition, three haplotype-tagged SNPs (htSNPs) were selected to represent all haplotypes with frequencies larger than 2% in the Taiwanese Han population. The defined TPH1 htSNPs significantly reduce the marker number for haplotype analysis thus provides useful information for future association studies in our population. CONCLUSION: Results of this study did not support the role of TPH1 gene in BPD etiology. As the current studies found the TPH1 gene under investigation belongs to the peripheral serotonin system and may link to a cardiac dysfunction phenotype, a second TPH gene that functions predominantly in the brain (i.e., nTPH or TPH2) should be the target for the future association study

Cytogenetic abnormalities and fragile-x syndrome in Autism Spectrum Disorder

BACKGROUND: Autism is a behavioral disorder with impaired social interaction, communication, and repetitive and stereotypic behaviors. About 5–10 % of individuals with autism have 'secondary' autism in which an environmental agent, chromosome abnormality, or single gene disorder can be identified. Ninety percent have idiopathic autism and a major gene has not yet been identified. We have assessed the incidence of chromosome abnormalities and Fragile X syndrome in a population of autistic patients referred to our laboratory. METHODS: Data was analyzed from 433 patients with autistic traits tested using chromosome analysis and/or fluorescence in situ hybridization (FISH) and/or molecular testing for fragile X syndrome by Southern and PCR methods. RESULTS: The median age was 4 years. Sex ratio was 4.5 males to 1 female [354:79]. A chromosome (cs) abnormality was found in 14/421 [3.33 %] cases. The aberrations were: 4/14 [28%] supernumerary markers; 4/14 [28%] deletions; 1/14 [7%] duplication; 3/14 [21%] inversions; 2/14 [14%] translocations. FISH was performed on 23 cases for reasons other than to characterize a previously identified cytogenetic abnormality. All 23 cases were negative. Fragile-X testing by Southern blots and PCR analysis found 7/316 [2.2 %] with an abnormal result. The mutations detected were: a full mutation (fM) and abnormal methylation in 3 [43 %], mosaic mutations with partial methylation of variable clinical significance in 3 [43%] and a permutation carrier [14%]. The frequency of chromosome and fragile-X abnormalities appears to be within the range in reported surveys (cs 4.8-1.7%, FRAX 2–4%). Limitations of our retrospective study include paucity of behavioral diagnostic information, and a specific clinical criterion for testing. CONCLUSIONS: Twenty-eight percent of chromosome abnormalities detected in our study were subtle; therefore a high resolution cytogenetic study with a scrutiny of 15q11.2q13, 2q37 and Xp23.3 region should be standard practice when the indication is autism. The higher incidence of mosaic fragile-X mutations with partial methylation compared to FRAXA positive population [50% vs 15–40%] suggests that faint bands and variations in the Southern band pattern may occur in autistic patients

Glutathione pathway gene variation and risk of autism spectrum disorders

Despite evidence that autism is highly heritable with estimates of 15 or more genes involved, few studies have directly examined associations of multiple gene interactions. Since inability to effectively combat oxidative stress has been suggested as a mechanism of autism, we examined genetic variation 42 genes (308 single-nucleotide polymorphisms (SNPs)) related to glutathione, the most important antioxidant in the brain, for both marginal association and multi-gene interaction among 318 case–parent trios from The Autism Genetic Resource Exchange. Models of multi-SNP interactions were estimated using the trio Logic Regression method. A three-SNP joint effect was observed for genotype combinations of SNPs in glutaredoxin, glutaredoxin 3 (GLRX3), and cystathione gamma lyase (CTH); OR = 3.78, 95% CI: 2.36, 6.04. Marginal associations were observed for four genes including two involved in the three-way interaction: CTH, alcohol dehydrogenase 5, gamma-glutamylcysteine synthetase, catalytic subunit and GLRX3. These results suggest that variation in genes involved in counterbalancing oxidative stress may contribute to autism, though replication is necessary