Diagnosis of Multisystem Inflammatory Syndrome in Children by a Whole-Blood Transcriptional Signature

BACKGROUND

To identify a diagnostic blood transcriptomic signature that distinguishes multisystem inflammatory syndrome in children (MIS-C) from Kawasaki disease (KD), bacterial infections, and viral infections.

METHODS

Children presenting with MIS-C to participating hospitals in the United Kingdom and the European Union between April 2020 and April 2021 were prospectively recruited. Whole-blood RNA Sequencing was performed, contrasting the transcriptomes of children with MIS-C (n = 38) to those from children with KD (n = 136), definite bacterial (DB; n = 188) and viral infections (DV; n = 138). Genes significantly differentially expressed (SDE) between MIS-C and comparator groups were identified. Feature selection was used to identify genes that optimally distinguish MIS-C from other diseases, which were subsequently translated into RT-qPCR assays and evaluated in an independent validation set comprising MIS-C (n = 37), KD (n = 19), DB (n = 56), DV (n = 43), and COVID-19 (n = 39).

RESULTS

In the discovery set, 5696 genes were SDE between MIS-C and combined comparator disease groups. Five genes were identified as potential MIS-C diagnostic biomarkers (HSPBAP1, VPS37C, TGFB1, MX2, and TRBV11-2), achieving an AUC of 96.8% (95% CI: 94.6%-98.9%) in the discovery set, and were translated into RT-qPCR assays. The RT-qPCR 5-gene signature achieved an AUC of 93.2% (95% CI: 88.3%-97.7%) in the independent validation set when distinguishing MIS-C from KD, DB, and DV.

CONCLUSIONS

MIS-C can be distinguished from KD, DB, and DV groups using a 5-gene blood RNA expression signature. The small number of genes in the signature and good performance in both discovery and validation sets should enable the development of a diagnostic test for MIS-C.

Wide-host-range plasmids function in the genus thiobacillus

Plasmids S-a, RP4, R388, and several RP4 derivatives (pMD101, pDT387, and pDT566) were transmissible by conjugation to Thiobacillus novellus from Escherichia coli. Genetic markers were expressed in T. novellus, with the exception of chloramphenicol resistance and ampicillin resistance. Plasmids were not transmissible by conjugation from E. coli donors to Thiobacillus intermedius, T. perometabolis, T. neapolitanus, or T. acidophilus recipients, although they could be mated into these strains from T. novellus. All Thiobacillus species tested could transfer plasmids back to E. coli, with the exception of T. acidophilus. The donor-specific bacteriophages PRR1 and PRD1 were incapable of initiating the lytic cycle in RP4-bearing strains of T. novellus. The cosmid cloning vehicle pVK100 could be mobilized from E. coli to T. novellus with the aid of the "helper" plasmid pRK2013. pVK100 is stable in T. novellus, but pRK2013 is not maintained in this species. pRK2013 was also used to mobilize another cloning vector, R300B, to T. novellus. A previously unreported cryptic plasmid of approximately 24 megadaltons was observed in T. intermedius. No native plasmids were demonstrated in the other Thiobacillus species except in T. acidophilus, which contained cryptic plasmids ranging in size from 7.6 to 56 megadaltons (molecular mass).

Glutamate-mediated transmission, alcohol, and alcoholism

Glutamate-mediated neurotransmission may be involved in the range of adaptive changes in brain which occur after ethanol administration in laboratory animals, and in chronic alcoholism in human cases. Excitatory amino acid transmission is modulated by a complex system of receptors and other effectors, the efficacy of which can be profoundly affected by altered gene or protein expression. Local variations in receptor composition may underlie intrinsic regional variations in susceptibility to pathological change. Equally, ethanol use and abuse may bring about alterations in receptor subunit expression as the essence of the adaptive response. Such considerations may underlie the regional localization characteristic of the pathogenesis of alcoholic brain damage, or they may form part of the homeostatic change that constitutes the neural substrate for alcohol dependence.

Differential expression of Egr-1-like DNA-binding activities in the naive rat brain and after excitatory stimulation

Egr-1 and related proteins are inducible transcription factors within the brain recognizing the same consensus DNA sequence. Three Egr DNA-binding activities were observed in regions of the naive rat brain. Egr-1 was present in all brain regions examined. Bands composed, at least in part, of Egr-2 and Egr-3 were present in different relative amounts in the cerebral cortex, striatum, hippocampus, thalamus, and midbrain. All had similar affinity and specificity for the Egr consensus DNA recognition sequence. Administration of the convulsants NMDA, kainate, and pentylenetetrazole differentially induced Egr-1 and Egr-2/3 DNA-binding activities in the cerebral cortex, hippocampus, and cerebellum. All convulsants induced Egr-1 and Egr-2 immunoreactivity in the cerebral cortex and hippocampus. These data indicate that the members of the Egr family are regulated at different levels and may interact at promoters containing the Egr consensus sequence to fine tune a program of gene expression resulting from excitatory stimuli.

Transpositional Mutagenesis of Thiobacillus novellus and Thiobacillus versutus

Transpositional mutagenesis of Thiobacillus novellus by Tn 501 was achieved by means of the incompatibility of IncP plasmids. Tn 501 insertion caused three types of mutant phenotypes: isoleucine auxotrophy, lysine auxotrophy, and a reduced ability to oxidize reduced sulfur compounds and to fix CO 2 . Oxidation rates for elemental sulfur (S 0 ), thiosulfate (S 2 O 3 2− ), and tetrathionate (S 4 O 6 2− ) in mutants of the latter type were reduced relative to those of the nonmutant control strain. Incorporation of labeled bicarbonate (H 14 CO 3 − ) was also significantly impaired. Although suicide vehicles were not useful for the introduction of transposons into T. novellus , this method was effective for the Tn 1721 -induced mutagenesis of Thiobacillus versutus. Tn 1721 insertions resulted in the loss of the natural resistance of T. versutus to arsenate and gentamicin and in auxotrophies for isoleucine-valine, arginine, phenylalanine, valine, and panthothenate. Transpositional mutagenesis by either method should prove to be a useful tool for further study of these and other members of the genus Thiobacillus.

Complement system in pneumococcal infections

The properdin or alternate complement pathway may function as a heat-labile opsonin for pneumococci, and evidence has been sought for its activation in pneumococcal infections. Twenty-two patients had determinations of C1q, C4, properdin factor B, C3, and hemolytic complement during hospitalization for pneumococcal infection. Measurements were made during the first 36 h after admission on 16 patients and later during recovery on 16. The admission and recovery values were compared statistically with each other and with the levels of 15 normal individuals. The admission and recovery mean values were normal and nearly identical for C1q and C4, which are two early components of the classical pathway. The mean level of factor N, a properdin pathway component, was significantly depressed on admission, but the mean recovery value was normal. Admission levels for C3, a component of the late common pathway, were depressed, and recovery values were normal. Total hemolytic complement was decreased on admission, although the decrease was not significant for the patients with both admission and recovery determinations. The findings are consistent with the hypothesis that factor B is turned over rapidly, or consumed, early in pneumococcal infections; alternatively, persons with low baseline factor B levels may be particularly susceptible to pneumococcal infection.