ImportanceAntemortem infection is a risk factor for sudden infant death syndrome (SIDS)—the leading postneonatal cause of infant mortality in the developed world. Manifestations of infection and inflammation are not always apparent in clinical settings or by standard autopsy; thus, enhanced resolution approaches are needed.ObjectiveTo ascertain whether a subset of SIDS cases is associated with neuroinflammation and occult infection.Design, Setting, and ParticipantsIn this case-control study, postmortem fluids from SIDS cases and controls collected between July 2011 and November 2018 were screened for elevated inflammatory markers, specifically cerebrospinal fluid (CSF) neopterin and CSF and serum cytokines. CSF, liver, and brain tissue from SIDS cases with elevated CSF neopterin were subjected to metagenomic next-generation sequencing (mNGS) to probe for infectious pathogens. Brainstem tissue from a subset of these cases was analyzed by single-nucleus RNA sequencing (snRNAseq) to measure cell type–specific gene expression associated with neuroinflammation and infection. All tissue and fluid analyses were performed from April 2019 to January 2023 in a pathology research laboratory. Included was autopsy material from infants dying of SIDS and age-matched controls dying of known causes.ExposuresThere were no interventions or exposures.Main Outcomes and MeasuresCSF neopterin levels were measured by high-performance liquid chromatography. Cytokines were measured by multiplex fluorometric assay. mNGS was performed on liver, CSF, brain, and brainstem tissue. snRNAseq was performed on brainstem tissue.ResultsA cohort of 71 SIDS cases (mean [SD] age, 55.2 [11.4] postconceptional weeks; 42 male [59.2%]) and 20 controls (mean [SD] age, 63.2 [16.9] postconceptional weeks; 11 male [55.0%]) had CSF and/or serum available. CSF neopterin was screened in 64 SIDS cases and 15 controls, with no exclusions. Tissues from 6 SIDS cases were further analyzed. For CSF neopterin measures, SIDS samples were from infants with mean (SD) age of 54.5 (11.3) postconceptional weeks (38 male [59.4%]) and control samples were from infants with mean (SD) age of 61.5 (17.4) postconceptional weeks (7 male [46.7%]). A total of 6 SIDS cases (9.3%) with high CSF neopterin were identified, suggestive of neuroinflammation. mNGS detected human parechovirus 3 (HPeV3) in tissue and CSF from 1 of these 6 cases. snRNAseq of HPeV3-positive brainstem tissue (medulla) revealed dramatic enrichment of transcripts for genes with predominately inflammatory functions compared with 3 age-matched SIDS cases with normal CSF neopterin levels.Conclusions and RelevanceNext-generation molecular tools in autopsy tissue provide novel insight into pathogens that go unrecognized by normal autopsy methodology, including in infants dying suddenly and unexpectedly.

中文翻译：

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婴儿猝死综合症神经炎症和隐匿性感染的多组学分析

重要性生前感染是婴儿猝死综合症 (SIDS) 的危险因素，而 SIDS 是发达国家婴儿死亡的主要原因。感染和炎症的表现在临床环境中或通过标准尸检并不总是明显的；因此，需要增强的解决方法。目的确定 SIDS 病例的子集是否与神经炎症和隐匿性感染相关。设计、设置和参与者在这项病例对照研究中，收集了 2011 年 7 月至 2018 年 11 月期间收集的 SIDS 病例和对照的尸检液体筛查了升高的炎症标志物，特别是脑脊液 (CSF) 新蝶呤、CSF 和血清细胞因子。对脑脊液新蝶呤升高的 SIDS 病例的脑脊液、肝脏和脑组织进行宏基因组下一代测序 (mNGS)，以探测感染性病原体。通过单核 RNA 测序 (snRNAseq) 分析了其中一部分病例的脑干组织，以测量与神经炎症和感染相关的细胞类型特异性基因表达。所有组织和体液分析均于 2019 年 4 月至 2023 年 1 月在病理研究实验室进行。包括死于 SIDS 的婴儿和因已知原因死亡的年龄匹配对照的尸检材料。暴露没有干预或暴露。主要结果和措施通过高效液相色谱法测量脑脊液新蝶呤水平。通过多重荧光测定法测量细胞因子。对肝脏、脑脊液、大脑和脑干组织进行 mNGS。对脑干组织进行 snRNAseq。 结果 71 名 SIDS 病例（平均 [SD] 年龄，55.2 [11.4] 孕后周；42 名男性 [59.2%]）和 20 名对照者（平均 [SD] 年龄，63.2 [16.9] 孕后周）组成的队列; 11 名男性 [55.0%]）有可用的脑脊液和/或血清。对 64 名 SIDS 病例和 15 名对照者进行了脑脊液新蝶呤筛查，无一例外。对 6 例 SIDS 病例的组织进行了进一步分析。对于脑脊液新蝶呤测量，SIDS 样本来自受孕后平均 (SD) 年龄为 54.5 (11.3) 周的婴儿（38 名男性 [59.4%]），对照样本来自受孕后平均 (SD) 年龄为 61.5 (17.4) 周的婴儿（7 名男性 [46.7%]）。共有 6 例 SIDS 病例（9.3%）被发现具有高脑脊液新蝶呤水平，提示存在神经炎症。mNGS 在这 6 例病例中的 1 例的组织和脑脊液中检测到人类副肠孤病毒 3 (HPeV3)。HPeV3 阳性脑干组织（髓质）的 snRNAseq 显示，与 3 例脑脊液新蝶呤水平正常的年龄匹配的 SIDS 病例相比，主要具有炎症功能的基因转录物显着富集。结论和相关性尸检组织中的下一代分子工具提供了对病原体的新见解正常尸检方法无法识别这种情况，包括婴儿突然意外死亡。