No abstract

Since its first identification in Scotland, over 1000 cases of unexplained pediatric hepatitis in children have been reported worldwide, including 278 cases in the UK 1 . Here we report investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator subjects, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in liver, blood, plasma or stool from 27/28 cases. We found low levels of Adenovirus (HAdV) and Human Herpesvirus 6B (HHV-6B), in 23/31 and 16/23 respectively of the cases tested. In contrast, AAV2 was infrequently detected at low titre in blood or liver from control children with HAdV, even when profoundly immunosuppressed.AAV2, HAdV and HHV-6 phylogeny excluded emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T-cells and B-lineage cells.Proteomic comparison of liver tissue from cases and healthy controls, identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins.HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and in severe cases HHV-6B, may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children.

Background Galactosialidosis (GS) is a rare inherited lysosomal storage disorder (LSD) which is characterized by a defect in the lysosomal glycoprotein catabolism. We report, for the first time, the case of a child affected by GS presenting with recurrent episodes of extensive joint inflammation in both knee joints. The aim of this case-report is to describe the clinical presentation as well as the laboratory, radiologic and microscopic features of this unique presentation of GS. Furthermore, we explore inflammatory mechanisms potentially responsible for the origination of the arthritic joint pathology observed in our patient. Case presentation We describe the rare case of a 12-year-old boy diagnosed with GS (late infantile form) who presented with multiple episodes of inflammatory arthritis involving both knees; no other joints were suspected for joint inflammation. Laboratory results did not indicate an autoimmune disorder. Synovial fluid tested negative for any bacterial infection and ruled out a malignancy and crystal-induced arthritis. Microscopic examination of the synovial tissue revealed numerous foamy macrophages with extensive vacuolization, consistent with the previous diagnosis of GS. Treatment consisted of aspiration of excessive joint fluid and subsequent intra-articular injection of triamcinolonhexacetonide with excellent but transient result. Given the evidence of storage products within macrophages of the inflamed synovial tissue and the absence of other etiological clues, GS itself was considered as the primary cause for the relapsing inflammatory joint pathology. According to the restricted data on articular manifestations in GS, to date, GS cannot be linked directly to joint inflammation. Nevertheless, in several other LSDs, the accumulation of storage material has been associated with numerous osteoimmunological changes that might play a role in the pathophysiology of arthritic processes. Conclusions We hypothesize that the articular build-up of GS storage products triggered systemic as well as local inflammatory processes, resulting in the extensive inflammatory joint pathology as observed in our patient. Future identification of other patients with GS is required to corroborate the existence of an arthritic clinical phenotype of GS and to assess the underlying pathophysiology.