Hairong Wu

Background: Variants in the ATP binding cassette protein subfamily D member 1 (ABCD1) gene are known to cause X‐linked adrenoleukodystrophy (X‐ALD). This study focused on the characteristics of ABCD1 variants in Chinese X‐ALD families and elucidated the value of genetic approaches for X‐ALD.Methods: 68 male probands diagnosed as X‐ALD were screened for ABCD1 variants by the Sanger sequencing of polymerase chain reaction (PCR) products and multiplex ligation‐dependent probe amplification (MLPA) combined with long‐range PCR. Prenatal diagnosis was performed in 20 foetuses of 17 probands’ mothers. Descriptive statistics were used to summarise the gene variants and prenatal diagnosis characteristics and outcomes.Results: This study allowed the identification of 61 variants occurring in 68 families, including 58 single nucleotide variants or small deletion/insertion variants and 3 large deletions. Three probands with no variants detected by next‐generation sequencing were found to have variants by PCR‐sequencing. Prenatal diagnosis found that 10 of the 20 foetuses had no variants in ABCD1.Conclusion: PCR primers that do not amplify the pseudogenes must be used for PCR‐sequencing. MLPA combined with long‐range PCR can detect large deletions and insertions, which are usually undetectable by PCR‐sequencing. Prenatal diagnosis could help to prevent the birth of infants with X‐ALD.

The innate immune system is an ancient defense system in the process of biological evolution, which can quickly and efficiently resist pathogen infection. In mammals, mannose-binding lectin (MBL) is a key molecule in the innate immune and plays an essential role in the first line of host defense against pathogenic bacteria. However, the evolutionary origins and ancient roles of immune defense of MBL and its mechanism in clearance of microbial pathogens are still unclear, especially in early vertebrates. In this study, Oreochromis niloticus MBL (OnMBL) was successfully isolated and purified from the serum of Nile tilapia (O. niloticus). The OnMBL was able to bind and agglutinate with two important pathogens of tilapia, Streptococcus agalactiae and Aeromonas hydrophila. Interestingly, the OnMBL was able to significantly inhibit the proliferation of pathogenic bacteria and reduce the inflammatory response. Upon bacterial challenge, the downregulation of OnMBL expression by RNA interference could lead to rapid proliferation of the pathogenic bacteria, ultimately resulting in tilapia death. However, the phenotype was rescued by reinjection of the OnMBL, which restored the healthy status of the knockdown tilapia. Moreover, a mechanistic analysis revealed that the OnMBL could clear pathogenic bacteria by collaborating with cell-surface calreticulin to facilitate phagocytosis in a complement activation-independent manner. To our knowledge, these results provide the first evidence on the antibacterial response mechanism of MBL performing evolutionary conserved function to promote opsonophagocytosis of macrophages in early vertebrates and reveals new insights into the understanding of the evolutionary origins and ancient roles basis of the C-type lectins in the innate immune defense. Key Points OnMBL was able to bind and agglutinate with pathogens. OnMBL was able to significantly reduce the proliferation of pathogens. OnMBL could promote phagocytosis of macrophages with OnCRT interaction.