Coinfections identified from metagenomic analysis of cervical lymph nodes from tularemia patients.

BACKGROUND: Underlying coinfections may complicate infectious disease states but commonly go unnoticed because an a priori clinical suspicion is usually required so they can be detected via targeted diagnostic tools. Shotgun metagenomics is a broad diagnostic tool that can be useful for identifying multiple microbes simultaneously especially if coupled with lymph node aspirates, a clinical matrix known to house disparate pathogens. The objective of this study was to analyze the utility of this unconventional diagnostic approach (shotgun metagenomics) using clinical samples from human tularemia cases as a test model. Tularemia, caused by the bacterium Francisella tularensis, is an emerging infectious disease in Turkey. This disease commonly manifests as swelling of the lymph nodes nearest to the entry of infection. Because swollen cervical nodes are observed from many different types of human infections we used these clinical sample types to analyze the utility of shotgun metagenomics. METHODS: We conducted an unbiased molecular survey using shotgun metagenomics sequencing of DNA extracts from fine-needle aspirates of neck lymph nodes from eight tularemia patients who displayed protracted symptoms. The resulting metagenomics data were searched for microbial sequences (bacterial and viral). RESULTS: F. tularensis sequences were detected in all samples. In addition, we detected DNA of other known pathogens in three patients. Both Hepatitis B virus (HBV) and Human Parvovirus B-19 were detected in one individual and Human Parvovirus B-19 alone was detected in two other individuals. Subsequent PCR coupled with Sanger sequencing verified the metagenomics results. The HBV status was independently confirmed via serological diagnostics, despite evading notice during the initial assessment. CONCLUSION: Our data highlight that shotgun metagenomics of fine-needle lymph node aspirates is a promising clinical diagnostic strategy to identify coinfections. Given the feasibility of the diagnostic approach demonstrated here, further steps to promote integration of this type of diagnostic capability into mainstream clinical practice are warranted.

Fatty acid binding protein 4 is expressed in distinct endothelial and non-endothelial cell populations in glioblastoma.

AIMS: Glioblastoma (GBM) is the most common and aggressive primary brain tumour in adults. Angiogenesis and vasculogenesis play key roles in progression of GBMs. Fatty acid binding protein 4 (FABP4) is an intracellular chaperone for free fatty acids. FABP4 is detected in microvascular endothelial cells (ECs) in several normal tissues and promotes proliferation of ECs. The goal of this study was to characterize the tissue distribution pattern of FABP4 in GBMs. METHODS: Immunohistochemistry for FABP4 was performed on paraffin-embedded tumour sections and the intensity and distribution of FABP4 immunoreactivity were analysed. Double immunofluorescence was employed for detailed characterization of FABP4-positive cells. RESULTS: FABP4 immunoreactivity was absent in normal brain tissue sections. FABP4-positive cells were detected in 33%, 43%, 64% and 89% of Grade I, Grade II, Grade III and Grade IV glial tumours, respectively. Thus, the percentage of FABP4-positive cells in GBMs was significantly higher than lower-grade gliomas. In general, FABP4-expressing cells were distributed in a non-homogenous pattern, as 'hot spots' in glial tumours. FABP4 expression was detected in a subset of vascular ECs as well as some non-ECs. CONCLUSION: FABP4 is expressed in a significantly higher percentage of GBMs in comparison to both normal brain tissues and lower-grade glial tumours. FABP4 is expressed in some tumour ECs as well as non-ECs in glial tumours. As FABP4 promotes proliferation of ECs, detection of FABP4 in GBM-ECs, but not normal brain ECs suggests that FABP4 may play a role in the robust angiogenesis associated with GBMs.