Genetic and functional characterisation of Immunoglobulin Heavy Chain Locus-CCAAT enhancer binding protein B-Cell acute lymphoblastic leukaemia

PhDB-cell precursor acute lymphoblastic leukaemia (BCP-ALL) is a heterogeneous disease in which patient outcome is influenced by genetic lesions. This outcome has improved due to increasingly tailored treatment regimens, selected through risk stratification by use of cytogenetic, copy number alterations (CNAs) classifiers, genomic, and molecular data. Translocations involving the Immunoglobulin Heavy Chain Locus (IGH) comprise 5% of BCP-ALL and lead to overexpression of juxtaposed genes, due to the powerful IGH enhancer elements. Multiple IGH partner genes have been described in BCP-ALL, including five members of the Ccaat Enhancer-Binding Protein (CEBP) transcription factor family. A cohort of 33 IGH-CEBP BCP-ALL patients was identified including 11 IGH-CEBPD, 10 IGH-CEBPA, 8 IGH-CEBPB, 3 IGH-CEBPE and 1 IGH-CEBPG patients, comprising 19% of the IGH cohort, and 1% of ALL as a whole. The patients displayed variation between individual CEBP subgroups, with IGH-CEBPB patients showing higher white blood cell counts (WBC), higher relapse rates, higher number of CNAs and older age than other CEBP patients. The CEBPD subgroup included mostly younger patients, under the age of 10 years, and had the lowest number of CNAs per patient. Deletions of CDKN2A/B were the most commonly occurring CNA followed by intragenic exon 4-7 deletions of IKZF1, which were found exclusively in the IGH-CEBPB and IGH-CEBPD subgroups (p=0.04). A novel intragenic deletion of the tyrosine kinase gene, ABL2, was found in four patients in the cohort, which may represent a deletion unique to this subgroup. This finding in combination with the IKZF1 deletions is suggestive of a BCR-ABL1-like profile. Retroviral expression of the CEBPD gene in CD34+ cells was found to hinder proliferation in transduced cells, potentially through cell cycle arrest via the RB/E2F pathway. RNA sequencing analysis of two IGH-CEBP patients showed very different expression profiles, suggesting two mechanisms of oncogenesis in IGH-CEBP patients: one through inactivation of the CEBP function, leading to deregulation of cell cycle and differentiation control, and another through upregulation of inflammatory factors

Variation in chemical composition and acaricidal activity against Dermanyssus gallinae of four eucalyptus essential oils

The results of this study suggest that certain eucalyptus essential oils may be of use as an alternative to synthetic acaricides in the management of the poultry red mite, Dermanyssus gallinae. At a level of 0.21 mg/cm², the essential oil from Eucalyptus citriodora achieved 85% mortality in D. gallinae over a 24 h exposure period in contact toxicity tests. A further two essential oils from different eucalyptus species, namely E. globulus and E. radiata, provided significantly (P < 0.05) lower mite mortality (11 and 19%, respectively). Notable differences were found between the eucalyptus essential oils regarding their chemical compositions. There appeared to be a trend whereby the essential oils that were composed of the fewer chemical components were the least lethal to D. gallinae. It may therefore be the case that the complexity of an essential oil’s chemical make up plays an important role in dictating the toxicity of that oil to pests such as D. gallinae

Toward a PCR-Independent Molecular Diagnosis of Veterinary and Medically Relevant Pathogenic Organisms

Bloodstream infections caused by bacteria and fungi are a major problem worldwide. These bloodstream infections can affect both people and livestock, placing a significant burden upon developed and developing economies. In this paper we describe a multiplexed testing format, which can identify a range of bacteria and fungi within a single blood sample. Key to this technique is the specificity and sensitivity of the nucleotide probes that capture the sample. The sensitivity and specificity of the probes may allow detection of disease-causing microorganisms without the need for polymerase chain reaction amplification if the dynamics of probe binding can be observed in real time

An analysis of mechanisms of central nervous system infiltration in acute lymphoblastic leukaemia using primary cells xenografted into immunodeficient mice

Despite great advances in the treatment of paediatric acute lymphoblastic leukaemia (ALL), disease in the central nervous system (CNS) continues to pose challenges. Current diagnostic tests are insensitive and risk factors for CNS relapse are poorly understood. This results in all children receiving intensive CNS-directed therapy which may be associated with acute and/or chronic neurotoxicity. A better understanding of the mechanisms of CNS engraftment is a necessary pre-requisite for diagnostic and therapeutic advances.  To investigate if primary cells infiltrate the CNS, and whether this property resides in any particular sub-clonal compartment we undertook a comprehensive analysis of the CNS engrafting potential of primary ALL cells in immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. In addition, we used this model to investigate whether chemokine receptor expression drives CNS infiltration in pre-B ALL, as previously shown for T-ALL. CNS engraftment was seen in 18/23 pre-B ALL samples (78%). A consistent pattern of engraftment was observed with plaques of disease in the leptomeninges, relative sparing of the ventricles and complete absence of parenchymal infiltration. This implies ALL transit across the blood-CSF barrier rather than the blood-brain barrier – an important distinction, as leucocytes utilise distinct physiological trafficking mechanisms to cross these two barriers. To examine the frequency of cells with CNS-engrafting potential, intra-femoral transfer of 10 to 10,000 cells was performed.  CNS engraftment was seen with as few as 10 initial cells. In addition, the ability to engraft the CNS was not restricted to any particular immunophenotypic compartment and was seen in CD19+CD10high, CD19+CD10low, CD19+CD20low, CD19+CD20high, CD19+CD34high, CD19+CD34low fractions. These data suggest that CNS engraftment potential is present at high-frequency in the bulk leukaemic population at diagnosis. To examine candidate trafficking molecules governing CNS entry, we investigated chemokine receptor expression on pre-B ALL blasts using quantitative PCR and flow cytometry. The chemokine receptors CXCR3, CXCR4 and CXCR7 were expressed by pre-B ALL but were not up-regulated in cells retrieved from the CNS compared to the bone marrow (BM). In conclusion, in xenograft models of pre-B ALL, CNS engrafting potential is present at high frequency in patient diagnostic BM specimens and does not appear to be restricted to sub-clonal compartments. These findings have important implications for the design of risk-adapted CNS therapy. Firstly, our studies indicate that CNS entry is a common property of leukaemic blasts and therefore the current dogma of CNS-directed therapy for all patients appears to have a rational scientific basis. Secondly, it is unlikely that chemokine receptor expression profiling will be a useful biomarker for CNS disease in pre-B ALL. Finally, identifying factors that facilitate long-term survival of cells in the CNS (which may also enhance long-term survival in the bone marrow) may be a better therapeutic strategy than attempts to block cell entry

Genomic characterization implicates iAMP21 as a likely primary genetic event in childhood B-cell precursor acute lymphoblastic leukemia

Intrachromosomal amplification of chromosome 21 (iAMP21) defines a distinct subgroup of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) that has a dismal outcome when treated with standard therapy. For improved diagnosis and risk stratification, the initiating genetic events need to be elucidated. To investigate the genetic basis of BCP-ALL, genomes of 94 iAMP21 patients were interrogated by arrays, FISH, and multiplex ligation-dependent probe amplification. Most copy number alterations targeted chromosome 21, reinforcing the complexity of this chromosome. The common region of amplification on chromosome 21 was refined to a 5.1-mb region that included RUNX1, miR-802, and genes mapping to the Down syndrome critical region. Recurrent abnormalities affecting genes in key pathways were identified: IKZF1 (22%), CDKN2A/B (17%), PAX5 (8%), ETV6 (19%), and RB1 (37%). Investigation of clonal architecture provided evidence that these abnormalities, and P2RY8-CRLF2, were secondary to chromosome 21 rearrangements. Patient outcome was uniformly poor with standard therapy irrespective of the presence or absence of these changes. This study has provided evidence that chromosome 21 instability is the only anomaly among those so far investigated that is common to all iAMP21 patients, and therefore the initiating event is likely to be found among the complex structural rearrangements of this abnormal chromosom

The ability to cross the blood-cerebrospinal fluid barrier is a generic property of acute lymphoblastic leukemia blasts

Prevention of central nervous system (CNS) relapse is critical for cure of childhood Bcell precursor acute lymphoblastic leukaemia (BCP-ALL). Despite this, mechanisms of CNS infiltration are poorly understood and the timing, frequency and properties of BCP-ALL blasts entering the CNS compartment are unknown. We investigated the CNS-engrafting potential of BCP-ALL cells xenotransplanted into immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice. CNS engraftment was seen in 23/29 diagnostic samples (79%), 2/2 from patients with overt CNS disease and 21/27 (78%) from patients thought to be CNS-negative by diagnostic lumbar puncture. Histological findings mimic human pathology and demonstrate that leukaemic cells primarily transit the blood-cerebrospinal-fluid barrier sitting in close proximity to the dural sinuses – the site of recently discovered CNS lymphatics. Retrieval of blasts from the CNS showed no evidence for chemokine receptor-mediated selective trafficking. The high frequency of infiltration and lack of selective trafficking led us to postulate that CNS tropism is a generic property of leukaemic cells. To test this we performed serial dilution experiments, CNS engraftment was seen in 5/6 mice following transplantation of as few as 10 leukaemic cells. Finally, clonal tracking techniques confirmed the polyclonal nature of CNS infiltrating cells with multiple clones engrafting in both the CNS and periphery. Overall, these findings suggest that sub-clinical seeding of the CNS is likely to be present in the majority of BCP-ALL patients at original diagnosis and efforts to prevent CNS relapse should concentrate on augmenting effective eradication of disease from this site, rather than targeting entry mechanisms