Identification of Genomic Loci Associated with Rhodococcus equi Susceptibility in Foals

Pneumonia caused by Rhodococcus equi is a common cause of disease and death in foals. Although agent and environmental factors contribute to the incidence of this disease, the genetic factors influencing the clinical outcomes of R. equi pneumonia are ill-defined. Here, we performed independent single nucleotide polymorphism (SNP)- and copy number variant (CNV)-based genome-wide association studies to identify genomic loci associated with R. equi pneumonia in foals. Foals at a large Quarter Horse breeding farm were categorized into 3 groups: 1) foals with R. equi pneumonia (clinical group [N = 43]); 2) foals with ultrasonographic evidence of pulmonary lesions that never developed clinical signs of pneumonia (subclinical group [N = 156]); and, 3) foals without clinical signs or ultrasonographic evidence of pneumonia (unaffected group [N = 49]). From each group, 24 foals were randomly selected and used for independent SNP- and CNV-based genome-wide association studies (GWAS). The SNP-based GWAS identified a region on chromosome 26 that had moderate evidence of association with R. equi pneumonia when comparing clinical and subclinical foals. A joint analysis including all study foals revealed a 3- to 4-fold increase in odds of disease for a homozygous SNP within the associated region when comparing the clinical group with either of the other 2 groups of foals or their combination. The region contains the transient receptor potential cation channel, subfamily M, member 2 (TRPM2) gene, which is involved in neutrophil function. No associations were identified in the CNV-based GWAS. Collectively, these data identify a region on chromosome 26 associated with R. equi pneumonia in foals, providing evidence that genetic factors may indeed contribute to this important disease of foals.The open access fee for this work was funded through the Texas A&M University Open Access to Knowledge (OAK) Fund

MAPK-ERK is a central pathway in T-cell acute lymphoblastic leukemia that drives steroid resistance

(Patho-)physiological activation of the IL7-receptor (IL7R) signaling contributes to steroid resistance in pediatric T-cell acute lymphoblastic leukemia (T-ALL). Here, we show that activating IL7R pathway mutations and physiological IL7R signaling activate MAPK-ERK signaling, which provokes steroid resistance by phosphorylation of BIM. By mass spectrometry, we demonstrate that phosphorylated BIM is impaired in binding to BCL2, BCLXL and MCL1, shifting the apoptotic balance toward survival. Treatment with MEK inhibitors abolishes this inactivating phosphorylation of BIM and restores its interaction with anti-apoptotic BCL2-protein family members. Importantly, the MEK inhibitor selumetinib synergizes with steroids in both IL7-dependent and IL7-independent steroid resistant pediatric T-ALL PDX samples. Despite the anti-MAPK-ERK activity of ruxolitinib in IL7-induced signaling and JAK1 mutant cells, ruxolitinib only synergizes with steroid treatment in IL7-dependent steroid resistant PDX samples but not in IL7-independent steroid resistant PDX samples. Our study highlights the central role for MAPK-ERK signaling in steroid resistance in T-ALL patients, and demonstrates the broader application of MEK inhibitors over ruxolitinib to resensitize steroid-resistant T-ALL cells. These findings strongly support the enrollment of T-ALL patients in the current phase I/II SeluDex trial (NCT03705507) and contributes to the optimization and stratification of newly designed T-ALL treatment regimens

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients. PATIENTS AND METHODS In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m$^{2}$ once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients. RESULTS Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m$^{2}$, 11 at 350 mg/m$^{2}$ (one DLT), and 10 at 400 mg/m$^{2}$ (one DLT). The mean AUCs at 300 mg/m$^{2}$, 350 mg/m$^{2}$, and 400 mg/m$^{2}$ were 2.20 μg h/mL, 2.52 μg h/mL, and 2.66 μg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children. CONCLUSION Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m$^{2}$ once daily (max 600 mg/d) with food in R/I patients and 300 mg/m$^{2}$ once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience

Intramuscular Administration of a Synthetic CpG-Oligodeoxynucleotide Modulates Functional Responses of Neutrophils of Neonatal Foals

Neutrophils play an important role in protecting against infection. Foals have age-dependent deficiencies in neutrophil function that may contribute to their predisposition to infection. Thus, we investigated the ability of a CpG-ODN formulated with Emulsigen to modulate functional responses of neutrophils in neonatal foals. Eighteen foals were randomly assigned to receive either a CpG-ODN with Emulsigen (N = 9) or saline intramuscularly at ages 1 and 7 days. At ages 1, 3, 9, 14, and 28, blood was collected and neutrophils were isolated from each foal. Neutrophils were assessed for basal and Rhodococcus equi-stimulated mRNA expression of the cytokines interferon-γ (IFN-γ), interleukin (IL)-4, IL-6, and IL-8 using real-time PCR, degranulation by quantifying the amount of β-D glucuronidase activity, and reactive oxygen species (ROS) generation using flow cytometry. In vivo administration of the CpG-ODN formulation on days 1 and 7 resulted in significantly (P<0.05) increased IFN-γ mRNA expression by foal neutrophils on days 3, 9, and 14. Degranulation was significantly (P<0.05) lower for foals in the CpG-ODN-treated group than the control group at days 3 and 14, but not at other days. No effect of treatment on ROS generation was detected. These results indicate that CpG-ODN administration to foals might improve innate and adaptive immune responses that could protect foals against infectious diseases and possibly improve responses to vaccination.The open access fee for this work was funded through the Texas A&M University Open Access to Knowledge (OAK) Fund

Mean (and 95% confidence intervals) for mRNA copy numbers estimated by mixed-effects modeling for IL-4, IL-6, and IL-8.

<p>Data represent back-transformed results of log₁₀-transformed data. Values in columns with the same letter indicate absence of statistical significance between groups for a given age. Values in rows with differing superscripted numbers indicate significant (P<0.05) differences among ages within group.</p><p>Mean (and 95% confidence intervals) for mRNA copy numbers estimated by mixed-effects modeling for IL-4, IL-6, and IL-8.</p

Mean (and 95% confidence intervals) for neutrophil parameters determined using flow cytometry (please see text for details) and estimated by mixed-effects modeling.

<p>Values in columns with the same letter indicate absence of statistical significance between groups for a given age. Values in rows with differing superscripted numbers indicate significant (P<0.05) differences among ages within group.</p><p>Mean (and 95% confidence intervals) for neutrophil parameters determined using flow cytometry (please see text for details) and estimated by mixed-effects modeling.</p

Boxplots of log₁₀ values of mRNA copy numbers by age and treatment group: blue boxes are data from the control (saline) group and red boxes are data from the CpG-treated foals.

<p>The triangles in the middle of boxes represent the median value; the bottom and top of the boxes represent the 25^th and 75^th percentiles, respectively. The vertical lines extending from the boxes to horizontal lines represent multiples of 1.75 of the respective interquartile distance. Numbers above boxes represent within-treatment group differences among ages: within treatment group, ages with different numbers differed significantly (P<0.05) between groups. Asterisks denote days on which values were significantly (P<0.05) different between the control and Cp-G-treated foals. Arrows along the horizontal axis indicate ages when treatment (saline or CpG) was administered.</p

Boxplots of values of liberated 4-methylumbelliferone (4-MU) measured fluorometrically by age and treatment group: blue boxes are data from the control (saline) group and red boxes are data from the CpG-treated foal (see <b>Figure 1</b> for boxplot description).

<p>Numbers above boxes represent within-treatment group differences among ages: within treatment group, ages with different numbers differed significantly (P<0.05) between groups. Asterisks denote days on which values were significantly (P<0.05) different between the control and Cp-G-treated foals. Arrows along the horizontal axis indicate ages when treatment (saline or CpG was administered.</p

Schematic diagram representing the distribution of the total population into the 3 subgroups (<i>R. equi</i> pneumonia foals [clinical], subclinical foals, and unaffected foals), and by genome-wide association studies versus PCR genotyping for TRPM2 SNP.

<p>The 3 comparisons among groups are also summarized.</p

Manhattan plots of standard chi-squared significance values for the 3 genome-wide association studies.

<p>Manhattan plots for (A) comparison 1, (B) comparison 2, and (C) comparison 3; (D) Mixed effects-model analysis of comparison 3.</p