Lysosomal phospholipase A2: A novel player in host immunity to Mycobacterium tuberculosis

Phospholipases catalyze the cleavage of membrane phospholipids into smaller bioactive molecules. The lysosomal phospholipase A₂ (LPLA₂) is specifically expressed in macrophages. LPLA₂ gene deletion in mice causes lysosomal phospholipid accumulation in tissue macrophages leading to phospholipidosis. This phenotype becomes most prominent in alveolar macrophages where LPLA₂ contributes to surfactant phospholipid degradation. High expression of LPLA₂ in alveolar macrophages prompted us to investigate its role in host immunity against the respiratory pathogen Mycobacterium tuberculosis, the causative agent of tuberculosis. Here we report that adaptive immune responses to M. tuberculosis were impaired in LPLA₂ deficient mice. Upon aerosol infection with M. tuberculosis, LPLA₂ deficient mice showed enhanced mycobacterial counts but less lung immunopathology and pulmonary inflammatory responses. Compromised T‐cell priming in the lymph nodes was associated with impaired pulmonary T‐cell recruitment and activation. Together with reduced Th1 type cytokine production, these results indicate that LPLA₂ is indispensable for the induction of adaptive T‐cell immunity to M. tuberculosis. Taken together, we identified an unexpected and novel function of a lysosomal phospholipid‐degrading enzyme.     

Examining the Associations Between Overeating,Disinhibition, and Hunger in a Nonclinical Sample of College Women

Background

Binge eating (BE) has long been identified as a correlate of overweight and obesity. However, less empirical attention has been given to overeating with and without loss of control (LOC) in nonclinical samples.

Purpose

The goal of the present study was to examine the association of (1) established correlates of BE, namely, weight and shape concerns, dietary restraint, and negative affect, and (2) three additional correlates, disinhibition, hunger, and interoceptive awareness (IA), to overeating in a nonclinical sample of college women.

Method

Female students (n?=?1,447) aged 18 to 21 years recruited from colleges in three Canadian metropolitan areas completed self-report questionnaires in class to assess sociodemographic and anthropomorphic characteristics, overeating, LOC, dietary restraint, negative affect, weight and shape concerns, IA, disinhibition, and hunger.

Results

The established correlates of BE were significant correlates of all types of overeating and explained 33 % of the variance. Disinhibition was the most strongly associated correlate of overeating.

Conclusions

Findings suggest that established correlates of BE are associated with other types of overeating such as objective overeating (OOE), as are disinhibition and hunger.

     

A New Workflow for Whole‐Genome Sequencing of Single Human Cells

Unbiased amplification of the whole‐genome amplification (WGA) of single cells is crucial to study cancer evolution and genetic heterogeneity, but is challenging due to the high complexity of the human genome. Here, we present a new workflow combining an efficient adapter‐linker PCR‐based WGA method with second‐generation sequencing. This approach allows comparison of single cells at base pair resolution. Amplification recovered up to 74% of the human genome. Copy‐number variants and loss of heterozygosity detected in single cell genomes showed concordance of up to 99% to pooled genomic DNA. Allele frequencies of mutations could be determined accurately due to an allele dropout rate of only 2%, clearly demonstrating the low bias of our PCR‐based WGA approach. Sequencing with paired‐end reads allowed genome‐wide analysis of structural variants. By direct comparison to other WGA methods, we further endorse its suitability to analyze genetic heterogeneity.     

Progranulin expression correlates with dense‐core amyloid plaque burden in Alzheimer disease mouse models

Amyloid‐β (Aβ) plaques are pathological hallmarks of Alzheimer disease (AD). In addition, innate inflammatory responses, such as those mediated by microglia, are integral to the pathogenesis of AD. Interestingly, only dense‐core plaques and not diffuse plaques are associated with neuritic and inflammatory pathology in AD patients as well as in mouse AD models. However, the precise neuropathological changes that occur in the brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for Aβ‐mediated neuropathology, we performed a gene expression analysis on laser‐microdissected brain tissue of Tg2576 and APPPS1 mice that are characterized by different types of amyloid plaques and genetic backgrounds. Data were validated by image and biochemical analyses on different ages of Tg2576, APPPS1, and Aβ42‐depositing BRI‐Aβ42 mice. Consistent with an important role of inflammatory responses in AD, we identified progranulin (mouse Grn; human GRN) as one of the top ten up‐regulated molecules in Tg2576 (≈8‐fold increased) and APPPS1 (≈2‐fold increased) mice compared to littermate controls, and among the eight significantly up‐regulated molecules common to both mouse models. In addition, Grn levels correlated significantly with amyloid load, especially the dense‐core plaque pathology (p < 0.001). We further showed that Grn is up‐regulated in microglia and neurons and neurites around dense‐core plaques, but not in astrocytes or oligodendrocytes, as has been shown in AD patients. Our data therefore support the ongoing use of these mouse models in drug trials, especially those with anti‐inflammatory compounds. Moreover, the correlation of Grn with increasing disease severity in AD mouse models prompts human studies exploring the viability of GRN as a disease biomarker. Because loss of GRN has recently been shown to cause frontotemporal dementia and serves as a risk factor for AD, the strong GRN reactivity around dense‐core plaques is consistent with an important role of this factor in AD pathogenesis. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

A longitudinal examination of associations between age and chemotherapy-induced peripheral neuropathy in patients with gynecologic cancer

Objective

Increasing age has been associated with higher risk of chemotherapy-related toxicities, often resulting in treatment disruptions or discontinuations. Age has also been evaluated as a potential risk factor for chemotherapy-induced peripheral neuropathy (CIPN), but current understanding of recovery from CIPN in older adults after treatment is limited. The goal of the current study was to: 1) evaluate longitudinal change in patient-reported CIPN symptoms from the start of chemotherapy to one year post-chemotherapy; and 2) examine treatment modifications in older (≥65?years) and younger patients (<65?years).

Juvenile paracoccidioidomycosis in urban area: report of two cases

We present two cases of juvenile form of paracoccidioidomycosis (PCM), a systemic mycosis frequently found in rural areas, whose prognosis is poor in children and young adults. They are a 14-year-old boy and a 25-year-old woman, both residents in an urban area in São Paulo – Brazil, without any history of travelling to an endemic area. They have been admitted to the hospital due to fever, weight loss and lymphadenopathy. The diagnosis was confirmed by serologic and histopathologic study. Patients have recovered after therapy with oral itraconazole and were discharged from hospital, maintaining outpatient visits. In this article, the authors discuss the unusual presentation of PCM in an urban area.     

Arginine transport in human erythroid cells: discrimination of CAT1 and 4F2hc/y+LAT2 roles

Since arginine metabolites, such as nitric oxide and polyamines, influence the expression of genes involved in erythroid differentiation, the transport of the cationic amino acid may play an important role in erythroid cells. However, available data only concern the presence in these cells of CAT1 transporter (system y⁺), while no information exists on the role of the heterodimeric transporters of system y⁺L (4F2hc/y⁺LAT1 and 4F2hc/y⁺LAT2) which operates transmembrane arginine fluxes cis-inhibited by neutral amino acids in the presence of sodium. Using erythroleukemia K562 cells and normal erythroid precursors, we demonstrate here that arginine transport in human erythroid cells is due to the additive contributions of a leucine-sensitive and leucine-insensitive component. In both cell types, leucine inhibition of arginine influx is much less evident in the absence of sodium, a hallmark of system y⁺L. In K562 cells, N-ethylmaleimide, a known inhibitor of CAT transporters (system y⁺), suppresses only a fraction of arginine influx corresponding to leucine-insensitive uptake. Moreover, in Xenopus oocytes coexpressing 4F2hc and y⁺LAT2, leucine exerts a marked inhibition of arginine transport, partially dependent on sodium, while no inhibition is seen in oocytes expressing CAT1. Lastly, silencing of SLC7A6, the gene for y⁺LAT2, lowers arginine transport and doubles the intracellular content of the cationic amino acid in K562 cells. We conclude that arginine transport in human erythroid cells is due to both system y⁺ (CAT1 transporter) and system y⁺L (4F2hc/y⁺LAT2 isoform), which mainly contribute, respectively, to the influx and to the efflux of the cationic amino acid.     

Conventional type 1 dendritic cells induce TH1, TH1-like follicular helper T cells and regulatory T cells after antigen boost via DEC205 receptor

Conventional dendritic cells (cDCs) are specialized in antigen presentation. In the mouse spleen, cDCs are classified in cDC1s and cDC2s, and express DEC205 and DCIR2 endocytic receptors, respectively. Monoclonal antibodies (mAbs) αDEC205 (αDEC) and αDCIR2 have been fused to different antigens to deliver them to cDC1s or cDC2s. We immunized mice with αDEC and αDCIR2 fused to an antigen using Poly(I:C) as adjuvant. The initial immune response was analyzed from days 3 to 6 after the immunization. We also studied the influence of a booster dose. Our results showed that antigen targeting to cDC1s promoted a pro-inflammatory T_H1 cell response. Antigen targeting to cDC2s induced T_FH cells, GCs, and plasma cell differentiation. After boost, antigen targeting to cDC1s improved the T_H1 cell response and induced T_H1-like T_FH cells that led to an increase in specific antibody titers and IgG class switch. Additionally, a population of regulatory T cells was also observed. Antigen targeting to cDC2s did not improve the specific antibody response after boost. Our results add new information on the immune response induced after the administration of a booster dose with αDEC and αDCIR2 fusion mAbs. These results may be useful for vaccine design using recombinant mAbs.     

Successful Hematopoietic Stem Cell Transplantation in a Patient with LPS-Responsive Beige-Like Anchor (<Emphasis Type="Italic">LRBA</Emphasis>) Gene Mutation

Purpose

Autosomal recessive mutations in LRBA, encoding for LPS-responsive beige-like anchor protein, were described in patients with a common variable immunodeficiency (CVID)-like disease characterized by hypogammaglobulinemia, autoimmune cytopenias, and enteropathy. Here, we detail the clinical, immunological, and genetic features of a patient with severe autoimmune manifestations.

Methods

Whole exome sequencing was performed to establish a molecular diagnosis. Evaluation of lymphocyte subsets was performed for immunological characterization. Medical files were reviewed to collect clinical and immunological data.

Results

A 7-year-old boy, born to consanguineous parents, presented with autoimmune hemolytic anemia, hepatosplenomegaly, autoimmune thyroiditis, and severe autoimmune gastrointestinal manifestations. Immunological investigations revealed low immunoglobulin levels and low numbers of B and NK cells. Treatment included immunoglobulin replacement and immunosuppressive therapy. Seven years after disease onset, the patient developed severe neurological symptoms resembling acute disseminated encephalomyelitis, prompting allogeneic hematopoietic stem cell transplantation (HSCT) with the HLA-identical mother as donor. Whole exome sequencing of the patient uncovered a homozygous 1 bp deletion in LRBA (c.7162delA:p.T2388Pfs*7). Importantly, during 2 years of follow-up post-HSCT, marked clinical improvement and recovery of immune function was observed.

Conclusions

Our data suggest a beneficial effect of HSCT in patients with LRBA deficiency.