Expression of the chemokine receptor CCR2 on immature B cells negatively regulates their cytoskeletal rearrangement and migration

Immature B cells are targeted to specific areas in the spleen, where a fraction of these cells receive signals that induce them to mature and participate in the immune response. In this study, we show that the C-C chemokine receptor 2 (CCR2) is transcribed in immature B cells, while its message is dramatically down-regulated at the mature stage. CCR2-deficient cells exhibit up-regulation of chemokine-induced actin polymerization, migration, and homing to the lymph nodes of immature B cells. In addition, we demonstrate that control of homing by CCR2 is mediated by its ligand, CCL2/JE, which is secreted by B cells and down-regulates the stromal derived factor-1 (SDF-1) signaling cascade. Thus, this study describes an additional, previously uncharacterized, role for CCR2 and its ligand as negative regulators of the homing of immature B cells.     

Evidence for Elizabethkingia anophelis Transmission from Mother to Infant,Hong Kong

Elizabethkingia anophelis, recently discovered from mosquito gut, is an emerging bacterium associated with neonatal meningitis and nosocomial outbreaks. However, its transmission route remains unknown. We use rapid genome sequencing to investigate 3 cases of E. anophelis sepsis involving 2 neonates who had meningitis and 1 neonate’s mother who had chorioamnionitis. Comparative genomics revealed evidence for perinatal vertical transmission from a mother to her neonate; the 2 isolates from these patients, HKU37 and HKU38, shared essentially identical genome sequences. In contrast, the strain from another neonate (HKU36) was genetically divergent, showing only 78.6% genome sequence identity to HKU37 and HKU38, thus excluding a clonal outbreak. Comparison to genomes from mosquito strains revealed potential metabolic adaptations in E. anophelis under different environments. Maternal infection, not mosquitoes, is most likely the source of neonatal E. anophelis infections. Our findings highlight the power of genome sequencing in gaining rapid insights on transmission and pathogenesis of emerging pathogens.     

Epstein–Barr virus antibodies mark systemic lupus erythematosus and scleroderma patients negative for anti‐DNA

Systemic lupus erythematosus (SLE) is an autoimmune disease that can attack many different body organs; the triggering event is unknown. SLE has been associated with more than 100 different autoantibody reactivities – anti‐dsDNA is prominent. Nevertheless, autoantibodies to dsDNA occur in only two‐thirds of SLE patients. We previously reported the use of an antigen microarray to characterize SLE serology. We now report the results of an expanded study of serology in SLE patients and scleroderma (SSc) patients compared with healthy controls. The analysis validated and extended previous findings: two‐thirds of SLE patients reacted to a large spectrum of self‐molecules that overlapped with their reactivity to dsDNA; moreover, some SLE patients manifested a deficiency of natural IgM autoantibodies. Most significant was the finding that many SLE patients who were negative for autoantibodies to dsDNA manifested abnormal antibody responses to Epstein–Barr virus (EBV): these subjects made IgG antibodies to EBV antigens to which healthy subjects did not respond or they failed to make antibodies to EBV antigens to which healthy subjects did respond. This observation suggests that SLE may be associated with a defective immune response to EBV. The SSc patients shared many of these serological abnormalities with SLE patients, but differed from them in increased IgG autoantibodies to topoisomerase and centromere B; 84% of SLE patients and 58% of SSc patients could be detected by their abnormal antibodies to EBV. Hence an aberrant immune response to a ubiquitous viral infection such as EBV might set the stage for an autoimmune disease.     

Surgical site abscess caused by Lactobacillus fermentum identified by 16S ribosomal RNA gene sequencing

We report the first case of surgical site abscess caused by Lactobacillus fermentum from a 53-year-old woman with squamous cell carcinoma of the esophagus after transthoracic esophagectomy and neoadjuvant chemoirradiation. 16S rRNA gene sequencing is a useful tool to better characterize the epidemiology and clinical significance of L. fermentum.     

A humanized tissue-engineered in vivo model to dissect interactions between human prostate cancer cells and human bone

Currently used xenograft models for prostate cancer bone metastasis lack the adequate tissue composition necessary to study the interactions between human prostate cancer cells and the human bone microenvironment. We introduce a tissue engineering approach to explore the interactions between human tumor cells and a humanized bone microenvironment. Scaffolds, seeded with human primary osteoblasts in conjunction with BMP7, were implanted into immunodeficient mice to form humanized tissue engineered bone constructs (hTEBCs) which consequently resulted in the generation of highly vascularized and viable humanized bone. At 12 weeks, PC3 and LNCaP cells were injected into the hTEBCs. Seven weeks later the mice were euthanized. Micro-CT, histology, TRAP, PTHrP and osteocalcin staining results reflected the different characteristics of the two cell lines regarding their phenotypic growth pattern within bone. Microvessel density, as assessed by vWF staining, showed that tumor vessel density was significantly higher in LNCaP injected hTEBC implants than in those injected with PC3 cells (p < 0.001). Interestingly, PC3 cells showed morphological features of epithelial and mesenchymal phenotypes suggesting a cellular plasticity within this microenvironment. Taken together, a highly reproducible humanized model was established which is successful in generating LNCaP and PC3 tumors within a complex humanized bone microenvironment. This model simulates the conditions seen clinically more closely than any other model described in the literature to date and hence represents a powerful experimental platform that can be used in future work to investigate specific biological questions relevant to bone metastasis.     

Novel mutation in FOXC1 wing region causing Axenfeld-Rieger anomaly

PURPOSE: To determine the possible molecular genetic defect underlying Axenfeld-Rieger anomaly (ARA) and to identify the pathogenic mutation causing this anterior segment dysgenesis in an Indian pedigree. METHODS: The FOXC1 gene was amplified from genomic DNA of members of an ARA-affected family and control subjects using four novel sets of primers. The amplicons were directly sequenced, and the sequences were analyzed to identify the disease-causing mutation. RESULTS: A heterozygous novel missense mutation was identified in the coding region of the FOXC1 gene in all three patients in this family. Consistent with the autosomal dominant inheritance pattern, the mutation segregated with the disease phenotype and was fully penetrant. The mutation was found in the wing region of the highly conserved forkhead domain of the FOXC1 gene and resulted in a very severe phenotype leading to blindness. CONCLUSIONS: This is the first study to demonstrate that a mutation in the FOXC1 wing region can cause an anterior segment dysgenesis of the eye. This mutation resulted in blindness in the ARA-affected family, and the findings suggest that the FOXC1 wing region has a functional role in the normal development of the eye. Moreover, this is the first study from India to report the genetic etiology of Axenfeld-Rieger anomaly. Genotype-phenotype correlations of FOXC1 may help in establishing the disease prognosis and also in understanding the clinical and genetic heterogeneity associated with various anterior segment dysgenesis caused by this gene.     

Cytomegalovirus pseudotumor of the duodenum in a patient with AIDS: an unrecognized and potentially treatable clinical entity

BackgroundCytomegalovirus (CMV) is a common pathogen affecting the gastrointestinal tract in patients with AIDS. We report a case of CMV-induced pseudotumor of the duodenum in a patient with AIDS and review other reported cases of CMV-induced pseudotumors in the gastrointestinal tract. CMV-induced pseudotumor in patients with AIDS is an exceptionally rare clinical entity, and to our knowledge no reports have previously summarized this clinical entity.MethodsAll previous cases included in our literature review were found using a PubMed search (1980–November 2008) of the English-language medical literature applying the terms ‘CMV infection’, ‘inflammatory mass’, ‘pseudotumor’, and ‘gastrointestinal tract’. The references cited in these articles were examined to identify additional reports.ResultsAlthough CMV-induced duodenitis has been described in patients with HIV infection, to our knowledge CMV-induced pseudotumor of the duodenum has not been previously reported in the literature. We describe the first case of an AIDS patient with CMV pseudotumor responding to oral treatment with valganciclovir with complete resolution of the CMV mass. Among reports of non-duodenal pseudotumor reported in the English literature, we found only 14 cases of CMV-induced gastrointestinal pseudotumors in HIV-positive patients. The clinical manifestations, pathologic findings of the CMV pseudotumors, as well as the treatment and outcome of these HIV patients are reviewed.ConclusionCMV pseudotumor should be included in the differential diagnosis of gastrointestinal mass lesions in AIDS patients and in other immunocompromised patients. The tumor often responds to antiviral therapy, but resolution of a CMV mass as a result of oral antiviral therapy has not been previously described. Since pseudotumors secondary to CMV often respond to medical treatment, it is important that the physicians treating severely immunocompromised patients are aware of this entity.     

Inhibitory factors associated with anaphase-promoting complex/cylosome in mitotic checkpoint

The mitotic (or spindle assembly) checkpoint system ensures accurate chromosome segregation by preventing anaphase initiation until all chromosomes are correctly attached to the mitotic spindle. It affects the activity of the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase that targets inhibitors of anaphase initiation for degradation. The mechanisms by which this system regulates APC/C remain obscure. Some models propose that the system promotes sequestration of the APC/C activator Cdc20 by binding to the checkpoint proteins Mad2 and BubR1. A different model suggests that a mitotic checkpoint complex (MCC) composed of BubR1, Bub3, Cdc20, and Mad2 inhibits APC/C in mitotic checkpoint [Sudakin V, Chan GKT, Yen TJ (2001) J Cell Biol 154:925-936]. We examined this problem by using extracts from nocodazole-arrested cells that reproduce some downstream events of the mitotic checkpoint system, such as lag kinetics of the degradation of APC/C substrate. Incubation of extracts with adenosine-5'-(gamma-thio)triphosphate (ATP[gammaS]) stabilized the checkpoint-arrested state, apparently by stable thiophosphorylation of some proteins. By immunoprecipitation of APC/C from stably checkpoint-arrested extracts, followed by elution with increased salt concentration, we isolated inhibitory factors associated with APC/C. A part of the inhibitory material consists of Cdc20 associated with BubR1 and Mad2, and is thus similar to MCC. Contrary to the original MCC hypothesis, we find that MCC disassembles upon exit from the mitotic checkpoint. Thus, the requirement of the mitotic checkpoint system for the binding of Mad2 and BubR1 to Cdc20 may be for the assembly of the inhibitory complex rather than for Cdc20 sequestration.