Revisiting the utility of prenatal ultrasound in the routine workup of first febrile UTI: A systematic review and meta-analysis of the negative predictive value of prenatal ultrasound for identification of urinary tract abnormalities after first febrile urinary tract infection in children.

CONTEXT: The current EAU/ESPU and recently retired AAP pediatric UTI guidelines recommend renal bladder ultrasound after first febrile UTI in children to screen for structural abnormalities, regardless of findings on prenatal ultrasound. OBJECTIVE: Test the hypothesis that a normal prenatal ultrasound could rule out urinary tract abnormality on post-UTI ultrasound. DATA SOURCES: Medline, Embase, Cochrane Library. STUDY SELECTION: Studies including pediatric patients with first febrile UTI who had both prenatal and post-UTI ultrasound. DATA EXTRACTION: Anatomical abnormalities detected by prenatal and post-UTI ultrasound as reported per individual study criteria were extracted. Meta-analyses of 9 studies (2981 patients) were performed using a random-effects model and composite estimates of the negative predictive value (NPV) of prenatal ultrasound were calculated. RESULTS: Overall summary NPV of prenatal ultrasound for all pediatric patients was 77%, with heterogeneity score (I2) 97.9%. Summary NPV of prenatal ultrasound for all patients under two years of age was similar at 75%, with I2 98.2% For the 4 studies to which we could apply a more stringent definition of abnormality, summary NPV was 85% and I2 97.5% for prediction of moderate post-UTI ultrasound abnormalities and summary NPV was 93% and I2 90.4% for severe abnormalities. DISCUSSION: While we calculated an 85% NPV for a normal prenatal ultrasound to rule out significant postnatal abnormality as defined within individual studies, substantial heterogeneity amongst publications limited the precision of our estimates. This highlights the need for more rigorous investigations with attention to timing of ultrasound and the application of clinically meaningful definitions for abnormal prenatal and post-UTI studies. This may allow judicious use of prenatal ultrasound to guide clinical management for children with first febrile UTI and minimize redundant imaging with potential for false positive results. Until then, the current guidelines are justified based on the limited and heterogenous data from the currently available published studies.

Robot-assisted Laparoscopic Resection of Renal Vein Leiomyosarcoma.

Leiomyosarcoma, a rare and aggressive retroperitoneal tumor, arises from the smooth muscle of the tunica media. Accurate preoperative diagnosis is rare as the origin is often unclear, and its involvement of the vessels makes biopsy prohibitively dangerous (Maturen et al, 20136). Herein, we describe the laparoscopic dissection of a retroperitoneal renal vein tumor using a robotic approach.

Siglecs facilitate HIV-1 infection of macrophages through adhesion with viral sialic acids.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) infects macrophages effectively, despite relatively low levels of cell surface-expressed CD4. Although HIV-1 infections are defined by viral tropisms according to chemokine receptor usage (R5 and X4), variations in infection are common within both R5- and X4-tropic viruses, indicating additional factors may contribute to viral tropism. METHODOLOGY AND PRINCIPAL FINDINGS: Using both solution and cell surface binding experiments, we showed that R5- and X4-tropic HIV-1 gp120 proteins recognized a family of I-type lectin receptors, the Sialic acid-binding immunoglobulin-like lectins (Siglec). The recognition was through envelope-associated sialic acids that promoted viral adhesion to macrophages. The sialic acid-mediated viral-host interaction facilitated both R5-tropic pseudovirus and HIV-1(BaL) infection of macrophages. The high affinity Siglec-1 contributed the most to HIV-1 infection and the variation in Siglec-1 expression on primary macrophages from different donors was associated statistically with sialic acid-facilitated viral infection. Furthermore, envelope-associated sialoglycan variations on various strains of R5-tropic viruses also affected infection. CONCLUSIONS AND SIGNIFICANCE OF THE FINDINGS: Our study showed that sialic acids on the viral envelope facilitated HIV-1 infection of macrophages through interacting with Siglec receptors, and the expression of Siglec-1 correlated with viral sialic acid-mediated host attachment. This glycan-mediated viral adhesion underscores the importance of viral sialic acids in HIV infection and pathogenesis, and suggests a novel class of antiviral compounds targeting Siglec receptors.

IFN-γ- and IL-10-expressing virus epitope-specific Foxp3(+) T reg cells in the central nervous system during encephalomyelitis.

Foxp3(+) CD4 regulatory T cells (T reg cells) are important in limiting immunopathology in infections. However, identifying pathogen-specific epitopes targeted by these cells has been elusive. Using MHC class II/peptide tetramers and intracellular cytokine staining, we identify T reg cells recognizing two virus-specific CD4 T cell epitopes in the coronavirus-infected central nervous system as well as naive T cell precursor pools. These T reg cells are detected at the same time as effector T cells (T eff cells) exhibiting the same specificity and can suppress T eff cell proliferation after stimulation with cognate peptide. These virus-specific T reg cells may be especially effective in inhibiting the immune response during the peak of infection, when virus antigen is maximal. Furthermore, these T reg cells express both IL-10 and IFN-γ after peptide stimulation. IFN-γ expression is maintained during both acute and chronic phases of infection. Identification of T reg cell target epitopes by cytokine production is also applicable in autoimmune disease because myelin oligodendrocyte glycoprotein-specific Foxp3(+) T reg cells express IL-10 and IL-17 at the peak of disease in mice with experimental autoimmune encephalomyelitis. These results show that pathogen epitope-specific Foxp3(+) T reg cells can be identified on the basis of cytokine production.

Virally expressed interleukin-10 ameliorates acute encephalomyelitis and chronic demyelination in coronavirus-infected mice.

The absence of interleukin-10 (IL-10), a potent anti-inflammatory cytokine results in increased immune-mediated demyelination in mice infected with a neurotropic coronavirus (recombinant J2.2-V-1 [rJ2.2]). Here, we examined the therapeutic effects of increased levels of IL-10 at early times after infection by engineering a recombinant J2.2 virus to produce IL-10. We demonstrate that viral expression of IL-10, which occurs during the peak of virus replication and at the site of disease, enhanced survival and diminished morbidity in rJ2.2-infected wild-type B6 and IL-10(-/-) mice. The protective effects of increased IL-10 levels were associated with reductions in microglial activation, inflammatory cell infiltration into the brain, and proinflammatory cytokine and chemokine production. Additionally, IL-10 increased both the frequency and number of Foxp3(+) regulatory CD4 T cells in the infected central nervous system. Most strikingly, the ameliorating effects of IL-10 produced during the first 5 days after infection were long acting, resulting in decreased demyelination during the resolution phase of the infection. Collectively, these results suggest that the pathogenic processes that result in demyelination are initiated early during infection and that they can be diminished by exogenous IL-10 delivered soon after disease onset. IL-10 functions by dampening the innate or very early T cell immune response. Further, they suggest that early treatment with IL-10 may be useful adjunct therapy in some types of viral encephalitis.

Highly activated cytotoxic CD8 T cells express protective IL-10 at the peak of coronavirus-induced encephalitis.

Acute viral encephalitis requires rapid pathogen elimination without significant bystander tissue damage. In this article, we show that IL-10, a potent anti-inflammatory cytokine, is produced transiently at the peak of infection by CD8 T cells in the brains of coronavirus-infected mice. IL-10(+)CD8 and IL-10(-)CD8 T cells interconvert during acute disease, possibly based on recent Ag exposure. Strikingly, IL-10(+)CD8 T cells were more highly activated and cytolytic than IL-10(-)CD8 T cells, expressing greater levels of proinflammatory cytokines and chemokines, as well as cytotoxic proteins. Even though these cells are highly proinflammatory, IL-10 expressed by these cells was functional. Furthermore, IL-10 produced by CD8 T cells diminished disease severity in mice with coronavirus-induced acute encephalitis, suggesting a self-regulatory mechanism that minimizes immunopathological changes.

Regulatory T cells inhibit T cell proliferation and decrease demyelination in mice chronically infected with a coronavirus.

Mice infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV) develop acute and chronic demyelinating diseases with histopathological similarities to multiple sclerosis. The process of demyelination is largely immune-mediated, as immunodeficient mice (RAG1(-/-) mice) do not develop demyelination upon infection; however, demyelination develops if these mice are reconstituted with either JHMV-immune CD4 or CD8 T cells. Because myelin destruction is a consequence of the inflammatory response associated with virus clearance, we reasoned that decreasing the amount of inflammation would diminish clinical disease and demyelination. Given that regulatory T cells (Tregs) have potent anti-inflammatory effects, we adoptively transferred Tregs into infected C57BL/6 and RAG1(-/-) mice. In both instances, transfer of Tregs decreased weight loss, clinical scores, and demyelination. Transferred Tregs were not detected in the CNS of infected RAG1(-/-) mice, but rather appeared to mediate their effects in the draining cervical lymph nodes. We show that Tregs dampen the inflammatory response mediated by transferred JHMV-immune splenocytes in infected RAG1(-/-) mice by decreasing T cell proliferation, dendritic cell activation, and proinflammatory cytokine/chemokine production, without inducing apoptosis. By extension, decreasing inflammation, whether by Treg transfer or by otherwise enhancing the anti-inflammatory milieu, could contribute to improved clinical outcomes in patients with virus-induced demyelination.

Role of regulatory T cells in coronavirus-induced acute encephalitis.

C57BL/6 mice infected with mouse hepatitis virus, strain JHM (JHMV) develop a rapidly fatal acute encephalitis. Previously, we showed that this disease is partially CD4 T cell-mediated since infection with a recombinant JHMV (rJ) mutated in only a single immunodominant CD4 T cell epitope (epitope M133, rJ.M(Y135Q)) results in a nonlethal disease. Increased mortality correlated with a greater number of JHMV-specific CD4 T cells in the brains of rJ compared to rJ.M(Y135Q)-infected mice. Here, we extend these results to show that the diminished number of virus-specific T cells correlates with a reduced cytokine/chemokine response in the infected brain. We also show that regulatory CD4 T cells (Tregs) are critical for mild disease in rJ.M(Y135Q)-infected mice because their depletion results in increased mortality. Further, a relative paucity of Tregs characterizes lethal infection because adoptive transfer of Tregs into rJ-infected mice increases survival from 0% to 50%. These results support the notion that clinical disease in coronavirus-induced acute encephalitis results from a balance between factors critical for virus clearance, such as virus-specific effector T cells and anti-inflammatory elements, such as Tregs. These findings also show that unlike chronic infections, in which an excessive number of Tregs contributes to pathogen persistence, Tregs in the setting of acute encephalitis may help to limit immunopathological disease without delaying virus clearance.

Structural implications of Siglec-5-mediated sialoglycan recognition.

Sialic acid (Sia) Ig-like binding lectins are important mediators of recognition and signaling events among myeloid cells. To investigate the molecular mechanism underlying sialic acid Ig-like lectin (Siglec) functions, we determined the crystal structure of the two N-terminal extracellular domains of human myeloid cell inhibitory receptor Siglec-5 (CD170) and its complexes with two sialylated carbohydrates. The native structure revealed an unusual conformation of the CC' ligand specificity loop and a unique interdomain disulfide bond. The alpha(2,3)- and alpha(2,6)-sialyllactose complexed structures showed a conserved Sia recognition motif that involves both Arg124 and a portion of the G-strand in the V-set domain forming beta-sheet-like hydrogen bonds with the glycerol side chain of the Sia. Only few protein contacts to the subterminal sugars are observed and mediated by the highly variable GG' linker and CC' loop. These structural observations, in conjunction with surface plasmon resonance binding assays, provide mechanistic insights into linkage-dependent Siglec carbohydrate recognition and suggest that Siglec-5 and other CD33-related Siglec receptors are more promiscuous in sialoglycan recognition than previously understood.

Murine encephalitis caused by HCoV-OC43, a human coronavirus with broad species specificity, is partly immune-mediated.

The human coronavirus HCoV-OC43 causes a significant fraction of upper respiratory tract infections. Most coronaviruses show a strong species specificity, although the SARS-Coronavirus crossed species from palm civet cats to infect humans. Similarly, HCoV-OC43, likely a member of the same coronavirus group as SARS-CoV, readily crossed the species barrier as evidenced by its rapid adaptation to the murine brain [McIntosh, K., Becker, W.B., Chanock, R.M., 1967. Growth in suckling-mouse brain of "IBV-like" viruses from patients with upper respiratory tract disease. Proc Natl Acad Sci U.S.A. 58, 2268-73]. Herein, we investigated two consequences of this plasticity in species tropism. First, we showed that HCoV-OC43 was able to infect cells from a large number of mammalian species. Second, we showed that virus that was passed exclusively in suckling mouse brains was highly virulent and caused a uniformly fatal encephalitis in adult mice. The surface glycoprotein is a major virulence factor in most coronavirus infections. We identified three changes in the HCoV-OC43 surface glycoprotein that correlated with enhanced neurovirulence in mice; these were located in the domain of the protein responsible for binding to host cells. These data suggest that some coronaviruses, including HCoV-OC43 and SARS-CoV, readily adapt to growth in cells from heterologous species. This adaptability has facilitated the isolation of HCoV-OC43 viral variants with markedly differing abilities to infect animals and tissue culture cells.