Fetal demise and failed antibody therapy during Zika virus infection of pregnant macaques

Zika virus (ZIKV) infection of pregnant women is associated with pathologic complications of fetal development. Here, we infect pregnant rhesus macaques (Macaca mulatta) with a minimally passaged ZIKV isolate from Rio de Janeiro, where a high rate of fetal development complications was observed. The infection of pregnant macaques with this virus results in maternal viremia, virus crossing into the amniotic fluid (AF), and in utero fetal deaths. We also treated three additional ZIKV-infected pregnant macaques with a cocktail of ZIKV-neutralizing human monoclonal antibodies (nmAbs) at peak viremia. While the nmAbs can be effective in clearing the virus from the maternal sera of treated monkeys, it is not sufficient to clear ZIKV from AF. Our report suggests that ZIKV from Brazil causes fetal demise in non-human primates (NHPs) without additional mutations or confounding co-factors. Treatment with a neutralizing anti-ZIKV nmAb cocktail is insufficient to fully stop vertical transmission.

Zika virus (ZIKV) infection in pregnant women has been associated with fetal developmental defects. Here, the authors show that a Brazilian ZIKV isolate causes fetal demise in non-human primates and that antibody treatment at time of peak viremia is insufficient to clear ZIKV replication from amniotic fluid.

Self-organizing tissue-engineered constructs in collagen hydrogels

A novel self-organizing behavior of cellularized gels composed of collagen type 1 that may have utility for tissue engineering is described. Depending on the starting geometry of the tissue culture well, toroidal rings of cells or hollow spheroids were prompted to form autonomously when cells were seeded onto the top of gels and the gels released from attachment to the culture well 12 to 24 h after seeding. Cells within toroids assumed distinct patterns of alignment not seen in control gels in which cells had been mixed in. In control gels, cells formed complex three-dimensional arrangements and assumed relatively higher levels of heterogeneity in expression of the fibronectin splice variant ED-A--a marker of epithelial mesenchymal transformation. The tissue-like constructs resulting from this novel self-organizing behavior may have uses in wound healing and regenerative medicine, as well as building blocks for the iterative assembly of synthetic biological structures.

Microglia are mediators of Borrelia burgdorferi-induced apoptosis in SH-SY5Y neuronal cells

Inflammation has long been implicated as a contributor to pathogenesis in many CNS illnesses, including Lyme neuroborreliosis. Borrelia burgdorferi is the spirochete that causes Lyme disease and it is known to potently induce the production of inflammatory mediators in a variety of cells. In experiments where B. burgdorferi was co-cultured in vitro with primary microglia, we observed robust expression and release of IL-6 and IL-8, CCL2 (MCP-1), CCL3 (MIP-1α), CCL4 (MIP-1β) and CCL5 (RANTES), but we detected no induction of microglial apoptosis. In contrast, SH-SY5Y (SY) neuroblastoma cells co-cultured with B. burgdorferi expressed negligible amounts of inflammatory mediators and also remained resistant to apoptosis. When SY cells were co-cultured with microglia and B. burgdorferi, significant neuronal apoptosis consistently occurred. Confocal microscopy imaging of these cell cultures stained for apoptosis and with cell type-specific markers confirmed that it was predominantly the SY cells that were dying. Microarray analysis demonstrated an intense microglia-mediated inflammatory response to B. burgdorferi including up-regulation in gene transcripts for TLR-2 and NFκβ. Surprisingly, a pathway that exhibited profound changes in regard to inflammatory signaling was triggering receptor expressed on myeloid cells-1 (TREM1). Significant transcript alterations in essential p53 pathway genes also occurred in SY cells cultured in the presence of microglia and B. burgdorferi, which indicated a shift from cell survival to preparation for apoptosis when compared to SY cells cultured in the presence of B. burgdorferi alone. Taken together, these findings indicate that B. burgdorferi is not directly toxic to SY cells; rather, these cells become distressed and die in the inflammatory surroundings generated by microglia through a bystander effect. If, as we hypothesized, neuronal apoptosis is the key pathogenic event in Lyme neuroborreliosis, then targeting microglial responses may be a significant therapeutic approach for the treatment of this form of Lyme disease.

Lyme disease, which is transmitted to humans through the bite of a tick, is currently the most frequently reported vector-borne illness in the northern hemisphere. Borrelia burgdorferi is the bacterium that causes Lyme disease and it is known to readily induce inflammation within a variety of infected tissues. Many of the neurological signs and symptoms that may affect patients with Lyme disease have been associated with B. burgdorferi-induced inflammation in the central nervous system (CNS). In this report we investigated which of the primary cell types residing in the CNS might be functioning to create the inflammatory environment that, in addition to helping clear the pathogen, could simultaneously be harming nearby neurons. We report findings that implicate microglia, a macrophage cell type in the CNS, as the key responders to infection with B. burgdorferi. We also present evidence indicating that this organism is not directly toxic to neurons; rather, a bystander effect is generated whereby the inflammatory surroundings created by microglia in response to B. burgdorferi may themselves be toxic to neuronal cells.

Closing the phenotypic gap between transformed neuronal cell lines in culture and untransformed neurons

Studies of neuronal dysfunction in the central nervous system (CNS) are frequently limited by the failure of primary neurons to propagate in vitro. Neuronal cell lines can be substituted for primary cells but they often misrepresent normal conditions. We hypothesized that a three-dimensional (3D) cell culture system would drive the phenotype of transformed neurons closer to that of untransformed cells, as has been demonstrated in non-neuronal cell lines. In our studies comparing 3D versus two-dimensional (2D) culture, neuronal SH-SY5Y (SY) cells underwent distinct morphological changes combined with a significant drop in their rate of cell division. Expression of the proto-oncogene N-myc and the RNA-binding protein HuD was decreased in 3D culture as compared to standard 2D conditions. We observed a decline in the anti-apoptotic protein Bcl-2 in 3D culture, coupled with increased expression of the pro-apoptotic proteins Bax and Bak. Moreover, thapsigargin (TG)-induced apoptosis was enhanced in the 3D cells. Microarray analysis demonstrated significantly differing mRNA levels for over 700 genes in the cells of the two culture types, and indicated that alterations in the G1/S cell-cycle progression contributed to the diminished doubling rate in the 3D-cultured SY cells. These results demonstrate that a 3D culture approach narrows the phenotypic gap between neuronal cell lines and primary neurons. The resulting cells may readily be used for in vitro research of neuronal pathogenesis.

Transcriptome profiles of host gene expression in a monkey model of human malaria

We used human microarrays to examine gene expression in a rhesus monkey model of human Plasmodium vivax malaria (P. cynomolgi in Macaca mulatta). Whole-blood cells were collected for extraction of RNA before infection, during both the initial liver phase of infection and bloodstream infection, and during the course of 2 bloodstream relapses. Clustering analysis showed that similarities in gene expression were greater at similar stages of the protocol for the 2 different monkeys than for the same monkey at different stages of the protocol. Interestingly, a large number of genes involved in RNA processing showed distinct down-regulation during the initial liver phase of infection. When only up-regulated genes were examined, there was evidence of an increasing number of "defense response" genes as the infection evolved but not of "cytoskeleton" genes (P</=.001). These results demonstrate the value of microarrays for studying the response of the primate transcriptome to malaria infection; they suggest that the host response is modulated by groups of genes.

The effects of bacterial overgrowth and hemorrhagic shock on mucosal immunity

Impairment in systemic and mucosal immune function is noted after hemorrhagic shock (HS). Overgrowth of gut microflora is common after shock insults and may act as a reservoir for intensive care unit-acquired infections and subsequent remote organ failure. Secretory immunoglobulin A (IgA), the principle immunoglobulin in intestinal secretions, is the first line of defense of mucosal surfaces. Although HS and gut bacterial overgrowth are often temporarily related, their combined effect on IgA is unknown and served as the basis for this study. After sham or HS, self-filling blind loops (SFBL) were created to affect bacterial overgrowth. Intestinal secretions were obtained 7 days later from SFBL and jejunal segments for quantitative culture. Gut washings were also obtained and secretory IgA levels determined by enzyme-linked immunosorbent assay. Bacterial overgrowth in the SFBL was associated with significant increases in IgA levels in the sham group only. IgA levels were depressed in both jejunal and SFBL segments in the HS group. Impaired humoral mucosal defense may be important mechanistically in the development of nosocomial infections and organ failure after HS, particularly with concurrent gut bacterial overgrowth.

An in vitro model to assess mucosal immune function and bacterial translocation

The importance of secretory immunoglobulin A (IgA) on intestinal barrier function has gained increasing acceptance. However, due to the complexity of the intestinal microenvironment, the relative role of secretory IgA (sIgA) in mucosal defense has been difficult to study in vivo. Polarized Madin-Darby canine kidney (MDCK) epithelial cells expressing the complementary DNA (cDNA) for the polymeric Ig receptor were grown as monolayers in an in vitro two-chamber cell culture system to study the impact of sIgA on bacterial translocation (BT). Polymeric sIgA or media alone was added to the apical chambers of cell monolayers followed by apical inoculation with bacteria. The basal compartment was sampled at timed intervals thereafter to determine BT. Bacterial passage across the MDCK epithelial cell monolayers occurred in a time and bacterial inoculum concentration gradient. Addition of sIgA led to significant reductions in BT across the epithelial cell monolayers. This is a useful model for further investigation on the role of sIgA in intestinal barrier function.

Hyperlipidemia in long-term survivors of pediatric renal transplantation

The prevalence of hyperlipidemia in adolescents and young adults who are long-term survivors of pediatric renal transplantation with stable graft function has not previously been examined. We studied 33 renal transplant recipients aged 5 to 23 years, who were an average of 7.4 years (range 3 to 11 years) post-transplant. We found hypercholesterolemia in 17 (total cholesterol (TC) > 5.18 mmol/l). Both low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels were increased, such that the mean TC/HDL-C and apolipoprotein B/apolipoprotein A1 (Apo B/Apo A1) ratios were below levels associated with increased coronary artery disease risk. Subjects with hypercholesterolemia did not differ from those with normal cholesterol values in current age or age at transplant, serum creatinine, serum albumin, serum triglycerides, HDL-C, TC/HDL-C ratio, Apo B/Apo A1 ratio, prednisone dose, body mass index, gender, use of thiazides or beta blockers, or family history of premature atherosclerosis. Coronary risk factors appear to cluster in these patients, with hypertension in 53% of those with hypercholesterolemia. Lipid profiles were not different in patients treated with prednisone-azathioprine vs. prednisone-azathioprine-cyclosporine A immunosuppression. A significant correlation was found between prednisone dose (mg/m2) and TC, LDL-C and TC/HDL-C. According to National Cholesterol Education Program guidelines, 32% of these long-term survivors of pediatric renal transplantation warrant at least dietary intervention and 10% are candidates for treatment with lipid-lowering drugs. This proportion is likely to increase as the safety of lipid-lowering agents is established in younger children.