Citations

ABSTRACT Nonprimate animal models of HIV-1 infection are prevented by missing cellular cofactors and by antiviral actions of species-specific host defense factors. These blocks are profound in rodents but may be less abundant in certain Carnivora. Here, we enabled productive, spreading replication and passage of HIV-1 in feline cells. Feline fibroblasts, T-cell lines, and primary peripheral blood mononuclear cells supported early and late HIV-1 life cycle phases in a manner equivalent to that of human cells, except that produced virions had low infectivity. Stable expression of feline immunodeficiency virus (FIV) Vif-green fluorescent protein (GFP) in HIV-1 entry receptor-complemented feline (CrFK) cells enabled robust spreading HIV-1 replication. FIV Vif colocalized with feline APOBEC3 (fA3) proteins, targeted them for degradation, and prevented G→A hypermutation of the HIV-1 cDNA by fA3CH and fA3H. HIV-1 Vif was inactive against fA3s as expected and even paradoxically augmented restriction in some assays. In an interesting contrast, simian immunodeficiency virus SIVmac Vif had substantial anti-fA3 activities, which were complete against fA3CH and partial against fA3H. Moreover, both primate lentiviral Vifs colocalized with fA3s and could be pulled down from cell lysates by fA3CH. HIV-1 molecular clones that encode FIV Vif or SIVmac Vif (HIV-1 VF and HIV-1 VS ) were then constructed. These viruses replicated productively in HIV-1 receptor-expressing CrFK cells and could be passaged serially to uninfected cells. Thus, with the exception of entry receptors, the cat genome can supply the dependency factors needed by HIV-1, and a main restriction can be countered by vif chimerism. The results raise the possibility that the domestic cat could yield an animal model of HIV-1 infection.

Atherosclerotic renal artery stenosis (ARAS) is increasingly identified in patients with end-stage renal disease. Renal function in ARAS patients deteriorates more frequently than in nonatherosclerotic renal artery stenosis (RAS). This study was designed to test the hypothesis that atherosclerosis modifies the relationship between single-kidney hemodynamics and function and the severity of stenosis. The degree of unilateral RAS in domestic pigs (4 normal, 26 RAS, and 22 ARAS) was correlated with renal function and hemodynamics evaluated by 64-slice multidetector computerized tomography before and after endothelium-dependent challenge with ACh. The degree of stenosis and increase in mean arterial pressure were similar in RAS and ARAS. Stenotic single-kidney volume, blood flow, glomerular filtration rate, and cortical perfusion were lower than normal in both RAS and ARAS, but only in RAS correlated inversely with increasing degree of stenosis ( r = −0.62, r = −0.49, r = −0.51, and r = −0.46, respectively, P < 0.05 for all). Basal tubular fluid concentration capacity and stenotic cortical perfusion response to ACh were both blunted only in ARAS. This study shows that atherosclerosis modulates the impact of a stenosis in the renal artery on stenotic kidney hemodynamics, function, and tubular dynamics. These observations underscore the direct intrarenal effect of atherogenic factors on the kidneys.

Abstract Fungal lung infections are being diagnosed with increasing frequency. This is related to the increased numbers of immune-compromised and other susceptible patient groups. This article will focus on the evolving epidemiology of fungal lung infections and clinical manifestations that should prompt the clinician to consider the possibility of fungal lung infection. In addition, current approaches for the diagnosis of these infection are also reviewed. Heightened awareness of fungal lung infection, and appropriate use of the available diagnostic modalities, will permit appropriate treatment of these important clinical infections in immune-compromised individuals.

Subsynaptic vesicles that contain the adaptor protein linker of activated T cells regulate T cell signaling.

ABSTRACTInternalization of the obligate intracellular apicomplexan parasite,Cryptosporidium parvum, results in the formation of a unique intramembranous yet extracytoplasmic niche on the apical surfaces of host epithelial cells, a process that depends on host cell membrane extension. We previously demonstrated that efficientC. parvuminvasion of biliary epithelial cells (cholangiocytes) requires host cell actin polymerization and localized membrane translocation/insertion of Na+/glucose cotransporter 1 (SGLT1) and of aquaporin 1 (Aqp1), a water channel, at the attachment site. The resultant localized water influx facilitates parasite cellular invasion by promoting host-cell membrane protrusion. However, the molecular mechanisms by whichC. parvuminduces membrane translocation/insertion of SGLT1/Aqp1 are obscure. We report here that cultured human cholangiocytes express several nonmuscle myosins, including myosins IIA and IIB. Moreover,C. parvuminfection of cultured cholangiocytes results in the localized selective aggregation of myosin IIB but not myosin IIA at the region of parasite attachment, as assessed by dual-label immunofluorescence confocal microscopy. Concordantly, treatment of cells with the myosin light chain kinase inhibitor ML-7 or the myosin II-specific inhibitor blebbistatin or selective RNA-mediated repression of myosin IIB significantly inhibits (P< 0.05)C. parvumcellular invasion (by 60 to 80%). Furthermore ML-7 and blebbistatin significantly decrease (P< 0.02)C. parvum-induced accumulation of SGLT1 at infection sites (by approximately 80%). Thus, localized actomyosin-dependent membrane translocation of transporters/channels initiated byC. parvumis essential for membrane extension and parasite internalization, a phenomenon that may also be relevant to the mechanisms of cell membrane protrusion in general.

AbstractBackground/purposeRefractory rejections still occur in the liver transplantation (LT) field. The aim of this study was to investigate significant factors for the introduction of therapy with muromonab‐CD3 (MCD3) after LT.MethodsA total of 1415 LT patients were retrospectively evaluated, and 11 of the recipients received MCD3 therapy because of steroid‐resistant rejections. The clinical factors before LT and before MCD3 therapy were investigated.ResultsThe recipients were retrospectively divided into two groups based on responses to MCD3 therapy, including their clinical courses after MCD3 therapy and their outcomes. The MCD3 therapy had positive effects in LT recipients with the following four factors: low score of model for end‐stage liver disease or pediatric end‐stage liver disease; earlier time point of the first incidence of rejection; more frequent steroid pulse therapy (SPT) within 2 weeks after LT; and the expression of CD3 in the peripheral blood before MCD3 introduction.ConclusionOptimal induction of MCD3 triggered recovery from refractory rejections, especially in LT recipients in a stable condition, but not in those in a critical or compromised condition.

Abstract Intratumoral accumulation of T regulatory cells (Tregs) creates an immunosuppressive environment that reduces the efficacy of antitumor immunotherapy. The immunosuppressive milieu within tumors is largely brought about by the presence of Tregs, which maintain self-tolerance by directly inhibiting T cells, NK cells, and dendritic cells. Depletion of Tregs enhances antitumor immune responses; however, current depletion therapies also affect the function of CD4 and CD8 T effector cells. Previous studies from our laboratory indicate that intratumoral delivery of CpG-ODN strongly reduces the levels of Tregs within the tumor, which is mainly mediated by IL-6. Because IL-6 promotes growth of some human cancers, alternate pathways to inactivate Tregs were sought through microarray analysis, resulting in gene candidates that can be exploited to modulate the function of Tregs. Analysis of these candidates indicates that neutralization of chemokine (C-C motif) ligand 1 (CCL1) prevented de novo conversion and suppressive function of Tregs without affecting the function of T effector cells. The combination of CpG-ODN and anti-CCL1 treatments induced complete rejection of tumors in BALB-neuT tolerant mice, and result in the generation of long-term protective memory responses. Tumor rejection correlated with changes in the lymphocyte composition within the tumor; we observed decreased Treg numbers and a concomitant accumulation of tumoricidal cells such as CD8+NKG2D+ and NK cells. These studies demonstrate that neutralization of CCL1 can be used as an adjuvant to antitumor immunotherapy, as a means of reversing the immunosuppressive function of Tregs without compromising T cell effector function.

Abstract The expression of pathogen recognition receptors in human FOXP3+ T regulatory cells is established, yet the function of these receptors is currently obscure. In the process of studying the function of both peripheral and lamina propria FOXP3+ lymphocytes in patients with the human inflammatory bowel disease Crohn’s disease, we observed a clear deficiency in the quantity of FOXP3+ lymphocytes in patients with disease-associated polymorphisms in the pathogen recognition receptor gene NOD2. Subsequently, we determined that the NOD2 ligand, muramyl dipeptide (MDP), activates NF-κB in primary human FOXP3+ T cells. This activation is functionally relevant, as MDP-stimulated human FOXP3+ T cells are protected from death receptor Fas-mediated apoptosis. Importantly, apoptosis protection was not evident in MDP-stimulated FOXP3+ T cells isolated from a patient with the disease-associated polymorphism. Thus, we propose that one function of pathogen recognition receptors in human T regulatory cells is the protection against death receptor-mediated apoptosis in a Fas ligand-rich environment, such as that of the inflamed intestinal subepithelial space.