Mitochondrial metabolism sustains CD8+ T cell migration for an efficient infiltration into solid tumors.

The ability of CD8+ T cells to infiltrate solid tumors and reach cancer cells is associated with improved patient survival and responses to immunotherapy. Thus, identifying the factors controlling T cell migration in tumors is critical, so that strategies to intervene on these targets can be developed. Although interstitial motility is a highly energy-demanding process, the metabolic requirements of CD8+ T cells migrating in a 3D environment remain unclear. Here, we demonstrate that the tricarboxylic acid (TCA) cycle is the main metabolic pathway sustaining human CD8+ T cell motility in 3D collagen gels and tumor slices while glycolysis plays a more minor role. Using pharmacological and genetic approaches, we report that CD8+ T cell migration depends on the mitochondrial oxidation of glucose and glutamine, but not fatty acids, and both ATP and ROS produced by mitochondria are required for T cells to migrate. Pharmacological interventions to increase mitochondrial activity improve CD8+ T cell intratumoral migration and CAR T cell recruitment into tumor islets leading to better control of tumor growth in human xenograft models. Our study highlights the rationale of targeting mitochondrial metabolism to enhance the migration and antitumor efficacy of CAR T cells in treating solid tumors.

Live Imaging of CAR T Cell Ca2+ Signals in Tumor Slices Using Confocal Microscopy.

The immune synapse is a key structure organizing T-cell activation against foreign entities, such as cancer cells expressing neoantigens. One crucial step in this activation cascade is the intracellular Ca2+ ([Ca2+]i) response that shapes T cells for proliferation, differentiation, and cytotoxicity. The development of calcium probes coupled to real-time fluorescence microscopy has allowed a close study of this phenomenon in vitro. Such systems have provided valuable insights on the consequences of Ca2+ responses on T cells, including cytotoxicity and cytoskeletal remodeling. However, in vitro models do not recapitulate the tissue architecture that T cells come in contact with in vivo. Thus, there is a growing necessity for better understanding the factors influencing Ca2+ response in T cells including in genetically modified T cells (e.g., CAR T cells). In this methodology chapter, we describe an experimental system to measure [Ca2+]i signals of CAR T cells loaded with the calcium probe Fluo-4 on fresh tumor slices. Combined with confocal fluorescent imaging, this model offers an approach to image early T-cell activation in a three-dimensional (3D) tissue environment.

The first isolation and molecular characterization of Toxoplasma gondii from horses in Serbia.

BACKGROUND: Consumption of undercooked or insufficiently cured meat is a major risk factor for human infection with Toxoplasma gondii. Although horsemeat is typically consumed rare or undercooked, information on the risk of T. gondii from infected horse meat to humans is scarce. Here, we present the results of a study to determine the presence of T. gondii infection in slaughter horses in Serbia, and to attempt to isolate viable parasites. METHODS: The study included horses from all regions of Serbia slaughtered at two abattoirs between June 2013 and June 2015. Blood sera were tested for the presence of specific IgG T. gondii antibodies by the modified agglutination test (MAT), and samples of trypsin-digested heart tissue were bioassayed in mice. Cyst-positive mouse brain homogenates were subjected to DNA extraction and T. gondii strains were genotyped using 15 microsatellite markers (MS). RESULTS: A total of 105 slaughter horses were sampled. At the 1:6 cut-off 48.6% of the examined horses were seropositive, with the highest titre being 1:400. Viable parasites were isolated from two grade type mares; both parasite isolates (RS-Eq39 and RS-Eq40) were T. gondii type III, and both displayed an increased lethality for mice with successive passages. These are the first cases of isolation of T. gondii from horses in Serbia. When compared with a worldwide collection of 61 type III and type III-like strains, isolate RS-Eq39 showed a combination of MS lengths similar to a strain isolated from a duck in Iran, and isolate RS-Eq40 was identical in all markers to three strains isolated from a goat from Gabon, a sheep from France and a pig from Portugal. Interestingly, the source horses were one seronegative and one weakly seropositive. CONCLUSIONS: The isolation of viable T. gondii parasites from slaughter horses points to horsemeat as a potential source of human infection, but the fact that viable parasites were isolated from horses with only a serological trace of T. gondii infection presents further evidence that serology may not be adequate to assess the risk of toxoplasmosis from horsemeat consumption. Presence of T. gondii type III in Serbia sheds more light into the potential origin of this archetypal lineage in Europe.

Prenatal and Early Postnatal Diagnosis of Congenital Toxoplasmosis in a Setting With No Systematic Screening in Pregnancy.

To determine the risk of congenital toxoplasmosis (CT) and provide early (pre- or postnatal) identification of cases of CT in the absence of systematic screening in pregnancy.I n the presented cross-sectional study, serological criteria were used to date Toxoplasma gondii infection versus conception in 80 pregnant women with fetal abnormalities or referred to as suspected of acute infection, and in 16 women after delivery of symptomatic neonates. A combination of serological, molecular (qPCR), and biological (bioassay) methods was used for prenatal and/or postnatal diagnosis of CT. Most (77.5%) pregnant women were examined in advanced pregnancy. Of all the examined seropositive women (n = 90), infection could not be ruled out to have occurred during pregnancy in 93.3%, of which the majority (69%) was dated to the periconceptual period. CT was diagnosed in 25 cases, of which 17 prenatally and 8 postnatally. Molecular diagnosis proved superior, but the diagnosis of CT based on bioassay in 7 instances and by Western blot in 2 neonates shows that other methods remain indispensable. In the absence of systematic screening in pregnancy, maternal infection is often diagnosed late, or even only when fetal/neonatal infection is suspected. In such situations, use of a complex algorithm involving a combination of serological, biological, and molecular methods allows for prenatal and/or early postnatal diagnosis of CT, but lacks the preventive capacity provided by early maternal treatment.

Autoantibody response and pregnancy-related pathology induced by combined LPS and tetanus toxoid hyperimmunization in BALB/c and C57BL/6 mice.

Recent data concerning antiphospholipid syndrome (APS) induction have shown that ß2-glycoprotein I (ß2GPI) binds lipopolysaccharide (LPS), which results in conformational changes, exposition of a cryptic epitope and possible pathological anti-ß2GPI antibody production. In order to investigate the effects of LPS on the induction of APS-related pathology, we performed hyperimmunization of BALB/c and C57BL/6 mice with LPS, alone or in combination with tetanus toxoid (TTd), a protein structurally similar to ß2GPI. We report that, although high affinity pathological anti-ß2GPI antibodies were produced in all groups of animals, the reproductive pathology was recorded only in mice that received both LPS and TTd, implying on the important roles of both infections and molecular mimicry in APS pathogenesis. Moreover, APS-related reproductive pathology was more pronounced in BALB/c (lowered fertility and fecundity) than C57BL/6 mice (lowered fecundity), which correlated well with the disruption in natural antibody network observed in BALB/c mouse strain.