Tailoring host immune responses to Listeria by manipulation of virulence genes -- the interface between innate and acquired immunity

Although attenuated strains of microbial pathogens have triggered vaccine development from its origin, the role of virulence factors in determining host immunity has remained largely unexplored. Using the murine listeriosis model, we investigated whether the induction and expansion of protective and inflammatory T cell responses may be modified by selective manipulation of virulence genes. We intentionally deleted specific genes of Listeria monocytogenes, including those encoding the positive regulatory factor (prfA), hemolysin (hly), the actin nucleator (actA), and phospholipase B (plcB). The resulting strains showed decisive differences in their immunogenic properties. In particular, we identified a double-deletion mutant that retained Listeria's profound ability to induce protective CD8(+) T cells, but that is strongly attenuated and exhibits a significantly reduced ability to induce CD4(+) T cell-mediated inflammation. We conclude that this mutant, L. monocytogenes DeltaactADeltaplcB, is at present the most promising mutant for a bacterial vaccine vector and is able to safely induce potent CD8(+) T cell-mediated immunity.     

Identification of biomarker panels as predictors of severity in coronary artery disease

Matrix metalloproteinases (MMPs) are implicated in atherosclerotic plaque rupture and recondition. Specific tissue inhibitors (TIMPs) control MMP functions. Both MMPs and TIMPs are potential biomarkers of plaque instability. Elevated Apo-CII and CIII and Apo-E levels are recognized as cardiovascular disease risk factors. We aimed to establish the best blood biomarker panel to evaluate the coronary artery disease (CAD) severity. Plasma levels of MMP-3 and MMP-9, TIMP-1 and TIMP-2, Apo-CII, Apo-CIII and Apo-E were measured in 472 patients with CAD evaluated by coronary angiography and electrocardiography, and in 285 healthy controls. MMP-3 and MMP-9 plasma levels in CAD patients were significantly increased (P < 0.001) compared to controls (3.54- and 3.81-fold, respectively). Furthermore, these increments are modulated by CAD severity as well as for Apo-CII and Apo-CIII levels (P < 0.001). TIMPs levels were decreased in CAD versus controls (P < 0.001) and in inverse correlation to MMPs. Standard ROC curve approach showed the importance of panels of biomarkers, including MMP-3, MMP-9, TIMP-1, TIMP-2, Apo-CII and Apo-CIII, for disease aggravation diagnosis. A high area under curve (AUC) value (0.995) was reached for the association of MMP-9, TIMP-2 and Apo-CIII. The unbalance between MMPs and TIMPs in vascular wall and dyslipidaemia creates favourable conditions for plaque disruption. Our study suggests that the combination of MMP-9, TIMP-2 and Apo-CIII values (‘CAD aggravation panel’) characterizes the severity of CAD, that is electrophysiological state, number of involved vessels, stent disposal and type of stent.     

Model-based identification of Helitrons results in a new classification of their families in Arabidopsis thaliana

Helitrons are a class of prolific transposable elements in the Arabidopsis thaliana genome. Although 37 families were identified after the recent discovery of Helitrons, no systematic classification is available because of the high variability of helitronic sequences. Since transposition proteins are assumed to interact with Helitron termini, a Helitron model was formalized based on terminus characterization in order to carry out an exhaustive analysis of all possible combinations of the pairs of termini present. This combinatorics approach resulted in the discovery of a number of new Helitron elements corresponding to termini associations from distinct previously-described Helitron families. The occurrence matrix of termini combinations yielded a structure that revealed clusters of Helitron families.     

Concomitant sertoli and leydig cell tumor of the testis: a case report

A rare intratubular gonadal stromal tumor was present in the testis of a 45-year-old man who was admitted to our hospital with the chief complaint of gradual enlargement of the left testis. Tumoral markers were negative and no extension was observed. The tumor comprised an intratubular mixture of two types of tumor cells with intercellular junctions: the predominant tumor cells were consistent with a Sertoli cell origin and cells comprising the minor population consistent with a Leydig cell origin. The patient is disease free after 6-month follow-up. The case is considered to be a testicular mixed tubular Sertoli-Leydig cell tumor. It highlights a rare type of primary tumor of the testis that features a good prognosis.     

Benign paratesticular fibrous pseudotumor with malignant clinical features

Paratesticular tumors are rare intrascrotal masses that grow mainly in structures containing connective tissue around the testis, epididymis, or spermatic cord. We report here on a case of a 55-year-old man with a mass in the hemiscrotum that was found to be a paratesticular fibrous pseudotumor in the orchiectomy specimen pathologic examination. From this case report and literature review, a diagnostic and therapeutic strategy is demonstrated for the management of this uncommon lesion.     

Increased Mitochondrial Fatty Acid Oxidation Is Sufficient to Protect Skeletal Muscle Cells from Palmitate-induced Apoptosis

The mechanisms underlying the protective effect of monounsaturated fatty acids (e.g. oleate) against the lipotoxic action of saturated fatty acids (e.g. palmitate) in skeletal muscle cells remain poorly understood. This study aimed to examine the role of mitochondrial long-chain fatty acid (LCFA) oxidation in mediating oleate''s protective effect against palmitate-induced lipotoxicity. CPT1 (carnitine palmitoyltransferase 1), which is the key regulatory enzyme of mitochondrial LCFA oxidation, is inhibited by malonyl-CoA, an intermediate of lipogenesis. We showed that expression of a mutant form of CPT1 (CPT1mt), which is active but insensitive to malonyl-CoA inhibition, in C2C12 myotubes led to increased LCFA oxidation flux even in the presence of high concentrations of glucose and insulin. Furthermore, similar to preincubation with oleate, CPT1mt expression protected muscle cells from palmitate-induced apoptosis and insulin resistance by decreasing the content of deleterious palmitate derivates (i.e. diacylglycerols and ceramides). Oleate preincubation exerted its protective effect by two mechanisms: (i) in contrast to CPT1mt expression, oleate preincubation increased the channeling of palmitate toward triglycerides, as a result of enhanced diacylglycerol acyltransferase 2 expression, and (ii) oleate preincubation promoted palmitate oxidation through increasing CPT1 expression and modulating the activities of acetyl-CoA carboxylase and AMP-activated protein kinase. In conclusion, we demonstrated that targeting mitochondrial LCFA oxidation via CPT1mt expression leads to the same protective effect as oleate preincubation, providing strong evidence that redirecting palmitate metabolism toward oxidation is sufficient to protect against palmitate-induced lipotoxicity.