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Cardiovascular magnetic resonance (CMR) is a useful noninvasive technique for determining the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH), frequently occurring in patients after reperfused myocardial infarction (MI). MVO, or the so-called no-reflow phenomenon, is associated with adverse ventricular remodeling and a poor prognosis during follow-up. Similarly, IMH is considered a severe damage after revascularization by percutaneous primary coronary intervention (PPCI) or fibrinolysis, which represents a worse prognosis. However, the pathophysiology of IMH is not fully understood and imaging modalities might help to better understand that phenomenon. While, during the past decade, several studies examined the distribution patterns of late gadolinium enhancement with different CMR sequences, the standardized CMR protocol for assessment of IMH is not yet well established. The aim of this review is to evaluate the available literature on this issue, with particular regard to CMR sequences. New techniques, such as positron emission tomography/magnetic resonance imaging (PET/MRI), could be useful tools to explore molecular mechanisms of the myocardial infarction healing process.

Dendritic cells (DC) sense saprophytic yeast and pathogenic, filamentous forms of Candida albicans in a specific way, resulting in disparate patterns of DC and T(h) cell activation. Using human and murine DC, such disparate patterns could be traced to the exploitation of distinct recognition receptors. Although usage of mannose receptors led to protective type 1 responses in mice, entry through Fcgamma receptors was responsible for suppression of mannose receptor-dependent reactivity, onset of type 2 responses and associated pathology. As the usage of distinct receptors selectively occurred with yeast or hyphal forms of the fungus, these findings suggest that the responsibility for pathogenicity of C. albicans is shared by the organism and DC, with implications for fungal virulence, immunity and vaccine development.

To find out whether polymorphonuclear neutrophils (PMN), abundantly recruited in disseminated Candida albicans infection, could directly affect the activation of Th cells we addressed the issues as to whether murine PMN, like their human counterparts, express costimulatory molecules and the functional consequence of this expression in terms of antifungal immune resistance. To this purpose, we assessed 1) the expression of CD80 (B7-1) and CD86 (B7-2) molecules on peripheral, splenic, and inflammatory murine Gr-1+ PMN; 2) its modulation upon interaction with C. albicans in vitro, in vivo, and in human PMN; 3) the effect of Candida exposure on the ability of murine PMN to affect CD4+ Th1 cell proliferation and cytokine production; and 4) the mechanism responsible for this effect. Murine PMN constitutively expressed CD80 molecules on both the surface and intracellularly; however, in both murine and human PMN, CD80 expression was differentially modulated upon interaction with Candida yeasts or hyphae in vitro as well as in infected mice. The expression of the CD86 molecule was neither constitutive nor inducible upon exposure to the fungus. In vitro, Gr-1+ PMN were found to inhibit the activation of IFN-γ-producing CD4+ T cells and to induce apoptosis through a CD80/CD28-dependent mechanism. A population of CD80+Gr-1+ myeloid cells was found to be expanded in conventional as well as in bone marrow-transplanted mice with disseminated candidiasis, but its depletion increased the IFN-γ-mediated antifungal resistance. These data indicate that alternatively activated PMN expressing CD80 may adversely affect Th1-dependent resistance in fungal infections.

Aspergilli are respiratory pathogens and pulmonary infections are usually acquired through the inhalation of conidia, able to reach small airways and the alveolar space where the impaired host defense mechanisms allow hyphal germination and subsequent tissue invasion. The invasive pulmonary aspergillosis is the most common manifestation of Aspergillus fumigatus infection in immunocompromised patients and is characterized by hyphal invasion and destruction of pulmonary tissue. A Th1/Th2 dysregulation and a switch to a Th2 immune response may contribute to the development and unfavorable outcome of invasive pulmonary aspergillosis. Dendritic cells (DC) have a primary role in surveillance for pathogens at the mucosal surfaces and are recognized as the initiators of immune responses to them. In the present study, we assessed the functional activity of pulmonary DC in response to A. fumigatus conidia and hyphae, both in vitro and in vivo. We analyzed mechanisms and receptors for phagocytosis by DC as well as DC migration, maturation, and Th priming in vivo upon exposure to either form of the fungus. We found a remarkable functional plasticity of DC in response to the different forms of the fungus, as pulmonary DC were able to: 1) internalize conidia and hyphae of A. fumigatus through distinct phagocytic mechanisms and recognition receptors; 2) discriminate between the different forms in terms of cytokine production; 3) undergo functional maturation upon migration to the draining lymph nodes and spleens; and 4) instruct local and peripheral Th cell reactivity to the fungus.

The fungus Candida albicans behaves as a commensal as well as a true pathogen of areas highly enriched in dendritic cells, such as skin and mucosal surfaces. The ability of the fungus to reversibly switch between unicellular yeast to filamentous forms is thought to be important for virulence. However, whether it is the yeast or the hyphal form that is responsible for pathogenicity is still a matter of debate. Here we show the interaction, and consequences, of different forms of C. albicans with dendritic cells. Immature myeloid dendritic cells rapidly and efficiently phagocytosed both yeasts and hyphae of the fungus. Phagocytosis occurred through different phagocytic morphologies and receptors, resulting in phagosome formation. However, hyphae escaped the phagosome and were found lying free in the cytoplasm of the cells. In vitro, ingestion of yeasts activated dendritic cells for interleukin (IL)-12 production and priming of T helper type 1 (Th1) cells, whereas ingestion of hyphae inhibited IL-12 and Th1 priming, and induced IL-4 production. In vivo, generation of antifungal protective immunity was induced upon injection of dendritic cells ex vivo pulsed with Candida yeasts but not hyphae. The immunization capacity of yeast-pulsed dendritic cells was lost in the absence of IL-12, whereas that of hypha-pulsed dendritic cells was gained in the absence of IL-4. These results indicate that dendritic cells fulfill the requirement of a cell uniquely capable of sensing the two forms of C. albicans in terms of type of immune responses elicited. By the discriminative production of IL-12 and IL-4 in response to the nonvirulent and virulent forms of the fungus, dendritic cells appear to meet the challenge of Th priming and education in C. albicans saprophytism and infections.

The role of IL-17 and Th17 cells in immunity vs. pathology associated with the human commensal Candida albicans remains controversial. Both positive and negative effects on immune resistance have been attributed to IL-17/Th17 in experimental candidiasis. In this study, we provide evidence that IL-22, which is also produced by Th17 cells, has a critical, first-line defense in candidiasis by controlling the growth of infecting yeasts as well as by contributing to the host's epithelial integrity in the absence of acquired Th1-type immunity. The two pathways are reciprocally regulated, and IL-22 is upregulated under Th1 deficiency conditions and vice versa. Whereas both IL-17A and F are dispensable for antifungal resistance, IL-22 mediates protection in IL-17RA-deficient mice, in which IL-17A contributes to disease susceptibility. Thus, our findings suggest that protective immunity to candidiasis is made up of a staged response involving an early, IL-22-dominated response followed by Th1/Treg reactivity that will prevent fungal dissemination and supply memory.

We investigated the subcellular distribution of S-100b protein in primary cultures of Schwann cells. The subcellular localization of the protein in cells fixed and then permeabilized is similar, if not identical, to that seen in Schwann cells in peripheral nerves, i.e., S-100b protein is found in the cytoplasm and associated with membranes and filamentous structures. In cells either fixed in the presence of Triton X-100 or exposed to Triton X-100 for a short time before fixation (Triton cytoskeletons), the immune reaction product is considerably less intense, and the protein is associated with filaments running parallel to the long axis of the cell as well as in a submembranous position. Including CaCl2 in the buffer during fixation in the presence of Triton X-100 does not result in any increase in the intensity of the immune reaction product in Triton cytoskeletons, suggesting that, within the limits of the technique employed, no binding of additional S-100b protein to the Triton X-100-resistant material can be induced. On the other hand, including EGTA results in a substantial decrease in the intensity of the immune reaction product in Triton cytoskeletons. Altogether, these findings suggest that a remarkable fraction of S-100b protein in cultured Schwann cells is associated with elements of the cytoskeleton and that Ca2+ exerts some regulatory role in the association of S-100b protein with the cytoskeleton.

The ultracytochemical localization of adenylate cyclase (AC) and guanylate cyclase B (GC-B) and C (GC-C) activity was studied after stimulation with pituitary adenylate cyclase activating peptide, C-type natriuretic peptide and guanylin, respectively, in normal human respiratory nasal mucosa and mucosa of nasal polyps. To demonstrate these enzymatic activities, we employed enzyme-ultracytochemical methods for electron microscopy. Both normal and pathologic nasal mucosa contained AC, GC-B and GC-C activity. In the upper portion of respiratory epithelium, the enzymes were detected on ciliary and microvillar membranes. In ciliary membranes, GC-B was the predominant form expressed. In goblet cells and in glands of the lamina propria, enzymatic activities were localized mainly on plasma membranes and on membranes lining secretory granules. The results did not reveal any evident differences between the enzymatic activities in normal and pathological nasal mucosa and suggest complementary activities for these enzymes and their stimulators in the regulation of mucociliary transport and glandular secretion.

The ultracytochemical localization of adenylate cyclase (AC) and guanylate cyclase B (GC-B) and C (GC-C) activity was studied after stimulation with pituitary adenylate cyclase activating peptide, C-type natriuretic peptide and guanylin, respectively, in normal human respiratory nasal mucosa and mucosa of nasal polyps. To demonstrate these enzymatic activities, we employed enzyme-ultracytochemical methods for electron microscopy. Both normal and pathologic nasal mucosa contained AC, GC-B and GC-C activity. In the upper portion of respiratory epithelium, the enzymes were detected on ciliary and microvillar membranes. In ciliary membranes, GC-B was the predominant form expressed. In goblet cells and in glands of the lamina propria, enzymatic activities were localized mainly on plasma membranes and on membranes lining secretory granules. The results did not reveal any evident differences between the enzymatic activities in normal and pathological nasal mucosa and suggest complementary activities for these enzymes and their stimulators in the regulation of mucociliary transport and glandular secretion.

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-catabolizing enzyme that, expressed by different cell types, has regulatory effects on T cells resulting from tryptophan depletion in specific local tissue microenvironments. Different mechanisms, however, might contribute to IDO-dependent immune regulation. We show here that tryptophan metabolites in the kynurenine pathway, such as 3-hydroxyanthranilic and quinolinic acids, will induce the selective apoptosis in vitro of murine thymocytes and of Th1 but not Th2 cells. T cell apoptosis was observed at relatively low concentrations of kynurenines, did not require Fas/Fas ligand interactions, and was associated with the activation of caspase-8 and the release of cytochrome c from mitochondria. When administered in vivo, the two kynurenines caused depletion of specific thymocyte subsets in a fashion qualitatively similar to dexamethasone. These data suggest that the selective deletion of T lymphocytes may be a major mechanism whereby tryptophan metabolism affects immunity under physiopathologic conditions.

Antiidiotypic monoclonal antibodies (MAbs) representing the internal image of a yeast killer toxin (KT) have therapeutic potential against several fungal infections. The efficacy of KT MAbs againstAspergillus fumigatuswas investigated in a mouse model of T-cell-depleted allogeneic bone marrow transplantation (BMT) with invasive pulmonary aspergillosis. Mice were highly susceptible to infection at 3 days post-BMT, when profound neutropenia was observed both in the periphery and in the lungs. Treatment with KT MAbs protected the mice from infection, as judged by the long-term survival and decreased pathology associated with inhibition of fungal growth and hyphal development in the lungs. In vitro, similar to polymorphonuclear neutrophils, KT MAbs significantly inhibited the hyphal development and metabolic activity of germinatedAspergillusconidia. These results indicate that mimicking the action of neutrophils could be a strategy through which KT MAbs exert therapeutic efficacy inA. fumigatusinfections.

Glucocorticoid hormones (GCH) induce apoptotic cell death in immature thymocytes through an active mechanism, characterized by extensive DNA fragmentation into oligonucleosomal subunits. This requires macromolecular synthesis and is inhibited by protein kinase C (PKC) inhibitors, interleukin-4 (IL-4) and heat shock (hs). We performed experiments to analyse the possible effect of GCH on more differentiated lymphocytes, i.e. mouse natural killer (NK) cells and CD8+ alloreactive cytotoxic T lymphocytes (CTL). The results show that dexamethasone (DEX) induces DNA fragmentation and cell death in NK cells and CTL in vitro. In both NK cells and CTL, DEX-induced apoptosis is inhibited by IL-2 and IL-4 but, unlike that induced in thymocytes, is augmented by mRNA and protein synthesis inhibitors, PKC inhibitors and HS.

By immunocytochemistry, we have identified two novel cell types, olfactory and supporting cells of lamb olfactory epithelium, expressing S-100 beta beta protein. S-100 immune reaction product was observed on ciliary and plasma membranes, on axonemes and in the cytoplasm adjacent to plasma membranes and to basal bodies of olfactory vesicles. A brief treatment of olfactory mucosae with Triton X-100 before fixation is necessary for detection of S-100 beta beta protein within olfactory vesicles. In the absence of such a treatment, the immune reaction product is restricted to ciliary and plasma membranes. On the other hand, irrespective of pre-treatment of olfactory mucosae, S-100 beta immune reaction product in supporting cells is restricted to microvillar and plasma membranes. The anti-S-100 beta antiserum used in these studies does not bind to basal cells of the olfactory epithelium or to cells of the olfactory glands, whereas it binds to Schwann cells of the olfactory nerve. An anti-S-100 alpha antiserum does not bind to cellular elements of the olfactory mucosa, Schwann cells, or axons of the olfactory nerve. The present data provide, for the first time, evidence for the presence of S-100 beta beta protein in mammalian neurons (olfactory cells).

The subcellular distribution of annexin V, a calcium-dependent phospholipid- and membrane-binding protein, in a human-derived cell line, GL15, was investigated by immunocytochemistry at light and electron microscope levels. Annexin V was found diffusely in the cytoplasm and associated with plasma membranes, membranes delimiting cytoplasmic vacuoles, membranes of the endoplasmic reticulum, and filamentous structures the identity of which remains to be established. By immunocytochemistry at the light microscope level and immunochemistry, the expression of annexin V in these cells was found to depend on cellular growth state, being maximal soon after plating and progressively declining thereafter. However, re-expression of annexin V was observed whenever cell proliferation slowed down or arrested. These findings suggest that annexin V in glioma cells is mostly expressed in connection with cell differentiation. Also, the present ultrastructural data suggest that plasma membranes, membranes of the endoplasmic reticulum and the cytoskeleton are prominent sites of action of annexin V in vivo, thus lending support to the possibility that this protein might have a role in the regulation of cytoskeleton elements and/or of the structural organization of membranes.