Fernando Gómez-Aguado

Folate Receptor β Is Expressed by Tumor-Associated Macrophages and Constitutes a Marker for M2 Anti-inflammatory/Regulatory Macrophages

Macrophage activation comprises a continuum of functional states critically determined by cytokine microenvironment. Activated macrophages have been functionally grouped according to their response to pro-Th1/proinflammatory stimuli [lipopolysaccharide, IFNgamma, granulocyte macrophage colony-stimulating factor (GM-CSF); M1] or pro-Th2/anti-inflammatory stimuli [interleukin (IL)-4, IL-10, M-CSF; M2]. We report that folate receptor beta (FRbeta), encoded by the FOLR2 gene, is a marker for macrophages generated in the presence of M-CSF (M2), but not GM-CSF (M1), and whose expression correlates with increased folate uptake ability. The acquisition of folate uptake ability by macrophages is promoted by M-CSF, maintained by IL-4, prevented by GM-CSF, and reduced by IFNgamma, indicating a link between FRbeta expression and M2 polarization. In agreement with in vitro data, FRbeta expression is detected in tumor-associated macrophages (TAM), which exhibit an M2-like functional profile and exert potent immunosuppressive functions within the tumor environment. FRbeta is expressed, and mediates folate uptake, by CD163(+) CD68(+) CD14(+) IL-10-producing TAM, and its expression is induced by tumor-derived ascitic fluid and conditioned medium from fibroblasts and tumor cell lines in an M-CSF-dependent manner. These results establish FRbeta as a marker for M2 regulatory macrophage polarization and indicate that folate conjugates of therapeutic drugs are a potential immunotherapy tool to target TAM.

Dendritic Cell-Specific ICAM-3―Grabbing Nonintegrin Expression on M2-Polarized and Tumor-Associated Macrophages Is Macrophage-CSF Dependent and Enhanced by Tumor-Derived IL-6 and IL-10

Dendritic cell-specific ICAM-3–grabbing nonintegrin (DC-SIGN; CD209) is a human pathogen-attachment C-type lectin with no obvious murine ortholog and for which ligation leads to enhanced anti-inflammatory cytokine release and altered proinflammatory cytokine production. Although induced by IL-4 in monocytes and considered as a DC marker, DC-SIGN expression on human APCs under homeostatic conditions is so far unexplained. We report in this study that M-CSF enhances DC-SIGN expression on in vitro derived anti-inflammatory macrophages and that M-CSF mediates the induction of DC-SIGN by fibroblast- and tumor cell-conditioned media. The M-CSF–inducible DC-SIGN expression along monocyte-to-macrophage differentiation is dependent on JNK and STAT3 activation, potentiated by STAT3-activating cytokines (IL-6, IL-10), and abrogated by the M1-polarizing cytokine GM-CSF. In pathological settings, DC-SIGN expression is detected in tumor tissues and on ex vivo-isolated CD14+ CD163+ IL-10–producing tumor-associated macrophages. Importantly, DC-SIGN Abs reduced the release of IL-10 from macrophages exposed to Lewisx-expressing SKBR3 tumor cells. These results indicate that DC-SIGN is expressed on both wound-healing (IL-4–dependent) and regulatory (M-CSF–dependent) alternative (M2) macrophages and that DC-SIGN expression on tumor-associated macrophages might help tumor progression by contributing to the maintenance of an immunosuppressive environment.

Serotonin Skews Human Macrophage Polarization through HTR2B and HTR7

Besides its role as a neurotransmitter, serotonin (5-hydroxytryptamine, 5HT) regulates inflammation and tissue repair via a set of receptors (5HT1–7) whose pattern of expression varies among cell lineages. Considering the importance of macrophage polarization plasticity for inflammatory responses and tissue repair, we evaluated whether 5HT modulates human macrophage polarization. 5HT inhibited the LPS-induced release of proinflammatory cytokines without affecting IL-10 production, upregulated the expression of M2 polarization–associated genes (SERPINB2, THBS1, STAB1, COL23A1), and reduced the expression of M1-associated genes (INHBA, CCR2, MMP12, SERPINE1, CD1B, ALDH1A2). Whereas only 5HT7 mediated the inhibitory action of 5HT on the release of proinflammatory cytokines, both 5HT2B and 5HT7 receptors mediated the pro-M2 skewing effect of 5HT. In fact, blockade of both receptors during in vitro monocyte-to-macrophage differentiation preferentially modulated the acquisition of M2 polarization markers. 5HT2B was found to be preferentially expressed by anti-inflammatory M2(M-CSF) macrophages and was detected in vivo in liver Kupffer cells and in tumor-associated macrophages. Therefore, 5HT modulates macrophage polarization and contributes to the maintenance of an anti-inflammatory state via 5HT2B and 5HT7, whose identification as functionally relevant markers for anti-inflammatory/homeostatic human M2 macrophages suggests their potential therapeutic value in inflammatory pathologies.

Isolation of Ani s 5, an excretory–secretory and highly heat-resistant allergen useful for the diagnosis of Anisakis larvae sensitization

Allergens Ani s 1 and Ani s 4 have demonstrated their utility for the diagnosis of the sensitization to larvae of the genus Anisakis. The aim was to determine the number of patients with compatible clinical history, who did not recognize Ani s 1 and Ani s 4, and characterize the allergens responsible for their sensitization. Eighty-four patients were studied by CAP and immunoglobulin E (IgE) immunoblotting. The 12% of the patients recognized allergens different from Ani s 1 and Ani s 4, being half sensitized to a heat-resistant 15-kDa allergen, which was isolated by ethanol fractionation, followed by a hydroxyapatite chromatography and a reversed-phase high-performance liquid chromatography and identified by its amino terminal sequence as Ani s 5. A total of 41 of the 84 patients studied (49%) showed specific IgE to Ani s 5 that was detected among the excretory–secretory products and immunohistochemically located at the excretory gland, ventriculus, and the luminal surface of the intestinal epithelium of the larvae.

The pathogen receptor liver and lymph node sinusoidal endotelial cell C-type lectin is expressed in human Kupffer cells and regulated by PU.1†

Human LSECtin (liver and lymph node sinusoidal endothelial cell C‐type lectin, CLEC4G) is a C‐type lectin encoded within the L‐SIGN/DC‐SIGN/CD23 gene cluster. LSECtin acts as a pathogen attachment factor for Ebolavirus and the SARS coronavirus, and its expression can be induced by interleukin‐4 on monocytes and macrophages. Although reported as a liver and lymph node sinusoidal endothelial cell‐specific molecule, LSECtin could be detected in the MUTZ‐3 dendritic‐like cell line at the messenger RNA (mRNA) and protein level, and immunohistochemistry analysis on human liver revealed its presence in Kupffer cells coexpressing the myeloid marker CD68. The expression of LSECtin in myeloid cells was further corroborated through the analysis of the proximal regulatory region of the human LSECtin gene, whose activity was maximal in LSECtin+ myeloid cells, and which contains a highly conserved PU.1‐binding site. PU.1 transactivated the LSECtin regulatory region in collaboration with hematopoietic‐restricted transcription factors (Myb, RUNX3), and was found to bind constitutively to the LSECtin proximal promoter. Moreover, knockdown of PU.1 through the use of small interfering RNA led to a decrease in LSECtin mRNA levels in THP‐1 and monocyte‐derived dendritic cells, thus confirming the involvement of PU.1 in the myeloid expression of the lectin. Conclusion: LSECtin is expressed by liver myeloid cells, and its expression is dependent on the PU.1 transcription factor. (HEPATOLOGY 2009;49:287–296.)

A rat model of intragastric infection with Anisakis spp. live larvae: histopathological study

Anisakiasis is a fish-borne parasitic disease caused by consumption of raw or undercooked fish or cephalopods parasited by Anisakis spp. third stage larvae. The pathological effects of the infection are the combined result of the mechanical action of the larva during tissue invasion, the direct tissue effects of the excretory/secretory products released by the parasite, and the complex interaction between the host immune system and the Anisakis antigens. The aim of this study was to develop an experimental model of infection with Anisakis spp. live larvae in rats, useful to study the acute and chronic histopathological effects of the Anisakis infection. Sprague–Dawley rats were subjected to esophageal catheterization to place larvae directly into the stomach. Reinfections at different intervals after the first infection were preformed. Live larvae were found anchored to the mucosa and passing through the wall of the stomach and showed a strong resistance being able to stay alive at different sites and at the different pH. Migration of larvae from the stomach to other organs out of the gastrointestinal tract was also observed. The histopathological study showed the acute inflammatory reaction, with predominance of polymorphonuclear eosinophils and a mild fibrotic reaction. The model of infection described is valid to study the behavior of the larvae inside the host body, the histopathological changes at the invasion site, and the effects of the repeated infections by ingestion of live larvae.

Evolving architectural patterns in microbial colonies development.

Semithin sections of colonies of three ATCC strains (Staphylococcus aureus, Escherichia coli, and Candida albicans) showed that their internal structure had specific patterns that evolved over the time. These patterns generally were defined by the presence of different layers composed of microorganisms with variable population densities and dead cells. The observed structures in this study could be explained as a particular form of biofilm with an air‐semisolid interface. Microsc. Res. Tech. 2010.

Hypodermal decidualized endometrioma with aberrant cytokeratin expression. A lesion mimicking malignancy.

Decidualized endometrioma is a pseudoneoplastic lesion that may appear as a solitary nodule in the hypodermis, simulate a malignant epithelioid tumor, and can represent a diagnostic challenge. A 36-year-old woman delivered a full-term baby by cesarean. At the immediate puerperium, she complained of a subcutaneous nodule measuring 2.5 cm, underneath a previous caesarean scar from the former full-term delivery 3 years earlier. Histologic features included a nodular growth pattern of large monomorphic epithelioid cells showing diffuse positivity for cytokeratin (AE1/AE3, 18), human placental lactogen, and CD10 and focal positivity for inhibin alpha. The main differential diagnoses include trophoblastic neoplasia and deciduoid mesothelioma. Good clinicopathological correlation is essential for the correct diagnosis. Immunohistochemical stains can be misleading. An important clue is the combination of large decidualized cells and lumens lined by flat or low cuboidal cells that are atrophic endometrial glands. This lesion has a benign behavior.