María Teresa Corcuera

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.)

Is Infection by Dermatophilus congolensis Underdiagnosed

ABSTRACT Dermatophilus congolensis, which affects animal species, is an uncommon human infection. Few cases, mainly in tropical areas, have been reported. We describe the first human infection in Spain in a traveler returning from Central America. Diagnosis of human infection may be underestimated in people in contact with animals.

The novel RUNX3/p33 isoform is induced upon monocyte-derived dendritic cell maturation and downregulates IL-8 expression.

RUNX proteins are heterodimeric factors that play crucial roles during development and differentiation of cells of the immune system. The RUNX3 transcription factor controls lineage decisions during thymopoiesis and T-cell differentiation, and modulates myeloid cell effector functions. We now report the characterization of the human RUNX3/p33 isoform, generated by splicing out a Runt DNA-binding domain-encoding exon, and whose transcriptional activities differ from those of the prototypic RUNX3/p44 molecule. Unlike RUNX3/p44, RUNX3/p33 is induced upon maturation of monocyte-derived dendritic cells (MDDC), and is unable to transactivate the regulatory regions of the CD11a, CD11c and CD49e integrin genes. Overexpression of RUNX3/p33 in myeloid cell lines led to diminished expression of genes involved in inflammatory responses. Moreover, overexpression of RUNX3/p33 down-modulated the basal level of IL-8 production from immature monocyte-derived dendritic cells (MDDC). Besides, siRNA-mediated knock-down of RUNX3 led to diminished levels of IL-8 RNA in immature MDDC, and modulated the neutrophil-recruiting capacity of myeloid cell line supernatants. Since IL-8 promotes neutrophil chemotaxis and degranulation during inflammatory responses, and exerts mitogenic and angiogenic actions within tumor microenvironment, our results imply that myeloid RUNX3 expression regulates the recruitment of leukocytes towards inflammatory foci and might also contribute to human cancer progression.

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.

LABELLING PATTERN OBTAINED BY NON‐ISOTOPIC IN SITU HYBRIDIZATION AS A PROGNOSTIC FACTOR IN HPV‐ASSOCIATED LESIONS

In the study of infection of the lower female genital tract caused by human papillomavirus (HPV), one of the main concerns is the search for prognostic factors to predict the evolution of premalignant low‐ and high‐grade squamous intraepithelial lesions. This study has evaluated the prognostic usefulness of the patterns of positive reaction obtained by non‐isotopic in situ hybridization (NISH), referred to as diffuse, punctate, or mixed ‘labelling patterns’. The study examined 141 vulvar and uterine cervical biopsy specimens that were positive for HPV by a NISH screening technique and that had the following histological diagnoses: low‐grade squamous intraepithelial lesion (LSIL; n=87); high‐grade squamous intraepithelial lesion (HSIL, n=40); and squamous cell carcinoma (SCC n=14). Typing of all the specimens was carried out by NISH with DNA probes specific for HPV types 6/11 (low risk), 16/18 (high risk), and 31/33/51 (intermediate risk), and the labelling pattern observed in each specimen was recorded. Statistical analysis of the results showed that there was a significant difference in the distribution of labelling patterns, both by lesion diagnosis (P≤0·004) and by infecting viral type (P≤10−6). Lesions with a punctate or mixed pattern are considered more likely to undergo malignant evolution and consequently have a worse prognosis than lesions with a diffuse pattern.

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.