The X-chromosomal GPR34 gene encodes an orphan G i protein-coupled receptor that is highly conserved among vertebrates. To evaluate the physiological relevance of GPR34, we generated a GPR34-deficient mouse line. GPR34-deficient mice were vital, reproduced normally, and showed no gross abnormalities in anatomical, histological, laboratory chemistry, or behavioral investigations under standard housing. Because GPR34 is highly expressed in mononuclear cells of the immune system, mice were specifically tested for altered functions of these cell types. Following immunization with methylated BSA, the number of granulocytes and macrophages in spleens was significantly lower in GPR34-deficient mice as in wild-type mice. GPR34-deficient mice showed significantly increased paw swelling in the delayed type hypersensitivity test and higher pathogen burden in extrapulmonary tissues after pulmonary infection with Cryptococcus neoformans compared with wild-type mice. The findings in delayed type hypersensitivity and infection tests were accompanied by significantly different basal and stimulated TNF-␣, GM-CSF, and IFN-␥ levels in GPR34-deficient animals. Our data point toward a functional role of GPR34 in the cellular response to immunological challenges. G protein-coupled receptors (GPCR)2 form the largest gene family among transmembrane receptors, including more than 900 genes in humans and other mammals (1). A great number of stimuli, such as light, hormones, neurotransmitters, peptides, and nucleotides, activate the distinct receptors. Nonodorant receptors form about one-third of the GPCR repertoire. Although more than 200 non-odorant GPCR have been assigned to specific agonists and functions, about 155 socalled "orphan" GPCR (2) await identification of their physiological relevance. The importance of GPCR in controlling almost every physiological function makes this receptor family the most frequently used target for therapeutic drugs. Therefore, unveiling the function of orphan GPCR is a central issue in academic and industrial research.Among the five structurally different GPCR families (1, 3), the rhodopsin-like receptors form the largest in humans and other vertebrates. The rhodopsin-like family is divided further into subfamilies and groups. The P2Y 12 -like receptor group includes the ADP receptors P2Y 12 and P2Y 13 , the UDP-glucose receptor P2Y 14 , and the orphan receptors GPR87, GPR82, and GPR34 (4). Apart from the ADP receptor P2Y 12 , which has a central role in platelet aggregation and is the therapeutic target of clopidogrel (5, 6), very little is known about the function of the other members of this group.GPR34, an orphan receptor of the P2Y 12 -like receptor group, was first discovered by mining GenBank TM for novel GPCR sequences and homology cloning and has been assigned to the human X chromosome (7,8). Phylogenetic studies revealed that GPR34 has been highly conserved over the past 450 million years of vertebrate evolution, and no GPR34-deficient vertebrate has been identified yet (9). To date, there i...

Horses are an approved large animal model for therapies of the musculoskeletal system. Especially for tendon disease where cell-based therapy is commonly used in equine patients, the translation of achieved results to human medicine would be a great accomplishment. Immunophenotyping of equine mesenchymal stromal cells (MSCs) remains the last obstacle to meet the criteria of the International Society for Cellular Therapy (ISCT) definition of human MSCs. Therefore, the surface antigen expression of CD 29, CD 44, CD 73, CD 90, CD 105, CD 14, CD 34, CD 45, CD 79a, and MHC II in equine MSCs from adipose tissue, bone marrow, umbilical cord blood, umbilical cord tissue, and tendon tissue was analyzed using flow cytometry. Isolated cells from the different sources and donors varied in their expression pattern of MSC-defining antigens. In particular, CD 90 and 105 showed most heterogeneity. However, cells from all samples were robustly positive for CD 29 and CD 44, while being mostly negative for CD 73 and the exclusion markers CD 14, CD 34, CD 45, CD 79a and MHC II. Furthermore, it was evident that enzymes used for cell detachment after in vitro-culture affected the detection of antigen expression. These results emphasize the need of standardization of MSC isolation, culturing, and harvesting techniques. As the equine MSCs did not meet all criteria the ISCT defined for human MSCs, further investigations for a better characterization of the cell type should be conducted. V C 2014 International Society for Advancement of Cytometry

Interleukin (IL)-4 and IL-13 are key factors in the pathogenesis of bronchopulmonary mycosis induced in mice by infection with Cryptococcus neoformans. Both cytokines use the IL-4 receptor alpha-chain (IL-4Ralpha). In this study, we investigated the role played by IL-4Ralpha expression in susceptibility to pulmonary C. neoformans infection. IL-4Ralpha(-/-) mice were extremely resistant. To characterize the effect of IL-4Ralpha expression level on disease outcome, we generated IL-4Ralpha(+/-) first-generation (F1) mice. IL-4Ralpha(+/-) mice showed intermediate levels of IL-4Ralpha expression, in contrast to higher levels in wild-type mice and no expression in IL-4Ralpha(-/-) mice, indicating biallelic expression of the gene for IL-4Ralpha (Il4ra). Concomitant with intermediate IL-4Ralpha expression, F1 mice showed intermediate susceptibility associated with altered Th2/Th17 cytokine production, decreased immunoglobulin E levels, and reduced allergic inflammation. This indicates a gene-dosage effect of IL-4Ralpha expression on susceptibility to bronchopulmonary mycosis. These data provide the basis for novel therapies antagonizing IL-4Ralpha in Th2-related pulmonary infection and possibly also in asthma.

Susceptibility to infection with Cryptococcus neoformans is tightly determined by production of IL-4. In this study, we investigated the time course of IL-4 production and its innate cellular source in mice infected intranasally with C. neoformans. We show that pulmonary IL-4 production starts surprisingly late after 6 weeks of infection. Interestingly, in the lungs of infected mice, pulmonary T helper (Th) cells and eosinophils produce significant amounts of IL-4. In eosinophil-deficient ⌬dblGATA mice, IL-33 receptor-expressing Th2s are significantly reduced, albeit not absent, whereas protective Th1 and Th17 responses are enhanced. In addition, recruitment of pulmonary inflammatory cells during infection with C. neoformans is reduced in the absence of eosinophils. These data expand previous findings emphasizing an exclusively destructive effector function by eosinophilic granulocytes. Moreover, in ⌬dblGATA mice, fungal control is slightly enhanced in the lung; however, dissemination of Cryptococcus is not prevented. Therefore, eosinophils play an immunoregulatory role that contributes to Th2-dependent susceptibility in allergic inflammation during bronchopulmonary mycosis. Cryptococcus neoformans is a facultative intracellular pathogen that is acquired by inhalation of spores and/or desiccated yeasts and leads to latent pulmonary infection in immunocompetent humans. 1 The development of cryptococcal meningitis occurs mainly in immunocompromised HIV-1-infected patients, most likely by reactivation of latent pulmonary C. neoformans infection. 2 It is estimated that 504,000 HIV-1-infected patients die every year from cryptococcal meningitis in sub-Saharan Africa, 3 which surprisingly exceeds the annual death rate of tuberculosis-associated HIV cases. Resistance against C. neoformans primarily involves monocytic effector mechanisms. 4 -6 In this context, T helper (Th) cells are central regulatory players with profound effects. Whereas IL-12-dependent Th1 responses are protective, with an additional contribution by IL-23-dependent Th17 responses, 7-9 Th2 cells producing IL-4, IL-13, and IL-5 are detrimental. 10,11 Studies 12-14 that used i.v. inoculation examined the traversal of the blood-brain barrier by C. neoformans and led to the conclusion that transmigration can occur with intracellular and extracellular fungi. In case of bronchopulmonary infection, dissemination seems to rely more on Th2 cytokines. This allergic Th2-driven inflammation represents the immunopathological pathway promoting disease by allowing cryptococci to grow inside the lung and finally enabling dissemination to the brain, ultimately causing fatal meningoencephalitis. 15 This sequela is accompanied by development of IL-4/IL-13-dependent alternatively activated macrophages, suggesting that those cells may be involved in dissemination. Alternatively activated macrophages are found only in susceptible mice 15 and show significantly reduced control of intracellular growth. 5 In addition, IL-13-dependent mucus production by goblet cells, IL-4 -...

Allergic airway inflammation (AAI) in response to environmental antigens is an increasing medical problem, especially in the Western world. Type 2 interleukins (IL) are central in the pathological response but their importance and cellular source(s) often rely on the particular allergen. Here, we highlight the cellular sources and regulation of the prototypic type 2 cytokine, IL-13, during the establishment of AAI in a fungal infection model using Cryptococcus neoformans. IL-13 reporter mice revealed a rapid onset of IL-13 competence within innate lymphoid cells type 2 (ILC2) and IL-33R(+) T helper (Th) cells. ILC2 showed IL-33-dependent proliferation upon infection and significant IL-13 production. Th cells essentially required IL-33 to become either GATA3(+) or GATA3(+)/Foxp3(+) hybrids. GATA3(+) Th cells almost exclusively contributed to IL-13 production but hybrid GATA3(+)/Foxp3(+) Th cells did not. In addition, alveolar macrophages upregulated the IL-33R and subsequently acquired a phenotype of alternative activation (Ym1(+), FIZZ1(+), and arginase-1(+)) linked to type 2 immunity. Absence of adaptive immunity in rag2(-/-) mice resulted in attenuated AAI, revealing the need for Th2 cells for full AAI development. Taken together, in pulmonary cryptococcosis ILC2 and GATA3(+) Th2 cells produce early IL-13 largely IL-33R-dependent, thereby promoting goblet cell metaplasia, pulmonary eosinophilia, and alternative activation of alveolar macrophages.