Interleukin-10 derived from macrophages and/or neutrophils regulates the inflammatory response to LPS but not the response to CpG DNA.

Interleukin-10 (IL-10) is an important regulator of immune responses secreted by different cell types. We have previously shown that mice with selective inactivation of the IL-10 gene in T cells suffer from deregulated T cell responses similar to those observed in IL-10(-/-) animals. Unlike IL-10(-/-) mice, however, T cell-specific mutants do not mount an enhanced innate immune response to LPS, which must, therefore, be subject to control by IL-10 from non-T cells. Herein we show that subcutaneous injection of LPS, which causes moderate local inflammation in WT and T cell-specific IL-10 mutant mice, results in augmented inflammatory infiltration and extensive tissue necrosis in mice with deficiency for IL-10 in macrophages and neutrophils. Correspondingly, we observed an enhanced sensitivity of the macrophage/neutrophil-specific IL-10 mutants to systemic LPS exposure when compared with WT animals. In contrast, the inflammatory response of these mutants to CpG oligodeoxynucleotides was not different from that of WT mice. While IL-10(-/-) mice developed massive inflammation, necrosis and increased serum cytokine levels after subcutaneous CpG injection, only moderate responses were observed in macrophage/neutrophil-specific IL-10 mutant and WT mice. These results show that different innate immune responses can be subject to control by IL-10 from different cellular sources

T Cell-Derived IL-10 Determines Leishmaniasis Disease Outcome and Is Suppressed by a Dendritic Cell Based Vaccine

Abstract In the murine model of Leishmania major infection, resistance or susceptibility to the parasite has been associated with the development of a Th1 or Th2 type of immune response. Recently, however, the immunosuppressive effects of IL-10 have been ascribed a crucial role in the development of the different clinical correlates of Leishmania infection in humans. Since T cells and professional APC are important cellular sources of IL-10, we compared leishmaniasis disease progression in T cell-specific, macrophage/neutrophil-specific and complete IL-10-deficient C57BL/6 as well as T cell-specific and complete IL-10-deficient BALB/c mice. As early as two weeks after infection of these mice with L. major, T cell-specific and complete IL-10-deficient animals showed significantly increased lesion development accompanied by a markedly elevated secretion of IFN-γ or IFN-γ and IL-4 in the lymph nodes draining the lesions of the C57BL/6 or BALB/c mutants, respectively. In contrast, macrophage/neutrophil-specific IL-10-deficient C57BL/6 mice did not show any altered phenotype. During the further course of disease, the T cell-specific as well as the complete IL-10-deficient BALB/c mice were able to control the infection. Furthermore, a dendritic cell-based vaccination against leishmaniasis efficiently suppresses the early secretion of IL-10, thus contributing to the control of parasite spread. Taken together, IL-10 secretion by T cells has an influence on immune activation early after infection and is sufficient to render BALB/c mice susceptible to an uncontrolled Leishmania major infection. Author Summary The clinical symptoms caused by infections with Leishmania parasites range from self-healing cutaneous to uncontrolled visceral disease and depend not only on the parasite species but also on the type of the host's immune response. It is estimated that 350 million people worldwide are at risk, with a global incidence of 1–1.5 million cases of cutaneous and 500,000 cases of visceral leishmaniasis. Murine leishmaniasis is the best-characterized model to elucidate the mechanisms underlying resistance or susceptibility to Leishmania major parasites in vivo. Using T cell-specific and macrophage-specific mutant mice, we demonstrate that abrogating the secretion of the immunosuppressive cytokine IL-10 by T cells is sufficient to render otherwise susceptible mice resistant to an infection with the pathogen. The healing phenotype is accompanied by an elevated specific inflammatory immune response very early after infection. We further show that dendritic cell-based vaccination against leishmaniasis suppresses the early secretion of IL-10 following challenge infection. Thus, our study unravels a molecular mechanism critical for host immune defense, aiding in the development of an effective vaccine against leishmaniasis

Injuries in equestrian vaulting: results of a prospective study

BACKGROUND: Equestrian vaulting is a sport, particularly popular among children and adolescents, in which gymnastic and dance routines are performed on horseback. Current data regarding injuries and thus, the risks of this sport, is meager and based only on retrospective studies. METHODS: In the current prospective study, 233 active members of a vaulting club were questioned monthly from November 2014 until October 2015. In addition to general information (training, competitions), the questionnaire collected the number of competitions, the competitive class, the discipline (single, team, Pas-de-Deux), and injuries (type, localization, treatment). RESULTS: There were 102 documented events resulting in 125 injuries, yielding an average 31.64 days of training lost. Each vaulter suffered an average 0.44 injuries per year. Frequency of injury was 2.15 injuries per 1000 training hours. Injuries occurred most often to the lower and upper extremities. Most common were bruises and muscle injuries. Injury risk increased with increasing age, number of falls from the horse, increasing competitive level, number of tournament entries and events (P=0.006), and previous injuries (P=0.010). CONCLUSIONS: Our study found that vaulting has a low risk of injury comparable to non-contact sports. The best focus for injury prevention strategies is on older vaulters at higher competitive levels performing more complex routines

T cell-specific inactivation of the interleukin 10 gene in mice results in enhanced T cell responses but normal innate responses to lipopolysaccharide or skin irritation

Interleukin (IL)-10 is a regulator of inflammatory responses and is secreted by a variety of different cell types including T cells. T regulatory cells have been shown to suppress immune responses by IL-10–dependent, but also IL-10–independent, mechanisms. Herein, we address the role of T cell–derived IL-10 in mice with an inactivation of the IL-10 gene restricted to T cells generated by Cre/loxP-mediated targeting of the IL-10 gene. Splenocytes from this T cell–specific mutant secrete increased amounts of proinflammatory cytokines after activation in vitro compared with show enhanced contact hypersensitivity reactions, and succumb to severe immunopathology upon infection with Toxoplasma gondii. Despite intact IL-10 genes in other cell types, the dysregulation of T cell responses observed in the T cell–specific IL-10 mutant closely resembles the phenotype in complete IL-10 deficiency. However, in contrast to complete IL-10 deficiency, sensitivity to endotoxic shock and irritant responses of the skin are not enhanced in the T cell–specific IL-10 mutant. Our data highlight the importance of T cell–derived IL-10 in the regulation of T cell responses and demonstrate that endotoxic shock and the irritant response of the skin are controlled by IL-10 from other cell types

Course of infection of T cell-specific, macrophage specific and complete IL-10-deficient C57BL/6 mice.

<p>T cell-specific and complete IL-10-deficient C57BL/6 mice develop enhanced inflammation despite unaltered parasite loads 7 days after infection with <i>L. major</i>. T cell-specific (CD4-Cre⁺), macrophage/neutrophil-specific (LysM-Cre⁺), complete (EIIa-Cre⁺) IL-10-deficient and IL-10-competent control mice (Cre⁻) on a C57BL/6 background were infected with <i>L. major</i> promastigotes into the right hind footpad. The increase in size of the infected compared with the non-infected footpad was measured (<b>A, B and C</b>). Mean ± SD of 8–10 mice/group (<b>A</b>). Footpad swelling 7 days after infection (<b>B</b>). Footpad swelling of T cell-specific IL-10-deficient C57BL/6 mice 7 days after injection of PBS or <i>L. major</i> parasites (<b>C</b>). Frequency of parasitized cells in the lymph nodes draining the lesions (<b>D, E and F</b>). Each symbol represents one individual mouse (<b>B, C, D and E</b>). One representative of two independent experiments is shown (<b>A, B, D and E</b>). Each time point represents the mean of two to four independent experiments with 4–6 mice in each group and experiment (<b>F</b>). * <i>p</i><0.05, ** <i>p</i><0.01. Differences in parasite load did not reach statistical significance (<b>D, E and F</b>).</p

Populations of IL-10 secreting leukocytes in lesions and draining lymph nodes early after infection with <i>L. major</i>.

<p>Following infection with <i>L. major</i>, the early secretion of IL-10 by CD4⁺ T cells in the draining lymph nodes is primarily due to FoxP3⁻/CD25⁻ T cells. Within the infected footpads, however, the low absolute number of IL-10 secreting CD4⁺ T cells is predominantly FoxP3⁺/CD25⁺. The remaining IL-10 secreting leukocytes within the infected footpads are primarily macrophages, whereas in the draining lymph nodes, also B cells and CD8⁺ T cells contribute to the overall IL-10 secretion Wild-type BALB/c mice were infected with <i>L. major</i> promastigotes into the hind footpads and 2 weeks later, cells from draining lymph nodes and lesion-derived cells were prepared. IL-10-secreting cells were identified using a cytokine secretion assay (<b>A and C</b>), and the proportion of CD4⁺ FoxP3⁺ (<b>B, D and E</b>), CD4⁺ CD25⁺ (<b>F</b>), CD8⁺, CD45⁺, F4/80⁺ or CD11c⁺ cells (<b>G</b>) was determined. The means of 4 (<b>E</b>) or 3 (<b>F and G</b>) independent experiments with 3 mice each are given.</p

Characterization of the early inflammation in <i>L. major</i>-infected T cell-specific IL-10-deficient BALB/c mice.

<p>Enhanced inflammation in T cell-specific IL-10-deficient BALB/c mice 2 weeks after infection is associated with a mixed Th1/Th2 immune response. T cell-specific IL-10 mutant and IL-10-competent BALB/c mice were infected with <i>L. major</i> promastigotes into the right hind footpad. Increase in size of the infected footpad 2 weeks after infection (<b>A</b>). Frequency of <i>L. major</i>-infected cells in the draining lymph nodes (<b>B</b>). Cytokine secretion upon restimulation of lymph node cells with <i>Leishmania</i> antigen <i>in vitro</i> (<b>C, D and E</b>). Each symbol represents an individual mouse (<b>A and B</b>); the results are representative of three independent experiments. Data show the mean ± SEM of three independent experiments with 5–6 mice per group and experiment (<b>C, D and E</b>). ** <i>p</i><0.01.</p

Characterization of the early inflammation in <i>L. major</i>-infected T cell-specific IL-10-deficient C57BL/6 mice.

<p>The early enhanced inflammation in T cell-specific and complete IL-10-deficient C57BL/6 mice is not associated with changes in the cell numbers but correlates with elevated secretion of IFN-γ by CD4⁺ and CD8⁺ cells. C57BL/6 IL-10 mutant mice were infected with <i>L. major</i> promastigotes into the right hind footpad. Increase in size of the infected compared with the non-infected footpads (<b>A</b>). Frequencies of cell populations in the infected feet (<b>B</b>). Cell numbers in the draining lymph nodes (<b>C</b>) and frequencies of cell populations in the draining lymph nodes (<b>D</b>). The results show the mean of two independent experiments with 2 mice per group and time point (<b>A to D</b>). Secretion of IFN-γ (<b>E</b>) and IL-4 (<b>F</b>) by draining lymph node cells 7 days after infection with <i>L. major</i>. Data show the mean ± SEM of four independent experiments with 2 mice per group and experiment (<b>E and F</b>). Draining lymph node cells of infected mice were stained for IFN-γ and the indicated surface markers; the fraction of double positive cells of all lymph node cells is shown. The results are representative of two experiments (<b>G</b>).</p