Interleukin‐12p70-dependent interferon‐γ production is crucial for resistance in African trypanosomiasis

African trypanosomiasis encompasses diseases caused by pathogenic trypanosomes, infecting both humans and animals. In the present article, we dissected the possible role of members of the interleukin ( IL)-12 family during infection with Trypanosoma brucei brucei and Trypanosoma evansi in mice. IL-12p35(-/-) , IL-12p40(-/-) , and IL-12p35(-/-)/p40(-/-) mice were susceptible to both pathogens, as was demonstrated by the increased mortality among these mice, compared with wild-type C57BL/6 mice. The different IL-12p70(-/-) mouse strains showed similar mortality kinetics, suggesting that IL-12p70 - but not the IL-12p80 homodimer or IL-23 plays a crucial role in survival. Although there were similar plasma levels of immunoglobulin (Ig) M and IgG2a in IL-12-deficient mice and wild-type mice, interferon (IFN) - g production, especially during early infection, was severely impaired in all IL-12p70(-/-) mouse strains, demonstrating an IL-12p70 - dependent mechanism for IFN-gamma production. Because IFN-gamma receptor-deficient mice (IFN-gamma R-/(-)) were also highly susceptible to both Trypanosoma species, IL-12p70 - dependent IFN-gamma production seems to be the important mechanism involved in resistance against both pathogens

Organisational design elements and competencies for optimising the expertise of knowledge workers in a shared services centre

ORIENTATION: Organisations are still structured according to the Industrial Age control model that restricts optimising the expertise of knowledge workers. RESEARCH PURPOSE: The general aim of the research was to explore the organisation design elements and competencies that contribute to optimising the expertise of knowledge workers in a shared services centre. MOTIVATION FOR THE STUDY: Current organisational design methodologies do not emphasise optimising the expertise of knowledge workers. This research addresses the challenge of how an organisation design can improve the creation and availability of the expertise of knowledge workers. RESEARCH DESIGN/APPROACH METHOD: The researcher followed a qualitative case study research design and collected data in six focus group sessions (N = 25). MAIN FINDINGS: The findings showed that the shared services centre (SSC) is not designed to enable its structure, culture and codifying system to optimise the expertise of knowledge workers. In addition, the SSC does not share the knowledge generated with other knowledge workers. Furthermore, it does not use the output of the knowledge workers to improve business processes. PRACTICAL/MANAGERIAL IMPLICATIONS: The expertise of knowledge workers is the basis of competitive advantage. Therefore, managers should create an organisational design that is conducive to optimising knowledge work expertise. CONTRIBUTION/VALUE ADD: This research highlights the important organisational design elements and supportive organisational structures for optimising the expertise of knowledge workers. The research also proposes a framework for optimising the expertise of knowledge workers and helping an organisation to achieve sustainable competitive advantage.http://www.sajhrm.co.z

NK-, NKT-and CD8-derived IFNγ drives myeloid cell activation and erythrophagocytosis, resulting in Trypanosomosis-associated acute anemia

African trypanosomes are the causative agents of Human African Trypanosomosis (HAT/Sleeping Sickness) and Animal African Trypanosomosis (AAT/Nagana). A common hallmark of African trypanosome infections is inflammation. In murine trypanosomosis, the onset of inflammation occurs rapidly after infection and is manifested by an influx of myeloid cells in both liver and spleen, accompanied by a burst of serum pro-inflammatory cytokines. Within 48 hours after reaching peak parasitemia, acute anemia develops and the percentage of red blood cells drops by 50%. Using a newly developed in vivo erythrophagocytosis assay, we recently demonstrated that activated cells of the myeloid phagocytic system display enhanced erythrophagocytosis causing acute anemia. Here, we aimed to elucidate the mechanism and immune pathway behind this phenomenon in a murine model for trypanosomosis. Results indicate that IFNγ plays a crucial role in the recruitment and activation of erythrophagocytic myeloid cells, as mice lacking the IFNγ receptor were partially protected against trypanosomosis-associated inflammation and acute anemia. NK and NKT cells were the earliest source of IFNγ during T. b. brucei infection. Later in infection, CD8+ and to a lesser extent CD4+ T cells become the main IFNγ producers. Cell depletion and transfer experiments indicated that during infection the absence of NK, NKT and CD8+ T cells, but not CD4+ T cells, resulted in a reduced anemic phenotype similar to trypanosome infected IFNγR-/- mice. Collectively, this study shows that NK, NKT and CD8+ T cell-derived IFNγ is a critical mediator in trypanosomosis-associated pathology, driving enhanced erythrophagocytosis by myeloid phagocytic cells and the induction of acute inflammation-associated anemia

Determination of the role of cytokines using gene deficient mice in African trypanosomiasis infection

Includes bibliographical references.African trypanosomiasis encompasses diseases caused by pathogenic trypanosomes, infecting both humans and animals alike. To determine the immunological role of IL=12 family members in Trypanosoma brucei brucei, Trypanosoma evansi and Trypanosoma congolense infections, IL-12p35¯/¯, IL-12p40¯/¯ and IL-12p35¯/¯/p40¯/¯ mice were used. While the two latter mouse strains lack all IL-12 homologues, IL-12p35¯/¯ mice still produce IL-12p80 homodimers and IL-23. In infection with T.b. brucei and T.evansi; IL-12p35¯/¯, IL-12p40¯/¯ or IL-12p35¯/¯/p40¯/¯ mice were susceptible to both these pathogens, demonstrated by increased mortality compared to wild type C57BL/6 mice. The different IL-12 deficient mouse strains showed similar mortality kinetics, suggesting that IL-12p70 but not the IL-12p80 homodimer or IL-23 plays a crucial role in survival. Similarly, parasitemia control was reduced in the absence of IL-12p70. While plasma levels of IgM and IgG2c were similar between IL-12 deficient mice and wild type mice, IF-γ production. As IFN-γR¯/¯ mice were also highly susceptible to both T.b. brucei and T. evansi, IL-12p70-dependent IFN-γ production seems to be important mechanism involved in resistance against both these pathogens

Interleukin-12p70 deficiency increases survival and diminishes pathology in Trypanosoma congolense infection

To determine the immunological role played by interleukin (IL)-12 family members in Trypanosoma congolense infection, IL-12p35(-/-), IL-12p40(-/-), and IL-12p35(/-/-)p40(-/-) mice were used. While the latter 2 strains lack all IL-12 homologues, IL-12p35m(-/-) ice still produce IL-12p80 homodimers and IL-23. Compared with wild-type mice, all infected IL-12-deficient mouse strains showed prolonged survival, whereas parasitemia levels were unaltered. Interferon (IFN)-gamma production in IL-12-deficient mice was strikingly reduced during the acute and chronic stages of infection, coinciding with significantly reduced chronic-stage hepatocellular damage, as demonstrated by histological analysis and plasma aspartate transaminase measurements. In contrast, IL-10 production was not affected by the absence of IL-12. Taken together, these results show that, during T. congolense infection, the absence of IL-12, but not the IL-12p80 homodimer or IL-23, leads to a reduction in IFN-gamma production, which reduces hepatic pathology and improves host survival in conjunction with IL-10 without negatively affecting parasitemia control

IL-4R{alpha}-responsive smooth muscle cells increase intestinal hypercontractility and contribute to resistance during acute Schistosomiasis.

Interleukin-(IL)-4 and IL-13 signal through heterodimeric receptors containing a common IL-4 receptor-alpha (IL-4Ralpha) subunit, which is important for protection against helminth infections, including schistosomiasis. Previous studies demonstrated important roles for IL-4Ralpha-responsive hematopoietic cells, including T cells and macrophages in schistosomiasis. In this study, we examined the role of IL-4Ralpha responsiveness by nonhematopoietic smooth muscle cells during experimental acute murine schistosomiasis. Comparative Schistosoma mansoni infection studies with smooth muscle cell-specific IL-4Ralpha-deficient (SM-MHC(cre)IL-4Ralpha(-/flox)) mice, heterozygous control (IL-4Ralpha(-/flox)) mice, and global IL-4Ralpha-deficient (IL-4Ralpha(-/-)) mice were conducted. S. mansoni-infected SM-MHC(cre)IL-4Ralpha(-/flox) mice showed increased weight loss and earlier mortalities compared with IL-4Ralpha(-/flox) mice, despite comparable T(H)2/type 2 immune responses. In contrast to highly susceptible IL-4Ralpha-deficient mice, increased susceptibility in SM-MHC(cre)IL-4Ralpha(-/flox) mice was not accompanied by intestinal tissue damage and subsequent sepsis. However, both susceptible mutant mouse strains failed to efficiently expel eggs, demonstrated by egg reduction in the feces compared with control mice. Reduced egg expulsion was accompanied by impaired IL-4/IL-13-mediated hypercontractile intestinal responses, which was present in the more resistant control mice. Together, we conclude that IL-4Ralpha responsiveness by smooth muscle cells and subsequent IL-4- and IL-13-mediated hypercontractility are required for host protection during acute schistosomiasis to efficiently expel S. mansoni eggs and to prevent premature mortality