Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated wit Show more
Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated with trained immunity and have long-term impacts on hematopoietic stem and progenitor cell (HSPC) development but can also compromise their function. While many cytokines support emergency myelopoiesis, less is known about the mechanisms that temper these events. When mice that lack the cytokine IL-27 were infected with Show less
Regulatory T (Treg) cells express high levels of the IL-27R, and in the setting of infection and autoimmunity, the cytokine IL-27 promotes Treg cell activities that mitigate tissue pathology. However, Show more
Regulatory T (Treg) cells express high levels of the IL-27R, and in the setting of infection and autoimmunity, the cytokine IL-27 promotes Treg cell activities that mitigate tissue pathology. However, IL-27 appears dispensable for Treg cell development and maintenance as lineage-specific depletion of the IL-27R on Treg cells does not impact these populations at steady state. In contrast, when mice were generated in which the Treg compartment comprised a mix of IL-27R-sufficient and -deficient Treg cells, those that lacked IL-27R were at a competitive disadvantage. Aging experiments illustrate that IL-27R-deficient Treg cells are preferentially eroded, and this defect was associated with reduced expression of CD122, the β chain of the IL-2/15R. Moreover, blockade of CD122 led to a similar loss of Treg cells, and in vitro and in vivo studies highlight that IL-27 promotes Treg cell expression of CD122 and improves responsiveness to IL-2/15. These datasets reveal that homeostatic IL-27 signals provide a competitive advantage that shapes the composition of the Treg cell pool by modulating responsiveness to growth factors. Show less
Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated wit Show more
Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated with trained immunity and have long-term impacts on hematopoietic stem and progenitor cell (HSPC) development but can also compromise their function. While many cytokines support emergency myelopoiesis, less is known about the mechanisms that temper these events. When mice that lack the cytokine IL-27 were infected with Show less
Mice that lack the genes for IL-27, or the IL-27 receptor, and infected with The molecule IL-27 is critical in limiting the immune response to the parasite
Interleukin-27 (IL-27) uniquely assembles p28 and EBI3 subunits to a heterodimeric cytokine that signals via IL-27Rα and gp130. To provide the structural framework for receptor activation by IL-27 and Show more
Interleukin-27 (IL-27) uniquely assembles p28 and EBI3 subunits to a heterodimeric cytokine that signals via IL-27Rα and gp130. To provide the structural framework for receptor activation by IL-27 and its emerging therapeutic targeting, we report here crystal structures of mouse IL-27 in complex with IL-27Rα and of human IL-27 in complex with SRF388, a monoclonal antibody undergoing clinical trials with oncology indications. One face of the helical p28 subunit interacts with EBI3, while the opposite face nestles into the interdomain elbow of IL-27Rα to juxtapose IL-27Rα to EBI3. This orients IL-27Rα for paired signaling with gp130, which only uses its immunoglobulin domain to bind to IL-27. Such a signaling complex is distinct from those mediated by IL-12 and IL-23. The SRF388 binding epitope on IL-27 overlaps with the IL-27Rα interaction site explaining its potent antagonistic properties. Collectively, our findings will facilitate the mechanistic interrogation, engineering, and therapeutic targeting of IL-27. Show less
The relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells whi Show more
The relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells while the so-called "helper" cells provide signals to B cells, influencing their class switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells exhibit an accelerated contraction after certain infections in B-cell-deficient mice. Here, we find that B cells significantly enhance primary CD8 T cell responses after vaccination. Moreover, memory CD8 numbers and function are impaired in B-cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also show that interleukin-27 production by B cells contributes to their impact on primary, but not memory, CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies. Show less