Biomedical subjects

Scott L Townley

Publications and source records attributed to Scott L Townley.

5 recordsLinked to original sources

PubMed2006

CXCL16 regulates cell-mediated immunity to Salmonella enterica serovar Enteritidis via promotion of gamma interferon production.

CXCL16 is a recently discovered multifaceted chemokine that has been shown not only to recruit activated T lymphocytes but also to play a direct role in the binding and phagocytosis of bacteria by professional antigen-presenting cells. In this study, we investigated the role of CXCL16 in vivo in the regulation of the immune response using a murine model of Salmonella enterica serovar Enteritidis infection. The expression of CXCL16 was strongly upregulated in the spleens and livers of animals developing an immune response to a primary acute infection but not in the Peyer's patches. Animals developing a secondary response after reexposure to the bacteria displayed a similar pattern of expression. During the primary response, prior treatment with neutralizing antibodies to CXCL16 induced a significant increase in bacterial burden in the spleen and liver. The production of gamma interferon (IFN-gamma) by the lymphocytes in the spleen was decreased by anti-CXCL16 treatment. In comparison, during the secondary response, anti-CXCL16 treatment also significantly increased bacterial burden in both the spleen and liver but had no effect on IFN-gamma production. No role was found for CXCL16 in the production of antibody against SefA, a major surface antigen of S. enteritidis. Together, these results demonstrate a role for CXCL16 in the control of bacterial colonization of target organs and, more specifically, in the regulation of the cell-mediated arm of the primary response to S. enteritidis.

Animals↗

PubMed2005

Primary defect in UVB-induced systemic immunomodulation does not relate to immature or functionally impaired APCs in regional lymph nodes.

UVB irradiation of the shaved dorsal skin of mice can cause both local and systemic suppression of contact hypersensitivity responses; the former demonstrated by administration of the sensitizing Ag/hapten to the irradiated site and the latter by its administration at least 72 h later to distal unirradiated sites. The immunological basis of systemic immunomodulation is not clear. When haptens (trinitrochlorobenzene, FITC) were administered to the shaved ventral skin 4 days after irradiation (8 kJ/m(2)) to the shaved dorsum of BALB/c mice, CD11c(+)/FITC(+) cells in the skin-draining lymph nodes from control and irradiated mice produced on a per cell basis similar levels of IL-12 and PGE(2) were phenotypically mature and efficient at presenting FITC to lymphocytes from FITC-sensitized mice. Ag presentation by FACS-sorted CD11c(+) lymph node cells isolated 4 days after UVB irradiation was as efficient as were cells from unirradiated mice at presentation in vitro of an OVA peptide (OVA(323-339)) to CD4(+) cells from OVA-TCR-transgenic DO11.10 mice. Further, IFN-gamma levels were increased in the cultures containing CD11c(+) cells from UVB-irradiated mice, suggesting that inflammation may precede downstream immunosuppression. These results suggest that the primary cause of reduced contact hypersensitivity responses in mice in which UV irradiation and the sensitizing Ag are applied to different sites several days apart must originate from cells other than CD11c(+) APCs that directly or by production of soluble mediators (IL-12, PGE(2)) affect cellular responses in the nodes of UVB-irradiated mice.

Administration, Topical↗

PubMed2004

Control of Salmonella dissemination in vivo by macrophage inflammatory protein (MIP)-3alpha/CCL20.

While chemokines are clearly important in the generation of protective immunity, the role of individual chemokines in the control of bacterial infection is still poorly understood. In this study, we investigated the role of macrophage inflammatory protein (MIP)-3alpha/CCL20, a chemokine that attracts activated T and B lymphocytes and immature dendritic cells, in host responses to bacterial infection. CCL20 production was induced in subcutaneous tissue in the BALB/c mouse in response to Salmonella enteritidis, Staphylococcus aureus and zymosan, with S. enteritidis being the most potent. S. enteritidis induced CCL20 production in the spleen following either oral administration or injection into the peritoneal cavity. In contrast, no increase was observed in the Peyer's patches. In this model, following intraperitoneal injection, dose-dependent colonization of the spleen and Peyer's patches by S. enteritidis, expression of IFNgamma and IL-4, and production of antibodies against the S. enteritidis surface antigen SefA were observed. Prior treatment with neutralizing antibodies against CCL20 enhanced bacterial dissemination to the spleen and Peyer's patches and strongly biased the IFNgamma/IL-4 ratio towards a type 2 profile in the spleen, while the humoral response was unaffected. In contrast, treatment with neutralizing anti-MIP-1alpha/CCL3 antibodies enhanced the bacterial burden in the Peyer's patches but not in the spleen, had no significant effect on the cytokine ratio, but significantly inhibited anti-SefA production. Together, these results demonstrate an important role for CCL20 in the control of bacterial infection and more specifically in the regulation of cell-mediated immunity against intracellular bacteria such as S. enteritidis.

Animals↗

PubMed2002

Mast cells, neuropeptides, histamine, and prostaglandins in UV-induced systemic immunosuppression.

There is a direct correlation between dermal mast cell prevalence in dorsal skin of different mouse strains and susceptibility to UVB-induced systemic immunosuppression; highly UV-susceptible C57BL/6 mice have a high dermal mast cell prevalence while BALB/c mice, which require considerable UV radiation for 50% immunosuppression, have a low mast cell prevalence. There is also a functional link between the prevalence of dermal mast cells and susceptibility to UVB- and cis-urocanic acid (UCA)-induced systemic immunosuppression. Mast cell-depleted mice are unresponsive to UVB or cis-UCA for systemic immunosuppression unless they are previously reconstituted at the irradiated or cis-UCA-administered site with bone marrow-derived mast cell precursors. cis-UCA does not stimulate mast cell degranulation directly. Instead, in support of studies showing that neither UVB nor cis-UCA was immunosuppressive in capsaicin-treated, neuropeptide-depleted mice, cis-UCA-stimulated neuropeptide release from sensory c-fibers which, in turn, could efficiently degranulate mast cells. Studies in mice suggested that histamine, and not tumor necrosis factor alpha (TNF-alpha), was the product from mast cells that stimulated downstream immunosuppression. Histamine receptor antagonists reduced by approximately 60% UVB and cis-UCA-induced systemic immunosuppression. Indomethacin administration to mice had a similar effect which was not cumulative with the histamine receptor antagonists. Histamine can stimulate keratinocyte prostanoid production. We propose that both histamine and prostaglandin E(2) are important in downstream immunosuppression; both are regulatory molecules supporting the development of T helper 2 cells and reduced expression of type 1 immune responses such as a contact hypersensitivity reaction.

Animals↗

PubMed2002

Nerve growth factor, neuropeptides, and mast cells in ultraviolet-B-induced systemic suppression of contact hypersensitivity responses in mice.

The induction of systemic immunosuppression following ultraviolet B radiation exposure has been linked with the release of inflammatory and immunomodulatory mediators by cells of the epidermis and dermis. Nerve growth factor has not previously been linked with ultraviolet-B-induced immunosuppressive effects. Nerve growth factor antibodies abrogated ultraviolet-B-induced systemic suppression of contact hypersensitivity responses in BALB/C mice. Subcutaneous injection of nerve growth factor (20 microg per mouse) into dorsal skin 5 d before hapten sensitization on ventral skin suppressed contact hypersensitivity responses in mast-cell-replete but not Wf/Wf mast-cell-depleted mice. Nerve growth factor injected 24 h prior to challenge was not able to suppress the efferent phase of the contact hypersensitivity response. Subcutaneous injection of nerve growth factor (20 microg per mouse) did not suppress contact hypersensitivity responses in capsaicin-pretreated (neuropeptide-depleted) BALB/c mice, and thus sensory c-fibers are necessary for nerve-growth-factor-mediated systemic suppression of contact hypersensitivity responses. Increased concentrations of nerve growth factor within epidermal keratinocytes 8 h after ultraviolet B irradiation were confirmed immunohistochemically. These findings support a role for keratinocyte-derived nerve growth factor via its action on sensory c-fibers, and subsequent release of neuropeptides to mediate mast cell degranulation in systemic suppression of contact hypersensitivity responses in mice following ultraviolet B exposure.

Animals↗