gp96 is an endoplasmic reticulum chaperone for cell-surface Toll-like receptors (TLRs). Little is known about its roles in chaperoning other TLRs or in the biology of macrophage in vivo. We generated a macrophage-specific gp96-deficient mouse. Despite normal development and activation by interferon-gamma, tumor necrosis factor-alpha, and interleukin-1beta, the mutant macrophages failed to respond to ligands of both cell-surface and intracellular TLRs including TLR2, TLR4, TLR5, TLR7, and TLR9. Furthermore, we found that TLR4 and TLR9 preferentially interacted with a super-glycosylated gp96 species. The categorical loss of TLRs in gp96-deficient macrophages operationally created a conditional and cell-specific TLR null mouse. These mice were resistant to endotoxin shock but were highly susceptible to Listeria monocytogenes. Our results demonstrate that gp96 is the master chaperone for TLRs and that macrophages, but not other myeloid cells, are the dominant source of proinflammatory cytokines during endotoxemia and Listeria infections.

Activated virus-specific CD8 T cells remain in the lung airways for several months after influenza virus infection. We show that maintenance of this cell population is dependent upon the route of infection and prolonged presentation of viral antigen in the draining lymph nodes (DLN) of the respiratory tract. The local effects on T cell migration have been examined. We show retention of virus-specific CD8 T cells in the mediastinal lymph node (MLN) and continuing recruitment of blood-borne migrants into the lung airways during antigen presentation. These data show that antigen that is retained after pulmonary influenza virus infection controls the migratory pattern and activation state of virus-specific CD8 T cells near the site of virus amplification.

Costimulatory signals from dendritic cells (DCs) are required for naive T cells to respond to antigenic stimulation. To what extent DCs reactivate memory T cells during recall responses is not known. Here, an in vivo depletion system has been used to analyze the role of DCs in reactivating CD8 memory T cells during recall responses to three different microbial infections. We show a profound decrease in the numbers of responding memory CD8 T cells in both lymphoid and nonlymphoid tissues during the recall responses to infection with vesicular stomatitis virus, Listeria monocytogenes (Lm), or influenza virus. These data show that interaction with DCs is a major mechanism driving T cell reactivation in vivo, even during a tissue-specific infection of the respiratory tract.

T cell activation by dendritic cells (DCs) is critical to the initiation of adaptive immune responses and protection against pathogens. Here, we demonstrate that a specialized DC subset in Peyer's patches (PPs) mediates the rapid activation of pathogen specific T cells. This DC subset is characterized by the expression of the chemokine receptor CCR6 and is found only in PPs. CCR6(+) DCs were recruited into the dome regions of PPs upon invasion of the follicle associated epithelium (FAE) by an enteric pathogen and were responsible for the rapid local activation of pathogen-specific T cells. CCR6-deficient DCs were unable to respond to bacterial invasion of PPs and failed to initiate T cell activation, resulting in reduced defense against oral infection. Thus, CCR6-dependent regulation of DCs is responsible for localized T cell dependent defense against entero-invasive pathogens.

SummaryBackground ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.ObjectivesThe objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate‐to‐severe AD. Methods A total of 36 patients with moderate‐to‐severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28‑day period (20 mg, 40 mg and 80 mg once daily).Results ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg −1·3 ± 2·1, P = 0·81; 40 mg −3·1 ± 2·7, P = 0·27; 80 mg −4·7 ± 2·1, P = 0·01; placebo −1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose‐dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis‐associated biomarker E selectin/SELE.ConclusionsIn patients with moderate‐to‐severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.