Inflammasomes within Hyperactive Murine Dendritic Cells Stimulate Long-Lived T Cell-Mediated Anti-tumor Immunity.

Central to anti-tumor immunity are dendritic cells (DCs), which stimulate long-lived protective T cell responses. Recent studies have demonstrated that DCs can achieve a state of hyperactivation, which is associated with inflammasome activities within living cells. Herein, we report that hyperactive DCs have an enhanced ability to migrate to draining lymph nodes and stimulate potent cytotoxic T lymphocyte (CTL) responses. This enhanced migratory activity is dependent on the chemokine receptor CCR7 and is associated with a unique transcriptional program that is not observed in conventionally activated or pyroptotic DCs. We show that hyperactivating stimuli are uniquely capable of inducing durable CTL-mediated anti-tumor immunity against tumors that are sensitive or resistant to PD-1 inhibition. These protective responses are intrinsic to the cDC1 subset of DCs, depend on the inflammasome-dependent cytokine IL-1ß, and enable tumor lysates to serve as immunogens. If these activities are verified in humans, hyperactive DCs may impact immunotherapy.

Substance P Release by Sensory Neurons Triggers Dendritic Cell Migration and Initiates the Type-2 Immune Response to Allergens.

Dendritic cells (DCs) of the cDC2 lineage initiate allergic immunity and in the dermis are marked by their expression of CD301b. CD301b+ dermal DCs respond to allergens encountered in vivo, but not in vitro. This suggests that another cell in the dermis may sense allergens and relay that information to activate and induce the migration of CD301b+ DCs to the draining lymph node (dLN). Using a model of cutaneous allergen exposure, we show that allergens directly activated TRPV1+ sensory neurons leading to itch and pain behaviors. Allergen-activated sensory neurons released the neuropeptide Substance P, which stimulated proximally located CD301b+ DCs through the Mas-related G-protein coupled receptor member A1 (MRGPRA1). Substance P induced CD301b+ DC migration to the dLN where they initiated T helper-2 cell differentiation. Thus, sensory neurons act as primary sensors of allergens, linking exposure to activation of allergic-skewing DCs and the initiation of an allergic immune response.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Syndrome Identified in the Electronic Health Record Allergy Module.

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare but severe hypersensitivity reaction that remains poorly characterized in the United States. OBJECTIVE: To identify and describe DRESS syndrome cases in an integrated health care system using electronic health record (EHR) allergy module free-text searches. METHODS: We identified DRESS syndrome cases with rash, absolute eosinophil count of 500/L or more, organ involvement, and a European Registry of Severe Cutaneous Adverse Reactions to Drugs and Collection of Biological Samples score of 2 or more by reviewing those patients from 1980 to 2016 whose EHR allergic reaction matched DRESS-related key words. Liver injury required alanine aminotransferase level of 100 U/L or more, and renal injury required creatinine increase by 0.5 mg/dL (or 50%) or more. Patient and DRESS characteristics were described, resource use was determined, and cost was estimated. RESULTS: Among 3,162,562 patients with 3,319,387 million allergy entries, 538 reactions matched key words, and 69 were DRESS syndrome cases (prevalence 2.18 per 100,000). Patients with DRESS had liver (42%) or renal (42%) injury; 11 (16%) had both liver and renal injury. Primary drug culprits were antibiotics (74%) (vancomycin [39%], ß-lactams [23%], fluoroquinolones [4%], tetracyclines [4%], and sulfonamides [3%]) and anticonvulsants (20%). Of 65 (94%) hospitalized patients with DRESS, 43 (66%) were hospitalized for DRESS syndrome management with median length of stay of 9 days (interquartile range, 6-17 days) and cost approximately $17,101 per patient. CONCLUSIONS: Using free-text search of the EHR allergy module identified a large US DRESS syndrome cohort. DRESS prevalence was 2.18 per 100,000 patients. Both liver and kidney injury were frequent, and vancomycin was the most common drug culprit. DRESS cases were morbid and resource-intensive.

Influences of chloride and hypochlorite on neutrophil extracellular trap formation.

BACKGROUND: The release by neutrophils of DNA-based extracellular traps (NETs) is a recently recognized innate immune phenomenon that contributes significantly to control of bacterial pathogens at tissue foci of infection. NETs have also been implicated in the pathogenesis of non-infectious diseases such as small vessel vasculitis, lupus and cystic fibrosis lung disease. Reactive oxygen species (ROS) are important mediators of NET generation (NETosis). Neutrophils with reduced ROS production, such as those from patients with chronic granulomatous disease or myeloperoxidase (MPO) deficiency, produce fewer NETs in response to inflammatory stimuli. To better understand the roles of various ROS in NETosis, we explore the role of MPO, its substrates chloride ion (Cl(-)) and hydrogen peroxide (H(2)O(2)), and its product hypochlorite (HOCl) in NETosis. FINDINGS: In human peripheral blood neutrophils, pharmacologic inhibition of MPO decreased NETosis. Absence of extracellular Cl(-), a substrate for MPO, also reduced NETosis. While exogenous addition of H(2)O(2) and HOCl stimulated NETosis, only exogenous HOCl could rescue NETosis in the setting of MPO inhibition. Neither pharmacological inhibition nor genetic deletion of MPO in murine neutrophils blocked NETosis, in contrast to findings in human neutrophils. CONCLUSIONS: Our results pinpoint HOCl as the key ROS involved in human NETosis. This finding has implications for understanding innate immune function in diseases in which Cl(-) homeostasis is disturbed, such as cystic fibrosis. Our results also reveal an example of significant species-specific differences in NET phenotypes, and the need for caution in extrapolation to humans from studies of murine NETosis.

Statins enhance formation of phagocyte extracellular traps.

Statins are inhibitors of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol biosynthesis. Recent clinico-epidemiologic studies correlate patients receiving statin therapy with having reduced mortality associated with severe bacterial infection. Investigating the effect of statins on the innate immune capacity of phagocytic cells against the human pathogen Staphylococcus aureus, we uncovered a beneficial effect of statins on bacterial clearance by phagocytes, although, paradoxically, both phagocytosis and oxidative burst were inhibited. Probing instead for an extracellular mechanism of killing, we found that statins boosted the production of antibacterial DNA-based extracellular traps (ETs) by human and murine neutrophils and also monocytes/macrophages. The effect of statins to induce phagocyte ETs was linked to sterol pathway inhibition. We conclude that a drug therapy taken chronically by millions alters the functional behavior of phagocytic cells, which could have ramifications for susceptibility and response to bacterial infections in these patients.