Cytokine receptor clustering in sensory neurons with an engineered cytokine fusion protein triggers unique pain resolution pathways.

New therapeutic approaches to resolve persistent pain are highly needed. We tested the hypothesis that manipulation of cytokine receptors on sensory neurons by clustering regulatory cytokine receptor pairs with a fusion protein of interleukin (IL)-4 and IL-10 (IL4-10 FP) would redirect signaling pathways to optimally boost pain-resolution pathways. We demonstrate that a population of mouse sensory neurons express both receptors for the regulatory cytokines IL-4 and IL-10. This population increases during persistent inflammatory pain. Triggering these receptors with IL4-10 FP has unheralded biological effects, because it resolves inflammatory pain in both male and female mice. Knockdown of both IL4 and IL10 receptors in sensory neurons in vivo ablated the IL4-10 FP-mediated inhibition of inflammatory pain. Knockdown of either one of the receptors prevented the analgesic gain-of-function of IL4-10 FP. In vitro, IL4-10 FP inhibited inflammatory mediator-induced neuronal sensitization more effectively than the combination of cytokines, confirming its superior activity. The IL4-10 FP, contrary to the combination of IL-4 and IL-10, promoted clustering of IL-4 and IL-10 receptors in sensory neurons, leading to unique signaling, that is exemplified by activation of shifts in the cellular kinome and transcriptome. Interrogation of the potentially involved signal pathways led us to identify JAK1 as a key downstream signaling element that mediates the superior analgesic effects of IL4-10 FP. Thus, IL4-10 FP constitutes an immune-biologic that clusters regulatory cytokine receptors in sensory neurons to transduce unique signaling pathways required for full resolution of persistent inflammatory pain.

FcαRI Dynamics Are Regulated by GSK-3 and PKCζ During Cytokine Mediated Inside-Out Signaling.

IgA binding to FcαRI (CD89) is rapidly enhanced by cytokine induced inside-out signaling. Dephosphorylation of serine 263 in the intracellular tail of FcαRI by PP2A and PI3K activation are instrumental in this process. To further investigate these signaling pathways, we targeted downstream kinases of PI3K. Our experiments revealed that PI3K activates PKCζ, which subsequently inhibits GSK-3, a constitutively active kinase in resting cells and found here to be associated with FcαRI. We propose that GSK-3 maintains FcαRI in an inactive state at homeostatic conditions. Upon cytokine stimulation, GSK-3 is inactivated through a PI3K-PKCζ pathway, preventing the maintenance of phosphorylated inactive FcαRI. The concomitantly activated PP2A is then able to dephosphorylate and activate FcαRI. Moreover, FRAP and FLIP studies showed that FcαRI activation coincides with an increased mobile fraction of the receptor. This can enhance FcαRI valency and contribute to stronger avidity for IgA immune complexes. This tightly regulated inside-out signaling pathway allows leukocytes to respond rapidly and efficiently to their environment and could be exploited to enhance the efficacy of future IgA therapeutics.

Expression of activated Fc gamma RII discriminates between multiple granulocyte-priming phenotypes in peripheral blood of allergic asthmatic subjects.

BACKGROUND: Allergic asthma is associated with chronic airway and systemic immune responses. Systemic responses include priming of peripheral blood eosinophils, which is enhanced after allergen challenge. In a subpopulation of asthmatic subjects, neutrophils are associated with bronchial inflammation. OBJECTIVE: We sought to monitor systemic granulocyte priming in allergic asthmatic subjects as a consequence of chronic and acute inflammatory signals initiated by allergen challenge. METHODS: Blood was taken at baseline and 6 to 24 hours after allergen challenge in asthmatic subjects with and without late asthmatic responses. Systemic granulocyte priming was studied by using expression of cellular markers, such as alpha-chain of Mac-1 (alpha m)/CD11b, L-selectin/CD62L, and an activation epitope present on Fc gamma RII/CD32 recognized by monoclonal phage antibody A17. RESULTS: Eosinophils of asthmatic subjects have a primed phenotype identified by cell-surface markers. Neutrophils of these patients were subtly primed, which was only identified after activation with N-formyl-methionyl-leucyl-phenylalanine. After allergen challenge, an acute increase in eosinophil priming characterized by enhanced expression of activated Fc gamma RII was found in patients experiencing a late asthmatic response and not in patients with a single early asthmatic response. In contrast, expression of alpha m/CD11b and L-selectin on granulocytes was not different between control and asthmatic subjects and was not affected by allergen challenge. Interestingly, expression of both adhesion molecules was positively correlated, and alpha m expression on eosinophils and neutrophils correlated positively with bronchial hyperresponsiveness. CONCLUSION: Different phases, phenotypes, or both of allergic asthma are associated with distinct priming profiles of inflammatory cells in peripheral blood. CLINICAL IMPLICATIONS: Insight in differences of systemic innate responses will lead to better definition of asthma subtypes and to better designs of new therapeutic options.

Expression of priming-associated cellular markers on neutrophils during an exacerbation of COPD.

Chronic inflammation of the airways is a hallmark of chronic obstructive pulmonary disease (COPD). We investigated the kinetics of priming of inflammatory cells in peripheral blood during exacerbations of COPD and during the resolution phase. Modulation of the leukocyte compartment as a consequence of systemic activation by cytokines/chemokines was determined by measuring the expression of priming-associated epitopes by novel antibodies designated A17 and A27. Furthermore, H2O2 was determined in breath condensate as a read out for local inflammation. Leukocytes were obtained from COPD patients (GOLD II-IV) during and after an exacerbation of their disease. During an exacerbation the expression of priming epitopes on leukocytes was increased. This priming phenotype disappeared upon treatment with intravenous corticosteroids. Similarly, H2O2 levels in breath condensate were also increased during an exacerbation and decreased upon treatment. We conclude that the activation status of neutrophils in the systemic compartment can be used as a read-out for systemic innate immune signals involved in the pathogenesis of COPD. The correlation between H2O2 in exhaled air with A27 priming on neutrophils showed that local inflammation has systemic effects on cells of the innate immune system.

Gradual increase in priming of human eosinophils during extravasation from peripheral blood to the airways in response to allergen challenge.

BACKGROUND: Eosinophils isolated from the blood of patients with allergic asthma exhibit enhanced responsiveness to multiple stimuli compared with cells from normal controls, a phenomenon generally referred to as priming . This priming response is essential for optimal activation with augmented responses including chemotaxis, cytotoxicity, respiratory burst, and the release of proinflammatory lipid mediators. OBJECTIVE: To monitor the kinetics of priming of eosinophils in the peripheral blood and in the bronchoalveolar lavage fluid of patients with allergic asthma before and after allergen challenge. METHODS: Priming of blood eosinophils obtained from patients with allergy and donors without allergy was measured by labeling with monoclonal phage antibodies A17 and A27 recognizing priming-associated epitopes on phagocytes. In addition, blood and bronchoalveolar lavage fluid eosinophils from subjects with allergy after segmental and whole lung allergen challenge were similarly analyzed. RESULTS: A dose-dependent cytokine-induced upregulation of priming-associated epitopes on blood eosinophils was found. Patients with allergic asthma exhibited an in vivo partially primed eosinophil phenotype, which is further primed in vitro after cytokine or chemokine incubation. Priming was increased in peripheral blood 6 hours after whole lung challenge as well as after segmental allergen challenge. Interestingly, eosinophils obtained from the bronchoalveolar lavage fluid 48 hours after segmental allergen challenge exhibited a higher primed phenotype. CONCLUSION: These data are consistent with a model in which local allergic inflammatory reactions induce partial systemic eosinophil priming in the peripheral blood. Eosinophils found in the airway are highly primed, consistent with the markedly upregulated inflammatory capacity observed in these cells.