PMID- 37614946 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20230825 IS - 2296-858X (Print) IS - 2296-858X (Electronic) IS - 2296-858X (Linking) VI - 10 DP - 2023 TI - Toll-like receptor 4 and Syk kinase shape dendritic cell-induced immune activation to major house dust mite allergens. PG - 1105538 LID - 10.3389/fmed.2023.1105538 [doi] LID - 1105538 AB - BACKGROUND: House dust mite (HDM) is a major cause of respiratory allergic diseases. Dendritic cells (DCs) play a central role in orchestrating adaptive allergic immune responses. However, it remains unclear how DCs become activated by HDM. Biochemical functions of the major HDM allergens Der p 1 (cysteine protease) and Der p 2 (MD2-mimick) have been implicated to contribute to DC activation. METHODS: We investigated the immune activating potential of HDM extract and its major allergens Der p 1 and Der p 2 using monocyte-derived DCs (moDCs). Maturation and activation markers were monitored by flow cytometry and cytokine production by ELISA. Allergen depletion and proteinase K digestion were used to investigate the involvement of proteins, and in particular of the major allergens. Inhibitors of spleen tyrosine kinase (Syk), Toll-like receptor 4 (TLR4) and of C-type lectin receptors (CLRs) were used to identify the involved receptors. The contribution of endotoxins in moDC activation was assessed by their removal from HDM extract. RESULTS: HDM extract induced DC maturation and cytokine responses in contrast to the natural purified major allergens Der p 1 and Der p 2. Proteinase K digestion and removal of Der p 1 or Der p 2 did not alter the immune stimulatory capacity of HDM extract. Antibodies against the CLRs Dectin-1, Dectin-2, and DC-SIGN did not affect cytokine responses. In contrast, Syk inhibition partially reduced IL-6, IL-12 and completely blocked IL-10. Blocking TLR4 signaling reduced the HDM-induced IL-10 and IL-12p70 induction, but not IL-6, while endotoxin removal potently abolished the induced cytokine response. CONCLUSION: Our data strongly suggest that HDM-induced DC activation is neither dependent on Der p 1 nor Der p 2, but depend on Syk and TLR4 activation, which might suggest a crosstalk between Syk and TLR4 pathways. Our data highlight that endotoxins play a potent role in immune responses targeting HDM. CI - Copyright (c) 2023 Busold, Akkerdaas, Zijlstra-Willems, van der Graaf, Tas, de Jong, van Ree and Geijtenbeek. FAU - Busold, Stefanie AU - Busold S AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. FAU - Akkerdaas, Jaap H AU - Akkerdaas JH AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. FAU - Zijlstra-Willems, Esther M AU - Zijlstra-Willems EM AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. FAU - van der Graaf, Kees AU - van der Graaf K AD - Citeq Biologics, Groningen, Netherlands. FAU - Tas, Sander W AU - Tas SW AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. AD - Amsterdam Rheumatology and Immunology Center, Department of Rheumatology and Clinical Immunology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands. FAU - de Jong, Esther C AU - de Jong EC AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. FAU - van Ree, Ronald AU - van Ree R AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. AD - Amsterdam University Medical Centers, location AMC, Department of Otorhinolaryngology, Amsterdam, Netherlands. FAU - Geijtenbeek, Teunis B H AU - Geijtenbeek TBH AD - Amsterdam University Medical Centers, location AMC, Department of Experimental Immunology, Amsterdam, Netherlands. AD - Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, Netherlands. LA - eng PT - Journal Article DEP - 20230808 PL - Switzerland TA - Front Med (Lausanne) JT - Frontiers in medicine JID - 101648047 PMC - PMC10442820 OTO - NOTNLM OT - Der p 1 OT - Der p 2 OT - Syk OT - TLR4 OT - dendritic cell activation OT - house dust mite allergy COIS- RR received consulting fees and/or speaker's fees from Angany Inc., HAL Allergy BV, and Citeq BV, ThermoFisher Scientific Reacta Healthcare Ltd., Mission MightyMe, AB Enzymes and ALK Abello. KG is the CEO/owner of Citeq Biologics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. EDAT- 2023/08/24 06:42 MHDA- 2023/08/24 06:43 PMCR- 2023/08/08 CRDT- 2023/08/24 04:12 PHST- 2022/11/22 00:00 [received] PHST- 2023/07/20 00:00 [accepted] PHST- 2023/08/24 06:43 [medline] PHST- 2023/08/24 06:42 [pubmed] PHST- 2023/08/24 04:12 [entrez] PHST- 2023/08/08 00:00 [pmc-release] AID - 10.3389/fmed.2023.1105538 [doi] PST - epublish SO - Front Med (Lausanne). 2023 Aug 8;10:1105538. doi: 10.3389/fmed.2023.1105538. eCollection 2023.