Characterization and expression of DEC205 in the cDC1 and cDC2 subsets of porcine dendritic cells from spleen, tonsil, and submaxillary and mesenteric lymph nodes

Abstract

Conventional dendritic cells (cDCs) are divided into the following different subtypes: cDC1, which promotes a Th1 response, and cDC2, which stimulates a Th2 and Th17 response. These cells have not been characterized in porcine lymphoid tissues. DEC205 is a receptor that increases antigen presentation and allows DCs to cross-present antigens. The objectives of this work were to characterize cDCs subsets in the tonsil, submaxillary and mesenteric lymph nodes and spleen lymphoid tissues and to determine their expression of DEC205 by flow cytometry. The cDC1 (MHCIICADM1CD172a) and cDC2 (MHCIICADM1CD172a) phenotypes were confirmed by the expression of characteristic cDC1 and cDC2 transcripts (FLT3, XCR1 and FCER1α). Among all lymphoid tissues, the spleen had the highest frequency of total cDCs. The cDC1:cDC2 ratio showed that all lymph tissues had higher levels of cDC1 than levels of cDC2. DEC205 cDCs were found in all analyzed tissues, albeit with different frequencies. Our research will facilitate the study on the function of these cells and the investigation of the strategies for DEC205 targeting and functional studies.

Characterization of the Myeloid Cell Populations’ Resident in the Porcine Palatine Tonsil

“…The cDC1-like cell population was identified by the high expression of MHC-II, the low/neg expression of CD172a, negative expression of CD4, CD14, and CD163 and high expression of CADM1 as described in porcine skin ( 8 ), lung ( 24 ), and blood ( 21 , 22 ). This phenotype was also described by Parra-Sanchez et al ( 25 ) in porcine tonsils. High levels of FLT3 and XCR1 mRNA expression confirmed the definition of this subset and orthology across species ( 35 , 42 ).…”

“…A key aim of this study was to align the identified myeloid cell populations with their human and mice counterparts and to correlate them with similar populations in porcine skin ( 7 , 8 ), lungs ( 24 ) blood ( 21 , 22 ), and lymphoid tissue, including tonsil ( 25 ). However, not all proteins can be assessed by flow cytometry in pigs, due to lack of suitable antibodies.…”

“…Porcine myeloid cell populations have recently been characterized in blood ( 21 , 22 ), lung ( 24 ), and skin ( 7 , 8 ); however, little is known regarding their frequency and phenotype in secondary lymphoid organs, including the tonsil. A very recent study reported the presence of two resident dendritic cell populations; cDC1s and cDC2s in swine palatine tonsil ( 25 ), however, to our knowledge, this is the first study to apply multi-color flow cytometry, confocal microscopy in addition to molecular and functional assays to delineate five distinct populations of myeloid cells resident in porcine tonsil.…”

“…In pigs, DCs and Mϴ/monocyte populations have been characterized successfully in skin ( 7 , 8 ), blood ( 21 – 23 ), lungs ( 24 ), and lymphoid tissue ( 25 ). In the skin, CD172a neg CD163 neg cells were identified as cDC1 cells given their high expression of CADM1 and XCR1.…”

“…The palatine tonsil is positioned at the opening of the respiratory and gastrointestinal tract, providing an immunological barrier (consisting of Mϴs, DCs, and lymphocytes) equipped to induce an immune response. In human tonsils, three populations of DCs have been described; pDCs, cDC1s, and cDC2s ( 26 ) and more lately, cDC1s and cDC2s have been identified in the porcine tonsil ( 25 ). However, the different populations that make up the milieu of myeloid cells, which reside in the porcine tonsil has received little attention.…”