Recruitment of dendritic cells and macrophages during T cell-mediated synovial inflammation

Abstract

Adoptive transfer of adjuvant-induced arthritis was used in this study to examine local macrophages and dendritic cells (DCs) during T cell-mediated synovial inflammation. We studied the influx of CD11b + CD11c + putative myeloid DCs and other nonlymphoid CD45 + cells into synovium-rich tissues (SRTs) of the affected hind paws in response to a pulse of autoreactive thoracic duct cells. Cells were prepared from the SRTs using a collagenase perfusion-digestion technique, thus allowing enumeration and phenotypic analysis by flow cytometry. Numbers of CD45 + cells increased during the first 6 days, with increases in CD45 + MHC (major histocompatibility complex) II + monocyte-like cells from as early as day 3 after transfer. In contrast, typical MHC II -monocytes, mainly of the CD4 -subset, did not increase until 12 to 14 days after cell transfer, coinciding with the main influx of polymorphonuclear cells. By day 14, CD45 + MHC II hi cells constituted approximately half of all CD45 + cells in SRT. Most of the MHC II hi cells expressed CD11c and CD11b and represented putative myeloid DCs, whereas only approximately 20% were CD163 + macrophages. Less than 5% of the MHC II hi cells in inflamed SRT were CD11b -, setting a maximum for any influx of plasmacytoid DCs. Of the putative myeloid DCs, a third expressed CD4 and both the CD4 + and the CD4 -subsets expressed the co-stimulatory molecule CD172a. Early accumulation of MHC II hi CD11c + monocyte-like cells during the early phase of T cell-mediated inflammation, relative to typical MHC II -blood monocytes, suggests that recruited monocytes differentiate rapidly toward the DC lineage at this stage in the disease process. However, it is possible also that the MHC II hi CD11c + cells originate from a specific subset of DC-like circulating mononuclear cells.

Efficacy and mechanisms of action of vitamin D in experimental polyarthritis

“…Previous studies published from this laboratory have been conducted using rats fed a standard rat chow diet 17 , 18 , 20 . An initial comparison was made, therefore, between ATA induced in vit D − mature offspring from dams fed the vit D − diet and in age‐matched rats fed standard chow.…”

“…Panayi et al 19 have suggested a similar mechanism of local recruitment and re‐stimulation of activated T cells in rheumatoid synovium. During the evolution of ATA, host‐derived MHC II hi mononuclear cells of myelo‐monocytic lineage accumulate in SRTs and many of these cells express CD11c and have the phenotypic characteristics of dendritic cells (DCs) in varying states of maturity 20 . Only a minority (∼20%) expressed the macrophage marker CD163.…”

“…Furthermore, the acute phase of the disease is self‐limiting with a reproducible time course, 18 which allows assessment of the effects of interventions on disease resolution. Finally, a method for obtaining cell suspensions from the SRTs of the paws of affected rats is available 23 and there is already considerable information on the inflammatory cell exudate in ATA 18 , 20 , 23 . To assess the effects of vit D status on ATA, diets were chosen with the aim of achieving either a state of vit D deficiency (serum 25OHD <40 nmol l –1 ), 24 or a replete state with vit D levels that correspond to the upper normal range for humans (serum 25OHD 100–200 nmol l –1 ) 25 …”

Nonclassical Ly6C− Monocytes Drive the Development of Inflammatory Arthritis in Mice

“…Flow cytometric analysis extending beyond assessment of CD11b or Gr-1 expression has only been reported in rats (Moghaddami et al, 2005a; Moghaddami et al, 2007; Moghaddami et al, 2005b) or synovial fluid of knee joints (Bruhns et al, 2003). None of these studies included techniques that determined the origin of synovial macrophages.…”

Prostaglandin D2in Inflammatory Arthritis and Its Relation with Synovial Fluid Dendritic Cells

“…Cytospin smears prepared from flow cytometrically sorted cells were fixed and stained as described [18]. …”