Anti-CD83 Monoclonal antibody, clone IC26f

Epidemiological studies have consistently shown associations between elevated concentrations of urban particulate matter (UPM) air pollution and exacerbations of asthma and chronic obstructive pulmonary disease, which are both associated with viral respiratory infections. The effects of UPM on dendritic cell (DC) -stimulated CD4 T lymphocytes have been investigated previously, but little work has focused on CD8 T-lymphocyte responses despite their importance in anti-viral immunity. To address this, we examined the effects of UPM on DC-stimulated naive CD8 T-cell responses. Expression of the maturation/activation markers CD83, CCR7, CD40 and MHC class I on human myeloid DCs (mDCs) was characterized by flow cytometry after stimulation with UPMin vitro in the presence/absence of granulocyte-macrophage colony-stimulating factor (GM-CSF). The capacity of these mDCs to stimulate naive CD8 T-lymphocyte responses in allogeneic co-culture was then assessed by measuring T-cell cytokine secretion using cytometric bead array, and proliferation and frequency of interferon- (IFN-)-producing T lymphocytes by flow cytometry. Treatment of mDCs with UPM increased expression of CD83 and CCR7, but not MHC class I. In allogeneic co-cultures, UPM treatment of mDCs enhanced CD8 T-cell proliferation and the frequency of IFN-(+) cells. The secretion of tumour necrosis factor-, interleukin-13, Granzyme A and Granzyme B were also increased. GM-CSF alone, and in concert with UPM, enhanced many of these T-cell functions. The PM-induced increase in Granzyme A was confirmed in a human experimental diesel exposure study. These data demonstrate that UPM treatment of mDCs enhances priming of naive CD8 T lymphocytes and increases production of pro-inflammatory cytokines. Such UPM-induced stimulation of CD8 cells may potentiate T-lymphocyte cytotoxic responses upon concurrent airway infection, increasing bystander damage to the airways.

Cardiac fibroblasts are important regulators of myocardial structure and function. Their implications in pathological processes such as Ischemia/Reperfusion are well characterized. Cardiac fibroblasts respond to stress by excessive proliferation and secretion of pro-inflammatory cytokines and other factors, e.g. ATP, leading to purinergic receptors activation. P2Y11 receptor (P2Y11R) is an ATP-sensitive GPCR playing an immunomodulatory role in human dendritic cells (DC). We hypothesized that P2Y11R stimulation modulated the pro-inflammatory responses of human cardiac fibroblasts (HCF) to Hypoxia/Reoxygenation (H/R) mainly by acting on their secretome. P2Y11R stimulation in HCF at the onset of reoxygenation significantly limited H/R-induced proliferation (-19%) and pro-inflammatory cytokines and ATP secretion (-44% and -83% respectively). Exposure of DC to HCF secretome increased their expression of CD83, CD25 and CD86, suggesting a switch from immature to mature phenotype. Under LPS stimulation, DC had a pro-inflammatory profile (high IL-12/IL-10 ratio) that was decreased by HCF secretome (-3,8-fold), indicating induction of a tolerogenic profile. Moreover, P2Y11R inhibition in HCF led to high IL-12 secretion in DC, suggesting that the immunomodulatory effect of HCF secretome is P2Y11R-dependant. HCF secretome reduced H/R-induced cardiomyocytes death (-23%) through RISK pathway activation. P2Y11R inhibition in HCF induced a complete loss of HCF secretome protective effect, highlighting the cardioprotective role of P2Y11R. Our data demonstrated paracrine interactions between HCF, cardiomyocytes and DC following H/R, suggesting a key role of HCF in the cellular responses to reperfusion. These results also demonstrated a beneficial role of P2Y11R in HCF during H/R and strongly support the hypothesis that P2Y11R is a modulator of I/R injury.