Human corneal endothelial cells (HCECs) easily become fibroblastic-like when cultured, rendering them unsuitable for tissue engineering of the cornea. Transforming growth factor β (TGF-β) could be a key factor in this phenomenon; however, TGF-β is also known to maintain the endothelium in a quiescent state in vivo. This work aimed to compare the effects of TGF-β1 on the phenotype of HCECs during the proliferation and maturation phases. Our results show that addition of TGF-β1 during the active proliferation phase produced fibroblastic HCECs and loss of the cell junction markers ZO-1 and n-cadherin, independent from the presence of epidermal growth factor (EGF). By contrast, addition of TGF-β1 in maturation media containing few mitogens led to an endothelial phenotype and functional cell junctions as HCECs developed a high trans-endothelial resistance. Furthermore, addition of AG-1478, an epithelial growth factor receptor inhibitor, enhanced the gain of the endothelial phenotype and cell barrier function. Overall, these results show that TGF-β1 can be used to promote the formation of a typical leaky endothelial barrier during the maturation phase of cultured HCECs. A two-phase culture of HCECs using distinct proliferation and maturation media could also be key for developing ideal HCEC culture conditions.

In allergic asthma, homeostatic pathways are dysregulated, which leads to an immune response toward normally innocuous antigens. The CD200-CD200 receptor pathway is a central regulator of inflammation, and CD200 expression was recently found to be down-regulated in circulating leukocytes of patients with asthma. Given the antiinflammatory properties of CD200, we investigated whether local delivery of recombinant CD200 (rCD200) could reinstate lung homeostasis in an experimental model of asthma. Brown Norway rats were sensitized with ovalbumin (OVA) and alum. rCD200 was intratracheally administered 24 hours before OVA challenge, and airway responsiveness to methacholine was measured 24 hours after the allergen challenge. Inflammation was also assessed by measuring cell recruitment and cytokine levels in bronchoalveolar lavages, as well as lung and draining lymph node accumulation of dendritic cells (DCs) and T cells. In sensitized rats, rCD200 abolished airway hyperresponsiveness, whereas the sham treatment had no effect. In addition, rCD200 strongly reduced OVA-induced lung accumulation of myeloid DCs, CD4(+) T cells, and T helper type 2 cells. This was associated with a strong reduction of OVA-induced IL-13 level and with an increase of IL-10 in supernatants of bronchoalveolar lavages. Lung eosinophilia and draining lymph node accumulation of myeloid DCs and T cells were not affected by rCD200. Overall, these data reveal that rCD200 can inhibit airway hyperresponsiveness in a model of asthma by a multistep mechanism associated with local alterations of the T cell response and the cytokine milieu.

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Purpose Transforming growth factor-beta (TGF-β) is known to influence many cell functions. In the corneal endothelium, TGF-β1 exerts contextual effects, promoting endothelial–mesenchymal transition in proliferating cells and enhancing barrier integrity in early confluent maturing cells. Herein, we studied how TGF-β isoforms participate in the formation of corneal endothelial intercellular junctions. Methods Corneal endothelial cells (CECs) were cultured using a two-phase media approach. When CECs reached confluence, the proliferation medium was replaced with maturation medium, which was supplemented or not with TGF-β isoforms. The cell morphology (circularity index), intercellular junction protein expression, trans-endothelial electrical resistance (TEER), and permeability of 7-day postconfluent CECs were assessed. Gene transcription and signaling pathways that were activated following maturation in the presence of TGF-β2 were also studied. The beneficial effect of TGF-β2 on CEC maturation was evaluated using ex vivo corneas mounted on a corneal bioreactor. Results The results showed increases in circularity index, membrane localization of junction-related proteins, and TEER when TGF-β isoforms were individually added during the maturation phase, and TGF-β2 was the most effective isoform. Gene profiling revealed an increase in extracellular matrix-related gene expression. In ex vivo cell adhesion experiments, CECs that were matured in the presence of TGF-β2 had a higher circularity index and cell density and exhibited cell membrane-localized junction-related protein expression at earlier time points. Conclusions These results suggest that TGF-β2 can strengthen cell–cell and cell–substrate adhesion, which accelerates barrier integrity establishment and thus enhances CEC functionality.

The Vision Health Research Network (VHRN) is a provincial scientific organization that aims to improve the ocular health of patients across Quebec by supporting local research endeavors in vision health. The VHRN Student Committee, composed of 288 trainees with diverse backgrounds, has demonstrated its commitment to the scholarly development of its members by providing leadership opportunities, creating networking events, increasing visibility of researchers-in-training and encouraging professional advancement through educational workshops and funding programs. In this article, we review the contributions of the VHRN Student Committee and discuss its future projects.

Alveolar Macrophages are central regulators of pulmonary immune responses, yet their regulatory functions are misunderstood. CD200, a transmembrane protein, and its receptor (CD200R) play a critical role in the resolution of inflammation, but their role in asthma is still unclear. CD200 is expressed on many cell types such as leukocytes, T cells, B cells, epithelial cells, and endothelial cells, while CD200R is expressed exclusively on myeloid cells including alveolar macrophages (AM) and mast cells (MC), which play a key role in asthma. Recent study showed that leukocytes from asthmatic patients express lower level of CD200 during exacerbations, suggesting a dysregulation of CD200 pathway. Thus, we investigated the modulation of CD200 expression on AM following allergen challenge and the inhibition of MC functions by AM CD200. Expression of CD200 and CD200R were measured on AM from naive and sensitized rats before and after allergen challenge using flow cytometry. AM modulation of antigen‐stimulated MC was investigated in vitro using co‐culture and MC degranulation and cytokine production. AM from naive and sensitized rats express similar level of CD200. However, allergen exposure increased CD200 expression on AM of naïve rats (that do not develop signs of asthma), but not on AM of sensitized rats (that develop experimental asthma). No difference between groups was observed for CD200R expression. Naive AM inhibited antigen‐stimulated MC degranulation and cytokine production. The addition of neutralizing anti‐CD200R antibody abrogated AM inhibitory effects. These results suggest that modulation of CD200 expression on AM could have an important role in asthma regulation.

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