Adenosine signaling via the adenosine 2B receptor is involved in bronchiolitis obliterans development

Abstract

Objectives Adenosine is produced in response to ischemia or inflammation and protects tissues from injury. There are four adenosine receptors, which play a critical role in the physiological negative-feedback mechanism for limitation and termination of tissue-specific and systemic inflammatory responses. Accumulating evidence has focused on the anti-inflammatory and immunosuppressive role of the adenosine 2A receptor (A2AR), and we have previously reported on its’ role in the development of bronchiolitis obliterans (BO) following lung transplantation. However, few studies have reported on the role of the adenosine 2B receptor (A2BR) in BO. Data suggests that the A2BR has pro-inflammatory and profibrotic roles. We hypothesized that adenosine signaling through the A2BR is involved in the development of BO. Methods A murine heterotopic tracheal model across a total alloantigeneic mismatch was used to study A2BR signaling in BO. Tracheal transplants consisted of Balb/c donor tracheas transplanted into wild-type or A2BR knockout C57BL/6 recipients. Transplanted tracheas were removed 3, 7, 12, and 21 days after transplantation. The luminal obliteration was evaluated through hematoxylin and eosin staining and the cellular infiltration (macrophage, neutrophil, CD3+ and Foxp3+ regulatory T cell) was detected by immunohistochemical staining. Results In comparison to allografts in wild type recipients, tracheas transplanted into A2BR knockout mice displayed less BO development on day 21. A2BR knockout mice had an increase in CD3+ T cells and CD4+/CD25+/Foxp3+ regulatory T cells when compared to wild type on day 7. By day 12, more CD3+ T cells were present in the wild-type trachea compared to the A2BR KO, but the percentage of CD4+/CD25+/Foxp3+ regulatory T cells remained higher in the tracheas of A2BR KO mice. Conclusions A2BR stimulation may promote the development of BO via inhibiting CD4+/CD25+/Foxp3+ regulatory T cell infiltration.

Increased PAI-1 in females compared with males is protective for abdominal aortic aneurysm formation in a rodent model

“…Sections were then incubated with the primary antibody overnight at a dilution of 1:100 in blocking solution and stained according to the instructions in the Vectastain ABC Elite and Novared Kits (Vector Laboratories, Burlingame, CA). Immunohistochemical staining of mouse migratory macrophage was performed as described in previous methods (21,45,46). Rat antimouse Mac-2 (Accurate Chemistry, Westbury, NY) was used as primary antibody (1:5,000 dilution).…”

“…Quantification of macrophage positive immunostaining signals was performed using Image-J software (21,45,46). Briefly, four photos were taken from each group with an Olympus BX51 microscope equipped with an Olympus DP70 digital camera (Minneapolis, MN).…”

Differential Gender And Species Specific Formation of Aneurysms Using A Novel Method Of Inducing Abdominal Aortic Aneurysms

“…Sections were prepared with Hematoxylin and Eosin and VerhoeffVanGieson (elastin) stains for elastic lamina evaluation. Further sections were stained using the following procedures 6,7,8 .…”

“…Twelve randomly selected 20x fields per aneurysm section were assessed for the density of staining. The positive signal in aneurysm for each group was semi quantified Immunohistochemical staining of CD3+ T cells was performed according to previous publications 7,8,9 . Briefly, the aorta sections (5μm) were dehydrated and incubated with 1% hydrogen peroxide followed by boiling in 1X unmasking solution (Vector Laboratories, Burlingame, CA) for 15 minutes and blocked with 10% serum.…”

Lung injury pathways: Adenosine receptor 2B signaling limits development of ischemic bronchiolitis obliterans organizing pneumonia

“…Pulmonary I/R increases adenosine production, with some studies reporting a pro-inflammatory role for A 2B adenosine receptor (A 2B AR) engagement in the transplanted lung (7–9). However, others describe A 2B AR conferring protection against lipopolysaccharide- or mechanical ventilation- induced direct lung injury (10–12).…”