An increased CD25-positive intestinal regulatory T lymphocyte population is dependent upon Cox-2 activity in the Apcmin/+ model.

Only mismatch repair (MMR)-deficient colorectal cancer (CRC) appears to respond well to programmed death (PD)-1 inhibition at the present time. Emerging evidence suggests a role for micro-environmental factors such as CD25+ cells modulating response to PD-1 inhibition. In the ApcMin/+ model of familial adenomatous polyposis (MMR-proficient CRC), increased Cyclooxygenase-2 (Cox-2) expression by cells which include alternatively activated mononuclear phagocytes promotes intestinal tumorigenesis by mechanisms which may include immune suppression. To gain insight into this, we compared regulatory T cell (Treg ) populations between ApcMin/+ and wild-type mice prior to and after the phase of increased intestinal Cox-2-dependent prostaglandin E2 (PGE2 ) production. There was no difference in systemic Treg function or numbers between ApcMin/+ and wild-type mice. However, increased numbers of small intestinal CD25+ Tregs were observed with increased Cox-2 activity in the absence of any difference in the expression of Tgf-ß or Tslp between ApcMin/+ and wild-type mice. Cox-2 inhibitor therapy (Celecoxib) reversed the increase in ApcMin/+ intestinal CD25+ Treg numbers, without decreasing numbers of CD25+ systemic Tregs . Forkhead box protein 3 (FoxP3+ ) and Cox-2+ cells were co-localized to the interstitium of adenomas of Apcmin/+ mice. These results suggest selective dependence of an 'activated Treg ' phenotype on paracrine Cox-2 activity in ApcMin/+ small intestine. For therapeutic potential, further studies are required to evaluate the relevance of these findings to human cancer as well as the functional significance of CD25+ intestinal Tregs in cancer.

The use of hyperosmotic saline for chondroprotection: implications for orthopaedic surgery and cartilage repair.

OBJECTIVE: Articular cartilage may experience iatrogenic injury during routine orthopaedic/arthroscopic procedures. This could cause chondrocyte death, leading to cartilage degeneration and posttraumatic osteoarthritis. In an in vitro cartilage injury model, chondrocyte death was reduced by increasing the osmolarity of normal saline (NS), the most commonly-used irrigation solution. Here, we studied the effect of hyperosmolar saline (HS) on chondrocyte viability and cartilage repair in an in vivo injury model. DESIGN: Cartilage injury was induced by a single scalpel cut along the patellar groove of 8 week old rats in the absence of irrigation or with either NS (300 mOsm) or HS (600 mOsm). The percentage of cell death (PCD) within the injured area was assessed using confocal microscopy. Repair from injury was evaluated by histology/immunostaining, and inflammatory response by histology, cytokine array analysis and ELISA (enzyme-linked immunosorbent assay). RESULTS: The PCD in saline-irrigated joints was increased compared to non-irrigated (NI) joints [PCD = 20.8% (95%CI; 14.5, 27.1); PCD = 9.14% (95%CI; 6.3, 11.9); P = 0.0017]. However, hyperosmotic saline reduced chondrocyte death compared to NS (PCD = 10.4% (95%CI; 8.5, 12.3) P = 0.0024). Repair score, type II collagen and aggrecan levels, and injury width, were significantly improved with hyperosmotic compared to NS. Mild synovitis and similar changes in serum cytokine profile occurred in all operated joints irrespective of experimental group. CONCLUSIONS: Hyperosmotic saline significantly reduced the chondrocyte death associated with scalpel-induced injury and enhanced cartilage repair. This irrigation solution might be useful as a simple chondroprotective strategy and may also reduce unintentional cartilage injury during articular reconstructive surgery and promote integrative cartilage repair, thereby reducing the risk of posttraumatic osteoarthritis.

NiO and Co3O4 nanoparticles induce lung DTH-like responses and alveolar lipoproteinosis.

Lung exposure to metal oxide nanoparticles (NPs) comprising soluble metal haptens may produce T-helper cell type 1 (Th1)- and Th17-associated delayed-type hypersensitivity (DTH) responses and pulmonary alveolar proteinosis (PAP). In order to study this, haptenic metal oxide NPs (NiO, Co(3)O(4), Cr(2)O(3) and CuO) were instilled into the lungs of female Wistar rats, and the immunoinflammatory responses were assessed at 24 h and 4 weeks post-instillation. Primary culture of alveolar macrophages from Wistar rats was used to evaluate the effect of the NPs on the ability to clear surfactant. NiO NPs induced chronic interstitial inflammation and pro-inflammatory Th1 and Th17 immune responses characterised by increases in the cytokines monocyte chemotactic protein (MCP)-1/CCL2, interleukin (IL)-12 p40, interferon-γ and IL-17A, whilst similar pathological responses induced by Co(3)O(4) NPs were associated with increases in MCP-1/CCL2 and IL-12 p40. However, neither Cr(2)O(3) nor CuO NPs elicited immunoinflammatory reactions. PAP was induced by both NiO and Co(3)O(4) NPs during the chronic phase. PAP was associated with over-production of surfactant by proliferation of type II cells and impaired clearance of surfactant by macrophages. These findings have implications for the risk management of occupational NP exposure and provide evidence that haptenic metal oxide NPs can induce chronic progressive lung immune responses via a DTH-like mechanism.

Ectopic lymphoid tissue formation in the lungs of mice infected with Chlamydia pneumoniae is associated with epithelial macrophage inflammatory protein-2/CXCL2 expression.

Infection with Chlamydia pneumoniae (Cp) accounts for around 10% of community acquired bacterial pneumonia and has been associated with other chronic inflammatory conditions. We describe a C57/Bl6 murine model of Cp lung infection characterized by a dose-dependent, resolving neutrophilia followed by lymphocytic infiltration of the lungs. By 21 days post-infection, mice exhibit a T helper type 1 (Th1) polarized serum antibody response with local mucosal antibody secretion and organization of ectopic lymphoid tissue which persisted in the absence of detectable Cp DNA. Macrophage inflammatory protein (MIP)-2/CXCL2, which recruits neutrophils and lymphocytes and is associated with ectopic lymphoid tissue formation, was secreted in the lungs post-infection. In vitro, lung epithelial cells up-regulated MIP-2/CXCL2 in response to both rough lipopolysaccharide (reLPS) and Cp infection. We conclude that Cp infection can have long-term inflammatory effects on tissue that persist after clearance of active infection.

High-fat feeding redirects cytokine responses and decreases allergic airway eosinophilia.

BACKGROUND: Dietary fat intake has been associated with obesity and obesity in its turn with attenuated airway function and asthma, but it is unclear whether or how high-fat intake per se alters immune function relevant to development of allergic asthma. OBJECTIVE: To use a non-obese mouse model of mild to moderate allergic asthma to compare effects of high-fat with isocaloric control-diet on allergic immune responses. METHODS: C57BL/6 mice weaned and maintained on control (11% fat calories) or isocaloric high-fat diet (58% fat calories) were systemically sensitized with ovalbumin and challenged in the lungs. Allergic airway inflammation was assessed by measuring lung inflammation; serum antibodies; and, cytokines in serum, bronchoalveolar lavage (BAL) fluid and in supernatants of in vitro stimulated lung draining lymph node and spleen lymphocytes. RESULTS: There was a significant reduction in lung eosinophilia and IL-5 in high-fat fed mice. Lung draining lymph node cells from these mice showed reduced pro-inflammatory cytokine (MCP-1 and TNF-alpha) release after ovalbumin re-stimulation and reduced release of IL-13 after concanavalin-A stimulation, indicating a general rather than just an antigen-specific change. There was no difference in IFN-gamma release. In contrast, pro-inflammatory cytokine release was increased from splenocytes. Decreased eosinophilia was not due to increased regulatory T cell or IL-10 induction in draining lymph nodes or spleen, nor to changes in antibody response to ovalbumin. However, decreased levels of serum and BAL eotaxin were found in high-fat fed animals. CONCLUSIONS: The data indicate that high-fat dietary content redirects local immune responses to allergen in the lungs and systemic responses in the spleen and serum. These effects are not due to changes in regulatory T cell populations but may reflect a failure to mobilize eosinophils in response to allergic challenge.

Human neutrophil elastase inhibitors in innate and adaptive immunity.

Recent evidence shows that human neutrophil elastase inhibitors can be synthesized locally at mucosal sites. In addition to efficiently targeting bacterial and host enzymes, they can be released in the interstitium and in the lumen of mucosa, where they have been shown to have antimicrobial activities, and to activate innate immune responses. This review will address more particularly the pleiotropic functions of low-molecular-mass neutrophil elastase inhibitors [SLPI (secretory leucocyte proteinase inhibitor) and elafin] and, more specifically, their role in the development of the adaptive immune response.

A comparative study of mRNA and protein expression of the autoimmune regulator gene (Aire) in embryonic and adult murine tissues.

Autoimmune polyendocrine syndrome type 1 (APS1) is a rare autosomal recessive human disorder caused by mutations in the autoimmune regulator gene (AIRE) and characterized by multiple autoimmune diseases. As reports of the tissue expression pattern of the murine Aire gene are discordant, a comprehensive survey of Aire expression was undertaken in adult and embryonic tissues at the mRNA and protein levels using real-time RT-PCR, in situ hybridization, and immunohistochemistry. In the adult, the highest Aire mRNA expression was in the thymus. All the other tissues investigated expressed Aire mRNA at low levels, but it was barely detectable in the adrenal gland. Aire protein expression was observed in the thymus, spleen, and lymph nodes. A common pattern was observed in other tissues, with staining in epithelial cells. An exception to this was the gut, where staining was seen in the mucin spaces. In embryonic tissue, Aire mRNA and protein expression was detected from E14.5 in the thymus. In the fetal liver, unlike the adult, staining was observed at E14.5 and decreased towards term. Thus, Aire is expressed in immunologically relevant tissues and in a restricted number of extra-immunological tissues in the adult. Furthermore, the presence of Aire protein is reported in extra-thymic tissues of the embryo.