UV-induced immunosuppressive and anti-inflammatory actions: mechanisms and clinical applications.

The introduction in 1974 of psoralens UVA (PUVA) therapy followed in 1987 by extracorporeal photopheresis (ECP) has launched UV light in medicine field. A significant number of potential mechanisms could be linked to the basic cellular UV action (i.e., DNA damage and subsequent cells apoptosis). Phagocytosis by macrophages and dendritic cells (DCs) leads, through a receptor-mediated process, to their modulation. A state of antigen-specific tolerance is induced by induction of Treg cells, inhibition of DCs, which remain at a an immature state, inhibition of production of the proinflammatory cytokines IL-2, IFN-gamma, TNF-alpha and IL-12, and induction of production of cytokines IL-10, TGF-beta and IL-1Ra. Beside cutaneous T-cell lymphoma, use of ECP remains experimental except for graft-versus-host disease, especially the chronic-resistant form. The sparing action of corticosteroids as described in studies on transplantation deserves further attention.

Apoptosis: a target for potentiation of UV-induced IL-1Ra synthesis by IVIg.

IL-1Ra prevents IL-1 induced inflammatory signalling, a mechanism potentially important for several pathological conditions characterized by inflammation. When administered as a drug in the recombinant form, it displays a protective effect towards them. We postulated that this action could also be achieved by pharmacological activation of endogenous IL-1Ra production. We previously showed that photochemotherapy and UV-light increased monocyte/macrophages IL-1Ra secretion. A similar effect has been shown for IVIg. The aim of this study was to define optimal in vitro conditions for induction of IL-1Ra secretion. As both agents induce lymphocytes apoptosis, we focused our analysis on the influence of IVIg on UV-induced-IL-1Ra production on this mechanism. After overnight preincubation at 37 degrees C, UV-irradiated PBL mixed with two IVIg concentrations (1 and 25 mg/ml) were cocultured with autologous PBMC. Apoptosis was measured by annexin V/PI. IL-1Ra secretion was evaluated by RT-PCR and Luminex microbead array assay. A significant additive dose-dependent influence of IVIg (+85%; p=0.0005) on UV-induced IL-1Ra secretion, involved both Fc-receptor activation at a low dose (1 mg/ml) and a potent apoptotic action on PBL reinforcing the UV effect at high concentrations (25 mg/ml). We conclude that lymphocyte apoptosis represents an important pathway contributing to enhancement of UV-induced monocyte/macrophages IL-1Ra production by IVIg and that these findings should be considered when evaluating in vivo protocols for photochemotherapy and IVIg treatment, in hope of improving efficacy.

A rapid test to monitor alloreactive responses in whole blood using real-time polymerase chain reaction.

Rapid, simple, and reliable assays to monitor allogeneic responses are essential for the safe development of novel protocols of tailored immunosuppression. Herein, we describe a real-time polymerase chain reaction method based on interleukin-2 and interferon-gamma mRNA quantification upon stimulation of whole blood with allogeneic T cell-depleted peripheral blood mononuclear cells. The technique requires only small blood volumes and results can be obtained within 48 hours. Data obtained in a liver transplant patient receiving a tolerance induction protocol based on the infusion of donor-type hematopoietic stem cells suggest that this rapid whole blood mixed lymphocyte reaction assay could be valuable for the monitoring of patients undergoing solid organ or hematopoietic stem cell transplantation.

Anti-inflammatory effects of UV-irradiated lymphocytes: induction of IL-1Ra upon phagocytosis by monocyte/macrophages.

One of the mechanisms proposed to explain immunomodulatory actions of ultraviolet light (UV) is production of endogenous anti-inflammatory cytokines. The purpose of the present study is to evaluate how UV light affects the production of IL-10 and IL-1Ra and to provide insight as to the role of phagocytosis of apoptotic lymphocytes in this process. Cytokine production was evaluated in a coculture system consisting in UV-treated lymphocytes in the presence of autologous PBMC. The impact of phagocytosis was tested by two blocking agents cytochalasin E and anti-CD36 mAb. The apoptotic process affecting irradiated lymphocytes was progressive, culminating at 48 h. To achieve significant cytokine production, irradiated lymphocytes were incubated overnight at 37 degrees C. Coculture of apoptotic lymphocytes with autologous PBMC resulted in a significant increase of IL-1Ra mRNA (+340%; P = 0.001) and protein (+72%; P = 0.001) production. This synthesis was blocked by cytochalasin E but upregulated by CD36 receptor cross-linking. Our study shows that UV light induces lymphocyte apoptosis followed by its phagocytosis by monocyte/macrophages, a step that preferentially activates IL-1Ra.

Association between the TNF-2 allele and a better survival in cardiogenic shock.

STUDY OBJECTIVES: Tumor necrosis factor (TNF)-alpha has been implicated in the pathophysiology of heart failure. We explored a possible association between TNF-alpha, interleukin (IL)-6, IL-10, transforming growth factor (TGF)-beta, and interferon (IFN)-gamma cytokine polymorphisms, their in vivo production, and mortality from cardiogenic shock. DESIGN: Prospective, observational study. SETTING: Thirty-one bed, university, medicosurgical department of intensive care. PATIENTS: Thirty-three adult patients with cardiogenic shock of recent (< 4 h) onset. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: TNF-alpha, IL-6, IL-10, TGF-beta1, and IFN-gamma plasma levels were measured by enzyme-linked immunosorbent assay. Polymorphisms of TNF-alpha within the promoter at position -308a-->g, IL-6 within the promoter at position -174c-->g, IL-10 within the promoter at position -1082a-->g/-819t-->c and -819t-->c/-592a-->c, TGF-beta1 at codon 10t-->c and codon 25c-->g, and IFN-gamma at intron 1 at position + 874t-->a were studied. The 33 patients had a mean (+/- SD) age of 64 +/- 17 years and a mean simplified acute physiology score II of 62.3 +/- 15.3. Twenty-three patients (70%) died in the ICU, including 21 of 26 patients (81%) in the TNF-1 group but only 2 of 7 patients (29%) in the TNF-2 group (p = 0.016). There were no significant differences in median plasma TNF-alpha levels between the TNF-1 and the TNF-2 groups, but TGF-beta1 levels were higher in the survivors than in the nonsurvivors (median, 866 pg/mL; range, 384 to 1,966 pg/mL; vs median, 454 pg/mL; range, 167 to 1,266 pg/mL, respectively; p = 0.02). There were no significant differences in TNF-2 polymorphism between the patients with cardiogenic shock and a group of healthy control subjects (7 of 33 patients vs 13 of 48 subjects, respectively; p = 0.61), but IFN-gamma polymorphism was less common in the cardiogenic shock group (p = 0.034). CONCLUSIONS: Patients with the TNF-2 allele have no greater risk of cardiogenic shock but a better survival rate when it develops. Different genetic factors appear to influence the risk of development of, and outcome from, cardiogenic shock.

Increased production of interleukin-10 and interleukin-1 receptor antagonist after extracorporeal photochemotherapy in chronic graft-versus-host disease.

BACKGROUND: Mechanisms of action of extracorporeal photochemotherapy (ECP) in graft-versus-host disease are incompletely understood. It has been proposed that phagocytosis of apoptotic bodies by monocytes and macrophages induces their activation, a process that increases production of immunosuppressive cytokines. We analyzed apoptosis and cytokine secretion in an autologous coculture system combining peripheral blood lymphocytes (PBL) obtained after ex vivo ECP treatment and nonirradiated peripheral blood mononuclear cells (PBMC). METHODS: We studied 11 leukapheresis products treated by ECP from six patients with resistant limited or extensive chronic graft-versus-host disease. Purified PBL obtained by monocyte depletion of the buffy coat from leukapheresis products were mixed with nonirradiated PBMC. Nonirradiated PBL were used as control. Cytokine production was tested at the mRNA level by real-time reverse transcriptase-polymerase chain reaction for interleukin (IL)-10, IL-1 receptor antagonist (IL-1Ra), IL-1beta, tumor necrosis factor-alpha, and IL-12p40. RESULTS: Morphologic analysis and flow cytometry displayed important lymphocyte apoptotic features culminating at 24 to 48 hr. Coculture of patient's PBMC with ultraviolet-irradiated PBL as compared with nonirradiated PBL resulted in significant increase of IL-10 mRNA (3418+/-1015 versus 10596+/-3402 mRNA copy numbers; P=0.001) and IL-1Ra mRNA (23890+/-6166 versus 41767+/-10181 mRNA copy numbers; P=0.001). Incubation with a neutralizing anti-IL-10 monoclonal antibody resulted in a marked decrease of IL-1Ra mRNA levels. CONCLUSION: Our findings are consistent with the fact that ECP modifies patient's autologous lymphocytes by inducing a process of apoptosis that activates monocytes and macrophages, leading to increased synthesis of IL-10 and IL-1Ra mRNAs. The induction of this latter mediator is dependent on IL-10.