CD28 superagonist antibody treatment attenuated obliterative bronchiolitis in rat allo-orthotopic tracheal transplantation by preferentially expanding Foxp3-expressing regulatory T cells

Analysis of long term CD4+CD25highCD127- T-reg cells kinetics in peripheral blood of lung transplant recipients

Background

The role of CD4⁺CD25^highCD127⁻ T-reg cells in solid-organ Transplant (Tx) acceptance has been extensively studied. In previous studies on kidney and liver recipients, peripheral T-reg cell counts were associated to graft survival, while in lung Tx, there is limited evidence for similar findings. This study aims to analyze long term peripheral kinetics of T-reg-cells in a cohort of lung recipients and tests its association to several clinical variables.

Methods

From jan 2009 to dec 2014, 137 lung Tx recipients were submitted to an immunological follow up (median: 105.9 months (6.7–310.5)). Immunological follow up consisted of a complete blood peripheral immuno-phenotype, inclusive of CD4⁺CD25^highCD127⁻ T and FOXP3+ cells. We tested the association between T-reg and relevant variables by linear OR regression models for repeated measures, adjusting for time from Tx. Also, by ordered logistic models for panel data, the association between Chronic Lung Allograft Dysfuncton (CLAD) onset/progression and T-reg counts in the previous 3 months was tested.

Results

Among all variables analyzed at multivariate analysis: Bronchiolitis Obliterans Syndrome (OR −6.51, p < 0.001), Restrictive Allograft Syndrome (OR −5.19, p = 0.04) and Extracorporeal photopheresis (OR −5.65, p < 0.001) were significantly associated to T-reg cell. T-reg cell counts progressively decreased according to the severity of CLAD. Furthermore, patients with higher mean T-reg counts in a trimester had a significantly lower risk (OR 0.97, p = 0.012) of presenting CLAD or progressing in the graft dysfunction in the following trimester.

Conclusions

Our present data confirm animal observations on the possible role of T-reg in the evolution of CLAD.

The rise and fall of the CD28 superagonist TGN1412 and its return as TAB08: a personal account

Two decades ago, we discovered 'superagonistic' monoclonal antibodies specific for the CD28 molecule which are able to polyclonally activate T cells, in particular regulatory T cells, and are therapeutically active in many rodent models of autoimmunity, inflammation, transplantation, and tissue repair. A phase I trial of the human CD28 superagonist TGN1412 failed in 2006 due to an unexpected cytokine release syndrome, but after it became clear that dose-reduction allows to preferentially address regulatory T cells also in humans, clinical development was resumed under the name TAB08. Here, I recount the story of CD28 superagonist development from a personal perspective with an emphasis on the dramatic events during and after the 2006 phase I trial, the reasons for the failure of preclinical research to warn of the impending cytokine storm, and on the research which allowed resumption of clinical development.

Rapamycin Combined with Immature Dendritic Cells Attenuates Obliterative Bronchiolitis in Trachea Allograft Rats by Regulating the Balance of Regulatory and Effector T Cells

BACKGROUND

Obliterative bronchiolitis (OB) ranks as the major obstacle for long-term survival of lung transplantation patients. Rapamycin (Rapa) has recently been confirmed as an immunosuppressant for antirejection due to its suppressive role in T cell activation. Here, we explore the effect of Rapa combined with immature dendritic cells (imDCs) on OB in trachea allograft rats.

METHODS

The effect of bone marrow-derived imDCs or Rapa-imDCs on lymphocyte cells and CD4+ T cells were evaluated by methyl thiazolyl tetrazolium and flow cytometry. Tracheal transplantation was performed from Lewis rats to Wistar recipients. Recipient rats received Rapa+imDCs for 10 consecutive days after implantation. Allograft rejection was assessed by micro-CT image, hematoxylin/eosinHE staining and flow cytometry. The underlying mechanism was also investigated.

RESULTS

Rapa-imDCs inhibited lymphocyte and CD4+ T cell growth. Furthermore, Rapa-imDC treatment induced T cell hyporesponsiveness by attenuating T cell differentiation into IFN-x03B3;-producing T cells (Th1), but increased CD4+CD25+Foxp3+ T cell (Treg) contents. Importantly, Rapa-imDC administration ameliorated airway obliteration symptoms and CD4+ and CD8+ T cell infiltration. Furthermore, the proinflammatory factor levels of IL-6, TNF-α, IFN-x03B3; and IL-17 were decreased, concomitant with the upregulation of immunosuppressive cytokines IL-10 and TGF-β1. Further analysis confirmed that Rapa-imDC treatment attenuated the amounts of infiltrated IL-17+CD4+ T cells (Th17 cells) and Th1 cells, but increased Treg contents in the spleens of recipients.

CONCLUSIONS

This research may corroborate a protective role of Rapa-imDCs in OB by regulating the balance between effector T cells and Tregs, suggesting a potential applicable strategy to treat OB after lung transplantation.