The Tribbles-1 protein in humans: roles and functions in health and disease

This review describes the key role of the serine-threonine kinase like protein Tribbles-1 in health as well as in diverse human pathologies. Tribbles-1 is a homolog protein of the Drosophila Tribbles. In Drosophila, the Tribbles protein is involved in the cell-cycle progression during mitosis and in mammals initial data showed TRIB1 to be involved in cell proliferation. In mammals, TRIB1 lacks a catalytic domain and thus acts as an adaptor protein by interacting with several partners. The activity of TRIB1 seems to be very specific to the environment and the cells type in which it is expressed, and a role for this molecule has been mainly described in several pathological states including various cancers such as acute myeloid leukemia and ovarian cancer. Further evidence has also linked TRIB1 to the control of plasmalipid homeostasis thus indicating the role of this molecule as a risk factor for myocardial infarction. Finally, TRIB1 is shown to be up-regulated during inflammatory events such as chronic inflammation of atherosclerotic arteries or chronic antibody-mediated rejection of transplanted organs. Here we provide a review of the current state of the scientific literature for TRIB1, highlighting its role in diverse pathologies and inflammatory states. A better understanding of the role of this protein as both a target as well as a biological marker in diseases should drive the development of new therapeutic strategies.

The natural history of clinical operational tolerance after kidney transplantation through twenty-seven cases

We report here on a European cohort of 27 kidney transplant recipients displaying operational tolerance, compared to two cohorts of matched kidney transplant recipients under immunosuppression and patients who stopped immunosuppressive drugs and presented with rejection. We report that a lower proportion of operationally tolerant patients received induction therapy (52% without induction therapy vs. 78.3%[p = 0.0455] and 96.7%[p = 0.0001], respectively), a difference likely due to the higher proportion (18.5%) of HLA matched recipients in the tolerant cohort. These patients were also significantly older at the time of transplantation (p = 0.0211) and immunosuppression withdrawal (p = 0.0002) than recipients who rejected their graft after weaning. Finally, these patients were at lower risk of infectious disease. Among the 27 patients defined as operationally tolerant at the time of inclusion, 19 still display stable graft function (mean 9 ± 4 years after transplantation) whereas 30% presented slow deterioration of graft function. Six of these patients tested positive for pre-graft anti-HLA antibodies. Biopsy histology studies revealed an active immunologically driven mechanism for half of them, associated with DSA in the absence of C4d. This study suggests that operational tolerance can persist as a robust phenomenon, although eventual graft loss does occur in some patients, particularly in the setting of donor-specific alloantibody.