Global landscape analysis of no-fault compensation programmes for vaccine injuries: A review and survey of implementing countries.

To update the landscape analysis of vaccine injuries no-fault compensation programmes, we conducted a scoping review and a survey of World Health Organization Member States. We describe the characteristics of existing no-fault compensation systems during 2018 based on six common programme elements. No-fault compensation systems for vaccine injuries have been developed in a few high-income countries for more than 50 years. Twenty-five jurisdictions were identified with no-fault compensation programmes, of which two were recently implemented in a low- and a lower-middle-income country. The no-fault compensation programmes in most jurisdictions are implemented at the central or federal government level and are government funded. Eligibility criteria for vaccine injury compensation vary considerably across the evaluated programmes. Notably, most programmes cover injuries arising from vaccines that are registered in the country and are recommended by authorities for routine use in children, pregnant women, adults (e.g. influenza vaccines) and for special indications. A claim process is initiated once the injured party or their legal representative files for compensation with a special administrative body in most programmes. All no-fault compensation programmes reviewed require standard of proof showing a causal association between vaccination and injury. Once a final decision has been reached, claimants are compensated with either: lump-sums; amounts calculated based on medical care costs and expenses, loss of earnings or earning capacity; or monetary compensation calculated based on pain and suffering, emotional distress, permanent impairment or loss of function; or combination of those. In most jurisdictions, vaccine injury claimants have the right to seek damages either through civil litigation or from a compensation scheme but not both simultaneously. Data from this report provide an empirical basis on which global guidance for implementing such schemes could be developed.

Role of HLA-G in innate immunity through direct activation of NF-kappaB in natural killer cells.

HLA-G is a non-classical HLA class I molecule involved in immunotolerance. HLA-G protects the fetus from maternal immune recognition and promotes allograft acceptance and tumor escape. Its low polymorphism and primary function, which is not peptide presentation to T lymphocytes, led us to compare the signal transduced after interaction between HLA-G and its receptor to those of innate immunity receptors with their ligands. We investigated the role of HLA-G in the classical NF-kappaB pathway in natural killer (NK) cells, which is the major pathway activated by innate immunity receptors. In NK cells stimulated with HLA-G1-expressed cells, we demonstrate that HLA-G induces the phosphorylation and the degradation of IkappaBalpha leading to nuclear translocation of NF-kappaB. This effect is independent of the presence of ILT-2 receptors and is still observed using a peptide corresponding to the alpha-1 domain of HLA-G. All these data support an unsuspected role for HLA-G in innate immunity by activating classical NF-kappaB pathway in NK cells.

Hypoxia modulates HLA-G gene expression in tumor cells.

Human leukocyte antigen G (HLA-G) molecules are expressed in cytotrophoblasts and play a key role in maintaining immune tolerance at the maternal-fetal interface. HLA-G expression was also reported in inflammatory diseases, organ transplantation, and malignant tumors. The regulatory mechanisms of HLA-G gene expression differ from those of classical HLA class I genes and are still only partially elucidated. Focusing on tumor cells, we previously demonstrated a tight control of HLA-G gene expression by cis-acting epigenetic mechanisms. In the present study, we hypothesized that these processes are dependent of microenvironment conditions, and more particularly, stress conditions like hypoxia. Cellular response to hypoxia is mainly driven by a key transcription factor, hypoxia-inducible factor 1 (HIF-1), and other factors, such as NF-kappaB, involved in angiogenesis and cell survival. Here we confirmed the influence of hypoxia on HLA-G gene induction in the HLA-G-negative M8 melanoma cell line. Moreover, upon treatment with the hypoxia-mimicking desferrioxamine, we demonstrated a decrease in HLA-G gene expression in melanoma FON and choriocarcinoma JEG-3 cell lines, both expressing constitutively HLA-G. Finally, we demonstrated for the first time that the modulation of HLA-G gene expression is dependent of HIF-1 stabilization and thus might be relevant for the control of HLA-G gene expression in hypoxic tumors.

Trogocytosis-based generation of suppressive NK cells.

Trogocytosis is a fast uptake of membranes and associated molecules from one cell by another. Trogocytosis between natural killer (NK) cells and tumors is already described, but the functional relevance of NK-tumor targets material exchange is unclear. We investigated whether the immunosuppressive molecule HLA-G that is commonly expressed by tumors in vivo and known to block NK cytolytic function, could be transferred from tumor cells to NK cells, and if this transfer had functional consequences. We show that activated NK cells acquire HLA-G1 from tumor cells, and that upon this acquisition, NK cells stop proliferating, are no longer cytotoxic, and behave as suppressor cells. Such cells can inhibit other NK cells' cytotoxic function and protect NK-sensitive tumor cells from cytolysis. These data are the first demonstration that trogocytosis of HLA-G1 can be a major mechanism of immune escape that acts through effector cells made to act as suppressor cells locally, temporarily, but efficiently. The broader consequences of membrane sharing between immune and non-immune cells on the function of effectors and the outcome of immune responses are discussed.

Activation of the mitogen-activated protein kinases Erk1/2 by erythropoietin receptor via a G(i )protein beta gamma-subunit-initiated pathway.

We have recently shown that a heterotrimeric G(i) protein is coupled to the erythropoietin (Epo) receptor. The G(i) protein constitutively associates in its heterotrimeric form with the intracellular domain of Epo receptor (EpoR). After Epo stimulation G(i) is released from the receptor and activated. In the present study we have investigated the functional role of the heterotrimeric G(i) protein bound to EpoR. In Chinese hamster ovary cells expressing EpoR, the G(i) inhibitor pertussis toxin blocked mitogen-activated protein kinase (MAPK) Erk1/2 activation induced by Epo. Epo-dependent MAPK activation was also sensitive to the G beta gamma competitive inhibitor beta ARK1-ct (C-terminal fragment of the beta-adrenergic receptor kinase), to the Ras dominant negative mutant RasN17, and to the phosphoinositide 3-kinase (PI3K) inhibitor LY 294002. A region of 7 amino acids (469-475) in the C-terminal end of EpoR was shown to be required for G(i) binding to EpoR in vivo. Deletion of this region in EpoR abolished both MAPK and PI3K activation in response to Epo. We conclude that in Chinese hamster ovary cells, Epo activates MAPK via a novel pathway dependent on G(i) association to EpoR, G beta gamma subunit, Ras, and PI3K. The tyrosine kinase Jak2 also contributes to this new pathway, more likely downstream of beta gamma and upstream of Ras and PI3K. This pathway is similar to the best characterized pathway used by seven transmembrane receptors coupled to G(i) to activate MAPK and may cooperate with other described Epo-dependent MAPK activation pathways in hematopoietic cells.