SDHA gain-of-function engages inflammatory mitochondrial retrograde signaling via KEAP1-Nrf2.

Whether screening the metabolic activity of immune cells facilitates discovery of molecular pathology remains unknown. Here we prospectively screened the extracellular acidification rate as a measure of glycolysis and the oxygen consumption rate as a measure of mitochondrial respiration in B cells from patients with primary antibody deficiency. The highest oxygen consumption rate values were detected in three study participants with persistent polyclonal B cell lymphocytosis (PPBL). Exome sequencing identified germline mutations in SDHA, which encodes succinate dehydrogenase subunit A, in all three patients with PPBL. SDHA gain-of-function led to an accumulation of fumarate in PPBL B cells, which engaged the KEAP1-Nrf2 system to drive the transcription of genes encoding inflammatory cytokines. In a single patient trial, blocking the activity of the cytokine interleukin-6 in vivo prevented systemic inflammation and ameliorated clinical disease. Overall, our study has identified pathological mitochondrial retrograde signaling as a disease modifier in primary antibody deficiency

Transplantation immunology: aspects of allo- and EBV-specific reactivity : the EBV non-infected elderly - factors of resistance

Defining the relevant components of cellular alloimmunity remains an important unresolved issue in clinical transplantation. The most promising marker of cellular alloreactivity available to date is donor-specific secretion of interferon-gamma (IFN-) as captured in Enzyme Linked Immuno-Spot (ELISPOT) assays (1, 2). How pre-transplantation allo-specific secretion of acute phase cytokines relates to allograft damage and to classic measures of adaptive allo-specific immune function has not been defined. We longitudinally assessed allo-specific secretion of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) in a prospective observational cohort of 38 renal transplant recipients. Allo-specific secretion of IL-6 pre-transplantation was more often detected in individuals with subsequent rejection. Levels of IL-6 correlated with the frequency of IFN- secreting cells, which themselves identified a subset of rejecting individuals with high specificity. These data for the first time link allo-inducible secretion of the acute phase signature cytokine IL-6 with subsequent allograft rejection and the frequency of IFN- secreting cells, suggesting a link between innate/acute phase and adaptive immunity in the pathogenesis of transplant injury. (Durovic, et al – in revision) Post-transplant Non-Hodgkin lymphoma is a life-threatening complication after solid organ and hematopoietic stem cell transplantation (HSCT). While pharmacologically suppressed adaptive immunity plays a major role in its development, the precise circumstances leading to tumor growth remain unclear (4). We explored the possibility that factors intrinsic to EBV-transformed B cells may induce EBV-specific T cell immunodeficiency as observed in individuals developing post-transplant lymphoproliferative disease (PTLD). Expression of T cell co-stimulatory molecules, MHC or maturation markers on EBV-transformed B cell clones did not impact their immunogenicity vis-à-vis T cells. By contrast, proliferation rates of B cell clones positively correlated with their capacity to induce IFN- secretion in EBV-specific CD8+ T cells, whereas they were associated inversely with CD8+ T cell mediated cytotoxicity. Induction of IFN- secreting, yet poorly cytotoxic, T cells represents an unexpected potential of EBV to induce CD8+ T cell responses skewed towards inefficiency. Knowledge of this viral capacity has Defining the relevant components of cellular alloimmunity remains an important unresolved issue in clinical transplantation. The most promising marker of cellular alloreactivity available to date is donor-specific secretion of interferon-gamma (IFN-) as captured in Enzyme Linked Immuno-Spot (ELISPOT) assays (1, 2). How pre-transplantation allo-specific secretion of acute phase cytokines relates to allograft damage and to classic measures of adaptive allo-specific immune function has not been defined. We longitudinally assessed allo-specific secretion of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) in a prospective observational cohort of 38 renal transplant recipients. Allo-specific secretion of IL-6 pre-transplantation was more often detected in individuals with subsequent rejection. Levels of IL-6 correlated with the frequency of IFN- secreting cells, which themselves identified a subset of rejecting individuals with high specificity. These data for the first time link allo-inducible secretion of the acute phase signature cytokine IL-6 with subsequent allograft rejection and the frequency of IFN- secreting cells, suggesting a link between innate/acute phase and adaptive immunity in the pathogenesis of transplant injury. (Durovic, et al – in revision) Post-transplant Non-Hodgkin lymphoma is a life-threatening complication after solid organ and hematopoietic stem cell transplantation (HSCT). While pharmacologically suppressed adaptive immunity plays a major role in its development, the precise circumstances leading to tumor growth remain unclear (4). We explored the possibility that factors intrinsic to EBV-transformed B cells may induce EBV-specific T cell immunodeficiency as observed in individuals developing post-transplant lymphoproliferative disease (PTLD). Expression of T cell co-stimulatory molecules, MHC or maturation markers on EBV-transformed B cell clones did not impact their immunogenicity vis-à-vis T cells. By contrast, proliferation rates of B cell clones positively correlated with their capacity to induce IFN- secretion in EBV-specific CD8+ T cells, whereas they were associated inversely with CD8+ T cell mediated cytotoxicity. Induction of IFN- secreting, yet poorly cytotoxic, T cells represents an unexpected potential of EBV to induce CD8+ T cell responses skewed towards inefficiency. Knowledge of this viral capacity has implications with regards to lymphomagenesis, and may help directing future screening and therapeutic strategies. (Durovic, et al – submitted) Epstein-Barr virus (EBV) is ubiquitous among the world’s population with greater than 90% of adults being infected. Why 5-10% of the adult population remain EBV-seronegative throughout their lives is not known. Insights into mechanisms that confer protection from EBV infection might help in understanding EBV-associated disease and disclose targets for therapeutic interventions. We screened 515 healthy donors aged >60 years and identified 17 EBV-negative individuals with no evidence of viral infection in terms of humoral and cellular immunity and absence of viral genome within peripheral B cells. In these 17 EBV-negative individuals and 39 EBV-positive age- and sex-matched controls, medical history, immunological profiles and immunogenetic factors were assessed. EBV-negative donors presented significantly more often with a history of tonsillectomy than EBV-positive controls. At the molecular level, detailed analysis of MHC class I / killer cell immunoglobulin receptor compound genotypes, associated an HLA-Bw4 / KIR3DL1 compound genotype –representing an inhibitory interaction– with EBV-negativity. These data identify anatomical and immunogenetic factors likely to be involved in protection from becoming latently infected with EBV. (Durovic, et al – in preparation

A sestrin-dependent Erk-Jnk-p38 MAPK activation complex inhibits immunity during aging.

Mitogen-activated protein kinases (MAPKs) including Erk, Jnk and p38 regulate diverse cellular functions and are thought to be controlled by independent upstream activation cascades. Here we show that the sestrins bind to and coordinate simultaneous Erk, Jnk and p38 MAPK activation in T lymphocytes within a new immune-inhibitory complex (sestrin-MAPK activation complex (sMAC)). Whereas sestrin ablation resulted in broad reconstitution of immune function in stressed T cells, inhibition of individual MAPKs allowed only partial functional recovery. T cells from old humans (>65 years old) or mice (16-20 months old) were more likely to form the sMAC, and disruption of this complex restored antigen-specific functional responses in these cells. Correspondingly, sestrin deficiency or simultaneous inhibition of all three MAPKs enhanced vaccine responsiveness in old mice. Thus, disruption of sMAC provides a foundation for rejuvenating immunity during aging

NKG2D ligand expression in AML increases in response to HDAC inhibitor valproic acid and contributes to allorecognition by NK-cell lines with single KIR-HLA class I specificities

This study exploited alloreactivity of natural killer (NK) cells for augmenting the recognition of human acute myeloid leukemia (AML). To circumvent the inhibitory effect of killer immunoglobulin receptor (KIR) signaling, we generated NK-cell lines with single KIR specificities for major human leukocyte antigen (HLA) class I allotypes. We demonstrated efficient cytolysis of KIR-HLA class I-mismatched primary AML blasts even at low effector-to-target ratios. To define the impact of tumor-associated activating NKG2D-ligands (NKG2D-L), 66 AML patients at diagnosis were analyzed. NKG2D-L were selectively expressed on monoblastic cells in AML M4 and M5 yet absent or weakly expressed on myeloblastic cells in all AML subtypes. Paucity of cell-surface NKG2D-L was not the result of shedding because levels of soluble ULBP1 ligand measured in AML plasma were in the normal range. Notably, purified NKG2D-L(+) monoblastic cells were more susceptible to NK-mediated killing than NKG2D-L(-) myeloblastic cells. Accordingly, induction of cell-surface NKG2D-L by treatment with the histone deacetylase inhibitor, valproic acid, rendered cells more sensitive to NK cytolysis. These data suggest that adoptive transfer of selected populations of alloreactive HLA class I-mismatched NK cells in combination with pharmacologic induction of NKG2D-L merits clinical evaluation as novel approaches to immunotherapy of human AML

A sestrin-dependent Erk–Jnk–p38 MAPK activation complex inhibits immunity during aging

Mitogen-activated protein kinases (MAPKs) including Erk, Jnk and p38 regulate diverse cellular functions and are thought to be controlled by independent upstream activation cascades. Here we show that the sestrins bind to and coordinate simultaneous Erk, Jnk and p38 MAPK activation in T lymphocytes within a new immune-inhibitory complex (sestrin–MAPK activation complex (sMAC)). Whereas sestrin ablation resulted in broad reconstitution of immune function in stressed T cells, inhibition of individual MAPKs allowed only partial functional recovery. T cells from old humans (>65 years old) or mice (16–20 months old) were more likely to form the sMAC, and disruption of this complex restored antigen-specific functional responses in these cells. Correspondingly, sestrin deficiency or simultaneous inhibition of all three MAPKs enhanced vaccine responsiveness in old mice. Thus, disruption of sMAC provides a foundation for rejuvenating immunity during aging