Primary oxidative phosphorylation defects lead to perturbations in the human B cell repertoire

Introduction

The majority of studies on oxidative phosphorylation in immune cells have been performed in mouse models, necessitating human translation. To understand the impact of oxidative phosphorylation (OXPHOS) deficiency on human immunity, we studied children with primary mitochondrial disease (MtD).

Methods

scRNAseq analysis of peripheral blood mononuclear cells was performed on matched children with MtD (N = 4) and controls (N = 4). To define B cell function we performed phage display immunoprecipitation sequencing on a cohort of children with MtD (N = 19) and controls (N = 16).

Results

Via scRNAseq, we found marked reductions in select populations involved in the humoral immune response, especially antigen presenting cells, B cell and plasma populations, with sparing of T cell populations. MTRNR2L8, a marker of bioenergetic stress, was significantly elevated in populations that were most depleted. mir4485, a miRNA contained in the intron of MTRNR2L8, was co-expressed. Knockdown studies of mir4485 demonstrated its role in promoting survival by modulating apoptosis. To determine the functional consequences of our findings on humoral immunity, we studied the antiviral antibody repertoire in children with MtD and controls using phage display and immunoprecipitation sequencing. Despite similar viral exposomes, MtD displayed antiviral antibodies with less robust fold changes and limited polyclonality.

Discussion

Overall, we show that children with MtD display perturbations in the B cell repertoire which may impact humoral immunity and the ability to clear viral infections.

Pyruvate dehydrogenase complex integrates the metabolome and epigenome in CD8+ memory T cell differentiation in vitro

Modulation of metabolic flux through pyruvate dehydrogenase complex (PDC) plays an important role in T cell activation and differentiation. PDC sits at the transition between glycolysis and the tricarboxylic acid cycle and is a major producer of acetyl-CoA, marking it as a potential metabolic and epigenetic node To understand the role of pyruvate dehydrogenase complex in T cell differentiation, we generated mice deficient in T cell pyruvate dehydrogenase E1A (Pdha) subunit using a CD4-cre recombinase-based strategy. Herein, we show that genetic ablation of PDC activity in T cells (TPdh-/-) leads to marked perturbations in glycolysis, the tricarboxylic acid cycle, and OXPHOS. TPdh-/- T cells became dependent upon substrate level phosphorylation via glycolysis, secondary to depressed OXPHOS. Due to the block of PDC activity, histone acetylation was also reduced, including H3K27, a critical site for CD8+ TM differentiation. Transcriptional and functional profiling revealed abnormal CD8+ TM differentiation in vitro. Collectively, our data indicate that PDC integrates the metabolome and epigenome in CD8+ memory T cell differentiation. Targeting this metabolic and epigenetic node can have widespread ramifications on cellular function.

Approach of using a system of evaluation indicators in determining the efficiency of ships in the Danube shipping

In modern conditions, there is an active interest in continuing research to reduce harmful emissions of marine engine exhaust gases into the atmosphere and prepare ships for the use of technologies with zero level of these emissions. It is known that the European Green Deal concept announced by the European Union is aimed not only at the modernization of the inland vessels, and coordinated qualitative change in its composition, but within this framework also at the large-scale implementation of the energy transition as the most effective way to achieve zero emissions into the atmosphere. At the same time, environmental aspects and issues of energy efficiency are considered as a complex task of transition to energy efficient eco-navigation. To date, for the European inland navigation participants, the stages of reducing harmful emissions into the atmosphere are clearly defined and regulated with established numerical standard (reference) values for each of the components (CO, HC, NOx, PM). As for energy efficiency, discussions are still ongoing at the international level about the advisability of introducing criteria according to the principle established by the International Maritime Organization for ships based on the specific mass of harmful emissions (in terms of CO2) per unit of transport work. At the same time, there is an understanding of the specifics of navigation conditions and technologies for transporting goods, which makes us return to comparing energy efficiency and economy indicators. The team of authors made an attempt to find and offer the most comprehensive approach to assessing the energy efficiency and economy of the inland navigation vessels operation, in particular for Danube vessels, with the maximum possible consideration of the features of their operation. An integrated approach to the use of estimated indicators of the efficiency of the existing pushers with heavy convoys allows to achieve an increase in the energy efficiency of the operation of the existing fleet, as well as lead to an improvement in environmental indicators.

Aberrant antibody affinity selection in SHIP-deficient B cells

The strength of the Ag receptor signal influences development and negative selection of B cells, and it might also affect B-cell survival and selection in the GC. Here, we have used mice with B-cell-specific deletion of the 5'-inositol phosphatase SHIP as a model to study affinity selection in cells that are hyperresponsive to Ag and cytokine receptor stimulation. In the absence of SHIP, B cells have lower thresholds for Ag- and interferon (IFN)-induced activation, resulting in augmented negative selection in the BM and enhanced B-cell maturation in the periphery. Despite a tendency to spontaneously downregulate surface IgM expression, SHIP deficiency does not alter anergy induction in response to soluble hen-egg lysozyme Ag in the MDA4 transgenic model. SHIP-deficient B cells spontaneously produce isotype-switched antibodies; however, they are poor responders in immunization and infection models. While SHIP-deficient B cells form GCs and undergo mutation, they are not properly selected for high-affinity antibodies. These results illustrate the importance of negative regulation of B-cell responses, as lower thresholds for B-cell activation promote survival of low affinity and deleterious receptors to the detriment of optimal Ab affinity maturation.

A BALB/c locus on chromosome 12 confers resistance to lupus in FcγR2-/- mice. (93.23)

FcγR2B-deficient (R2-/-) mice develop autoantibodies and glomerulonephritis with a pathology resembling human lupus when on the C57Bl/6 background. The same mutation on the BALB/c background does not lead to spontaneous disease, suggesting differences in lupus susceptibility between the BALB/c and B6 strains. An F2 genetic analysis from a B6/BALB cross identified region from the B6 chromosome 12 with positive linkage for autoantibodies. We have generated a congenic strain (B6.R2-/-sbb2) that contains the suppressor allele from the BALB/c centromeric region of chromosome 12 in an otherwise B6.R2-/- background. We have observed that the presence of sbb2 renders B6.R2-/- mice resistant to lupus disease by suppressing all antibody autoreactivity and spontaneous immune cell activation. Mixed bone marrow reconstitution experiments indicated that the sbb2 resistant allele is most likely T cell intrinsic. The sbb2 congenic interval contains several candidate genes that are currently being investigated. We generated transgenic lines containing BAC DNA insertions spanning the sbb2 interval. The new BAC transgenic strains were tested in the induced model of lupus by pristane administration. Newly generated BAC transgenic strains were also bred to B6.R2-/- to test for suppression of lupus in spontaneous disease. The goal of our experiments is to identify a new lupus susceptibility gene within the sbb2 interval that is able to suppress lupus disease by altering T cell function.