Development Of Memory Cells Research Articles

Dietary iron deficiency impairs effector function of memory T cells following influenza infection.

The establishment of memory T cell responses is critical to protection against pathogens and is influenced by the conditions under which memory formation occurs. Iron is an essential micronutrient for multiple immunologic processes and nutritional deficiency is a common problem worldwide. Despite its prevalence, the impact of nutritional iron deficiency on the establishment of memory T cell responses is not fully understood. In this study we investigate the impact of nutritional iron deficiency on the generation, phenotype, and function of memory T cell responses using a murine model of dietary iron modulation in the context of influenza infection. Iron deficient mice have decreased systemic iron levels and develop significant anemia. Increased T cell expression of the transferrin receptor (CD71) is seen in iron deficient mice at baseline. During primary influenza infection, iron deficient mice experience increased weight loss and phenotypic evidence of impairments in T cell activation. Following recovery from infection, iron deficient mice generate increased influenza specific memory T cells which exhibit impaired ability to produce IFNγ, most notably within the lung. Importantly, the ability to produce IFNγ and TNFα is not recovered by co-culture with iron replete dendritic cells, suggesting a T cell intrinsic alteration in functional memory formation. Altogether, these results isolate a critical effect of nutritional iron deficiency on T cell memory development and function.

340 Anti-CD20 attenuates lung humoral and cellular immune responses: implications for gene therapy in Cystic Fibrosis

OBJECTIVES/GOALS: Re-administration of inhaled gene therapies has the potential to overcome low correction efficiencies and limiting immune responses observed in previous trials of gene therapy for Cystic Fibrosis. We therefore tested the hypothesis that pre-treatment with a B-cell depleting α ± CD20 antibody would permit vector re-administration. METHODS/STUDY POPULATION: We first selected Adenoviral (Ad) vectors to study initially due to their well-known ability to elicit potent immune responses. Mice were dosed with a depleting α ± CD20 antibody or isotype control 2 days prior to delivery of Ad-Luc. 4 weeks later, mice were euthanized to assess the development of anti-vector immune responses. Flow cytometry and single-cell RNA sequencing were used to evaluate the development of lung-resident memory cells. Serum and airway antibody responses were assessed by ELISA. After 4 weeks, mice were dosed with Ad-LacZ and euthanized 3 days later to assess efficiency of second-round gene transfer by β-galactosidase activity assay. Similar methods were used in a pilot experiment with Adeno-associated virus vector (AAV), but with euthanasia 3 weeks after secondary gene transfer. RESULTS/ANTICIPATED RESULTS: Delivery of Ad vectors leads to the development of lung-resident memory B and T-cells. The depletion of B-cells prior to first-round vector delivery attenuated airway T-cell infiltration and serum IgG production, abrogated mucosal IgG and IgA production, and completely rescued secondary gene transfer. Genetically modified mouse models suggest secreted antibodies are critical in prevention of vector redosing. AAV vectors were found to be less immunogenic than Ad vectors, with only partial reduction of second-round gene transfer. However, anti-CD20 provided no benefit for AAV redelivery. DISCUSSION/SIGNIFICANCE: Mucosal humoral immunity is critical in preventing re-administration of Adenoviral vectors. Impairment of B-cell responses by α ± CD20 treatment prior to vector delivery allows re-administration and may help overcome low efficiencies of CF gene therapy. AAV vectors may be less susceptible to neutralization by pre-existing immunity.

Expression of the monocarboxylate transporter MCT1 is required for virus-specific mouse CD8+ T cell memory development

Lactate-proton symporter monocarboxylate transporter 1 (MCT1) facilitates lactic acid export from T cells. Here, we report that MCT1 is mandatory for the development of virus-specific CD8+ T cell memory. MCT1-deficient T cells were exposed to acute pneumovirus (pneumonia virus of mice, PVM) or persistent γ-herpesvirus (Murid herpesvirus 4, MuHV-4) infection. MCT1 was required for the expansion of virus-specific CD8+ T cells and the control of virus replication in the acute phase of infection. This situation prevented the subsequent development of virus-specific T cell memory, a necessary step in containing virus reactivation during γ-herpesvirus latency. Instead, persistent active infection drove virus-specific CD8+ T cells toward functional exhaustion, a phenotype typically seen in chronic viral infections. Mechanistically, MCT1 deficiency sequentially impaired lactic acid efflux from activated CD8+ T cells, caused an intracellular acidification inhibiting glycolysis, disrupted nucleotide synthesis in the upstream pentose phosphate pathway, and halted cell proliferation which, ultimately, promoted functional CD8+ T cell exhaustion instead of memory development. Taken together, our data demonstrate that MCT1 expression is mandatory for inducing T cell memory and controlling viral infection by CD8+ T cells.

Polyinosinic: polycytidylic acid induced inflammation enhances while lipopolysaccharide diminishes alloimmunity to platelet transfusion in mice.

Alloimmune responses against platelet antigens, which dominantly target the major histocompatibility complex (MHC), can cause adverse reactions to subsequent platelet transfusions, platelet refractoriness, or rejection of future transplants. Platelet transfusion recipients include individuals experiencing severe bacterial or viral infections, and how their underlying health modulates platelet alloimmunity is not well understood. This study investigated the effect of underlying inflammation on platelet alloimmunization by modelling viral-like inflammation with polyinosinic-polycytidylic acid (poly(I:C)) or gram-negative bacterial infection with lipopolysaccharide (LPS), hypothesizing that underlying inflammation enhances alloimmunization. Mice were pretreated with poly(I:C), LPS, or nothing, then transfused with non-leukoreduced or leukoreduced platelets. Alloantibodies and allogeneic MHC-specific B cell (allo-B cell) responses were evaluated two weeks later. Rare populations of allo-B cells were identified using MHC tetramers. Relative to platelet transfusion alone, prior exposure to poly(I:C) increased the alloantibody response to allogeneic platelet transfusion whereas prior exposure to LPS diminished responses. Prior exposure to poly(I:C) had equivalent, if not moderately diminished, allo-B cell responses relative to platelet transfusion alone and exhibited more robust allo-B cell memory development. Conversely, prior exposure to LPS resulted in diminished allo-B cell frequency, activation, antigen experience, and germinal center formation and altered memory B cell responses. In conclusion, not all inflammatory environments enhance bystander responses and prior inflammation mediated by LPS on gram-negative bacteria may in fact curtail platelet alloimmunization.

IMMU-41. IMMUNOLOGICAL TARGETING OF SLOW-CYCLING CELLS TO PREVENT RECURRENCE IN GBM

Abstract Glioblastoma (GBM) is the most common primary malignancy of the central nervous system (CNS) and is typically fatal due to recurrence despite aggressive treatment. Targeting residual cells after surgical tumor removal is challenging due to the infiltrative nature of GBM. It is crucial to develop effective adjuvant therapies that can combat the drivers of disease recurrence. Traditional anticancer treatments tend to eliminate rapidly dividing cells while sparing dormant or infrequently dividing populations. Numerous studies have identified slow-cycling cells (SCCs) in various cancers, including high-grade glioma, which are resistant to therapies. Our laboratory has discovered SCCs in high-grade glioma, which are highly infiltrative and treatment-resistant cells responsible for driving recurrence. It is imperative to develop an effective strategy to specifically eliminate this cell population in order to reduce recurrence and improve survival rates. Importantly, these cells have a defined cellular niche that contains potentially immunogenic neoantigens, making them suitable targets for immune-based therapies. Our primary objective is to utilize SCC antigens in the form of RNA or peptides to stimulate the immune system and enable it to identify and target treatment-resistant clones. By focusing on these crucial drivers of recurrence, our aim is to achieve strong and effective tumor control. Our research findings indicate that our approach effectively primes T cells to identify and target treatment-resistant cells in glioma. Our results demonstrated that T cells specific to slow-cycling cells (SCC-T cells) showed greater activation when exposed to treatment-resistant tumor cells, as evidenced by increased differentiation of CD8 cells and enhanced development of effector and memory cells. Furthermore, SCC-T cells exhibited the highest level of anti-tumor activity, resulting in a significant reduction in tumor cell proliferation and an increase in apoptosis. Taken together, these results highlight the effectiveness and superiority of our SCC-based immunotherapy platform in targeting treatment-resistant glioblastoma cells.

CD4 depletion enhances the efficacy of Super2 IL-33 armored CAR T cell against solid tumors and leads memory formation of both endogenous and CAR T cells

Abstract Chimeric antigen receptor (CAR) T cells exhibit tremendous efficacy in patients with relapsed and recurrent liquid cancers. However, CAR T cells fail to control solid tumors because of their inability to infiltrate the suppressive tumor environment and their poor persistence in vivo. The development of 4 thgeneration armored CAR T cells that employ direct tumor killing and release cytokines that can modulate the immune response to enhance tissue/tumor infiltration may improve CAR T cell persistence. Our lab has developed Super2 and IL-33 (S233) armored CAR T cells that significantly delayed B16F10 melanoma tumor growth and enhanced tumor infiltration of CARs and endogenous immune cells. Combination therapy of S233 CAR T Cells with anti-CTLA4 or anti-CD4 further enhanced this phenotype. S233 CAR T cells and anti-CD4 combination therapy promoted Melanoma-associated vitiligo (MAV), which correlates with development of tumor protective Tissue Resident Memory (TRM) cells. To assess whether CAR T cells differentiate into memory T cells, we treated tumor-bearing mice with S233 CAR T Cells with or without anti-CD4, resected their residual tumors and tracked memory T cell responses. We found that S233 CAR T cells persisted longer in the tumor draining lymph node and developed accelerated MAV when combined with anti-CD4. Both CAR T cells and endogenous T cells differentiated into central and effector memory but only endogenous T cells in the CD4 depleted group became TRM cells. While these findings provide insights on strategies to enhance long-term persistence of CAR T cells, additional studies are needed to induce CAR TRM cells and assess the durability of anti-tumor responses. NIH grant T32-AI007363 NIH grant P30-CA023108

Loss of HLA-DO function impairs the development of memory CD4 T cells

Abstract DO is an accessory protein that binds DM for trafficking to MIIC and has peptide editing functions. DO is mainly expressed in thymic medulla and B cells. Using biochemical experiments, our lab has discovered that DO has differential effects on editing peptides of different sequences. DO increases binding of DM-resistant peptides, and reduces the binding of DM-sensitive peptides to the HLA-DR1 molecules. In a separate line of work, we have established that reduced densities of antigen presentation by B cells during the contraction phase of an infection, induces quiescence in antigen experienced CD4 T cells as they differentiate into memory T cells. This quiescent phenotype helps memory CD4 T cell survival and promotes effective memory responses to secondary Ag challenge. Based on our mechanistic understanding of DO function, it would be expected that in immunized DO-KO mice, presentation of altered densities of pMHC by B cells would lead to faulty development of memory CD4 T cells. We tracked the development of DR1 restricted H5N1 flu specific memory CD4 T cells and B cells post flu vaccine immunization in DR1+/DO-KO mice and found that immunized DR1+/DO-KO mice had fewer CD4 memory T cells and memory B cells than DR1+/DO-WT mice. By in vitroand in vivorecall experiments, we found that memory responses elicited in DR1+/DO-KO mice were compromised. Using a second model antigen, OVA, we confirmed our findings, i.e., altered memory development and secondary responses in DO-KO mice. These results demonstrate that in the absence of DO, the presentation of cognate foreign antigens in the DO-KO mice is altered and can hamper the proper development of memory cells. These findings suggest a justification for the late appearance of DO in warm blooded mammals. R37 AI060040 R01 AI121174 R01 AI130210

A Novel Probiotic Combination Ameliorates Crohn's Disease-Like Ileitis by Increasing Short-Chain Fatty Acid Production and Modulating Essential Adaptive Immune Pathways.

Crohn's disease (CD) represents a significant public health challenge. We identified a combination of beneficial probiotic strains (Saccharomyces boulardii, Lactobacillus rhamnosus, Lactobacillus acidophilus, and Bifidobacterium breve) and amylase that may antagonize elevated bacterial pathogens in the inflamed gut. Our aim was to characterize the effect(s) of this novel probiotic supplement in SAMP1/YitFc (SAMP) mice with CD-like ileitis. Three groups of 7-week-old SAMP mice were used in this study. The first experimental group was administered 1 dose of the probiotic supplement (probiotic strains + amylase) diluted in sterile phosphate-buffered saline (PBS) (0.25 mg in 100 µL of PBS) every day for 56 days through the gavage technique, the second group had a probiotic supplement (probiotic strains without amylase), and the third group was a control group in which animals were administered sterile PBS. At the end of the treatment, mice were sacrificed and ilea were collected for histological scoring of ileitis and NanoString analysis. Stool samples were evaluated by 16S ribosomal RNA and gas chromatography-mass spectrometry analyses. Histology scores showed that mice treated with probiotics + amylase had a significant decrease of ileitis severity compared with the other 2 groups. 16S ribosomal RNA and gas chromatography-mass spectrometry analysis showed that abundance of species belonging to genus Lachnoclostridium and Mucispirillum schaedleri were significantly increased compared with the other 2 groups, and this increase was associated with augmented production of short-chain fatty acids. NanoString data showed that 21 genes involved in B memory cell development and T cell infiltration were significantly upregulated in probiotic-treated mice and that 3 genes were significantly downregulated. Our data provide experimental proof for a beneficial effect of the designed probiotic formulation on the severity of CD-like ileitis in the SAMP mouse model, involving both alteration of intestinal genetic pathways and microbial rearrangements. Thus, we propose that this novel probiotic mixture should be further tested as an adjuvant therapy in the treatment of biofilm-associated disorders such as CD, in which it has been proven that polymicrobial imbalance plays a critical role in dysbiosis and gut inflammation.

Mexico's experience when vaccinating against Avian Influenza: Advantages, disadvantages, and needs. Proceeding of The First International Avian Influenza Summit, University of Arkansas- October 16-17, 2023”

The experience. The silent entry of the Avian Influenza (AI) virus into Mexican territory, for the experience. In March 1994, a Low Pathogenicity (LP) subtype H5N2 virus entered Mexico stealthily and spread fast in poultry districts. The virus was common in flocks when discovered. It became an HP virus in December, jeopardizing food security. A biological was developed using biosafety. December 1995 saw HPAI-free nation. From January to December 1995, 383 million vaccinations were given. The biological was an intravenous emulsion-inactivated vaccine. Due to excessive mortality in two Altos de Jalisco districts, the National Emergency Device in Animal Health (DINESA) was established in June 2012, and the HPAI H7N3 subtype was determined as the cause. About 20 towns in Los Altos de Jalisco generate 80% of the region's eggs, with 70,000,000 birds and 40% of per capita consumption. This endangered national food security. A 2006 migratory duck virus was used to develop a vaccination, then a reverse genetics vaccine. Both vaccinations were inactivated and emulsified for parenteral administration. A recombinant vaccine was made from the Newcastle virus vector and HA protein insert. Final data: 22.4 million birds infected, 140 million vaccinated. Wild, backyard, and production birds had HPAI virus subtype H5N1 in October 2022. The outbreaks occurred in strategic poultry regions: the Yucatan Peninsula, where parent and reproductive farms are; Jalisco, which produces 54.84% of the nation's eggs and 15.60% of chickens; Sonora, which produces 7.88% of eggs, and Nuevo León which produces 2.8% of eggs and 1.82% of Control was achieved with two emulsified parenteral subunit and reverse genetics vaccinations. Following the outbreak, 201,652,000 doses were delivered. In April, authorities halted immunization against this subtype because there were no isolates, hoping to weaken antibodies and declare the country free. Advantages and disadvantages of vaccinating. Emulsified vaccines are the most common in Mexico to combat the infection. These vaccines provide robust systemic protection, protect against mortality and productivity drops, do not promote local IgA production or memory cell development, require continual revaccination, and do not prevent infection. Since local immunity is poor and delayed, emulsified vaccinations should be used with recombinant vaccines. Vaccinating in Mexico protects food safety and indirectly reduces zoonoses because vaccinated birds remove less virus. Main drawback: Vaccination can make the virus endemic. Needs. Mexico produces a lot of chicken and eggs; therefore, HPAI has been a major issue for the sector. If we keep vaccinating, our most urgent needs will be (1) new vaccines from seed viruses, which must be refreshed cyclically to match the challenge virus, (2) a biological that stimulates local neutralizing immunity (IgA), (3) bivalent or trivalent biologicals that facilitate flock management to protect productive parameters, and (4) diffusion of the information about viral behavior and vaccine use. Insufficient information is a dangerous weapon.

Regulation of effector and memory CD8 + T cell differentiation: a focus on orphan nuclear receptor NR4A family, transcription factor, and metabolism.

CD8 + T cells undergo rapid expansion followed by contraction and the development of memory cells after their receptors are activated. The development of immunological memory following acute infection is a complex phenomenon that involves several molecular, transcriptional, and metabolic mechanisms. As memory cells confer long-term protection and respond to secondary stimulation with strong effector function, understanding the mechanisms that influence their development is of great importance. Orphan nuclear receptors, NR4As, are immediate early genes that function as transcription factors and bind with the NBRE region of chromatin. Interestingly, the NBRE region of activated CD8 + T cells is highly accessible at the same time the expression of NR4As is induced. This suggests a potential role of NR4As in the early events post T cell activation that determines cell fate decisions. In this review, we will discuss the influence of NR4As on the differentiation of CD8 + T cells during the immune response to acute infection and the development of immunological memory. We will also discuss the signals, transcription factors, and metabolic mechanisms that control cell fate decisions. HIGHLIGHTS: Memory CD8 + T cells are an essential subset that mediates long-term protection after pathogen encounters. Some specific environmental cues, transcriptional factors, and metabolic pathways regulate the differentiation of CD8 + T cells and the development of memory cells. Orphan nuclear receptor NR4As are early genes that act as transcription factors and are highly expressed post-T cell receptor activation. NR4As influence the effector function and differentiation of CD8 + T cells and also control the development of immunological memory following acute infection.

Ammonia detoxification promotes CD8+ T cell memory development by urea and citrulline cycles.

Amino acid metabolism is essential for cell survival, while the byproduct ammonia is toxic and can injure cellular longevity. Here we show that CD8+ memory T (TM) cells mobilize the carbamoyl phosphate (CP) metabolic pathway to clear ammonia, thus promoting memory development. CD8+ TM cells use β-hydroxybutyrylation to upregulate CP synthetase 1 and trigger the CP metabolic cascade to form arginine in the cytosol. This cytosolic arginine is then translocated into the mitochondria where it is split by arginase 2 to urea and ornithine. Cytosolic arginine is also converted to nitric oxide and citrulline by nitric oxide synthases. Thus, both the urea and citrulline cycles are employed by CD8+ T cells to clear ammonia and enable memory development. This ammonia clearance machinery might be targeted to improve T cell-based cancer immunotherapies.

Emerging insights and challenges for understanding T cell function through the proteome.

T cells rapidly transition from a quiescent state into active proliferation and effector function upon exposure to cognate antigen. These processes are tightly controlled by signal transduction pathways that influence changes in chromatin remodeling, gene transcription, and metabolism, all of which collectively drive specific T cell memory or effector cell development. Dysregulation of any of these events can mediate disease and the past several years has shown unprecedented novel approaches to understand these events, down to the single-cell level. The massive explosion of sequencing approaches to assess the genome and transcriptome at the single cell level has transformed our understanding of T cell activation, developmental potential, and effector function under normal and various disease states. Despite these advances, there remains a significant dearth of information regarding how these events are translated to the protein level. For example, resolution of protein isoforms and/or specific post-translational modifications mediating T cell function remains obscure. The application of proteomics can change that, enabling significant insights into molecular mechanisms that regulate T cell function. However, unlike genomic approaches that have enabled exquisite visualization of T cell dynamics at the mRNA and chromatin level, proteomic approaches, including those at the single-cell level, has significantly lagged. In this review, we describe recent studies that have enabled a better understanding of how protein synthesis and degradation change during T cell activation and acquisition of effector function. We also highlight technical advances and how these could be applied to T cell biology. Finally, we discuss future needs to expand upon our current knowledge of T cell proteomes and disease.

Endothelial Cells Activate Alloreactive CD4+ T Cells to Initiate Acute Graft-Versus-Host Disease

Allogeneic donor T cells can exert an anti-leukemic response (GvL effect) after hematopoietic cell transplantation (allo-HCT). However, allogeneic donor T cells can also cause life-threatening acute graft-versus-host disease (aGvHD). Therefore, donor T cell priming is considered as a crucial event determining allo-HCT outcome. In aGvHD, donor CD4+ T cells are activated by antigen presenting cells (APCs), proliferate, differentiate and migrate to cause tissue damage. However, non-hematopoietic APCs have been shown to drive aGvHD pathology, making hematopoietic APCs dispensable in the initiation of aGvHD (Toubai et al., Blood 2012, Koyama et al., Nat Med 2012). During the aGvHD initiation phase allogenic T cells exclusively migrate to secondary lymphoid organs (SLOs) before they enter target tissues in the aGvHD effector phase (Beilhack et al., Blood 2005, Beilhack et al., Blood 2008). These observations led us to investigate the role of MHC class II mediated antigen presentation by non-hematopoietic lymph node (LN) stromal (SCs) and endothelial cells (ECs) in aGvHD. Recently we learned that alloreactive CD4+ T cells are activated in SLOs by non-hematopoietic APCs independently from Ccl19 expressing SCs, while these SCs provide protective niches to donor Tregs mitigating GvHD. Consequently, here we explored MHCII mediated antigen presentation by SLO blood endothelial cells (BECs) and lymph endothelial cells (LECs). BECs and LECs expressed endogenous MHCII, costimulatory receptors CD80/CD86 and acquired MHCII from dendritic cells via trogocytosis. Upon myeloablative irradiation, BECs and LECs upregulated CD80 and CD86 whereas MHCII expression decreased upon loss of radiosensitive host DCs. scRNA-seq revealed, BECs and LECs subsets expressing genes involved in MHCII antigen presentation (e.g. Cd74, Ctss, Ctsl, Tap2, H2-Aa, H2-Ab1, H2-Eb1) leading to exogenous antigen presentation (DQ-OVA) by EC subsets. To elucidate MHCII antigen presentation in ECs we crossed Cdh5-Cre to H2-Ab1fl mice to conditionally knockout MHCII on ECs (MHCIIΔCdh5). Allo-HCT in MHCIIΔCdh5 recipients utilizing an MHC major mismatched model (FVB→B6) did not alter allogeneic CD4+ T cell activation during aGvHD initiation. However, MHCIIΔCdh5 showed marginally reduced aGvHD and better survival. Notably, MHCIIΔCdh5 recipients retained functional hematopoietic APCs presenting alloantigens via MHCII. Therefore, we generated bone marrow (BM) chimeras by syngeneic (syn) HCT from MHCII-deficient (MHCIIΔ) donors into B6.WT mice. After allo-HCT of these BM chimeras, donor CD4+ T cells got activated in SLOs during the aGvHD initiation phase. However, to our surprise also syngeneic BM chimeric animals spontaneously developed GvHD-like symptoms making them unsuitable for studying MHCII mediated non-hematopoietic antigen presentation after allo-HCT. This striking phenotype could be explained by a defective CD44hiCD62Llow CD4+ T cell memory development in MHCIIΔ BM chimeras (Huang et al., J Immunol. 2014). Utilizing our scRNA seq dataset we identified Tie2 and Vav1 to be expressed on cells of hematopoietic lineage, however Tie2 expression was observed on ECs of the LNs. Therefore, we generated MHCIIΔVav1 mice by crossing Vav1-Cre to H2-Ab1fl. CD45- LNs cells from these animals activated CD4+ T cell in mixed lymphocyte reaction as well as in vivo. MHCIIΔVav1 mice developed less aGvHD with delayed kinetics. Subsequently, we surgically transplanted LNs from syngeneic MHCIIΔVav1 mice into complete MHCIIΔ mice. After MHCIIΔVav1 LN engraftment, these MHCIIΔ recipients underwent allo-HCT with allogenic CD4+ T cells. Alloreactive donor CD4+ T cells expressed more IFNγ and TNFα compared to controls. These experiments proved that non-hematopoietic cells in LNs can activate alloreactive CD4+ T cells to initiate aGvHD. Ultimately, we crossed MHCIIΔCdh5 to MHCIIΔVav1, resulting in mice deficient for MHCII in the entire hematopoietic and endothelial compartments. After allo-HCT MHCIIΔVav1ΔCdh5 were significantly better protected from aGvHD than littermate controls, revealing a previously unidentified role of ECs in initiating CD4+ T cell mediated aGvHD. Based on these findings we propose ECs as important non-hematopoietic APCs to activate alloreactive CD4+ T cells to trigger aGvHD suited for therapeutic interventions after allo-HCT.

Deciphering the interdependent labyrinth between gut microbiota and the immune system

The human gut microbiome interacts with each other and the host, which has significant effects on health and disease development. Intestinal homeostasis and inflammation are maintained by the dynamic interactions between gut microbiota and the innate and adaptive immune systems. Numerous metabolic products produced by the gut microbiota play a role in mediating cross-talk between gut epithelial and immune cells. In the event of an imbalance between the immune system and microbiota, the body becomes susceptible to infections, and homeostasis is compromised. This review mainly focuses on the interplay between microbes and the immune system, such as, T-cell and B-cell mediated adaptive responses to microbiota and signaling pathways for effective communication between the two. We have also highlighted the role of microbes in the activation of the immune response, the development of memory cells, and how the immune system determines the diversity of human gut microbiota. The review also explains the relationship of commensal microbiota and their relation in the production of immunoglobulins.

Discovering how DO regulates lymphocyte function

HLA-DO or H-2O (DO) in mice is a non-classical, non-polymorphic MHC II molecule primarily expressed in the thymic medulla and B cells. While the common belief is that DO inhibits the activity of DM, controversial data opposes that point of view. Applying physicochemical studies to purified DO, DM, and HLA-DR1, we have demonstrated that DO interacts directly with HLA-DR1 molecules in a peptide-receptive-conformation, augmenting binding of ‘DM-resistant’ peptides, while inhibiting binding of ‘DM-sensitive’ peptides to HLA-DR1. Indeed, we have observed that DO-WT B cells express higher densities of pMHC from naturally processed protein antigens in vivo. Accordingly, DO-KO mice are more susceptible to development of EAE due to presence of larger numbers MOG/IAb-specific CD4 T cells in periphery, likely due to a less effective thymic deletion. Since DO is also expressed in B cells, and B cell antigen presentation is a critical step in differentiation of CD4 memory T cells, we tested the contributions of DO to the development of CD4 memory T cells. To do so, we used DR1+/DO-KO mice, and examined CD4 memory development to DR1 restricted flu specific T cells three months post flu vaccine immunization. We found that consistent with our hypothesis, the DR1+/DO-KO mice had fewer flu specific CD4 memory T cells than DR1+/DO-WT mice. By in vitro and in vivo recall experiments, we also found that the secondary immunological responses in DR1+/DO-KO mice were compromised. In addition, we recovered fewer memory B cells from immunized DR1+/DO-KO mice. These results demonstrate that in the absence of DO, the presentation of cognate foreign antigens in the DO-KO mice is altered and can potentially hamper the proper development of memory cells after the resolution of the infection. These findings support the idea that the expression of DO might ensure the proper development of memory cells.

The ketone body β-hydroxybutyrate mitigates ILC2-driven airway inflammation by regulating mast cell function.

Ketone bodies are increasingly understood to have regulatory effects on immune cell function, with β-hydroxybutyrate (BHB) exerting a predominantly anti-inflammatory response. Dietary strategies to increase endogenous ketone body availability such as the ketogenic diet (KD) have recently been shown to alleviate inflammation of the respiratory tract. However, the role of BHB has not been addressed. Here, we observe that BHB suppresses group 2 innate lymphoid cell (ILC2)-mediated airway inflammation. Central to this are mast cells, which support ILC2 proliferation through interleukin-2 (IL-2). Suppression of the mast cell/IL-2 axis by BHB attenuates ILC2 proliferation and the ensuing type 2 cytokine response and immunopathology. Mechanistically, BHB directly inhibits mast cell function in part through GPR109A activation. Similar effects are achieved with either the KD or 1,3-butanediol. Our data reveal the protective role of BHB in ILC2-driven airway inflammation, which underscores the potential therapeutic value of ketone body supplementation for the management of asthma.

Adrenergic signaling controls early transcriptional programs during CD8+ T cell responses to viral infection.

Norepinephrine is a key sympathetic neurotransmitter, which acts to suppress CD8 + T cell cytokine secretion and lytic activity by signaling through the β2-adrenergic receptor (ADRB2). Although ADRB2 signaling is considered generally immunosuppressive, its role in regulating the differentiation of effector T cells in response to infection has not been investigated. Using an adoptive transfer approach, we compared the expansion and differentiation of wild type (WT) to Adrb2-/- CD8 + T cells throughout the primary response to vesicular stomatitis virus (VSV) infection in vivo. We measured the dynamic changes in transcriptome profiles of antigen-specific CD8 + T cells as they responded to VSV. Within the first 7 days of infection, WT cells out-paced the expansion of Adrb2-/- cells, which correlated with reduced expression of IL-2 and the IL-2Rα in the absence of ADRB2. RNASeq analysis identified over 300 differentially expressed genes that were both temporally regulated following infection and selectively regulated in WT vs Adrb2-/- cells. These genes contributed to major transcriptional pathways including cytokine receptor activation, signaling in cancer, immune deficiency, and neurotransmitter pathways. By parsing genes within groups that were either induced or repressed over time in response to infection, we identified three main branches of genes that were differentially regulated by the ADRB2. These gene sets were predicted to be regulated by specific transcription factors involved in effector T cell development, such as Tbx21 and Eomes. Collectively, these data demonstrate a significant role for ADRB2 signaling in regulating key transcriptional pathways during CD8 + T cells responses to infection that may dramatically impact their functional capabilities and downstream memory cell development.

IL-4 prevents adenosine-mediated immunoregulation by inhibiting CD39 expression.

The ectonucleotidase CD39 functions as a checkpoint in purinergic signaling on effector T cells. By depleting eATP and initiating the generation of adenosine, it impairs memory cell development and contributes to T cell exhaustion, thereby causing defective tumor immunity and deficient T cell responses in older adults who have increased CD39 expression. Tuning enzymatic activity of CD39 and targeting the transcriptional regulation of ENTPD1 can be used to modulate purinergic signaling. Here, we describe that STAT6 phosphorylation downstream of IL-4 signaling represses CD39 expression on activated T cells by inducing a transcription factor network including GATA3, GFI1, and YY1. GATA3 suppresses ENTPD1 transcription through prevention of RUNX3 recruitment to the ENTPD1 promoter. Conversely, pharmacological STAT6 inhibition decreases T cell effector functions via increased CD39 expression, resulting in the defective signaling of P2X receptors by ATP and stimulation of A2A receptors by adenosine. Our studies suggest that inhibiting the STAT6 pathway to increase CD39 expression has the potential to treat autoimmune disease while stimulation of the pathway could improve T cell immunity.

Protection of Quiescence and Longevity of IgG Memory B Cells by Mitochondrial Autophagy.

The development of long-lived immune memory cells against pathogens is critical for the success of vaccines to establish protection against future infections. However, the mechanisms governing the long-term survival of immune memory cells remain to be elucidated. In this article, we show that the maintenance mitochondrial homeostasis by autophagy is critical for restricting metabolic functions to protect IgG memory B cell survival. Knockout of mitochondrial autophagy genes, Nix and Bnip3, leads to mitochondrial accumulation and increases in oxidative phosphorylation and fatty acid synthesis, resulting in the loss of IgG+ memory B cells in mice. Inhibiting fatty acid synthesis or silencing necroptosis gene Ripk3 rescued Nix-/-Bnip3-/- IgG memory B cells, indicating that mitochondrial autophagy is important for limiting metabolic functions to prevent cell death. Our results suggest a critical role for mitochondrial autophagy in the maintenance of immunological memory by protecting the metabolic quiescence and longevity of memory B cells.

Nonlinear Quantum Phenomena During the Polarization of Nanometer Layers of Proton Semiconductors and Dielectrics

This paper investigates the influence of the structure and parameters of the degenerate quasi-discrete energy spectrum of relaxers (protons) on the mechanism of nonlinear quantum diffusion polarization in nanoscale layers of hydrogen bonded crystals (HBC) in a wide range of parameters of fields (100 kV/m - 1000 MV/m) and temperatures (0-1550 K). The temperature dependence of the quantum transparency of the parabolic potential barrier for protons in HBC is calculated using the Gibbs quantum canonical distribution for the ensemble of non-interacting protons (ideal proton gas balanced with the ions of anion sub-lattice) moving in an onedimensional potential field of a crystalline lattice (in the field of hydrogen bonds) with a zone structure distributed by energy levels. The influence of "zero" oscillations of protons on the temperature dependences of the proton subsystem kinetic coefficients in HBC is considered. It is revealed that proton tunneling influences the nonlinear space-charge polarization kinetics in HBC at high (150-550 K) and ultrahigh (550-1550 K) temperatures when crystalline layer thickness ranges from 1 to 10 nm. The results of theoretical studies (based on earlier experiments) are bound to be prospective for the prediction of HBC-class (KDP, DKDP) ferroelectrics properties, studying the second-order nonlinear optical effects of femtosecond lasers, and the development of memory cells for non-volatile high-speed memory devices.