scholarly journals Lymphocyte Changes in Severe COVID-19: Delayed Over-Activation of STING?

2020 ◽  
Vol 11 ◽  
Author(s):  
Jean-Marie Berthelot ◽  
Frédéric Lioté ◽  
Yves Maugars ◽  
Jean Sibilia
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd8 T Cells ◽  
Human Lymphocytes ◽  
Dna Damages ◽  
Human B Cells ◽  
Antigen Presenting ◽  
Microbial Dna ◽  
Th2 Differentiation

Upon recognition of microbial DNA or self-DNA, the cyclic-GMP-AMP synthase (cGAS) of the host catalyzes the production of the cyclic dinucleotide cGAMP. cGAMP is the main activator of STING, stimulator of interferon genes, leading to interferon synthesis through the STING-TBK1-IRF3 pathway. STING is also a hub for activation of NF-κB and autophagy. The present review details the striking similarities between T and B cell responses in severe coronavirus disease 2019 (COVID-19) and both animal or human models of STING gain of function (SAVI syndromes: STING-associated vasculopathy with onset in infancy). Those similarities may be further clues for a delayed activation of STING in severe COVID-19 patients, due to DNA damages following severe acute respiratory syndrome coronaviruses (SARS-CoV-2) infection and unusual role of STING in SARS-CoV-2 control. In early stages, Th2 differentiation are noticed in both severe COVID-19 and SAVI syndromes; then, CD4+ and CD8+ T cells functional exhaustion/senescent patterns due to TCR hyper-responsiveness are observed. T cell delayed over-responses can contribute to pneumonitis and delayed cytokine secretion with over-production of IL-6. Last, STING over-activation induces progressive CD4+ and CD8+ T lymphopenia in SAVI syndromes, which parallels what is observed in severe COVID-19. ACE2, the main receptor of SARS-CoV-2, is rarely expressed in immune cells, and it has not been yet proven that some human lymphocytes could be infected by SARS-CoV-2 through CD147 or CD26. However, STING, expressed in humans T cells, might be triggered following excessive transfer of cGAMP from infected antigen presenting cells into activated CD4+ and CD8+ T cells lymphocytes. Indeed, those lymphocytes highly express the cGAMP importer SLC19A1. Whereas STING is not expressed in human B cells, B cells counts are much less affected, either in COVID-19 or SAVI syndromes. The recognition of delayed STING over-activation in severe COVID-19 patients could prompt to target STING with specific small molecules inhibitors already designed and/or aspirin, which inhibits cGAS.

scholarly journals The Role of Lymphocyte Subsets in Accelerated Diabetes in Nonobese Diabetic–Rat Insulin Promoter–B7-1 (NOD-RIP-B7-1) Mice

1998 ◽  
Vol 187 (12) ◽  
pp. 1985-1993 ◽  
Author(s):  
F. Susan Wong ◽  
Irene Visintin ◽  
Li Wen ◽  
Jennifer Granata ◽  
Richard Flavell ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd8 T Cells ◽  
Nod Mice ◽  
Diabetic Rat ◽  
Nonobese Diabetic ◽  
Autoimmune Attack ◽  
Insulin Promoter ◽  
Onset Of Diabetes ◽  
Antigen Presenting

B7-1 transgene expression on the pancreatic islets in nonobese diabetic (NOD) mice leads to accelerated diabetes, with >50% of animals developing diabetes before 12 wk of age. The expression of B7-1 directly on the pancreatic β cells, which do not normally express costimulator molecules, converts the cells into effective antigen-presenting cells leading to an intensified autoimmune attack. The pancreatic islet infiltrate in diabetic mice consists of CD8 T cells, CD4 T cells, and B cells, similar to diabetic nontransgenic NOD mice. To elucidate the relative importance of each of the subsets of cells, the NOD–rat insulin promoter (RIP)-B7-1 animals were crossed with NOD.β2microglobulin −/− mice which lack major histocompatibility complex class I molecules and are deficient in peripheral CD8 T cells, NOD.CD4 −/− mice which lack T cells expressing CD4, and NOD.μMT −/− mice which lack B220-positive B cells. These experiments showed that both CD4 and CD8 T cells were necessary for the accelerated onset of diabetes, but that B cells, which are needed for diabetes to occur in normal NOD mice, are not required. It is possible that B lymphocytes play an important role in the provision of costimulation in NOD mice which is unnecessary in the NOD-RIP-B7-1 transgenic mice.

A Crucial Role for Antigen Presenting Cells in Donor CD4+CD25+ Regulatory T Cell Mediated Suppression of Experimental Gvhd.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 688-688
Author(s):  
Isao Tawara ◽  
Tomomi Toubai ◽  
Chelsea Malter ◽  
Yaping Sun ◽  
Evelyn Nieves ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Conflicts Of Interest ◽  
Antigen Presenting Cells ◽  
Class Ii ◽  
Indoleamine 2 ◽  
Effector Phase ◽  
Antigen Presenting

Abstract Abstract 688 Several lines of evidence show that donor derived mature CD4+CD25+Foxp3+ regulatory T cells (Tregs) suppress experimental GVHD. The mechanism of GVHD suppression by donor Tregs is, however, not well understood. Recent observations have brought in a renewed focus on the role of professional antigen presenting cells (APCs) in the induction and maintenance of GVHD by alloreactive T cell effectors (Teffs). But the role of APCs in modulating the responses of Tregs after allogeneic BMT is not known. We first tested the requirement of host APCs in Treg mediated regulation of GVHD. We utilized a clinically relevant CD8+ T cell dependent MHC matched but miHA disparate C3H.SW (H-2b) → wild type (wt) or Class II deficient Abb (II-/-) B6 (H-2b) model of GVHD because host APCs and target tissues from the Abb animals do not express class II and as such donor CD4+CD25+ Tregs will not directly interact with the host tissues while alloreactive CD8+ T cells could still respond to miHA allo-antigens presented by the intact class I on host APCs. The recipient Abb (II-/-) and wt B6 animals were lethally irradiated and transplanted with 2 × 105 CD8+ T cells along with or without CD4+CD25+ Tregs at 1:2 ratio from either syngeneic B6 or allogeneic C3H.SW animals. The wt recipients that received Tregs showed significantly better survival compared with the wt animals that did not receive any Tregs (P< 0.01) while the class II-/- animals showed similar GVHD mortality regardless of Treg infusion (P>0.8). To confirm whether the lack of Treg mediated protection was only due to the absence of interaction with host type APCs and also to exclude the possibility of development of Tregs from the infused BM we thymectomized wt B6 animals and then generated [B6 B6] controls and the [Abb B6] chimeras. These chimeric animals were used as recipients in a second BMT and transplanted with CD8+ Teffs and Tregs from allogeneic C3H.SW mice. Tregs reduced GVHD mortality in the [B6 B6] (P<0.01) but not in the [Abb B6] animals (P>0.7). We next evaluated whether host APC expression of allo-antigens alone was sufficient for Treg mediated GVHD protection in the absence of class II expression on target tissues by generating [B6 B6] and [B6 Abb] chimeras and found that Tregs demonstrated equivalent GVHD protection even when the class II allo-antigens were expressed only on the host APCs. Mechanistic studies demonstrated that Tregs significantly inhibited the expansion of CD8+ Teffs on days +10 and 17 after BMT in the spleens of the WT recipients (P<0.05) but not in the class II-/- animals. However, infused Tregs demonstrated reduced expansion in the class II-/- animals only early after BMT (on day +10) but was equivalent at later time-point (days 17 and 29) to the WT recipients. We further determined the mechanisms by which host APCs might contribute to Treg mediated protection. To this end we used IL-10-/-, indoleamine 2, 3 dioxygenase (IDO)-/- deficient animals and generated [IL-10-/- B6] and [IDO-/- B6] animals as recipients. Tregs mitigated GVHD mortality regardless of the ability of the host APCs to express IL-10 or IDO. We next determined whether Tregs suppressed Teffs in their activation phase at the level of their interaction with host APCs or in the effector phase. C3H.SW CD8+ T cells were primed (both in vivo and ex vivo with B6 allo-antigens) and then infused into the [β2mg-/- B6] animals such that pre-activated CD8 Teffs would still be able to initiate GVHD without the need for host APCs for their activation. Infusion of donor Tregs into [β2mg-/- B6] animals that were transplanted with the pre-activated Teffs mitigated GVHD severity demonstrating that Tregs, once activated by host APCs, were capable of suppressing Teff cells in their effector phase. Collectively our data show (a) host APCs are critical (b) expression of allo-antigens on host target tissues is not obligatory (c) host derived IL-10 and IDO are not critical for Treg mediated GVHD protection and (d) Tregs can mitigate GVHD by suppressing alloreactive Teffs in the effector phase even after they have been activated. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Fibroblastic reticular cells predict response to immune checkpoint inhibitors

2020 ◽  
Author(s):  
Daniele Biasci ◽  
James Thaventhiran ◽  
Simon Tavaré
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cancer Immunotherapy ◽  
Cd8 T Cells ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitors ◽  
Checkpoint Inhibitors ◽  
Reticular Cells

While the role of CD8+ T cells in mediating response to cancer immunotherapy is well established, the role of B cells remains more controversial (1–3). By conducting a large gene expression study of response to immune checkpoint inhibitors (ICI), we show that pre-treatment expression of B cell genes is associated with ICI response independently of CD8+ T cells. However, we discovered that such association can be completely explained by a single gene (FDCSP) expressed outside of the B cell compartment, in fibroblastic reticular cells (FRCs), which form the reticular network that facilitates interactions between B cells, T cells and cognate antigens (4–6) and are required to initiate efficient adaptive immune responses in secondary lymphoid organs (SLO) and tertiary lymphoid structures (TLS) (4, 7). We validated this finding in three independent cohorts of patients treated with ICI in melanoma and renal cell carcinoma. Taken together, these results suggest that FDCSP is an independent predictor of ICI response, thus opening new avenues to explain the mechanisms of resistance to cancer immunotherapy.

scholarly journals Restoration of leukomonocyte counts is associated with viral clearance in COVID-19 hospitalized patients

2020 ◽  
Author(s):  
Xiaoping Chen ◽  
Jiaxin Ling ◽  
Pingzheng Mo ◽  
Yongxi Zhang ◽  
Qunqun Jiang ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd8 T Cells ◽  
Lymphocyte Subsets ◽  
Viral Clearance ◽  
Important Indicator ◽  
Cell Responses ◽  
Standardized Treatment ◽  
Clinical Records

SummaryBackgroundViral clearance is one important indicator for the recovery of SARS-CoV-2 infected patients. Previous studies have pointed out that suboptimal T and B cell responses can delay viral clearance in MERS-CoV and SARS-CoV infected patients. The role of leukomonocytes in viral clearance of COVID-19 patients is not yet well defined.MethodsFrom January 26 to February 28, 2020, an observational study was launched at the Department of Infectious Diseases, Zhongnan Hospital of Wuhan University, Wuhan, China. We enrolled 25 laboratory-confirmed COVID-19 patients, whose throat-swab specimens were tested positive for SARS-CoV-2 infection by qRT-PCR. To investigate the factors that contribute to the viral clearance, we comprehensively analyzed clinical records, counts of lymphocyte subsets including CD3+, CD4+, CD8+ T cells, B cells and NK cells in the patients who successfully cleared SARS-CoV-2, and compared to those that failed to, after a standardized treatment of 8-14 days.FindingsIn 25 enrolled COVID-19 patients, lymphopenia was a common feature. After the treatment, 14 out of the 25 enrolled patients were tested negative for SARS-CoV-2. The patients that cleared the infection had restored the numbers of CD3+, CD4+, CD8+ T cells and B cells as compared to the still viral RNA positive patients, while the recovered patients had a higher count of leukomonocytes.ConclusionsBy comparison of leukomonocytes counts in COVID-19 patients at different stages of the disease, we found that CD3+, CD4+, CD8+ T cells and B cells appear to play important roles in viral clearance. The restoration of leukomonocytes counts from peripheral blood can be used as prognosis for the recovery of an COVID-19 infection. We propose that restoration of leukomonocytes counts can be added to the COVID-19 diagnostic guidance as a criterion for releasing and discharging patients.

scholarly journals B Cells Activated by Lipopolysaccharide, But Not By Anti-Ig and Anti-CD40 Antibody, Induce Anergy in CD8+T Cells: Role of TGF-β1

2003 ◽  
Vol 170 (12) ◽  
pp. 5897-5911 ◽  
Author(s):  
Vrajesh V. Parekh ◽  
Durbaka V. R. Prasad ◽  
Pinaki P. Banerjee ◽  
Bimba N. Joshi ◽  
Anil Kumar ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd8 T Cells ◽  
Tgf Β1

scholarly journals Distinct mechanisms of neonatal tolerance induced by dendritic cells and thymic B cells.

1991 ◽  
Vol 173 (3) ◽  
pp. 549-559 ◽  
Author(s):  
M Inaba ◽  
K Inaba ◽  
M Hosono ◽  
T Kumamoto ◽  
T Ishida ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
B Cells ◽  
Cell Types ◽  
Cell Sorter ◽  
Histocompatibility Complex ◽  
Different Types ◽  
Induced Tolerance ◽  
Antigen Presenting

To assess the role of different types of antigen-presenting cells (APC) in the induction of tolerance, we isolated B cells, macrophages, and dendritic cells from thymus and spleen, and injected these into neonatal BALB/c mice across an Mls-1 antigenic barrier. One week after injection of APC from Mls-1-incompatible mice or from control syngeneic mice, we measured the number of thymic, Mls-1a-reactive, V beta 6+ T cells and the capacity of thymocytes to induce a graft-vs.-host (GVH) reaction in popliteal lymph nodes of Mls-1a mice. Injection of thymic but not spleen B cells deleted thymic, Mls-1a-reactive V beta 6+ T cells and induced tolerance in the GVH assay. The thymic B cells were primarily of the CD5+ type, and fluorescence-activated cell sorter-purified CD5+ thymic B cells were active. Injection of dendritic cells from spleen or thymus also induced tolerance, but the V beta 6 cells were anergized rather than deleted. Macrophages from thymus did not induce tolerance. Dendritic cells and thymic B cells were also effective in inducing tolerance even when injected into Mls-, major histocompatibility complex-incompatible, I-E- mice, but only thymic B cells depleted V beta 6-expressing T cells. Therefore, different types of bone marrow-derived APC have different capacities for inducing tolerance, and the active cell types (dendritic cells and CD5+ thymic B cells) can act by distinct mechanisms.

Novel Role of Histone Deacetylase 11 (HDAC11) in Hematopoiesis

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4728-4728
Author(s):  
Eva Sahakian ◽  
John Powers ◽  
Pedro Horna ◽  
Jennifer Rock-Klotz ◽  
Susan Deng ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Cd8 T Cells ◽  
Transcriptional Activation ◽  
Effector Memory ◽  
Egfp Expression ◽  
Cell Compartment ◽  
The Common

Abstract Abstract 4728 HDAC11 is the newest member of the HDAC family. The physiological role of this HDAC was mainly unknown until the discovery by our group that HDAC11 regulates IL-10 gene expression in immune cells in-vitro1. To better elucidate the role of HDAC11 in lineage differentiation and hematopoiesis, we have utilized an HDAC11 promoter-driven eGFP reporter transgenic mice (TgHDAC11-eGFP) which allow us to “visualize” dynamic changes in HDAC11 gene expression/transcriptional activity in immune cell compartments in vivo. Thus far, our data indicates that in hematopoietic stem cells (CD34+/Lin−), transcriptional activation of HDAC11, indicated by eGFP expression appears to be absent. Also, no eGFP expression is seen in the common lymphoid progenitors (CLP-CD34+/CD127+/CD117low/Lin−) and/or the common myeloid progenitors (CMP-CD34+/CD127−/CD117high/Lin−). In the T-cell compartment, transcriptional activation of HDAC11 increases from CD4−/CD8− T-cells to CD4+/CD8+ T-cells to single positive CD4+ and CD8+ T-cells. The expression of eGFP then decreases from naive to effector memory, but then increases again at terminal effector memory. Expression of eGFP, in the bone marrow moderately increase transitioning from Pro-B-cells (CD3−/CD200+/CD19low/CD43high), Pre-B-cells (CD3−/CD200+/CD19int/CD43int), and Immature (CD3−/CD200+/CD19high/CD43low) respectively. Interestingly eGFP expression doubles in the B-1 (CD3−/CD19+/CD200low/−) stage of differentiation in the periphery. Remarkably, eGFP expression appears to be at its highest in the plasma cell compartment of the bone marrow. A second murine model also available to us, HDAC11 knockout mice (HDAC11KO) were also utilize to confirm these findings. When compared to wild-type mice, HDAC11KO mice have increased B-1 B-cells and decreased plasma cells. In the myeloid compartment, using TgHDAC11-eGFP mice, expression of HDAC11 transcript in myeloblasts (CD34+/CD45dim/CD117+/Lin-) appears to be absent. However the expression increases to 50% in the promyelocytes (Side Scatter high/CD45dim/+/CD34−/CD117+) and to 98% in the granulocytes specifically Neutrophils (Side scatter high/CD45dim+/CD34−/CD117−/CD14−/Ly6Gbright+). Strikingly, monocytes (dendritic cells and macrophages) showed no expression of eGFP. Taken together, HDAC11 appears to be essential for proper B-cells and T-cell differentiation. It also seems to play a critical role in differentiation of granulocytes and monocytes. Therefore it is plausible that HDAC11 might function as a regulator of hematopoietic differentiation and expansion in vivo. A better understanding of this previously unknown role of HDAC11 in hematopoiesis might lead to targeted epigenetic therapies in hematological malignancies to influence the appropriate differentiation of these cells, and possibly augmenting the efficacy of immunotherapeutic approaches against malignancies. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The CD8 T Cell-Epstein-Barr Virus-B Cell Trialogue: A Central Issue in Multiple Sclerosis Pathogenesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Caterina Veroni ◽  
Francesca Aloisi
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cd8 T Cells ◽  
Epstein Barr Virus ◽  
Cd8 T Cell ◽  
Barr Virus ◽  
Epstein Barr

The cause and the pathogenic mechanisms leading to multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system (CNS), are still under scrutiny. During the last decade, awareness has increased that multiple genetic and environmental factors act in concert to modulate MS risk. Likewise, the landscape of cells of the adaptive immune system that are believed to play a role in MS immunopathogenesis has expanded by including not only CD4 T helper cells but also cytotoxic CD8 T cells and B cells. Once the key cellular players are identified, the main challenge is to define precisely how they act and interact to induce neuroinflammation and the neurodegenerative cascade in MS. CD8 T cells have been implicated in MS pathogenesis since the 80’s when it was shown that CD8 T cells predominate in MS brain lesions. Interest in the role of CD8 T cells in MS was revived in 2000 and the years thereafter by studies showing that CNS-recruited CD8 T cells are clonally expanded and have a memory effector phenotype indicating in situ antigen-driven reactivation. The association of certain MHC class I alleles with MS genetic risk implicates CD8 T cells in disease pathogenesis. Moreover, experimental studies have highlighted the detrimental effects of CD8 T cell activation on neural cells. While the antigens responsible for T cell recruitment and activation in the CNS remain elusive, the high efficacy of B-cell depleting drugs in MS and a growing number of studies implicate B cells and Epstein-Barr virus (EBV), a B-lymphotropic herpesvirus that is strongly associated with MS, in the activation of pathogenic T cells. This article reviews the results of human studies that have contributed to elucidate the role of CD8 T cells in MS immunopathogenesis, and discusses them in light of current understanding of autoreactivity, B-cell and EBV involvement in MS, and mechanism of action of different MS treatments. Based on the available evidences, an immunopathological model of MS is proposed that entails a persistent EBV infection of CNS-infiltrating B cells as the target of a dysregulated cytotoxic CD8 T cell response causing CNS tissue damage.

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