A paradox of immunodeficiency and inflammation in human aging: lessons learned from apoptosis

Aging is associated with a paradox of immunodeficiency and inflammation (an evidence of hyperactive immune system). Apoptosis is associated with cellular depletion and suppression of inflammatory response. In this brief review, we will present evidence for the role of increased apoptosis in immunodeficiency and paradoxical increased inflammation associated with human aging. In particular, a role of apoptotic cells in failure to generate anti-inflammatory responses and directly activating inflammatory responses will be discussed

Life and death of lymphocytes: a role in immunesenescence

Human aging is associated with progressive decline in immune functions, increased frequency of infections. Among immune functions, a decline in T cell functions during aging predominates. In this review, we will discuss the molecular signaling in two major pathways of apoptosis, namely death receptor pathway and mitochondrial pathway, and their alterations in both T and B lymphocytes in human aging with a special emphasis on naïve and different memory subsets of CD8+ T cells. We will also discuss a possible role of lymphocyte apoptosis in immune senescence

Leptin Activates Human B Cells to Secrete TNF-α, IL-6, and IL-10 via JAK2/STAT3 and p38MAPK/ERK1/2 Signaling Pathway

Leptin, one of the adipokines, functions as a hormone and a cytokine. In this investigation, we show for the first time that leptin, in a concentration-dependent manner, activates human peripheral blood B cells to induce secretion of IL-6, IL-10, and TNF-α. Leptin increased B cells expressing CD25 and HLA-DR. Leptin induces phosphorylation of Janus activation kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), p38 mitogen-activated protein kinase (p38MAPK), and extracellular signal-regulated kinase (ERK1/2). Furthermore, leptin-induced cytokine secretion by B cells was blocked by inhibitors of JAK2, STAT3, p38MAPK, and ERK1/2. These data demonstrate that leptin activates human B cells to secrete cytokines via activation of JAK2/STAT3 and p38MAPK/ERK1/2 signaling pathways, which may contribute to its inflammatory and immunoregulatory properties

CD8 Treg Cells Inhibit B-Cell Proliferation and Immunoglobulin Production.

AimThe role of CD4+ Treg in immune responses has been well established. More recently, a role of CD8+ T regulatory cells (CD8 Treg) in the regulation of immune responses in health and autoimmune diseases has been investigated. Furthermore, different investigators have used different markers to define CD8 Treg. Finally, regulatory effects of CD8 Treg have been studied against T-cell responses; however, their role in regulating B-cell proliferation and immunoglobulin production has not been evaluated. Therefore, in this study we examined the effect of two types of CD8 Treg on B-cell proliferation and immunoglobulin production.MethodsPurified CD8+ T cells were activated with anti-CD3/CD28 for 48 h and then sorted into two different types of CD8 Treg as defined by two different sets of markers, CD8+CD183+CD197+CD45RA- and CD8+CD183+CD25highCD278+. Purified B cells were cocultured with sorted CD8 Treg at 1:1, 1:1/2, and 1:1/4 ratios and activated with anti-CD40 and CpG. B-cell proliferation was assessed by the CFSE dye dilution assay and immunoglobulin production by the ELISA assay.ResultsOur data show CD183+CD197+CD45RA-CD8 Treg significantly inhibited B-cell proliferation and inhibited IgM and IgG production but not IgA production at 1:1 ratio only. However, CD183+CD25highCD278+CD8 Treg inhibited significantly B-cell proliferation at 1:1 and 1:1/2 ratios and IgM, IgG, and IgA production at all ratios.ConclusionCD8 Treg regulate B-cell responses, and CD183+CD25highCD278+CD8 Treg are more powerful regulators of B-cell proliferation and immunoglobulin production than CD183+CD197+CD45RA-CD8 Treg and, therefore, may be used as preferred markers for CD8 Treg

Immune Response to SARS-CoV-2 Vaccine in 2 Men.

IntroductionIn the trials of corona virus vaccines, detailed analyses of subsets of lymphocytes were not carried out. We present perhaps the most comprehensive immunological analysis of 29 subsets of B and T cells in 2 healthy subjects receiving 2 doses of the Pfizer SARS-CoV-2 (COVID-19) vaccine.MethodsAnalyses were performed prior to vaccination, 3 weeks following the 1st dose, and 4 weeks following the 2nd dose. Total, naïve (TN), and different memory and effector subsets (TCM, TEM, and TEMRA) of CD4+ and CD8+ T cells; SARS-CoV-2 spike protein-specific tetramer+, and cytotoxic CD8+ T; subsets of T follicular cells (TFH, TFH1, TFH2, TFH1/TFH17, and TFH17); B-cell subsets (mature B cells, naive B cells, transitional B cells, marginal zone B cells, class-switched memory B cells, germinal center B cells, and CD21low B cells), and plasmablasts; and regulatory lymphocytes (CD4+ Treg, CD8+ Treg, Breg, and TFR cells) were evaluated with specific monoclonal antibodies by flow cytometry.ResultsA lack of COVID-19 IgG antibodies after the 1st dose in one of 2 subjects was associated with increased regulatory lymphocytes and decreased plasmablasts. Seroconversion after the 2nd dose in this subject was associated with decreased TFR cells and increased plasmablasts. In both subjects, CD4 TEM and CD8 TCM were markedly increased following the 2nd dose. TFH1 and regulatory lymphocytes were increased (except Breg) following the 1st dose. A striking increase in SARS-CoV-2-specific CD8+ T cells was observed following the 2nd dose.ConclusionOur data support the need for 2nd dose of vaccine to induce strong SARS-CoV-2 CD8 T-cell specific response and generation of memory subsets of CD4+ and CD8+ T cells. Regulatory lymphocytes appear to play a role in the magnitude of response

Collagenous Gastritis in Primary Selective IgM Deficiency: Transition to EBV+ Gastric Adenocarcinoma.

Selective IgM deficiency (SIgMD) and isolated collagenous gastritis are two independent rare disorders. Our purpose is to report the 1st case of SIgMD and isolated collagenous gastritis and collagenous gastritis that has transitioned to EBV + gastric adenocarcinoma. Gastric biopsy tissue was analyzed by EBV-related encoded RNA in situ hybridization assay. Subsets of CD4, CD8, T follicular helper cells (TFH), and members of the "regulatory lymphocytes club" were measured with multiple panels of monoclonal antibodies and isotype controls by multicolor flow cytometry. The patient was diagnosed with SIgMD (extremely low serum IgM 9 mg/dl and normal IgG and IgA and exclusion of secondary causes of low IgM). Soon after SIgMD diagnosis, the patient developed collagenous gastritis and, 8 years later, developed gastric adenocarcinoma that was positive for EBV. An extensive immunological analysis revealed reduced naïve CD4 and CD8 effector memory T cells and increased naïve and central memory CD8 T cells. Among the circulating follicular helper T cells (cTFH), TFH1 and TFH2 were increased whereas TFH17 was decreased. CD4 Treg cells and TFR cells were increased, whereas Breg and CD8 Treg were comparable to control. In conclusion, SIgMD may be associated with isolated collagenous gastritis, and collagenous gastritis may transition to EBV + gastric adenocarcinoma. A role of regulatory lymphocytes in gastric cancer is discussed

SARS-CoV-2-Associated T-Cell Responses in the Presence of Humoral Immunodeficiency.

We report perhaps the most comprehensive study of subsets of CD4+ and CD8+ and subsets of B cells in a mild symptomatic SARS-CoV-2+ immunocompetent patient and a common variable immunodeficiency disease (CVID) patient who had normal absolute lymphocyte counts and remained negative for SARS-CoV-2 IgG antibodies. Naïve (TN), central memory (TCM), effector memory (TEM), and terminally differentiated effector memory (TEMRA) subsets of CD4+ and CD8+ T cells, subsets of T follicular helper cells (cTFH, TFH1, TFH2, TFH17, TFH1/TFH17, and TFR), CD4 Treg, CD8 Treg, mature B cells, transitional B cells, marginal zone B cells, germinal center (GC) B cells, CD21low B cells, antibody-secreting cells (plasmablasts), and Breg cells were examined in patients and age-matched controls with appropriate monoclonal antibodies and isotype controls using multicolor flow cytometry. Different patterns of abnormalities (often contrasting) were observed in the subsets of CD4+ T, CD8+ T, B-cell subsets, and regulatory lymphocytes among the immunocompetent patient and CVID patient as compared to corresponding healthy controls. Furthermore, when data were analyzed between the 2 patients, the immunocompetent patient demonstrated greater changes in various subsets as compared to the CVID patient. These data demonstrate different immunological responses to SARS-CoV-2 infection in an immunocompetent patient and the CVID patient. A marked decrease in GC B cells and plasmablasts may be responsible for failure to make SARS-CoV-2 antibodies. The lack of SARS-CoV-2 antibodies with mild clinical disease suggests an important role of T-cell response in defense against SARS-CoV-2 infection

CD8 Treg Cells Inhibit B-Cell Proliferation and Immunoglobulin Production

AimThe role of CD4+ Treg in immune responses has been well established. More recently, a role of CD8+ T regulatory cells (CD8 Treg) in the regulation of immune responses in health and autoimmune diseases has been investigated. Furthermore, different investigators have used different markers to define CD8 Treg. Finally, regulatory effects of CD8 Treg have been studied against T-cell responses; however, their role in regulating B-cell proliferation and immunoglobulin production has not been evaluated. Therefore, in this study we examined the effect of two types of CD8 Treg on B-cell proliferation and immunoglobulin production.MethodsPurified CD8+ T cells were activated with anti-CD3/CD28 for 48 h and then sorted into two different types of CD8 Treg as defined by two different sets of markers, CD8+CD183+CD197+CD45RA- and CD8+CD183+CD25highCD278+. Purified B cells were cocultured with sorted CD8 Treg at 1:1, 1:1/2, and 1:1/4 ratios and activated with anti-CD40 and CpG. B-cell proliferation was assessed by the CFSE dye dilution assay and immunoglobulin production by the ELISA assay.ResultsOur data show CD183+CD197+CD45RA-CD8 Treg significantly inhibited B-cell proliferation and inhibited IgM and IgG production but not IgA production at 1:1 ratio only. However, CD183+CD25highCD278+CD8 Treg inhibited significantly B-cell proliferation at 1:1 and 1:1/2 ratios and IgM, IgG, and IgA production at all ratios.ConclusionCD8 Treg regulate B-cell responses, and CD183+CD25highCD278+CD8 Treg are more powerful regulators of B-cell proliferation and immunoglobulin production than CD183+CD197+CD45RA-CD8 Treg and, therefore, may be used as preferred markers for CD8 Treg