IgG4-Related Disease (IgG4-RD) with Unique Combined Generalized Skin Rashes and Biliary Tract Manifestation: A Comprehensive Immunological Analysis.

IgG4-RD is a multisystem fibroinflammatory disease characterized by the infiltration of tissues by IgG4 plasma cells. Combined skin and biliary tract involvement in IgG4-RD has not been described. We present perhaps the most comprehensive analysis of lymphocyte subsets in the first case of IgG4-related generalized skin rash and first case of combined skin and biliary tract manifestations. A 55-year-old male presented with painful jaundice and generalized macular pigmented pruritic eruptions, and CT abdomen revealed biliary obstruction. Ampulla and skin biopsies were subjected to histology and immunostaining. Naïve, central memory (TCM), effector memory (TEM), terminally differentiated effector memory (TEMRA) subsets of CD4+ and CD8+ T cells, T follicular helper subsets, naïve, transitional, marginal zone (MZ), germinal center (GC), IgM memory, and class-switched memory (CSM) B cells, and T follicular regulatory, regulatory B cells, CD4 Treg, and CD8 Treg were analyzed. Serum IgG4 was elevated at 448 mg/dL. Ampula biopsy showed lamina propria fibrosis and increased IgG4-positive plasma cells. Skin punch biopsy showed lymphoplasmacytic infiltrates with a 67% ratio of IgG4+:IgG+ plasma cells. CD4+TN and CD4+TCM decreased, whereas CD4+TEM increased. Naïve B cells increased; transitional, MZ, CSM, GC B cells, and plasmablasts decreased compared to control. CD4 Treg increased, whereas CD8 Treg and Breg decreased. In conclusion, IgG-RD may present with combined biliary tract and generalized dermatological manifestations. Changes in regulatory lymphocytes suggest their role in the pathogenesis of IgG4-RD.

Adaptive Cellular Responses following SARS-CoV-2 Vaccination in Primary Antibody Deficiency Patients.

Since the start of the COVID-19 pandemic, in a short span of 3 years, vaccination against SARS-CoV-2 has resulted in the end of the pandemic. Patients with inborn errors of immunity (IEI) are at an increased risk for SARS-CoV-2 infection; however, serious illnesses and mortality, especially in primary antibody deficiencies (PADs), have been lower than expected and lower than other high-risk groups. This suggests that PAD patients may mount a reasonable effective response to the SARS-CoV-2 vaccine. Several studies have been published regarding antibody responses, with contradictory reports. The current study is, perhaps, the most comprehensive study of phenotypically defined various lymphocyte populations in PAD patients following the SARS-CoV-2 vaccine. In this study, we examined, following two vaccinations and, in a few cases, prior to and following the 1st and 2nd vaccinations, subsets of CD4 and CD8 T cells (Naïve, TCM, TEM, TEMRA), T follicular helper cells (TFH1, TFH2, TFH17, TFH1/17), B cells (naïve, transitional, marginal zone, germinal center, IgM memory, switched memory, plasmablasts, CD21low), regulatory lymphocytes (CD4Treg, CD8Treg, TFR, Breg), and SARS-CoV-2-specific activation of CD4 T cells and CD8 T cells (CD69, CD137), SARS-CoV-2 tetramer-positive CD8 T cells, and CD8 CTL. Our data show significant alterations in various B cell subsets including Breg, whereas only a few subsets of various T cells revealed alterations. These data suggest that large proportions of PAD patients may mount significant responses to the vaccine.

Biobran/MGN-3, an Arabinoxylan Rice Bran, Exerts Anti-COVID-19 Effects and Boosts Immunity in Human Subjects.

Corona Virus Disease 19 (COVID-19) has been a major pandemic impacting a huge population worldwide, and it continues to present serious health threats, necessitating the development of novel protective nutraceuticals. Biobran/MGN-3, an arabinoxylan rice bran, is a potent immunomodulator for both humans and animals that has recently been demonstrated to protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. We here investigate Biobran/MGN-3's potential to enhance an antiviral immune response in humans. Peripheral blood mononuclear cells (PBMCs) derived from eight subjects taking Biobran/MGN-3 (age 55-65 years) and eight age-matched control subjects were stimulated with irradiated SARS-CoV-2 virus and then subjected to immuno-phenotyping and multiplex cytokine/chemokine assays. Results showed that PBMCs from subjects supplemented with Biobran/MGN-3 had significantly increased activation of plasmacytoid dendritic cells (pDCs) coupled with increased IFN-α secretion. We also observed higher baseline expression of HLA-DR (human leukocyte antigen-DR isotype) on dendritic cells (DCs) and increased secretion of chemokines and cytokines, as well as a substantial increase in cytotoxic T cell generation for subjects taking Biobran/MGN-3. Our results suggest that Biobran/MGN-3 primes immunity and therefore may be used for boosting immune responses against SARS-CoV-2 infections and other diseases, particularly in high-risk populations such as the elderly.

Changes in the innate immune response to SARS-CoV-2 with advancing age in humans.

BACKGROUND: Advancing age is a major risk factor for respiratory viral infections. The infections are often prolonged and difficult to resolve resulting hospitalizations and mortality. The recent COVID-19 pandemic has highlighted this as elderly subjects have emerged as vulnerable populations that display increased susceptibility and severity to SARS-CoV-2. There is an urgent need to identify the probable mechanisms underlying this to protect against future outbreaks of such nature. Innate immunity is the first line of defense against viruses and its decline impacts downstream immune responses. This is because dendritic cells (DCs) and macrophages are key cellular elements of the innate immune system that can sense and respond to viruses by producing inflammatory mediators and priming CD4 and CD8 T-cell responses. RESULTS: We investigated the changes in innate immune responses to SARS-CoV-2 as a function of age. Our results using human PBMCs from aged, middle-aged, and young subjects indicate that the activation of DCs and monocytes in response to SARS-CoV-2 is compromised with age. The impairment is most apparent in pDCs where both aged and middle-aged display reduced responses. The secretion of IL-29 that confers protection against respiratory viruses is also decreased in both aged and middle-aged subjects. In contrast, inflammatory mediators associated with severe COVID-19 including CXCL-8, TREM-1 are increased with age. This is also apparent in the gene expression data where pathways related host defense display an age dependent decrease with a concomitant increase in inflammatory pathways. Not only are the inflammatory pathways and mediators increased after stimulation with SARS-CoV-2 but also at homeostasis. In keeping with reduced DC activation, the induction of cytotoxic CD8 T cells is also impaired in aged subjects. However, the CD8 T cells from aged subjects display increased baseline activation in accordance with the enhanced baseline inflammation. CONCLUSIONS: Our results demonstrate a decline in protective anti-viral immune responses and increase in damaging inflammatory responses with age indicating that dysregulated innate immune responses play a significant role in the increased susceptibility of aged subjects to COVID-19. Furthermore, the dysregulation in immune responses develops early on as middle-aged demonstrate several of these changes.

Cell-Sized Lipid Vesicles as Artificial Antigen-Presenting Cells for Antigen-Specific T Cell Activation.

In this study, efficient T cell activation is demonstrated using cell-sized artificial antigen-presenting cells (aAPCs) with protein-conjugated bilayer lipid membranes that mimic biological cell membranes. The highly uniform aAPCs are generated by a facile method based on standard droplet microfluidic devices. These aAPCs are able to activate the T cells in peripheral blood mononuclear cells, showing a 28-fold increase in interferon gamma (IFNγ) secretion, a 233-fold increase in antigen-specific CD8 T cells expansion, and a 16-fold increase of CD4 T cell expansion. The aAPCs do not require repetitive boosting or additional stimulants and can function at a relatively low aAPC-to-T cell ratio (1:17). The research presents strong evidence that the surface fluidity and size of the aAPCs are critical to the effective formation of immune synapses essential for T cell activation. The findings demonstrate that the microfluidic-generated aAPCs can be instrumental in investigating the physiological conditions and mechanisms for T cell activation. Finally, this method demonstrates the feasibility of customizable aAPCs for a cost-effective off-the-shelf approach to immunotherapy.

Impact of IL-21-associated peripheral and brain crosstalk on the Alzheimer's disease neuropathology.

Alzheimer's disease (AD) is associated with dysregulated immune and inflammatory responses. Emerging evidence indicates that peripheral immune activation is linked to neuroinflammation and AD pathogenesis. The present study focuses on determining the role of IL-21 in the pathogenesis of AD using human samples and the 5xFAD mice model. We find that the levels of IL-21 are increased in the periphery of both humans and mice in AD. In addition, the proportions of IL-21 target cells, Tfh and B plasma cells as well as activation of monocytes is increased in PBMCs from AD and mild cognitively impaired (MCI) subjects as compared to age-matched controls, indicating immune activation. In contrast, the percentage of B1 cells that control inflammation is decreased. These changes are due to IL-21 as the expression of IL-21 receptor (IL-21R) is higher on all these cells in AD. Furthermore, treatment with recombinant IL-21 in AD mice also leads to similar alterations in Tfh, B, B1, and macrophages. The effect of IL-21 is not confined to the periphery since increased expression of IL-21R is also observed in both humans and mice hippocampus derived from the AD brains. In addition, mice injected with IL-21 display increased deposition of amyloid beta (Aß) plaques in the brain which is reduced following anti-IL-21R antibody that blocks the IL-21 signaling. Moreover, activation of microglia was enhanced in IL-21-injected mice. In keeping with enhanced microglial activation, we also observed increased production of pro-inflammatory cytokines, IL-18 and IL-6 in IL-21-injected mice. The microglial activation and cytokines were both inhibited following IL-21R blockage. Altogether, IL-21 escalates AD pathology by enhancing peripheral and brain immune and inflammatory responses leading to increased Aß plaque deposition. IL-21 impacts AD neuropathology by enhancing peripheral and neuronal immune activation, inflammation, and Aß plaque deposition. Increased levels of IL-21 in the circulation of AD and MCI subjects enhances the proportions of Tfh and B plasma cells indicative of peripheral immune activation. On the other hand, the proportions of B1 cells that help reduce inflammation and clear Aß are reduced. In addition to the periphery, IL-21 also acts on the brain via IL-21 receptor, IL-21R that displays increased expression in the hippocampi of AD and MCI subjects. IL-21 enhances the activation of microglia, induces the secretion of pro-inflammatory cytokines and deposition of Aß plaques in the brain in AD.

Metabolites and growth factors produced by airway epithelial cells induce tolerance in macrophages.

Macrophages play a role in preventing inflammation in the respiratory tract. To investigate the mechanisms that lead to tolerance in macrophages, we examined the crosstalk between airway epithelial cells (AECs) and macrophages using a 2D coculture model. Culture of macrophages with AECs led to a significant inhibition of LPS induced pro-inflammatory responses. More importantly, AECs induced the secretion of TGF-ß and IL-10 from macrophages even in the absence of LPS stimulation. In addition, the expression of inhibitory molecule, CD200R was also upregulated on AEC exposed macrophages. Furthermore, the AECs exposed macrophages induced significantly increased level of T regulatory cells. Investigation into the possible mechanisms indicated that a combination of growth factor, G-CSF, and metabolites, Kynurenine and lactic acid produced by AECs is responsible for inducing tolerance in macrophages. Interestingly, all these molecules had differential effect on macrophages with G-CSF inducing TGF-ß, Kynurenine elevating IL-10, and lactic acid upregulating CD200R. Furthermore, a cocktail of these factors/metabolites induced similar changes in macrophages as AEC exposure. Altogether, these data identify factors secreted by AECs that enhance tolerance in the respiratory tract. These mediators thus have the potential to be used for therapeutic purposes to modulate respiratory inflammation following local viral infections and lung diseases.

SARS-CoV-2-Specific and Functional Cytotoxic CD8 Cells in Primary Antibody Deficiency: Natural Infection and Response to Vaccine.

PURPOSE: CD8 cytotoxic T cells (CTLs) play a critical role in the clearance of virally infected cells. SARS-CoV-2-specific CD8 T cells and functional CTLs in natural infections and following COVID-19 vaccine in primary antibody deficiency (PAD) have not been reported. In this study, we evaluated T cell response following COVID-19 or COVID-19 mRNA vaccination in patients with PADs by assessing SARS-CoV-2 tetramer-positive CD8 T cells and functional CTLs. METHODS: SARS-CoV-2-specific CD8 and functional CTLs were examined in a patient with X-linked agammaglobulinemia (XLA) and a patient with common variable immunodeficiency (CVID) following COVID-19 infection, and in 5 patients with CVID and 5 healthy controls 1 month following 2nd dose of COVID-19 mRNA vaccine (Pfizer-BioNTech). Cells were stained with SARS-CoV-2 spike protein-specific tetramers, and for functional CTLs (CD8+ CD107a+ granzyme B+ perforin+), with monoclonal antibodies and isotype controls and analyzed by flow cytometry. RESULTS: SARS-CoV-2-specific tetramer + CD8 T cells and functional CTLs in the patient with XLA following COVID-19 infection were higher, as compared to healthy control subject following COVID-19 infection. On the other hand, SARS-CoV2-tetramer + CD8 T cells and functional CTLs were lower in CVID patient following COVID19 infection as compared to healthy control following COVID-19 infection. SARS-CoV2-tetramer + CD8 T cells and functional CTLs were significantly lower in SARS-CoV2-naive CVID patients (n = 10) following vaccination when compared to SARS-CoV-2-naive healthy vaccinated controls (n = 10). CONCLUSIONS: CVID is associated with reduced SARS-CoV-2-specific CD8 T cells and functional CTLs in both natural SARS-CoV-2 infection and in response to SARS-CoV-2 mRNA vaccine, whereas natural infection in XLA is associated with a robust SARS-CoV-2-specific CD8 and functional CTL responses.

L-methionine enhances neuroinflammation and impairs neurogenesis: Implication for Alzheimer's disease.

The disruption of methionine (L-MET) metabolism has been linked with neurodevelopmental disorders such as autism and schizophrenia and neurodegenerative disorders such as Alzheimer's disorder. We previously showed that repeated administration to adult mice of methionine produced impairments of cognitive deficits. Considering the decreased neurogenesis and increased molecular inflammation hypotheses of cognitive deficits in Alzheimer's, we aimed to explore whether the methionine regimen that produced cognitive deficits is associated with altered neuroinflammation, neurogenesis, or neurodegeneration. We found that repeated administration of L-MET at a dose equivalent to two-fold of daily dietary intake for seven days enhanced the activation of microglia and inflammation in the brain, and decreased neurogenesis in the hippocampus without affecting degeneration. Furthermore, sub-chronic and chronic L-MET treatment of human neuroblastoma (SH-SY5Y) inhibited cell cycle progression, an effect that was reversed by decreasing removing L-MET from the medium. These results support a role for neuroinflammation and neurogenesis in mediating the mechanism through which L-MET induces cognitive deficits. The results also uncover L-MET restriction, neuroinflammation, and neurogenesis as potential preventive and/or therapeutic targets for mental disorders associated with cognitive disorders, including schizophrenia and Alzheimer's disease.

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

INTRODUCTION: In 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. METHODS: Analyses 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. RESULTS: A 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. CONCLUSION: Our 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.

Dietary Supplementation with Biobran/MGN-3 Increases Innate Resistance and Reduces the Incidence of Influenza-like Illnesses in Elderly Subjects: A Randomized, Double-Blind, Placebo-Controlled Pilot Clinical Trial.

Influenza-like illness (ILI) remains a major cause of severe mortality and morbidity in the elderly. Aging is associated with a decreased ability to sense pathogens and mount effective innate and adaptive immune responses, thus mandating the development of protective nutraceuticals. Biobran/MGN-3, an arabinoxylan from rice bran, has potent anti-aging and immunomodulatory effects, suggesting that it may be effective against ILI. The objective of the current study was to investigate the effect of Biobran/MGN-3 on ILI incidence, natural killer (NK) cell activity, and the expressions of RIG-1 (retinoic acid-inducible gene 1), MDA5 (melanoma differentiation-associated protein 5), and their downstream signaling genes ISG-15 (interferon-stimulated genes 15) and MX1 (myxovirus (influenza) resistance 1, interferon-inducible). A double-blind, placebo-controlled clinical trial included eighty healthy older adults over 55 years old, 40 males and 40 females, who received either a placebo or Biobran/MGN-3 (500 mg/day) for 3 months during known ILI seasonality (peak incidence) in Egypt. The incidence of ILI was confirmed clinically according to the WHO case definition criteria. Hematological, hepatic, and renal parameters were assessed in all subjects, while the activity of NK and NKT (natural killer T) cells was assessed in six randomly chosen subjects in each group by the degranulation assay. The effect of Biobran/MGN-3 on RIG-1 and MDA5, as well as downstream ISG15 and MX1, was assessed in BEAS-2B pulmonary epithelial cells using flow cytometry. The incidence rate and incidence density of ILI in the Biobran/MGN-3 group were 5.0% and 0.57 cases per 1000 person-days, respectively, compared to 22.5% and 2.95 cases per 1000 person-days in the placebo group. Furthermore, Biobran/MGN-3 ingestion significantly enhanced NK activity compared to the basal levels and to the placebo group. In addition, Biobran/MGN-3 significantly upregulated the expression levels of RIG-1, MDA5, ISG15, and MX1 in the human pulmonary epithelial BEAS-2B cell lines. No side effects were observed. Taken together, Biobran/MGN-3 supplementation enhanced the innate immune response of elderly subjects by upregulating the NK activity associated with reduction of ILI incidence. It also upregulated the intracellular RIG-1, MDA5, ISG15, and MX1 expression in pulmonary epithelial tissue cultures. Biobran/MGN-3 could be a novel agent with prophylactic effects against a wide spectrum of respiratory viral infections that warrants further investigation.

Sex-Related Differences in Innate and Adaptive Immune Responses to SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) exhibits a sex bias with males showing signs of more severe disease and hospitalizations compared with females. The mechanisms are not clear but differential immune responses, particularly the initial innate immune response, between sexes may be playing a role. The early innate immune responses to SARS-CoV-2 have not been studied because of the gap in timing between the patient becoming infected, showing symptoms, and getting the treatment. The primary objective of the present study was to compare the response of dendritic cells (DCs) and monocytes from males and females to SARS-CoV-2, 24 h after infection. To investigate this, peripheral blood mononuclear cells (PBMCs) from healthy young individuals were stimulated in vitro with the virus. Our results indicate that PBMCs from females upregulated the expression of HLA-DR and CD86 on pDCs and mDCs after stimulation with the virus, while the activation of these cells was not significant in males. Monocytes from females also displayed increased activation than males. In addition, females secreted significantly higher levels of IFN-α and IL-29 compared with males at 24 h. However, the situation was reversed at 1 week post stimulation and males displayed high levels of IFN-α production compared with females. Further investigations revealed that the secretion of CXCL-10, a chemokine associated with lung complications, was higher in males than females at 24 h. The PBMCs from females also displayed increased induction of CTLs. Altogether, our results suggest that decreased activation of pDCs, mDCs, and monocytes and the delayed and prolonged IFN-α secretion along with increased CXCL-10 secretion may be responsible for the increased morbidity and mortality of males to COVID-19.

Vitamin C Enhances Antiviral Functions of Lung Epithelial Cells.

Vitamin C is well documented to have antiviral functions; however, there is limited information about its effect on airway epithelial cells-the first cells to encounter infections. Here, we examined the effect of vitamin C on human bronchial epithelium transformed with Ad12-SV40 2B (BEAS-2B) cells, and observed that sodium-dependent vitamin C transporter 2 (SVCT2) was the primary vitamin C transporter. Transcriptomic analysis revealed that treating BEAS-2B cells with vitamin C led to a significant upregulation of several metabolic pathways and interferon-stimulated genes (ISGs) along with a downregulation of pathways involved in lung injury and inflammation. Remarkably, vitamin C also enhanced the expression of the viral-sensing receptors retinoic acid-inducible gene 1 (RIG-1) and melanoma differentiation-associated protein 5 (MDA-5), which was confirmed at the protein and functional levels. In addition, the lungs of l-gulono-γ-lactone oxidase knockout (GULO-KO) mice also displayed a marked decrease in these genes compared to wild-type controls. Collectively, our findings indicate that vitamin C acts at multiple levels to exert its antiviral and protective functions in the lungs.

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.

Patho-Physiology of Aging and Immune-Senescence: Possible Correlates With Comorbidity and Mortality in Middle-Aged and Old COVID-19 Patients.

During the last 2 years, the entire world has been severely devastated by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic (COVID-19) as it resulted in several million deaths across the globe. While the virus infects people indiscriminately, the casualty risk is higher mainly in old, and middle-aged COVID-19 patients. The incidences of COVID-19 associated co-morbidity and mortality have a great deal of correlation with the weakened and malfunctioning immune systems of elderly people. Presumably, due to the physiological changes associated with aging and because of possible comorbidities such as diabetes, hypertension, obesity, cardiovascular, and lung diseases, which are more common in elderly people, may be considered as the reason making the elderly vulnerable to the infection on one hand, and COVID-19 associated complications on the other. The accretion of senescent immune cells not only contributes to the deterioration of host defense, but also results in elevated inflammatory phenotype persuaded immune dysfunction. In the present review, we envisage to correlate functioning of the immune defense of older COVID-19 patients with secondary/super infection, increased susceptibility or aggravation against already existing cancer, infectious, autoimmune, and other chronic inflammatory diseases. Moreover, we have discussed how age-linked modulations in the immune system affect therapeutic response against administered drugs as well as immunological response to various prophylactic measures including vaccination in the elderly host. The present review also provides an insight into the intricate pathophysiology of the aging and the overall immune response of the host to SARS-CoV-2 infection. A better understanding of age-related immune dysfunction is likely to help us in the development of targeted preemptive strategies for deadly COVID-19 in elderly patients.

Rapid isolation of circulating cancer associated fibroblasts by acoustic microstreaming for assessing metastatic propensity of breast cancer patients.

We demonstrate a label free and high-throughput microbubble-based acoustic microstreaming technique to isolate rare circulating cells such as circulating cancer associated fibroblasts (cCAFs) in addition to circulating tumor cells (CTCs) and immune cells (i.e. leukocytes) from clinically diagnosed patients with a capture efficiency of 94% while preserving cell functional integrity within 8 minutes. The microfluidic device is self-pumping and was optimized to increase flow rate and achieve near perfect capturing of rare cells enabled by having a trapping capacity above the acoustic vortex saturation concentration threshold. Our approach enables rapid isolation of CTCs, cCAFs and their associated clusters from blood samples of cancer patients at different stages. By examining the combined role of cCAFs and CTCs in early cancer onset and metastasis progression, the device accurately diagnoses both cancer and the metastatic propensity of breast cancer patients. This was confirmed by flow cytometry where we observed that metastatic breast cancer blood samples had significantly higher percentage of exhausted CD8+ T cells expressing programmed cell death protein 1 (PD1), higher number of CD4+ T regulatory cells and T helper cells. We show for the first time that our lateral cavity acoustic transducers (LCATs)-based approach can thus be developed into a metastatic propensity assay for clinical usage by elucidating cancer immunological responses and the complex relationships between CTCs and its companion tumor microenvironment.

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

AIM: The 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. METHODS: Purified 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. RESULTS: Our 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. CONCLUSION: CD8 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.

In vitro Effects of CD8+ Regulatory T Cells on Human B Cell Subpopulations.

BACKGROUND: CD8+ regulatory T cells (CD8+ Tregs) are relatively recently described T cell subsets that have been shown to regulate various T cell responses and appear to play a role in autoimmunity. However, their effects on B cells have not been explored. OBJECTIVES: In this investigation we examine the effect of CD8+ Tregs on various subsets of peripheral B cells include naïve B cells, transitional B cells, marginal zone B cells, IgM memory B cells, class switched memory B cells, and plasmablasts, and on the expression of B cell-activating factor receptor (BAFF-R). METHODS: CD8+ T cells were first purified and then activated with anti-CD3/CD28 beads to generate CD8+ Tregs. Purified CD19+ B cells were cultured alone or with sorted CD8+ Tregs (CD8+CD183+CCR7+CD45RA-) and activated with anti-CD40 monoclonal antibody and CpG. B cell subsets and the expression of BAFF-R on naïve and memory B cells were analyzed using various monoclonal antibodies and corresponding control isotypes. Ten thousand cells were acquired and analyzed by FACSCalibur using the FlowJo software. RESULTS: CD8+ Tregs selectively and significantly suppressed plasmablasts without any significant effect on other B cell subsets or on the expression of BAFF-R. CONCLUSION: CD8+ Tregs may play a role in autoimmunity by regulating antibody production via suppression of plasmablasts.

Nicotine Impairs the Response of Lung Epithelial Cells to IL-22.

Smoking is a major risk factor for pulmonary diseases that include chronic obstructive pulmonary diseases (COPD) and cancer. Nicotine is the toxic and addictive component of tobacco products, like cigarettes, that negatively affects the immune system. Here, we examined the effect of nicotine on the IL-22 pathway that protects lung function by increasing transepithelial resistance and epithelial cell regeneration and repair. Our results indicate that exposure to nicotine impairs the regenerative capacity of primary bronchial epithelial cells in scratch assays. IL-22 at 100 ng/ml significantly improved wound healing in epithelial cells; however, the exposure to nicotine hampered the IL-22-mediated effect of wound healing. Investigation into the mechanisms showed that IL-22 receptor, IL-22Rα1, was downregulated in the presence of nicotine as determined by q-PCR and flow cytometry. We also investigated the effect of nicotine on IL-22 production by T cells. Results indicate that nicotine inhibited the secretion of IL-22 from T cells in response to aryl hydrocarbon receptor (AHR) ligand, FICZ. Altogether, the data suggests that nicotine negatively influences the IL-22-IL-22R axis. This impairment may contribute to the nicotine-mediated detrimental effects on lung function.