The effect of metformin on influenza vaccine responses in nondiabetic older adults: a pilot trial

BACKGROUND

Aging is associated with progressive declines in immune responses leading to increased risk of severe infection and diminished vaccination responses. Influenza (flu) is a leading killer of older adults despite availability of seasonal vaccines. Geroscience-guided interventions targeting biological aging could offer transformational approaches to reverse broad declines in immune responses with aging. Here, we evaluated effects of metformin, an FDA approved diabetes drug and candidate anti-aging drug, on flu vaccination responses and markers of immunological resilience in a pilot and feasibility double-blinded placebo-controlled study.

RESULTS

Healthy older adults (non-diabetic/non-prediabetic, age: 74.4 ± 1.7 years) were randomized to metformin (n = 8, 1500 mg extended release/daily) or placebo (n = 7) treatment for 20 weeks and were vaccinated with high-dose flu vaccine after 10 weeks of treatment. Peripheral blood mononuclear cells (PBMCs), serum, and plasma were collected prior to treatment, immediately prior to vaccination, and 1, 5, and 10 weeks post vaccination. Increased serum antibody titers were observed post vaccination with no significant differences between groups. Metformin treatment led to trending increases in circulating T follicular helper cells post-vaccination. Furthermore, 20 weeks of metformin treatment reduced expression of exhaustion marker CD57 in circulating CD4 T cells.

CONCLUSIONS

Pre-vaccination metformin treatment improved some components of flu vaccine responses and reduced some markers of T cell exhaustion without serious adverse events in nondiabetic older adults. Thus, our findings highlight the potential utility of metformin to improve flu vaccine responses and reduce age-related immune exhaustion in older adults, providing improved immunological resilience in nondiabetic older adults.

Longitudinal transcriptional analysis of peripheral blood leukocytes in COVID-19 convalescent donors

BACKGROUND

SARS-CoV2 can induce a strong host immune response. Many studies have evaluated antibody response following SARS-CoV2 infections. This study investigated the immune response and T cell receptor diversity in people who had recovered from SARS-CoV2 infection (COVID-19).

METHODS

Using the nCounter platform, we compared transcriptomic profiles of 162 COVID-19 convalescent donors (CCD) and 40 healthy donors (HD). 69 of the 162 CCDs had two or more time points sampled.

RESULTS

After eliminating the effects of demographic factors, we found extensive differential gene expression up to 241 days into the convalescent period. The differentially expressed genes were involved in several pathways, including virus-host interaction, interleukin and JAK-STAT signaling, T-cell co-stimulation, and immune exhaustion. A subset of 21 CCD samples was found to be highly "perturbed," characterized by overexpression of PLAU, IL1B, NFKB1, PLEK, LCP2, IRF3, MTOR, IL18BP, RACK1, TGFB1, and others. In addition, one of the clusters, P1 (n = 8) CCD samples, showed enhanced TCR diversity in 7 VJ pairs (TRAV9.1_TCRVA_014.1, TRBV6.8_TCRVB_016.1, TRAV7_TCRVA_008.1, TRGV9_ENST00000444775.1, TRAV18_TCRVA_026.1, TRGV4_ENST00000390345.1, TRAV11_TCRVA_017.1). Multiplexed cytokine analysis revealed anomalies in SCF, SCGF-b, and MCP-1 expression in this subset.

CONCLUSIONS

Persistent alterations in inflammatory pathways and T-cell activation/exhaustion markers for months after active infection may help shed light on the pathophysiology of a prolonged post-viral syndrome observed following recovery from COVID-19 infection. Future studies may inform the ability to identify druggable targets involving these pathways to mitigate the long-term effects of COVID-19 infection.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT04360278 Registered April 24, 2020.

Antiretroviral therapy duration and immunometabolic state determine efficacy of ex vivo dendritic cell-based treatment restoring functional HIV-specific CD8+ T cells in people living with HIV

Background

Dysfunction of CD8⁺ T cells in people living with HIV-1 (PLWH) receiving anti-retroviral therapy (ART) has restricted the efficacy of dendritic cell (DC)-based immunotherapies against HIV-1. Heterogeneous immune exhaustion and metabolic states of CD8⁺ T cells might differentially associate with dysfunction. However, specific parameters associated to functional restoration of CD8⁺ T cells after DC treatment have not been investigated.

Methods

We studied association of restoration of functional HIV-1-specific CD8⁺ T cell responses after stimulation with Gag-adjuvant-primed DC with ART duration, exhaustion, metabolic and memory cell subsets profiles.

Findings

HIV-1-specific CD8⁺ T cell responses from a larger proportion of PLWH on long-term ART (more than 10 years; LT-ARTp) improved polyfunctionality and capacity to eliminate autologous p24⁺ infected CD4⁺ T cells in vitro. In contrast, functional improvement of CD8⁺ T cells from PLWH on short-term ART (less than a decade; ST-ARTp) after DC treatment was limited. This was associated with lower frequencies of central memory CD8⁺ T cells, increased co-expression of PD1 and TIGIT and reduced mitochondrial respiration and glycolysis induction upon TCR activation. In contrast, CD8⁺ T cells from LT-ARTp showed increased frequencies of TIM3⁺ PD1⁻ cells and preserved induction of glycolysis. Treatment of dysfunctional CD8⁺ T cells from ST-ARTp with combined anti-PD1 and anti-TIGIT antibodies plus a glycolysis promoting drug restored their ability to eliminate infected CD4⁺ T cells.

Interpretation

Together, our study identifies specific immunometabolic parameters for different PLWH subgroups potentially useful for future personalized DC-based HIV-1 vaccines.

Funding

NIH (R21AI140930), MINECO/FEDER RETOS (RTI2018-097485-A-I00) and CIBERINF grants.

Cytokine Deficiencies in Patients with Long-COVID

Up to half of individuals who contract SARS-CoV-2 develop symptoms of long-COVID approximately three months after initial infection. These symptoms are highly variable, and the mechanisms inducing them are yet to be understood. We compared plasma cytokine levels from individuals with long-COVID to healthy individuals and found that those with long-COVID had 100% reductions in circulating levels of Interferon Gamma (IFNγ) and Interleukin-8 (IL-8). Additionally, we found significant reductions in levels of IL-6, IL-2, IL-17, IL-13, and IL-4 in individuals with long-COVID. We propose immune exhaustion as the driver of long-COVID, with the complete absence of IFNγ and IL-8preventing the lungs and other organs from healing after acute infection, and reducing the ability to fight off subsequent infections, both contributing to the myriad of symptoms suffered by those with long-COVID.

Chronically Activated T-cells Retain Their Inflammatory Properties in Common Variable Immunodeficiency

Purpose

Immune dysregulation complications cause significant morbidity and mortality in common variable immunodeficiency (CVID), but the underlying pathophysiology is poorly understood. While CVID is primarily considered a B-cell defect, resulting in the characteristic hypogammaglobulinemia, T-cells may also contribute to immune dysregulation complications. Here, we aim to further characterize T-cell activation and regulation in CVID with immune dysregulation (CVIDid).

Methods

Flow cytometry was performed to investigate T-cell differentiation, activation and intracellular cytokine production, negative regulators of immune activation, regulatory T-cells (Treg), and homing markers in 12 healthy controls, 12 CVID patients with infections only (CVIDio), and 20 CVIDid patients.

Results

Both CD4 + and CD8 + T-cells in CVIDid showed an increased activation profile (HLA-DR + , Ki67 + , IFNγ +) when compared to CVIDio, with concomitant upregulation of negative regulators of immune activation PD1, LAG3, CTLA4, and TIGIT. PD1 + and LAG3 + subpopulations contained equal or increased frequencies of cells with the capacity to produce IFNγ, Ki67, and/or GzmB. The expression of PD1 correlated with serum levels of CXCL9, 10, and 11. Treg frequencies were normal to high in CVIDid, but CVIDid Tregs had reduced CTLA-4 expression, especially on CD27 + effector Tregs. Increased migratory capacity to inflamed and mucosal tissue was also observed in CVIDid T-cells.

Conclusion

CVIDid was characterized by chronic activation of peripheral T-cells with preserved inflammatory potential rather than functional exhaustion, and increased tissue migratory capacity. While Treg numbers were normal in CVIDid Tregs, low levels of CTLA-4 indicate possible Treg dysfunction. Combined studies of T-cell dysfunction and circulating inflammatory proteins may direct future treatment strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10875-021-01084-6.

Flow cytometry data mining by cytoChain identifies determinants of exhaustion and stemness in TCR-engineered T cells

The phenotype of infused cells is a major determinant of Adoptive T-cell therapy (ACT) efficacy. Yet, the difficulty in deciphering multiparametric cytometry data limited the fine characterization of cellular products. To allow the analysis of dynamic and complex flow cytometry samples, we developed cytoChain, a novel dataset mining tool and a new analytical workflow. CytoChain was challenged to compare state-of-the-art and innovative culture conditions to generate stem-like memory cells (T_SCM ) suitable for ACT. Noticeably, the combination of IL-7/15 and superoxides scavenging sustained the emergence of a previously unidentified nonexhausted Fit-T_SCM signature, overlooked by manual gating and endowed with superior expansion potential. CytoChain proficiently traced back this population in independent datasets, and in T-cell receptor engineered lymphocytes. CytoChain flexibility and function were then further validated on a published dataset from circulating T cells in COVID-19 patients. Collectively, our results support the use of cytoChain to identify novel, functionally critical immunophenotypes for ACT and patients immunomonitoring.

Epigenetic Features of HIV-Induced T-Cell Exhaustion Persist Despite Early Antiretroviral Therapy

T cell dysfunction occurs early following HIV infection, impacting the emergence of non-AIDS morbidities and limiting curative efforts. ART initiated during primary HIV infection (PHI) can reverse this dysfunction, but the extent of recovery is unknown. We studied 66 HIV-infected individuals treated from early PHI with up to three years of ART. Compared with HIV-uninfected controls, CD4 and CD8 T cells from early HIV infection were characterised by T cell activation and increased expression of the immune checkpoint receptors (ICRs) PD1, Tim-3 and TIGIT. Three years of ART lead to partial – but not complete – normalisation of ICR expression, the dynamics of which varied for individual ICRs. For HIV-specific cells, epigenetic profiling of tetramer-sorted CD8 T cells revealed that epigenetic features of exhaustion typically seen in chronic HIV infection were already present early in PHI, and that ART initiation during PHI resulted in only a partial shift of the epigenome to one with more favourable memory characteristics. These findings suggest that although ART initiation during PHI results in significant immune reconstitution, there may be only partial resolution of HIV-related phenotypic and epigenetic changes.

Interaction between hepatitis B virus and SARS-CoV-2 infections

Coronavirus disease 2019 (COVID-19) has become a global pandemic and garnered international attention. The causative pathogen of COVID-19 is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel, highly contagious coronavirus. Numerous studies have reported that liver injury is quite common in patients with COVID-19. Hepatitis B has a worldwide distribution as well as in China. At present, hepatitis B virus (HBV) remains a leading cause of cirrhosis, liver failure, and hepatocellular carcinoma. Because both viruses challenge liver physiology, it raises questions as to how coinfection with HBV and SARS-CoV-2 affect disease progression and mortality. Is there an increased risk of COVID-19 in patients with HBV infection? In this review, we summarize the current reports of SARS-CoV-2 and HBV coinfection and elaborate the interaction of the two diseases. The emphasis was placed on evaluating the impact of HBV infection on disease severity and clinical outcomes in patients with COVID-19 and discussing the potential mechanism behind this effect.

[Exhaustion of CD8+ T cell immune functions in spleen of mice with different doses of Echinococcus multilocularis infections]

OBJECTIVE

To examine the changes in the immune functions of CD8⁺ T cells in the spleen of mice following Echinococcus multilocularis infections at various doses and at different time points.

METHODS

The E. multilocularis protoscoleces were collected, and E. multilocularis infection was modeled in mice via the hepatic portal vein at doses of 50 (low-dose), 500 (medium-dose) and 2 000 protoscoleces (high-dose), while physiological saline served as controls. Mouse spleen was isolated 2 (earlystage), 12 (middle-stage) and 24 weeks post-infection (late-stage), and spleen lymphocytes were harvested. The phenotype of memory CD8⁺ T cells and 2B4 expression were quantified in the mouse spleen, and the secretion of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-17A and IL-10 was measured.

RESULTS

A central-memory phenotype was predominant in the CD8⁺ T cells in the spleen of mice at the early stage of high-dose protoscolece infections, and the proportion of central-memory CD8⁺ T cells was significantly greater in the high-dose group than in the control group (35.50% ± 2.00% vs. 25.90% ± 2.46%, P < 0.01), while a effector- memory phenotype was predominant in the CD8⁺ T cells in the spleen of mice at the late stage of medium- and high-dose protoscolece infections, and the proportions of effector-memory CD8⁺ T cells were significantly greater in the medium- (25.70% ± 4.12%) and high-dose group (28.40% ± 4.12%) than in the control group (10.50% ± 6.45%) (P < 0.05). The proportions of the central-memory CD8⁺ T cells were significantly higher in the high-dose group than at middle and late stages than at the early stage (P < 0.01), and the proportion of effector-memory CD8⁺ T cells was significantly greater in the high-dose group at the late stage than at early and middle stages (P < 0.05). The secretion of IFN-γ and IL-17A by spleen CD8⁺ T cells was elevated in the low- and medium-dose groups at the early stage of infection, and high-dose protoscolece infection promoted the secretion of IFN-γ and TNF-α by spleen CD8⁺ T cells; however, the levels of IFN-γ and TNF-α were significantly lower at the late stage than at the early and middle stages (P < 0.05). In addition, high 2B4 expression was detected in spleen CD8⁺ T cells in the middle- and high-dose groups at the late stage of infection, and the 2B4 expression was significantly higher in the medium(4.73% ± 1.56%) and high-dose groups (4.94% ± 1.90%) than in the low-dose group (2.49% ± 0.58%) and the control group (2.92% ± 0.60%) (P < 0.05).

CONCLUSIONS

E. multilocularis may be killed and eliminated through the host immune responses at the middle and late stages of low- and medium-dose protoscolece infections, while high-dose protoscolece infections may trigger the upregulation of 2B4 expression in mouse spleen CD8⁺ T cells at the late stage, which leads to immune exhaustion and the resultant chronic infections.

High Serum OX40 and OX40 Ligand (OX40L) Levels Correlate with Reduced Survival in Patients with Advanced Lung Adenocarcinoma

INTRODUCTION

Interaction of OX40 and OX40 ligand (OX40L) is associated with immune activation. OX40-OX40L axis is also suggested to play a role in immunity against several solid malignancies.

OBJECTIVE

In this study, serum OX40 and OX40L levels in patients with advanced lung adenocarcinoma were assessed and their correlation with survival and clinicopathologic parameters was determined.

METHODS

Serum samples were collected from patients with advanced lung adenocarcinoma, then OX40 and OX40L were quantified via enzyme-linked immunosorbent assay. Immunohistochemical (IHC) analysis of OX40 and OX40L in resected primary lesions was also performed. The association between OX40 and OX40L levels and clinicopathologic status and patient survival was retrospectively analyzed.

RESULTS

A total of 56 patients were analyzed. Median serum OX40 and OX40L levels were 156.2 pg/mL and 186.6 pg/mL, respectively. IHC analysis in 5 patients indicated high positivity of OX40 in tumor-infiltrating lymphocytes and of OX40L in tumor cells in mucinous adenocarcinoma. Patients with a high OX40 level (≥152.2 pg/mL) had poorer prognosis than those with a low serum OX40 level (median survival, 7.36 vs. 21.19 months, respectively, p = 0.04). Patients with a high OX40L level (≥207.3 pg/mL) had poorer prognosis than those with a low serum OX40L level (median survival, 7.36 vs. 14.26 months, respectively, p = 0.04). In the subset of patients treated with immune checkpoint inhibitors (ICIs) (n = 12), those with a high OX40L level were found to have longer survival from ICI initiation than those with a low OX40L level (p = 0.023).

CONCLUSIONS

High OX40 and OX40L levels are associated with poor prognosis and may reflect the immune-exhausted status against lung adenocarcinoma.

High Serum Soluble CD27 Level Correlates with Poor Performance Status and Reduced Survival in Patients with Advanced Lung Cancer

INTRODUCTION

Soluble CD27 (sCD27) is associated with somatic immune reaction status. Moreover, sCD27 level is associated with the prognosis of patients with prostate cancer who receive immunotherapy.

OBJECTIVE

In this study, we assessed sCD27 levels in patients with advanced lung cancer and determined their correlation with survival and clinicopathologic parameters.

METHODS

Serum samples were collected from patients with advanced lung cancer, and sCD27 was quantified via enzyme-linked immunosorbent assay. The association between sCD27 levels and clinicopathologic status and patient survival was retrospectively analyzed.

RESULTS

Of 96 patients analyzed, 73 had adenocarcinoma, 7 had squamous cell carcinoma, and 15 had small cell carcinoma. Median serum sCD27 level was 36.54 U/mL (range, undetectable-104.47); this is lower than that previously reported for patients with lung cancer, including those with localized stages. Patients with squamous cell carcinoma had higher sCD27 levels (p = 0.010). Age, performance status, and serum albumin levels were significantly correlated with serum sCD27 level. Patients with high serum sCD27 levels (≥32.52 U/mL; n = 58) had poorer prognosis than those with low serum sCD27 levels (<32.52 U/mL, n = 38; median survival, 7.3 vs. 21.8 months, respectively, p< 0.0001).

CONCLUSIONS

High sCD27 level is associated with poor prognosis and may reflect the immune-exhausted status of patients with advanced lung cancer.

BET protein targeting suppresses the PD-1/PD-L1 pathway in triple-negative breast cancer and elicits anti-tumor immune response

Therapeutic strategies aiming to leverage anti-tumor immunity are being intensively investigated as they show promising results in cancer therapy. The PD-1/PD-L1 pathway constitutes an important target to restore functional anti-tumor immune response. Here, we report that BET protein inhibition suppresses PD-1/PD-L1 in triple-negative breast cancer. BET proteins control PD-1 expression in T cells, and PD-L1 in breast cancer cell models. BET protein targeting reduces T cell-derived interferon-γ production and signaling, thereby suppressing PD-L1 induction in breast cancer cells. Moreover, BET protein inhibition improves tumor cell-specific T cell cytotoxic function. Overall, we demonstrate that BET protein targeting represents a promising strategy to overcome tumor-reactive T cell exhaustion and improve anti-tumor immune responses, by reducing the PD-1/PD-L1 axis in triple-negative breast cancer.

Treatment duration with immune-based therapies in Cancer: an enigma

Unlike chemotherapy treatments that target the tumor itself (rather nonspecifically), immune-based therapies attempt to harness the power of an individual patient’s immune system to combat cancer. Similar to chemotherapeutic agents, the dosage and Administration section of labeling for all five currently approved PD-1/PD-L1 inhibitors (immunotherapy) recommends duration of treatment until disease progression or unacceptable toxicity. Overactivation or constitutive activation of the immune system with immune based therapies can lead to T-cell exhaustion and activation induced cell death (AICD) in T- and B-cells. Examples of immune exhaustion and T-cell depletion is noted in preclinical and clinical studies. Overactivation or constitutive activation leading to Immune exhaustion is a real phenomenon and of profound concern as immune cells are the true arsenal for control of the tumor growth. Designing trials rigorously to address the optimum treatment duration with immune based therapies is critical. By addressing this concern now, not only we may improve patient outcomes, but also gather a deeper understanding of the role and mechanisms of the immune system in the control of tumor growth.

Chemotherapy and immune-based therapies provide antitumor effects through completely different mechanisms. Chemotherapeutic agents are cytotoxic in that they directly inhibit basic cellular mechanisms, killing both malignant and nonmalignant cells (hopefully with a preference for malignant cells), while immune based therapies wake-up the host immune system to recognize malignant cells and eliminate them.

While there is a burgeoning excitement surrounding development of immune based therapies for the treatment of cancer, the optimal duration for these therapies need to be explored with equal fervor. Dosing for chemotherapy has been determined over years through large-scale prospective randomized trials to pinpoint the dose which maximizes therapeutic effect while minimizing side effects. Also, due to the mechanism of chemotherapeutic action, the duration of treatment with these agents is generally until disease progression or patient intolerance. However, experience with immune based therapies is limited, with current dosing and duration guidelines based primarily on initial trials required for approval of the agents. Since immune based therapies work by activating the body’s own immune system, there is concern that overactivation or constitutive activation of the immune system may lead to immune exhaustion and depletion of effector T-cells thereby causing decreased anti-tumor effects and possible allowing for tumor progression.

Similar to chemotherapeutic agents, the Dosage and Administration section of labeling for all five currently approved PD-1/PD-L1 inhibitors recommends duration of treatment until disease progression or unacceptable toxicity. However, since immune based therapies work with a completely different mechanism compared to chemotherapy, using the same therapy duration may not be the optimal approach.

In exploring treatment duration with immune based therapies, we need to answer the following: (1) does indefinite treatment with immune based therapies exhaust the immune system counteracting its own mechanism of action leading to tumor progression and (2) how can clinical trials be designed to identify the optimal duration of immune-based therapy that prevents immune cell exhaustion but supports anti-tumor immunity.

Recent advances on T-cell exhaustion in malaria infection

T-cell exhaustion reportedly leads to dysfunctional immune responses of antigen-specific T cells. Investigations have revealed that T cells expand into functionally defective phenotypes with poor recall/memory abilities to parasitic antigens. The exploitation of co-inhibitory pathways represent a highly viable area of translational research that has very well been utilized against certain cancerous conditions. Malaria, at times, evolve into a sustained chronic state where T cells express several co-inhibitory molecules (negative immune checkpoints) facilitating parasite escape and sub-optimal protective responses. Experimental evidence suggests that blockade of co-inhibitory molecules on T cells in malaria could result in the sustenance of protective responses together with dramatic parasite clearance. The role of several co-inhibitory molecules in malaria infection largely remain unclear, and here we discussed the potential applicability of co-inhibitory molecules in the management of malaria with a view to harness protective host responses against chronic disease and associated consequences.

Current understanding of HIV-1 and T-cell adaptive immunity: progress to date

The cellular immune response to human immunodeficiency virus (HIV) has different components originating from both the adaptive and innate immune systems. HIV cleverly utilizes the host machinery to survive by its intricate nature of interaction with the host immune system. HIV evades the host immune system at innate ad adaptive, allows the pathogen to replicate and transmit from one host to another. Researchers have shown that HIV has multipronged effects especially on the adaptive immunity, with CD4(+) cells being the worst effect T-cell populations. Various analyses have revealed that, the exposure to HIV results in clonal expansion and excessive activation of the immune system. Also, an abnormal process of differentiation has been observed suggestive of an alteration and blocks in the maturation of various T-cell subsets. Additionally, HIV has shown to accelerate immunosenescence and exhaustion of the overtly activated T-cells. Apart from causing phenotypic changes, HIV has adverse effects on the functional aspect of the immune system, with evidences implicating it in the loss of the capacity of T-cells to secrete various antiviral cytokines and chemokines. However, there continues to be many aspects of the immune- pathogenesis of HIV that are still unknown and thus required further research in order to convert the malaise of HIV into a manageable epidemic.