Aging affects human B cell responses

Clostridioides difficile infection: history, epidemiology, risk factors, prevention, clinical manifestations, treatment, and future options

SUMMARYClostridioides difficile infection (CDI) is one of the major issues in nosocomial infections. This bacterium is constantly evolving and poses complex challenges for clinicians, often encountered in real-life scenarios. In the face of CDI, we are increasingly equipped with new therapeutic strategies, such as monoclonal antibodies and live biotherapeutic products, which need to be thoroughly understood to fully harness their benefits. Moreover, interesting options are currently under study for the future, including bacteriophages, vaccines, and antibiotic inhibitors. Surveillance and prevention strategies continue to play a pivotal role in limiting the spread of the infection. In this review, we aim to provide the reader with a comprehensive overview of epidemiological aspects, predisposing factors, clinical manifestations, diagnostic tools, and current and future prophylactic and therapeutic options for C. difficile infection.

Insights into vaccines for elderly individuals: from the impacts of immunosenescence to delivery strategies

Immunosenescence increases the risk and severity of diseases in elderly individuals and leads to impaired vaccine-induced immunity. With aging of the global population and the emerging risk of epidemics, developing adjuvants and vaccines for elderly individuals to improve their immune protection is pivotal for healthy aging worldwide. Deepening our understanding of the role of immunosenescence in vaccine efficacy could accelerate research focused on optimizing vaccine delivery for elderly individuals. In this review, we analyzed the characteristics of immunosenescence at the cellular and molecular levels. Strategies to improve vaccination potency in elderly individuals are summarized, including increasing the antigen dose, preparing multivalent antigen vaccines, adding appropriate adjuvants, inhibiting chronic inflammation, and inhibiting immunosenescence. We hope that this review can provide a review of new findings with regards to the impacts of immunosenescence on vaccine-mediated protection and inspire the development of individualized vaccines for elderly individuals.

Determination of the factors associated with antigen-specific CD4+ T-cell responses to BNT162b2 in patients with rheumatoid arthritis

OBJECTIVES

Understanding interpatient variation in CD4+T-cell responses is the bases for understanding the pathogenesis and management of rheumatoid arthritis (RA). We examined immune responses to SARS-CoV-2 vaccine in a cohort of patients with RA and determined factors associated with the responses.

METHODS

Four hundred and thirty-one patients with RA having received two doses of BNT162b2, a messenger RNA-based vaccine for SARS-CoV-2, were included. Vaccine antigen-specific IgG was detected by ELISA, and antigen-specific CD4+T cells were detected by CD154 expression in response to antigenic stimulation. Expression of cytokines was concomitantly detected by intracellular staining. Associations among background variables, antigen-specific antibody production and the CD4+T-cell responses were analysed. Unsupervised hierarchical clustering was performed based on the profiles of antigen-specific cytokine production by CD4+T cells to stratify patients with RA.

RESULTS

Multivariate analysis indicated that ageing negatively affects CD4+T-cell response as well as antibody production. No association was detected between the presence or the levels of rheumatoid factor/anti-cyclic citrullinated peptide antibody and anti-vaccine immune responses. Methotrexate and prednisolone reduced B cell but not T-cell responses. Conventional immunophenotyping by the expression of chemokine receptors was not associated with the actual CD4+T-cell response, except for T helper cells (Th1). Functional immunophenotyping based on the profiles of antigen-specific cytokine production of CD4+T cells stratified patients with RA into three clusters, among which Th1-dominant type less frequently underwent joint surgery.

CONCLUSIONS

Clinical and immunological variables that are associated with antigen-specific CD4 T-cell responses in patients with RA were determined by analysing immune responses against SARS-CoV-2 vaccine.

Baseline immune states (BIS) associated with vaccine responsiveness and factors that shape the BIS

Vaccines are among the greatest inventions in medicine, leading to the elimination or control of numerous diseases, including smallpox, polio, measles, rubella, and, most recently, COVID-19. Yet, the effectiveness of vaccines varies among individuals. In fact, while some recipients mount a robust response to vaccination that protects them from the disease, others fail to respond. Multiple clinical and epidemiological factors contribute to this heterogeneity in responsiveness. Systems immunology studies fueled by advances in single-cell biology have been instrumental in uncovering pre-vaccination immune cell types and genomic features (i.e., the baseline immune state, BIS) that have been associated with vaccine responsiveness. Here, we review clinical factors that shape the BIS, and the characteristics of the BIS associated with responsiveness to frequently studied vaccines (i.e., influenza, COVID-19, bacterial pneumonia, malaria). Finally, we discuss potential strategies to enhance vaccine responsiveness in high-risk groups, focusing specifically on older adults.

Human Metapneumovirus Reinfection in Aged Mice Recapitulates Increased Disease Severity in Elderly Humans Infected with Human Metapneumovirus

Human metapneumovirus (HMPV) is a leading cause of respiratory infection in adults >65 y. Nearly all children worldwide are seropositive for HMPV by age 5 y, but reinfections occur throughout life, and there is no licensed vaccine. Recurrent HMPV infection is mild and self-resolving in immunocompetent individuals. However, elderly individuals develop severe respiratory disease on HMPV reinfection that leads to a high risk for morbidity and mortality. In this study, we developed a mouse model to mirror HMPV reinfection in elderly humans. C57BL/6J mice were infected with HMPV at 6-7 wk old, aged in-house, and rechallenged with high-dose virus at 70 wk. Aged rechallenged mice had profound weight loss similar to primary infected mice, increased lung histopathology, and accumulated cytotoxic CD8+CD44+CD62L-CD69+CD103+ memory cells despite having undetectable lung virus titer. When aged mice 14 mo postinfection (p.i.) or young mice 5 wk p.i. were restimulated with HMPV cognate Ag to mimic epitope vaccination, aged mice had an impaired CD8+ memory response. Convalescent serum transfer from young naive or 5 wk p.i. mice into aged mice on day of infection did not protect. Aged mice vaccinated with UV-inactivated HMPV also exhibited diminished protection and poor CD8+ memory response compared with young mice. These results suggest aged individuals with HMPV reinfection have a dysregulated CD8+ memory T cell response that fails to protect and exacerbates disease. Moreover, aged mice exhibited a poor memory response to either epitope peptide or UV-inactivated vaccination, suggesting that aged CD8+ T cell dysfunction presents a barrier to effective vaccination strategies.

Serological response to vaccines against SARS-CoV-2 in patients with inflammatory bowel disease

Objective

To study the serological response (SR) and tolerability of COVID-19 vaccine in patients with inflammatory bowel disease (IBD) and its relation with IBD treatment and type of vaccine.

Methods

Observational, cross-sectional study in patients with IBD vaccinated against COVID-19 without known previous infection. SR was analyzed by the determination of IgG antibodies against the S1 subunit. Safety was studied using a questionnaire to identify adverse effects (AE).

Results

280 patients with IBD were included. Type of vaccines: Comirnaty® 68.8%; Spikevax® 10.8%, Vaxzevria® 18.3%, Ad26.COV2-S® 2.2%. 51.3% had AE, being 100% mild. 65% developed IgG antibodies after vaccination. The SR was higher for vaccines with mRNA technology (100% Spikevax®, 68.5% Comirnaty®) compared to those based on adenovirus vector (38.0% Vaxzevria®, 33.3% Ad26.COV2-S®) (P < .001). In the multivariate analysis, SR was related to age (<60 years; OR: 3.8, 95% CI 1.9–7.0; P < .001). The SR in patients with aminosalicylates was 65.4%, 61.4% with immunosuppressants, 65.8% with anti-TNF, and 68.7% with non-anti-TNF biologicals (P = .9).

Conclusions

One third of patients with IBD did not develop antibodies with the initial vaccination against SARS-CoV-2. The SR to vaccines based on mRNA technology was higher, and it was related to age (higher in younger patients). Immunosuppressants and biologicals did not decrease SR. More than half of the patients presented AD, being mild in all cases.

Serological response to vaccines against SARS-CoV-2 in patients with inflammatory bowel disease

OBJECTIVE

To study the serological response (SR) and tolerability of COVID-19 vaccine in patients with inflammatory bowel disease (IBD) and its relation with IBD treatment and type of vaccine.

METHODS

Observational, cross-sectional study in patients with IBD vaccinated against COVID-19 without known previous infection. SR was analyzed by the determination of IgG antibodies against the S1 subunit. Safety was studied using a questionnaire to identify adverse effects (AE).

RESULTS

280 patients with IBD were included. Type of vaccines: Comirnaty® 68.8%; Spikevax® 10.8%, Vaxzevria® 18.3%, Ad26.COV2-S® 2.2%. 51.3% had AE, being 100% mild. 65% developed IgG antibodies after vaccination. The SR was higher for vaccines with mRNA technology (100% Spikevax®, 68.5% Comirnaty®) compared to those based on adenovirus vector (38.0% Vaxzevria®, 33.3% Ad26.COV2-S®) (P<.001). In the multivariate analysis, SR was related to age (<60 years; OR: 3.8, 95% CI 1.9-7.0; P<.001). The SR in patients with aminosalicylates was 65.4%, 61.4% with immunosuppressants, 65.8% with anti-TNF, and 68.7% with non-anti-TNF biologicals (P=.9).

CONCLUSIONS

One third of patients with IBD did not develop antibodies with the initial vaccination against SARS-CoV-2. The SR to vaccines based on mRNA technology was higher, and it was related to age (higher in younger patients). Immunosuppressants and biologicals did not decrease SR. More than half of the patients presented AD, being mild in all cases.

Crosstalk between the aging intestinal microflora and the brain in ischemic stroke

Aging is an inevitable phenomenon experienced by animals and humans, and its intensity varies from one individual to another. Aging has been identified as a risk factor for neurodegenerative disorders by influencing the composition of the gut microbiota, microglia activity and cognitive performance. The microbiota-gut-brain axis is a two-way communication path between the gut microbes and the host brain. The aging intestinal microbiota communicates with the brain through secreted metabolites (neurotransmitters), and this phenomenon leads to the destruction of neuronal cells. Numerous external factors, such as living conditions and internal factors related to the age of the host, affect the condition of the intestinal microflora in the form of dysbiosis. Dysbiosis is defined as changes in the composition and function of the gut microflora that affect the pathogenesis, progress, and response to treatment of a disease entity. Dysbiosis occurs when changes in the composition and function of the microbiota exceed the ability of the microflora and its host to restore equilibrium. Dysbiosis leading to dysfunction of the microbiota-gut-brain axis regulates the development and functioning of the host’s nervous, immune, and metabolic systems. Dysbiosis, which causes disturbances in the microbiota-gut-brain axis, is seen with age and with the onset of stroke, and is closely related to the development of risk factors for stroke. The review presents and summarizes the basic elements of the microbiota-gut-brain axis to better understand age-related changes in signaling along the microbiota-gut-brain axis and its dysfunction after stroke. We focused on the relationship between the microbiota-gut-brain axis and aging, emphasizing that all elements of the microbiota-gut-brain axis are subject to age-related changes. We also discuss the interaction between microbiota, microglia and neurons in the aged individuals in the brain after ischemic stroke. Finally, we presented preclinical and clinical studies on the role of the aged microbiota-gut-brain axis in the development of risk factors for stroke and changes in the post-stroke microflora.

Association of B cell profile and receptor repertoire with the progression of Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent type of dementia. Reports have revealed that the peripheral immune system is linked to neuropathology; however, little is known about the contribution of B lymphocytes in AD. For this longitudinal study, 133 participants are included at baseline and second-year follow-up. Also, we analyze B cell receptor (BCR) repertoire data generated from a public dataset of three normal and 10 AD samples and perform BCR repertoire profiling and pairwise sharing analysis. As a result, longitudinal increase in B lymphocytes is associated with increased cerebral amyloid deposition and hyperactivates induced pluripotent stem cell-derived microglia with loss-of-function for beta-amyloid clearance. Patients with AD share similar class-switched BCR sequences with identical isotypes, despite the high somatic hypermutation rate. Thus, BCR repertoire profiling can lead to the development of individualized immune-based therapeutics and treatment. We provide evidence of both quantitative and qualitative changes in B lymphocytes during AD pathogenesis.

Immunotherapies for Alzheimer’s Disease—A Review

Alzheimer’s disease (AD) is a chronic neurodegenerative disorder that falls under the umbrella of dementia and is characterised by the presence of highly neurotoxic amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFTs) of tau protein within the brain. Historically, treatments for AD have consisted of medications that can slow the progression of symptoms but not halt or reverse them. The shortcomings of conventional drugs have led to a growing need for novel, effective approaches to the treatment of AD. In recent years, immunotherapies have been at the forefront of these efforts. Briefly, immunotherapies utilise the immune system of the patient to treat a condition, with common immunotherapies for AD consisting of the use of monoclonal antibodies or vaccines. Most of these treatments target the production and deposition of Aβ due to its neurotoxicity, but treatments specifically targeting tau protein are being researched as well. These treatments have had great variance in their efficacy and safety, leading to a constant need for the research and development of new safe and effective treatments.

Low quantity and quality of anti-spike humoral response is linked to CD4 T-cell apoptosis in COVID-19 patients

In addition to an inflammatory reaction, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-infected patients present lymphopenia, which we recently reported as being related to abnormal programmed cell death. As an efficient humoral response requires CD4 T-cell help, we hypothesized that the propensity of CD4 T cells to die may impact the quantity and quality of the humoral response in acutely infected individuals. In addition to specific immunoglobulins (Ig)A, IgM, and IgG against SARS-CoV-2 nucleocapsid (N), membrane (M), and spike (S1) proteins, we assessed the quality of IgG response by measuring the avidity index. Because the S protein represents the main target for neutralization and antibody-dependent cellular cytotoxicity responses, we also analyzed anti-S-specific IgG using S-transfected cells (S-Flow). Our results demonstrated that most COVID-19 patients have a predominant IgA anti-N humoral response during the early phase of infection. This specific humoral response preceded the anti-S1 in time and magnitude. The avidity index of anti-S1 IgG was low in acutely infected individuals compared to convalescent patients. We showed that the percentage of apoptotic CD4 T cells is inversely correlated with the levels of specific IgG antibodies. These lower levels were also correlated positively with plasma levels of CXCL10, a marker of disease severity, and soluble Fas ligand that contributes to T-cell death. Finally, we found lower S-Flow responses in patients with higher CD4 T-cell apoptosis. Altogether, these results demonstrate that individuals with high levels of CD4 T-cell apoptosis and CXCL10 have a poor ability to build an efficient anti-S response. Consequently, preventing CD4 T-cell death might be a strategy for improving humoral response during the acute phase, thereby reducing COVID-19 pathogenicity.

Investigating population-level immunosenescence: From bench to bedside

The immune response is remodeled with aging in a process called immunosenescence. Some immunologists conceive immunosenescence as an adaptation of immunity to the aged immune-environment rather than a merely collapsed reactivity of immune cells against microbes and tumor cells. Others believe on an uninterrupted activation of the innate immune system with aging, leading to a low grade, sterile and chronic proinflammatory state called inflammaging. For instance, it is possible that chronic infection by cytomegalovirus leads to persistent production of viral load. This phenomenon offers periodic stimuli to the immune system that ultimately contribute to the remodeling of the immune response. If investigating immunosenescence at the cellular level is already a difficult task, considering the population level is much more complex. However, by studying immunosenescence at the population level, we can extract valuable results with viable applications. While studies with animal models allow scientists to deepen their understanding of the mechanisms of immunosenescence, studying large populations can bring practical innovations to medicine and the health system. Many researchers and funders have dedicated themselves to producing methods for the evaluation of immunosenescence on a large scale, aiming to elucidate new mechanisms by which diseases are established in the elderly. The description of how the immune response is remodeled with aging emerges as a new tool to identify the subset of subjects in which unhealthy aging is a matter of time, to help better individualize clinical management and select patients who may benefit. of early interventions. This review focuses on functional assays as valuable methods for measuring the remodeling of the immune response with aging and discuss their clinical impact. We also recall fundamental concepts for understanding the aging process of the immune response. In addition, we highlight future prospects for immunosenescence research.

Immunoglobulin gene expression profiles and microbiome characteristics in periodontitis in nonhuman primates

Colonization of mucosal tissues throughout the body occurs by a wide array of bacteria in the microbiome that stimulate the cells and tissues, as well as respond to changes in the local milieu. A feature of periodontitis is the detection of adaptive immune responses to members of the oral microbiome that show specificity and changes with disease and treatment. Thus, variations in antibody responses are noted across the population and affected by aging, albeit, data are still unclear as to how these differences relate to disease risk and expression. This study used a nonhuman primate model of experimental periodontitis to track local microbiome changes as they related to the use and expression of a repertoire of immunoglobulin genes in gingival tissues. Gingival tissue biopsies from healthy tissues and following ligature-placement for disease initiation and progression provided gene expression analysis. Additionally, following removal of the ligatures, clinical healing occurs with gene expression in disease resolved tissues. Groups of 9 animals (young: <3 yrs., adolescent: 3-7 yrs., adult -12 to 15 yrs.; aged: 17-22 yrs) were used in the investigation. In healthy tissues, young and adolescent animals showed levels of expression of 78 Ig genes that were uniformly less than adults. In contrast, ⅔ of the Ig genes were elevated by > 2-fold in the aged samples. Specific increases in an array of the Ig gene transcripts were detected in adults at disease initiation and throughout progression, while increases in young and adolescent animals were observed only with disease progression, and in aged samples primarily late in disease progression. Resolved lesions continued to demonstrate elevated levels of Ig gene expression in only young, adolescent and adult animals. The array of Ig genes significantly correlated with inflammatory, tissue biology and hypoxia genes in the gingival tissues, with variations associated with age. In the young group of animals, specific members of the oral microbiome positively correlated with Ig gene expression, while in the older animals, many of these correlations were negative. Significant correlations were observed with a select assortment of bacterial OTUs and multiple Ig genes in both younger and older animal samples, albeit the genera/species showed little overlap. Incorporating this array of microbes and host responses clearly discriminated the various time points in transition from health to disease and resolution in both the young and adult animals. The results support a major importance of adaptive immune responses in the kinetics of periodontal lesion formation, and support aging effects on the repertoire of Ig genes that may relate to the increased prevalence and severity of periodontitis with age.

Immune mechanisms behind prostate cancer in men of African ancestry: A review

BACKGROUND

Men of African ancestry (AA) with prostate cancer suffer from worse outcomes. However, a recent analysis of patients treated with the dendritic cell vaccine sipuleucel-T for prostate cancer suggested that AA patients could have improved outcomes relative to whites.

METHODS

We conducted a focused literature review of Medline-indexed articles and clinical trials listed on clinicaltrials.gov.

RESULTS

We identify several studies pointing to enrichment of inflammatory cellular infiltrates and cytokine signaling among AA patients with prostate cancer. We outline potential genomic and transcriptomic alterations that may contribute to immunogenicity. Last, we investigate differences in host immunity and vaccine responsiveness that may be enhanced in AA patients.

CONCLUSIONS

AA patients with prostate cancer may be enriched for an immunogenic phenotype. Dedicated studies are needed to better understand the immune mechanisms that contribute to existing cancer disparities and test immune-based therapies in this population.

Factors associated with anti-SARS-CoV-2 antibody titres 3 months post-vaccination with the second dose of BNT162b2 vaccine: a longitudinal observational cohort study in western Greece

OBJECTIVES

Vaccination against SARS-CoV-2 has been extensively deployed during COVID-19 pandemic. One efficient method to evaluate response to vaccination is the assessment of humoral immunity by measuring SARS-CoV-2 antibody titres. We investigated the association between anthropometric parameters (age, body mass index), smoking, diabetes, statin use, hypertension, levels of 25(OH)D and dehydroepiandrosterone sulfate (DHEAS), and SARS-CoV-2 antibody titres after vaccination.

DESIGN

In this longitudinal observational cohort study, 712 subjects were tested for SARS-CoV-2 antibodies 3 months after the second dose of BNT162b2 vaccine. Multiple linear regression analysis was performed to identify which factors are associated with the antibody titres.

SETTING

Healthcare units of western Greece (University Hospital of Patras and "St Andrews" State General Hospital of Patras).

PARTICIPANTS

All adults receiving their second dose of BNT162b2 vaccine at the participating healthcare units were eligible to participate in the study. Exclusion criteria were SARS-CoV-2 infection or positive SARS-CoV-2 antibody titre at baseline. Patients who did not provide all necessary information were excluded from our analyses.

RESULTS

We found age to be negatively associated with antibody titre (-0.005; 95% CI -0.009 to -0.001, p=0.0073), as was male gender (-0.11; 95% CI -0.1738 to -0.04617, p=0.0008). The interaction of age and gender was significant (-0.01090; 95% CI -0.01631 to -0.005490, p<0.0001), highlighting that the rate of decline in antibody titre with increasing age tends to be higher in men rather than in women. No linear trend was found between DHEAS levels and antibody titres when the lower quartile of DHEAS levels was used as reference. Tobacco use was associated with low antibody titre (-0.1097; 95% CI -0.174 to -0.046, p=0.0008) but overweight, obese or underweight subjects had similar antibody responses to normal-weight individuals. Although subjects with diabetes and hypertension had numerically lower antibody titres, this association was not statistically significant. Vitamin D levels showed no clear relationships with antibody titres.

CONCLUSIONS

Age, male gender and tobacco use are negatively associated with antibody titres after COVID-19 vaccination, but our data showed no clear correlation with vitamin D levels.

TRIAL REGISTRATION NUMBER

NCT04954651; Results.

Aging Microbiota-Gut-Brain Axis in Stroke Risk and Outcome

The microbiota-gut-brain-axis (MGBA) is a bidirectional communication network between gut microbes and their host. Many environmental and host-related factors affect the gut microbiota. Dysbiosis is defined as compositional and functional alterations of the gut microbiota that contribute to the pathogenesis, progression and treatment responses to disease. Dysbiosis occurs when perturbations of microbiota composition and function exceed the ability of microbiota and its host to restore a symbiotic state. Dysbiosis leads to dysfunctional signaling of the MGBA, which regulates the development and the function of the host's immune, metabolic, and nervous systems. Dysbiosis-induced dysfunction of the MGBA is seen with aging and stroke, and is linked to the development of common stroke risk factors such as obesity, diabetes, and atherosclerosis. Changes in the gut microbiota are also seen in response to stroke, and may impair recovery after injury. This review will begin with an overview of the tools used to study the MGBA with a discussion on limitations and potential experimental confounders. Relevant MGBA components are introduced and summarized for a better understanding of age-related changes in MGBA signaling and its dysfunction after stroke. We will then focus on the relationship between the MGBA and aging, highlighting that all components of the MGBA undergo age-related alterations that can be influenced by or even driven by the gut microbiota. In the final section, the current clinical and preclinical evidence for the role of MGBA signaling in the development of stroke risk factors such as obesity, diabetes, hypertension, and frailty are summarized, as well as microbiota changes with stroke in experimental and clinical populations. We conclude by describing the current understanding of microbiota-based therapies for stroke including the use of pre-/pro-biotics and supplementations with bacterial metabolites. Ongoing progress in this new frontier of biomedical sciences will lead to an improved understanding of the MGBA's impact on human health and disease.

Patients of 75 years and over with ANCA-associated vasculitis have a lower relapse risk than younger patients: A multicentre cohort study

BACKGROUND

Little is known about antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) in older patients. We aim to study relapse risk of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) in patients diagnosed after 75 years and compare it with those of patients aged 65-75 years.

METHODS

Data from AAV patients aged ≥65 years were extracted from the French Vasculitis Study Group (FVSG) database and from a call for observation to FVSG members. Cox and Fine-Gray models were used to assess relapse risk, taking death into account either as a censoring or a competing event, respectively.

RESULTS

The analysis included 219 patients aged ≥75 years (median 79) and 80 patients aged 65-75 years (median 70), of those 155 had GPA (52%), 136 MPA (45%), with 95 (32%) anti-proteinase 3 positivity and 179 (61%) anti-myeloperoxidase. Patients aged ≥75 years had a lower relapse risk in multivariate analysis (cause-specific hazards ratio [CSHR] 0.54, 95% CI [0.33-0.89], p = 0.016, Cox model; subdistribution hazard ratio [SHR] 0.46, 95% CI [0.29-0.74], p = 0.001, Fine-Gray model) after taking into account vasculitis type. Patients aged ≥75 years had a lower probability of being treated for remission maintenance with a combination of glucocorticoids and immunosuppressants (vs. glucocorticoids alone, HR 0.28, 95% CI [0.11-0.68], p = 0.005) after adjusting to Five Factor Score, although relapse-free survival was significantly longer when receiving such combination (CSHR 0.40, 95% [CI 0.24-0.67], p < 0.001).

CONCLUSIONS

AAV patients ≥75 years have a lower relapse risk than patients aged 65-75 years despite a lower probability of having received maintenance therapy with a combination of glucocorticoids and immunosuppressants, but they still benefit from such treatment regimen.

Autoreactive antibodies control blood glucose by regulating insulin homeostasis

The random nature of antibody repertoire generation includes the potential of producing autoantibodies recognizing self-structures. It is believed that establishing immunological tolerance and prevention of autoimmune diseases require the removal of antibody specificities recognizing self. Using insulin as a common and physiologically important autoantigen, we show that anti-insulin antibodies associated with autoimmune diabetes can readily be detected in mice and humans and are involved in the physiological regulation of blood glucose levels. Importantly, human high-affinity, anti-insulin IgM antibodies protect insulin from autoimmune degradation by anti-insulin IgG antibodies. Thus, in contrast to the proposed negative selection, self-recognition and the production of highly autoreactive IgM antibodies are important for tolerance induction.

Homeostasis of metabolism by hormone production is crucial for maintaining physiological integrity, as disbalance can cause severe metabolic disorders such as diabetes mellitus. Here, we show that antibody-deficient mice and immunodeficiency patients have subphysiological blood glucose concentrations. Restoring blood glucose physiology required total IgG injections and insulin-specific IgG antibodies detected in total IgG preparations and in the serum of healthy individuals. In addition to the insulin-neutralizing anti-insulin IgG, we identified two fractions of anti-insulin IgM in the serum of healthy individuals. These autoreactive IgM fractions differ in their affinity to insulin. Interestingly, the low-affinity IgM fraction (anti-insulin IgM^low) neutralizes insulin and leads to increased blood glucose, whereas the high-affinity IgM fraction (anti-insulin IgM^high) protects insulin from neutralization by anti-insulin IgG, thereby preventing blood glucose dysregulation. To demonstrate that anti-insulin IgM^high acts as a protector of insulin and counteracts insulin neutralization by anti-insulin IgG, we expressed the variable regions of a high-affinity anti-insulin antibody as IgG and IgM. Remarkably, the recombinant anti-insulin IgM^high normalized insulin function and prevented IgG-mediated insulin neutralization. These results suggest that autoreactive antibodies recognizing insulin are key regulators of blood glucose and metabolism, as they control the concentration of insulin in the blood. Moreover, our data suggest that preventing autoimmune damage and maintaining physiological homeostasis requires adaptive tolerance mechanisms generating high-affinity autoreactive IgM antibodies during memory responses.

Age-related functional decline of human B cells

This study aimed to investigate the changes in B cell functional decline and antigen sensitization with aging using two Epstein Barr virus (EBV)-immortalized human B cell lines, one from a 22-year-old man (EBV-B young) and the other from a 65-year-old man (EBV-B old). The activity of senescence-associated β-galactosidase, a marker of cellular senescence, was enhanced in the EBV-B old cells compared with EBV-B young cells. Moreover, the levels of p16, p21, IL-6, TNF-α, and TGF-β1, which are senescence-associated secretary phenotypes, were also increased in EBV-B old cells. In vitro immunization of EBV-B cells with β-lactoglobulin further showed that EBV-B old cells had a reduced cell population of naïve B cells than that of EBV-B young cells. Furthermore, HLA-DR expression, which is important for antigen presentation, was decreased in the EBV-B old cells. Comparative microarray analysis between EBV-B young and old cells also showed decreased expression of antibody genes, such as those of the heavy chain and light chain (κ chain). These results suggest that cellular senescence and decreased gene expression are responsible, at least in part, for the decline in B cell function and antigen sensitization capacity with aging, which ultimately impairs the function of the acquired immune system.

Stent infection and pseudoaneurysm formation after carotid artery stent treated by excision and in situ reconstruction with polytetrafluoroethylene graft: A case report

Background:

Stent infection after carotid artery stenting (CAS) can be a life-threatening postoperative complication, but there is a paucity of data due to its exceedingly low frequency. We report a case of stent infection with pseudoaneurysm formation after CAS that was treated through replacing the infected stent and pseudoaneurysm with a polytetrafluoroethylene (PTFE) synthetic vessel graft.

Case Description:

An 86-year-old man was treated for the right internal carotid artery with CAS in local hospital. One month after stenting, he suffered aspiration pneumonia and septicemia. Three months after stenting, swelling and tenderness of the right side of his neck appeared. His general condition deteriorated due to septicemia and he was unable to ingest anything by mouth as a result of decreasing levels of consciousness. He was transferred to our hospital. Computed tomography and digital subtraction angiography showed the presence of a pseudoaneurysm around the stent. The neck mass enlarged daily and surgical intervention was required to prevent closure of the airway. Stent and pseudoaneurysm resection and in situ reconstruction with a PTFE synthetic vessel graft were performed. The patient returned to his local hospital 36 days after surgery and had a modified Rankin Score of 5.

Conclusion:

Although the risk of reinfection is high due to the nature of artificial material, stent/pseudoaneurysm resection and in situ reconstruction with a PTFE synthetic vessel graft might be one of the best options for patients suffering stent infection after CAS. To the best of our knowledge, this is the first report of treatment using this material.

Immunity to SARS-CoV-2 induced by infection or vaccination

Adaptive immune responses play critical roles in viral clearance and protection against re-infection, and SARS-CoV-2 is no exception. What is exceptional is the rapid characterization of the immune response to the virus performed by researchers during the first 20 months of the pandemic. This has given us a more detailed understanding of SARS-CoV-2 compared to many viruses that have been with us for a long time. Furthermore, effective COVID-19 vaccines were developed in record time, and their rollout worldwide is already making a significant difference, although major challenges remain in terms of equal access. The pandemic has engaged scientists and the public alike, and terms such as seroprevalence, neutralizing antibodies, antibody escape and vaccine certificates have become familiar to a broad community. Here, we review key findings concerning B cell and antibody (Ab) responses to SARS-CoV-2, focusing on non-severe cases and anti-spike (S) Ab responses in particular, the latter being central to protective immunity induced by infection or vaccination. The emergence of viral variants that have acquired mutations in S acutely highlights the need for continued characterization of both emerging variants and Ab responses against these during the evolving pathogen-immune system arms race.

Aging, Bone Marrow and Next-Generation Sequencing (NGS): Recent Advances and Future Perspectives

The aging of bone marrow (BM) remains a very imperative and alluring subject, with an ever-increasing interest among fellow scientists. A considerable amount of progress has been made in this field with the established ‘hallmarks of aging’ and continued efforts to investigate the age-related changes observed within the BM. Inflammaging is considered as a low-grade state of inflammation associated with aging, and whilst the possible mechanisms by which aging occurs are now largely understood, the processes leading to the underlying changes within aged BM remain elusive. The ability to identify these changes and detect such alterations at the genetic level are key to broadening the knowledgebase of aging BM. Next-generation sequencing (NGS) is an important molecular-level application presenting the ability to not only determine genomic base changes but provide transcriptional profiling (RNA-seq), as well as a high-throughput analysis of DNA–protein interactions (ChIP-seq). Utilising NGS to explore the genetic alterations occurring over the aging process within alterative cell types facilitates the comprehension of the molecular and cellular changes influencing the dynamics of aging BM. Thus, this review prospects the current landscape of BM aging and explores how NGS technology is currently being applied within this ever-expanding field of research.

Aging weakens Th17 cell pathogenicity and ameliorates experimental autoimmune uveitis in mice

Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure. Lymph nodes, which filter the lymph to identify and fight infections, play a central role in this process. However, careful characterization of the impact of aging on lymph nodes and associated autoimmune diseases is lacking. We combined single-cell RNA sequencing (scRNA-seq) with flow cytometry to delineate the immune cell atlas of cervical draining lymph nodes (CDLNs) of both young and old mice with or without experimental autoimmune uveitis (EAU). We found extensive and complicated changes in the cellular constituents of CDLNs during aging. When confronted with autoimmune challenges, old mice developed milder EAU compared to young mice. Within this EAU process, we highlighted that the pathogenicity of T helper 17 cells (Th17) was dampened, as shown by reduced GM-CSF secretion in old mice. The mitigated secretion of GM-CSF contributed to alleviation of IL-23 secretion by antigen-presenting cells (APCs) and may, in turn, weaken APCs’ effects on facilitating the pathogenicity of Th17 cells. Meanwhile, our study further unveiled that aging downregulated GM-CSF secretion through reducing both the transcript and protein levels of IL-23R in Th17 cells from CDLNs. Overall, aging altered immune cell responses, especially through toning down Th17 cells, counteracting EAU challenge in old mice.

Implications of Inflammatory States on Dysfunctional Immune Responses in Aging and Obesity

Aging and obesity are two conditions characterized by chronic, low-grade inflammation. While both conditions are also associated with dysfunctional immune responses, the shared and distinct underlying mechanisms are just starting to be uncovered. In fact, recent findings have suggested that the effects of obesity on the immune system can be thought of as a state of accelerated aging. Here we propose that chronic, low-grade inflammation seen in obesity and aging is complex, affects multiple cell types, and results in an altered basal immune state. In aging, part of this altered state is the emergence of regulatory immune populations that lead to further immune dysfunction in an attempt to reduce chronic inflammation. While in obesity, part of the altered state is the effect of expanding adipose tissue on immune cell function. Thus, in this review, we compare, and contrast altered immune states in aging and obesity and discuss their potential contribution to a shared clinical problem- decreased vaccine responsiveness.

Evolution of Human Memory B Cells From Childhood to Old Age

High quality medical assistance and preventive strategies, including pursuing a healthy lifestyle, result in a progressively growing percentage of older people. The population and workforce is aging in all countries of the world. It is widely recognized that older individuals show an increased susceptibility to infections and a reduced response to vaccination suggesting that the aged immune system is less able to react and consequently protect the organism. The SARS-CoV-2 pandemic is dramatically showing us that the organism reacts to novel pathogens in an age-dependent manner. The decline of the immune system observed in aging remains unclear. We aimed to understand the role of B cells. We analyzed peripheral blood from children (4-18 years); young people (23-60 years) and elderly people (65-91 years) by flow cytometry. We also measured antibody secretion by ELISA following a T-independent stimulation. Here we show that the elderly have a significant reduction of CD27dull memory B cells, a population that bridges innate and adaptive immune functions. In older people, memory B cells are mostly high specialized antigen-selected CD27bright. Moreover, after in vitro stimulation with CpG, B cells from older individuals produced significantly fewer IgM and IgA antibodies compared to younger individuals. Aging is a complex process characterized by a functional decline in multiple physiological systems. The immune system of older people is well equipped to react to often encountered antigens but has a low ability to respond to new pathogens.

Variation of B cell subsets with age in healthy Malawians

Although a number of previous studies have shown that different lymphocyte subsets, including B cells, vary with age, how different B cell subsets vary with age in Malawian population has not been shown before. We recruited Malawian participants of different ages and analyzed their venous blood samples for different B cell subsets. We found that both percentage and absolute counts of B cells varied with age peaking in the 7 to 12 months age group. Proportion of naïve B cells was highest in neonates and decreased with age whereas the percentage of memory B cells was lowest in neonates and increased with age. When we zeroed in on the age band within which the proportion of B cells was highest, both classical and activated memory B cells increased with age and the naïve followed the opposite trend. These results provide additional knowledge in our understanding of the dynamics of B cell subsets in individuals of a specific ethnicity as they age.

Assessment of potential risk factors for coronavirus disease-19 (COVID-19) among health care workers

Background

Understanding COVID-19 infection among health workers and the risk factors for adverse outcomes is important not only for characterizing virus transmission patterns and risk factors for infection, but also for preventing the future infection of health workers and other patients and reducing secondary COVID-19 transmission within health care settings. Our aim was to identify risk factors for infection among health care workers to limit adverse events in health care facilities.

Subjects and Methods

A total of 336 HCWs from COVID-19 treatment hospitals took part in the study with varying COVID-19 exposure risk depending on job function and working site. All participants were asked about risk factors for COVID-19 infection.

Results

Among our participants, 42.6% were medical doctors, 28.6% nurses and 7.4% assistant nurses and 21.4% were others. Forty four percent of participants had work experience 5–10 years. More than half of participants received training in Infection Prevention and Control (IPC) (56.8%) about COVID 19; 91% have hand hygiene facilities and 69% admitted availability of PPE. More than half of participants admitted that they always follow IPC measures. Two thirds of participants (66.7%) had close contact with a patient since admission; 42.3% were present in aerosolizing procedures for patients. Forty two percent of participants had respiratory symptom; the most common was sore throat representing (32.4%). The highest frequency of respiratory symptoms was among of nurses and assistant nurses 51%. Frequency of respiratory symptoms was higher among those who contacted the patient directly or for prolonged period compared to those who do not admitted these contacts.

Conclusions

Risk factors for COVID-19 represented by those who were smokers, nurses and assistant nurses were more liable to catch COVID-19 than doctors as they contacted the patient directly for prolonged period or his/her body fluids, materials or surfaces around him.

Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease.

METHODS

In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation.

RESULTS

cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses.

CONCLUSIONS

Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.

Vaccine-induced ICOS+CD38+ circulating Tfh are sensitive biosensors of age-related changes in inflammatory pathways

Humoral immune responses are dysregulated with aging, but the cellular and molecular pathways involved remain incompletely understood. In particular, little is known about the effects of aging on T follicular helper (Tfh) CD4 cells, the key cells that provide help to B cells for effective humoral immunity. We performed transcriptional profiling and cellular analysis on circulating Tfh before and after influenza vaccination in young and elderly adults. First, whole-blood transcriptional profiling shows that ICOS⁺CD38⁺ cTfh following vaccination preferentially enriches in gene sets associated with youth versus aging compared to other circulating T cell types. Second, vaccine-induced ICOS⁺CD38⁺ cTfh from the elderly had increased the expression of genes associated with inflammation, including tumor necrosis factor-nuclear factor κB (TNF-NF-κB) pathway activation. Finally, vaccine-induced ICOS⁺CD38⁺ cTfh display strong enrichment for signatures of underlying age-associated biological changes. These data highlight the ability to use vaccine-induced cTfh as cellular “biosensors” of underlying inflammatory and/or overall immune health.

Vaccine-induced ICOS⁺CD38⁺ cTfh show increased TNF-NF-κB signaling with aging

TNF-NF-κB signaling is beneficial for cTfh survival in the elderly

Vaccine-induced cTfh are sensors of background changes in immune environment

A Point-of-Care Serum Lactate Level and Mortality in Adult Sepsis Patients: A Community Hospital Setting

Introduction:

Sepsis is a serious and emergency condition that may lead to acute circulatory failure associated with infection. Serum lactate level of over 4 mmol/L is associated with sepsis mortality. However, there is limited data on using a point of care (POC) for fingertip lactate level on sepsis mortality in community hospital setting. This study aimed to evaluate roles of POC for serum lactate with combination of clinical factors on mortality prediction in sepsis patients.

Methods:

This was a retrospective cohort study conducted at 7 community hospitals. The inclusion criteria were adult patients with diagnosis of sepsis who were tested for POC lactate level. Electronic chart reviews of eligible patients were performed. Predictors for mortality were computed using clinical factors and POC lactate level.

Results:

There were 1641 patients met the study criteria. The mortality rate was 8.96% (147 patients). There were 3 independent factors associated with mortality: age, co-morbid diseases, and POC lactate level. The adjusted odds ratio (95% CI) of POC lactate level was 1.025 (1.002, 1.048). The cut point of serum lactate was 1.6 mmol/L gave sensitivity of 79.59% and specificity of 32.10%.

Conclusion:

POC serum lactate level may be associated with mortality in sepsis patients at community hospitals. Lactate level of 1.6 mmol/L may be an indicator for mortality with good sensitivity. Physicians may consider more aggressive and prompt management in individuals with sepsis and POC serum lactate of 1.6 mmol/L or over.

Leukocyte transcriptome indicators of development of infection in kidney transplant recipients

After kidney transplantation, infection and death are important clinical complications, especially for the growing numbers of older patients with limited resilience to withstand adverse events. Evaluation of changes in gene expression in immune cells can reveal the underlying mechanisms behind vulnerability to infection. A cohort of 60 kidney transplant recipients was evaluated. Gene expression in peripheral blood mononuclear cells 3 months after kidney transplantation was analyzed to compare differences between patients with infection and those who were infection-free in the first-year post-transplant. Pro-inflammatory genes such as IL1B, CCL4, and TNF were found to be downregulated in post-transplant PBMC from patients who developed infection. In contrast, genes involved in metabolism, HLA genes, and transcripts involved in type I interferon innate antiviral responses were found to be upregulated. Promoter-based bioinformatic analyses implicated increased activity of interferon regulatory factors, erythroid nuclear factor (E2), and CCAAT-enhancer-binding protein (C/EBP) in patients who developed infections. Differential patterns of gene expression were observed in patients who developed infection after kidney transplantation, with patterns distinct from changes associated with patient age, suggesting possible mechanisms behind vulnerability to infection. Assessment of gene expression in blood may offer an approach for patient risk stratification and monitoring after transplantation.

Risk assessment and seroprevalence of SARS-CoV-2 infection in healthcare workers of COVID-19 and non-COVID-19 hospitals in Southern Switzerland

BACKGROUND

Hospital healthcare workers (HCW), in particular those involved in the clinical care of COVID-19 cases, are presumably exposed to a higher risk of acquiring the disease than the general population.

METHODS

Between April 16 and 30, 2020 we conducted a prospective, SARS-CoV-2 seroprevalence study in HCWs in Southern Switzerland. Participants were hospital personnel with varying COVID-19 exposure risk depending on job function and working site. They provided personal information (including age, sex, occupation, and medical history) and self-reported COVID-19 symptoms. Odds ratio (OR) of seropositivity to IgG antibodies was estimated by univariate and multivariate logistic regressions.

FINDINGS

Among 4726 participants, IgG antibodies to SARS-CoV-2 were detected in 9.6% of the HCWs. Seropositivity was higher among HCWs working on COVID-19 wards (14.1% (11.9-16.5)) compared to other hospital areas at medium (10.7% (7.6-14.6)) or low risk exposure (7.3% (6.4-8.3)). OR for high vs. medium wards risk exposure was 1.42 (0.91-2.22), P = 0.119, and 1.98 (1.55-2.53), P<0.001 for high vs. low wards risk exposure. The same was for true for doctors and nurses (10.1% (9.0-11.3)) compared to other employees at medium (7.1% (4.8-10.0)) or low risk exposure (6.6% (5.0-8.4)). OR for high vs. medium profession risk exposure was 1.37 (0.89-2.11), P = 0.149, and 1.75 (1.28-2.40), P = 0.001 for high vs. low profession risk exposure. Moreover, seropositivity was higher among HCWs who had household exposure to COVID-19 cases compared to those without (18.7% (15.3-22.5) vs. 7.7% (6.9-8.6), OR 2.80 (2.14-3.67), P<0.001).

INTERPRETATION

SARS-CoV-2 antibodies are detectable in up to 10% of HCWs from acute care hospitals in a region with high incidence of COVID-19 in the weeks preceding the study. HCWs with exposure to COVID-19 patients have only a slightly higher absolute risk of seropositivity compared to those without, suggesting that the use of PPE and other measures aiming at reducing nosocomial viral transmission are effective. Household contact with known COVID-19 cases represents the highest risk of seropositivity.

FUNDING

Henry Krenter Foundation, Ente Ospedaliero Cantonale and Vir Biotechnology.

Factors Associated with Lymph Node Count in Mucosal Squamous Cell Carcinoma Neck Dissection

OBJECTIVE/HYPOTHESIS

Decreased lymph node count (LNC) from neck dissection (ND) for mucosal head and neck squamous cell carcinoma (HNSCC) patients is correlated with decreased survival. Advanced age and low BMI due to undernutrition from dysphagia from advanced T-stage tumors are common in patients with HNSCC. We studied the relationship between these two well-described causes for immune dysfunction and LNC in patients undergoing neck dissection.

STUDY DESIGN

We conducted a retrospective review at a single tertiary care institution of patients with HNSCC that underwent neck dissection from 2006 to 2017.

METHODS

Stepwise linear and logistic regression analyses were performed on 247 subjects to identify independent significant factors associated with 1) the LNC per neck level dissected; 2) advanced T-stage. One-way ANOVA was utilized to demonstrate differences between the p16 positive and negative subgroups.

RESULTS

Low BMI (<23 vs. ≥23) (P = .03), extra nodal extension (ENE) (P = .0178), and advanced age (P = .005) were associated with decreased LNC per neck level dissected on multivariable analysis. Higher T-stage (P = .0005) was correlated with low BMI (<23) after controlling for the effects of tobacco, smoking, sex, ECE, and p16 status. p16+ patients, on average had higher BMI, were younger and produced a higher nodal yield (P < .0001, .007, and .035).

CONCLUSIONS

Patient intrinsic factors known to correlate with decreased immune function and worse outcomes, including p16 negative status, advanced age, and low BMI from undernutrition and ENE are associated with low nodal yield in neck dissections. LNC may be a metric for anti-tumor immune function that correlates with prognosis and T-stage.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1516-1521, 2021.

Association between periodontal bacteria and degenerative aortic stenosis: a pilot study

Purpose

Although several reports have described the relationship between periodontal disease and cardiovascular disease, information about the association between periodontal disease and the progression of degenerative aortic stenosis (AS) is lacking. Therefore, we performed a retrospective, single-center, pilot study to provide insight into this potential association.

Methods

Data from 45 consecutive patients (19 men; median age, 83 years) with mild or moderate degenerative aortic stenosis were analyzed for a mean observation period of 3.3±1.9 years. The total amount of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and titers of serum immunoglobulin G (IgG) against periodontal bacteria and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Aortic valve area (AVA), maximal velocity (Vmax), mean pressure gradient (mean PG), and the Doppler velocity index (DVI) were evaluated. The change in each parameter per year ([Parameter_LATEST–Parameter_BASELINE]/Follow-up Years) was calculated from the retrospective follow-up echocardiographic data (baseline vs. the most recently collected data [latest]).

Results

No correlation was found between the concentration of periodontopathic bacteria in the saliva and AS status/progression. The anti-P. gingivalis antibody titer in the serum showed a significant positive correlation with AVA and DVI. Additionally, there was a negative correlation between the anti-P. gingivalis IgG antibody titer and mean PG. The hs-CRP concentration showed positive correlations with Vmax and mean PG. Meanwhile, a negative correlation was observed between the anti-P. gingivalis IgG antibody titer and ΔAVA/year and Δmean PG/year. The hs-CRP concentration showed positive correlations with Vmax and mean PG, and it was significantly higher in patients with rapid aortic stenosis progression (ΔAVA/year <−0.1) than in their counterparts.

Conclusions

Our results suggest that periodontopathic bacteria such as A. actinomycetemcomitans and P. gingivalis are not directly related to the status/progression of degenerative AS. However, inflammation and a lower immune response may be associated with disease progression.

Age-related susceptibility to coronavirus infections: role of impaired and dysregulated host immunity

Human coronaviruses (hCoVs) cause severe respiratory illness in the elderly. Age-related impairments in innate immunity and suboptimal virus-specific T cell and antibody responses are believed to cause severe disease upon respiratory virus infections. This phenomenon has recently received increased attention, as elderly patients are at substantially elevated risk for severe COVID-19 disease and experience increased rates of mortality following SARS-CoV-2 infection compared with younger populations. However, the basis for age-related fatal pneumonia following pathogenic hCoVs is not well understood. In this Review, we provide an overview of our current understanding of hCoV-induced fatal pneumonia in the elderly. We describe host immune response to hCoV infections derived from studies of young and aged animal models and discuss the potential role of age-associated increases in sterile inflammation (inflammaging) and virus-induced dysregulated inflammation in causing age-related severe disease. We also highlight the existing gaps in our knowledge about virus replication and host immune responses to hCoV infection in young and aged individuals.

Lysophosphatidic acid receptors 2 and 3 regulate erythropoiesis at different hematopoietic stages

Hematopoiesis, the complex developmental process that forms blood components and replenishes the blood system, involves multiple intracellular and extracellular mechanisms. We previously demonstrated that lysophosphatidic acid (LPA), a lipid growth factor, has opposing regulatory effects on erythrocyte differentiation through activation of LPA receptors 2 and 3; yet the mechanisms underlying this process remain unclear. In this study, LPA₂ is observed that highly expressed in common myeloid progenitors (CMP) in murine myeloid cells, whereas the expression of LPA₃ displaces in megakaryocyte-erythroid progenitors (MEP) of later stage of myeloid differentiation. Therefore, we hypothesized that the switching expression of LPA₂ and LPA₃ determine the hematic homeostasis of mammalian megakaryocytic-erythroid lineage. In vitro colony-forming unit assays of murine progenitors reveal that LPA₂ agonist GRI reduces the erythroblast differentiation potential of CMP. In contrast, LPA₃ agonist OMPT increases the production of erythrocytes from megakaryocyte-erythrocyte progenitor cells (MEP). In addition, treatment with GRI reduces the erythroid, CMP, and MEP populations in mice, indicating that LPA₂ predominantly inhibits myeloid differentiation at an early stage. In contrast, activation of LPA₃ increases the production of terminally differentiated erythroid cells through activation of erythropoietic transcriptional factor. We also demonstrate that the LPA₃ signaling is essential for restoration of phenylhydrazine (PHZ)-induced acute hemolytic anemia in mice and correlates to erythropoiesis impairment of Hutchinson-Gilford progeria Symptom (HGPS) premature aging expressed K562 model. Our results reveal the distinct roles of LPA₂ and LPA₃ at different stages of hematopoiesis in vivo, providing potentiated therapeutic strategies of anemia treatment.

Age-associated changes in the circulating human antibody repertoire are upregulated in autoimmunity

Background

The immune system undergoes a myriad of changes with age. While it is known that antibody-secreting plasma and long-lived memory B cells change with age, it remains unclear how the binding profile of the circulating antibody repertoire is impacted.

Results

To understand humoral immunity changes with respect to age, we characterized serum antibody binding to high density peptide microarrays in a diverse cohort of 1675 donors. We discovered thousands of peptides that bind antibodies in age-dependent fashion, many of which contain di-serine motifs. Peptide binding profiles were aggregated into an “immune age” by a machine learning regression model that was highly correlated with chronological age. Applying this regression model to previously-unobserved donors, we found that a donor’s predicted immune age is longitudinally consistent over years, suggesting it could be a robust long-term biomarker of humoral immune ageing. Finally, we assayed serum from donors with autoimmune disease and found a significant association between “accelerated immune ageing” and autoimmune disease activity.

Conclusions

The circulating antibody repertoire has increased binding to thousands of di-serine peptide containing peptides in older donors, which can be represented as an immune age. Increased immune age is associated with autoimmune disease, acute inflammatory disease severity, and may be a broadly relevant biomarker of immune function in health, disease, and therapeutic intervention.

Remodeling of the Immune Response With Aging: Immunosenescence and Its Potential Impact on COVID-19 Immune Response

Elderly individuals are the most susceptible to an aggressive form of coronavirus disease (COVID-19), caused by SARS-CoV-2. The remodeling of immune response that is observed among the elderly could explain, at least in part, the age gradient in lethality of COVID-19. In this review, we will discuss the phenomenon of immunosenescence, which entails changes that occur in both innate and adaptive immunity with aging. Furthermore, we will discuss inflamm-aging, a low-grade inflammatory state triggered by continuous antigenic stimulation, which may ultimately increase all-cause mortality. In general, the elderly are less capable of responding to neo-antigens, because of lower naïve T cell frequency. Furthermore, they have an expansion of memory T cells with a shrinkage of the T cell diversity repertoire. When infected by SARS-CoV-2, young people present with a milder disease as they frequently clear the virus through an efficient adaptive immune response. Indeed, antibody-secreting cells and follicular helper T cells are thought to be effectively activated in young patients that present a favorable prognosis. In contrast, the elderly are more prone to an uncontrolled activation of innate immune response that leads to cytokine release syndrome and tissue damage. The failure to trigger an effective adaptive immune response in combination with a higher pro-inflammatory tonus may explain why the elderly do not appropriately control viral replication and the potential clinical consequences triggered by a cytokine storm, endothelial injury, and disseminated organ injury. Enhancing the efficacy of the adaptive immune response may be an important issue both for infection resolution as well as for the appropriate generation of immunity upon vaccination, while inhibiting inflamm-aging will likely emerge as a potential complementary therapeutic approach in the management of patients with severe COVID-19.

Should we Try to Alleviate Immunosenescence and Inflammaging - Why, How and to What Extent?

With advancing age, immune responses of human beings to external pathogens, i.e., bacteria, viruses, fungi and parasites, and to internal pathogens - malignant neoplasm cells - become less effective. Two major features in the process of aging of the human immune system are immunosenescence and inflammaging. The immune systems of our predecessors co-evolved with pathogens, which led to the occurrence of effective immunity. However, the otherwise beneficial activity may pose problems to the organism of the host and so it has builtin brakes (regulatory immune cells) and - with age - it undergoes adaptations and modifications, examples of which are the mentioned inflammaging and immunosenescence. Here we describe the mechanisms that first created our immune systems, then the consequences of their changes associated with aging, and the mechanisms of inflammaging and immunosenescence. Finally, we discuss to what extent both processes are detrimental and to what extent they might be beneficial and propose some therapeutic approaches for their wise control.

Age-related changes in B cell metabolism

Antibody responses to vaccinations or infections decline upon aging. In this study we tested if metabolic changes in B cells may contribute to attenuation of responses to influenza vaccination in aged humans. Our data show that aging affects mitochondrial functions in B cells leading to increases in mitochondrial reactive oxygen species (MROS) and mitochondrial mass (MM) in some aged B cell subsets and decreases in expression levels of Sirtuin 1 (SIRT1), Forkhead box protein (FOX)O1 and carnitine palmitoyltransferase 1 (CPT-1). Seahorse analyses showed minor defects in glycolysis in the aged B cells after activation but a strong reduction in oxidative phosphorylation. The analyses of the transcriptome revealed further pronounced defects in one-carbon metabolism, a pathway that is essential for amino acid and nucleotide metabolism. Overall our data support the notion that the declining ability of aged B cells to increase their metabolism following activation contributes to the weakened antibody responses of the elderly.

Age and Periodontal Health - Immunological View

PURPOSE OF THE REVIEW

Aging clearly impacts a wide array of systems, in particular the breadth of the immune system leading to immunosenescence, altered immunoactivation, and coincident inflammaging processes. The net result of these changes leads to increased susceptibility to infections, increased neoplastic occurrences, and elevated frequency of autoimmune diseases with aging. However, as the bacteria in the oral microbiome that contribute to the chronic infection of periodontitis is acquired earlier in life, the characteristics of the innate and adaptive immune systems to regulate these members of the autochthonous microbiota across the lifespan remains ill defined.

RECENT FINDINGS

Clear data demonstrate that both cells and molecules of the innate and adaptive immune response are adversely impacted by aging, including in the oral cavity, yielding a reasonable tenet that the increased periodontitis noted in aging populations is reflective of the age-associated immune dysregulation. Additionally, this facet of host-microbe interactions and disease needs to accommodate the population variation in disease onset and progression, which may also reflect an accumulation of environmental stressors and/or decreased protective nutrients that could function at the gene level (ie. epigenetic) or translational level for production and secretion of immune system molecules.

SUMMARY

Finally, the majority of studies of aging and periodontitis have emphasized the increased prevalence/severity of disease with aging, all based upon chronological age. However, evolving areas of study focusing on "biological aging" to help account for population variation in disease expression, may suggest that chronic periodontitis represents a co-morbidity that contributes to "gerovulnerability" within the population.

Age-related changes in the levels and kinetics of pulmonary cytokine and chemokine responses to Streptococcuspneumoniae in mouse pneumonia models

Streptococcuspneumoniae is a major human pathogen at the extremes of age. The elderly are particularly vulnerable to S.pneumoniae, the most common causative agent of bacterial pneumonia in this population. Despite the availability of vaccines and antibiotics, mortality rates associated with pneumococcal pneumonia in this age group remain high. In light of globally increasing life-expectancy, a better understanding of the patho-mechanisms of elderly pneumococcal pneumonia, including alterations in innate immune responses, is needed to develop improved therapies. In this study we aimed at investigating how increased susceptibility to pneumococcal infection relates to inflammation kinetics in the aged mouse pneumonia model by determining pulmonary cytokine and chemokine levels and comparing these parameters to those measured in young adult mice. Firstly, we detected overall higher pulmonary cytokine and chemokine levels in aged mice. However, upon induction of pneumococcal pneumonia in aged mice, delayed production of certain analytes, such as IFN-γ, MIG (CXCL9), IP-10 (CXCL10), MCP-1 (CCL2), TARC (CCL17) and MDC (CCL22) became apparent. In addition, aged mice were unable to control excess inflammatory responses: while young mice showed peak inflammatory responses at 20 h and subsequent resolution by 48 h post intranasal challenge, in aged mice increasing cytokine and chemokine levels were measured. These findings highlight the importance of considering multiple time points when delineating inflammatory responses to S.pneumoniae in an age-related context. Finally, correlation between pulmonary bacterial burden and cytokine or chemokine levels in young mice suggested that appropriately controlled inflammatory responses support the host to fight pneumococcal infection.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND

Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production.

METHODS

We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-γ of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry.

RESULTS

We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion.

CONCLUSIONS

These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity.

Cytokine production in whole-blood cultures following immunization with an influenza vaccine

A clinical trial of a quadrivalent split influenza vaccine was performed in the 2014/15 season. Sixty-four subjects aged 6 months to 18 years were enrolled in order to investigate the relationship between cellular and humoral immune responses. Subjects were categorized into two groups by measuring neutralizing antibodies: non-primed naïve/primed or seroconverted/non-seroconverted groups. Whole-blood cultures were stimulated with the H1N1 split antigen before immunization and one month after the first and second immunizations for subjects < 13 years and before and one month after the first dose for those ≥ 13 years in order to investigate cytokine production. Significant amounts of IL-2, IL-12, IL-13, MCP-1, MIP-1β, and TNF-α were detected from one month after the first dose in the naïve group. In addition to these cytokines, the production of IL-1β, IL-4, IL-6, IL-8, IL-10, IL-17, G-CSF, and IFN-γ was enhanced one month after the second dose. No significant increase was noted in the primed group, except in the production of IL-10. In seroconverted subjects, the production of IL-2, IL-4, IL-8, IL-10, G-CSF, MCP-1, TNF-α, and IFN-γ increased one month after the first dose, which was earlier than in the naïve group, whereas no significant cytokine response was noted in subjects without seroconversion. Subjects ≥ 13 years were primed and the production of G-CSF, IL-4, and IL-1β increased in subjects with seroconversion. Whole-blood cultures were also stimulated with the H3N2 split antigen and similar cytokine profiles were obtained. Many cytokines and chemokines, including inflammatory cytokines, were produced in seroconverted, but not non-seroconverted subjects.

Clonal Hematopoiesis in Aging

Purpose of Review

Clonal hematopoiesis of indeterminate potential (CHIP) is a common, age-associated condition characterized by the acquisition of somatic mutations. This concise review explores our current understanding of the mechanisms that influence the development of clonality with aging and its potential malignant and non-malignant clinical implications.

Recent Findings

Aging of the hematopoietic system results in phenotypic changes that favor clonal dominance. Cell-extrinsic factors provide additional selective pressures that further shape clonal architecture. Even so, small clones with candidate driver mutations appear to be ubiquitous with age and largely benign in the absence of strong selective pressures. Benign clonal expansion may compensate for the loss of regenerative HSC capacity as we age.

Summary

CHIP is a marker of aging that reflects the biologic interplay between HSC aging and cell-extrinsic factors. The clinical significance of CHIP is highly variable and dependent on clinical context. Distinguishing the causal relationships and confounding factors that regulate clonal behavior will be essential to define the mechanistic role of CHIP in aging and potentially mitigate its clinical consequences.

Race-related differences in antibody responses to the inactivated influenza vaccine are linked to distinct pre-vaccination gene expression profiles in blood

We conducted a 5-year study analyzing antibody and B cell responses to the influenza A virus components of the inactivated influenza vaccine, trivalent (IIV3) or quadrivalent (IIV4) in younger (aged 35-45) and aged (≥65 years of age) Caucasian and African American individuals. Antibody titers to the two influenza A virus strains, distribution of circulating B cell subsets and the blood transcriptome were tested at baseline and after vaccination while expression of immunoregulatory markers on B cells were analyzed at baseline. African Americans mounted higher virus neutralizing and IgG antibody responses to the H1N1 component of IIV3 or 4 compared to Caucasians. African Americans had higher levels of circulating B cell subsets compared to Caucasians. Expression of two co-regulators, i.e., programmed death (PD)-1 and the B and T cell attenuator (BTLA) were differentially expressed in the two cohorts. Race-related differences were caused by samples from younger African Americans, while results obtained with samples of aged African Americans were similar to those of aged Caucasians. Gene expression profiling by Illumina arrays revealed highly significant differences in 1368 probes at baseline between Caucasians and African Americans although samples from both cohorts showed comparable changes in transcriptome following vaccination. Genes differently expressed between samples from African Americans and Caucasians regardless of age were enriched for myeloid genes, while the transcripts that differed in expression between younger African Americans and younger Caucasians were enriched for those specific for B-cells.

Long-term administration of pDC-Stimulative Lactococcus lactis strain decelerates senescence and prolongs the lifespan of mice

The decline in immune function caused by aging increases the risk of infectious diseases, tumorigeneses and chronic inflammation, resulting in accelerating senescence. We previously reported a lactic acid bacteria, Lactococcus lactis strain Plasma (synonym of Lactococcus lactis subsp. lactis JCM 5805, Lc-Plasma), that stimulates plasmacytoid dendritic cells (pDCs), which play a crucial role in phylaxis from viral infection. In this study, we investigated the anti-aging effects of long-term oral administration of Lc-Plasma in a senescence-accelerated mouse strain, SAMP6. Mice given Lc-Plasma showed a significant improvement in survival rate at 82 weeks and a decreased senescence score as compared with control mice throughout this study. Anatomic analysis at 82 weeks revealed that the frequency of altered hepatocellular foci was significantly lower, and the incidence of other pathological findings in the liver and lungs tended to be lower in Lc-Plasma mice than in control mice. Transcription level of the IL-1β gene in lungs also tended to be lower in Lc-Plasma mice. Furthermore, the thinning of skin and age-related decrease in muscle mass were also significantly suppressed in the Lc-Plasma group as compared with the control group. Consistent with these phenotypic features, pDCs activity was significantly higher in Lc-Plasma mice than in control mice. In conclusion, long-term administration of Lc-Plasma can decelerate senescence and prolong lifespan via maintenance of the immune system due to activation of pDCs.

Impact of pre-existing immunity on the induction of functional cross-reactive anti-hemagglutinin stalk antibodies following vaccination with an AS03 adjuvanted pandemic H1N1 vaccine

The 2009 pandemic H1N1 (A(H1N1)pdm09) virus had a highly divergent hemagglutinin (HA) compared to pre-2009 seasonal H1N1 strains. Most peoples were immunologically naïve to the A(H1N1)pdm09, although hospital workers were exposed early in the pandemic before pandemic vaccines became available. Here, we evaluated how pre-existing antibodies influence the induction of cross-functional HA stalk antibodies following A(H1N1)pdm09 vaccination. Fifty-six healthcare workers vaccinated with AS03 adjuvanted A(H1N1)pdm09 vaccine were chosen by their pre-vaccination priming status (primed HI titers ≥ 40 or unprimed < 40). We analyzed the HA head- and stalk-specific serum IgG subclasses at pre- and 21 days post-vaccination. We also assessed the functionality of the HA stalk-specific antibodies to neutralize virus and mediate antibody dependent cellular cytotoxicity (ADCC). Primed individuals had higher pre-existing HA head- and stalk-specific IgG1, as well as higher ADCC functionality of stalk antibodies. However, following vaccination with the adjuvanted pandemic vaccine, only the quantity of HA head specific IgG1 antibodies were significantly higher than in unprimed individuals. The priming status did not impact upon the cross-reactive HA stalk specific IgG antibodies or their ability to neutralize virus or induce ADCC post-vaccination. In conclusion, a single dose of AS03 adjuvanted pandemic vaccine elicited similar levels of functional antibodies in naïve and primed individuals. These findings are important for understanding the immunological factors that impact or modulate pandemic vaccine responses in humans.

Immunosenescence: the Role of Aging in the Predisposition to Neuro-Infectious Complications Arising from the Treatment of Multiple Sclerosis

PURPOSE OF REVIEW

This review highlights some of the important changes in the immune system that occur in the process of normal aging. Immunosenescence as a concept is directly relevant to the world of neuro-inflammation, as it may be a contributing factor to the risks associated with some of the current immunosuppressive and immunomodulatory therapies used in treating multiple sclerosis (MS) and other inflammatory disorders.

RECENT FINDINGS

Profound qualitative and quantitative changes occur in the adaptive and innate immunity compartments during aging. These changes may explain why patients of older age are at an increased risk of infections and infection-associated mortality. Immunosenescence-associated changes may be additive or synergistic with the effects produced by immunomodulatory and immunosuppressive medications. Clinicians should exercise a high level of vigilance in monitoring the risk of infections in older patients on these treatments.

Reduced Immunocompetent B Cells and Increased Secondary Infection in Elderly Patients With Severe Sepsis

Lymphocyte exhaustion was recently recognized as a mechanism of immunosuppression in sepsis. While B cells are known to play pivotal roles in bacterial infection and sepsis, changes in B-cell-mediated humoral immunity have not been evaluated in critically ill septic patients. We aimed to investigate changes in humoral immunity caused by defective B-cell function during severe sepsis. Thirty-three severe sepsis patients and 44 healthy subjects were prospectively enrolled. Blood was collected from patients within 72 h of and 8 to 11 h after sepsis onset to measure B-cell subtypes, serum immunoglobulin M concentration, and CpG-B oligodeoxynucleotide-induced immunoglobulin M (IgM) production ex vivo. Participants were divided into two age groups: adults (18-64 years) and elderly (≥65 years). The fraction of CD21 exhausted B cells in acute sepsis patients (3.18%) was higher than that observed in healthy donors (0.77%, respectively, P <0.01). Significantly, serum IgM in elderly septic patients (≥65 years) was negatively correlated with acute physiology and chronic health evaluation II score (r = -0.57, P <0.05). Consistently, in B cells stimulated ex vivo, both aging and sepsis induced significant reductions in supernatant IgM (P <0.01). This finding was clinically relevant, as elderly patients with decreased IgM production might be more susceptible to infection by Gram-negative bacteria and fungi. Reduced immunocompetent B cells may be related to increased secondary infection after sepsis, especially in the elderly. Finally, impaired humoral immunity with increased CD21 exhausted B cells and insufficient immunoglobulin M production may be a critical immunological change in sepsis.