Aging of the human innate immune system in HIV infection

Dectin-1 stimulation promotes a distinct inflammatory signature in the setting of HIV-infection and aging

Dectin-1 is an innate immune receptor that recognizes and binds β-1, 3/1, 6 glucans on fungi. We evaluated Dectin-1 function in myeloid cells in a cohort of HIV-positive and HIV-negative young and older adults. Stimulation of monocytes with β-D-glucans induced a pro-inflammatory phenotype in monocytes of HIV-infected individuals that was characterized by increased levels of IL-12, TNF-α, and IL-6, with some age-associated cytokine increases also noted. Dendritic cells showed a striking HIV-associated increase in IFN-α production. These increases in cytokine production paralleled increases in Dectin-1 surface expression in both monocytes and dendritic cells that were noted with both HIV and aging. Differential gene expression analysis showed that HIV-positive older adults had a distinct gene signature compared to other cohorts characterized by a robust TNF-α and coagulation response (increased at baseline), a persistent IFN-α and IFN-γ response, and an activated dendritic cell signature/M1 macrophage signature upon Dectin-1 stimulation. Dectin-1 stimulation induced a strong upregulation of MTORC1 signaling in all cohorts, although increased in the HIV-Older cohort (stimulation and baseline). Overall, our study demonstrates that the HIV Aging population has a distinct immune signature in response to Dectin-1 stimulation. This signature may contribute to the pro-inflammatory environment that is associated with HIV and aging.

Impaired pulmonary function and associated factors in the elderly with tuberculosis on admission: a preliminary report

BACKGROUND

Pulmonary tuberculosis (TB) can impair pulmonary function (PF), especially in the elderly. The risk factors associated with the severity of PF impairment in the elderly with pulmonary TB remain unclear. Hence, this retrospective study aimed to address this issue to help improve the management of TB in the elderly population.

METHODS

From January 2019 to February 2022, the elderly who were admitted to our hospital for pulmonary TB and underwent PF testing were included in this analysis. The forced expiratory volume in one second percent of predicted (FEV1% predicted) and clinical characteristics were collected and analyzed retrospectively. The extent of impaired PF was then categorized based on the FEV1% predicted and classified as grade 1-5. Logistic regression analysis was used to analyze the risk factors for impaired PF.

RESULTS

A total of 249 patients who met the enrollment criteria were included in this analysis. According to the results of FEV1% predicted, all patients were classified as grade 1 (n = 37), grade 2 (n = 46), grade 3 (n = 55), grade 4 (n = 56), or grade 5 (n = 55). Statistical analysis showed that albumin (adjusted odds ratio (aOR) = 0.928, P = 0.013), body mass index (BMI) < 18.5 kg/m² (aOR = 4.968, P = 0.046), lesion number ≥ 3 (aOR = 4.229, P < 0.001), male (aOR = 2.252, P = 0.009), respiratory disease (aOR = 1.669, P = 0.046), and cardiovascular disease (aOR = 2.489, P = 0.027) were related to the impairment of PF.

CONCLUSIONS

PF impairment is common in the elderly with pulmonary TB. The male sex, BMI < 18.5 kg/m², lesion number ≥ 3, hypoproteinemia, and respiratory and cardiovascular comorbidities were identified as risk factors for significant PF impairment. Our findings highlight the risk factors associated with PF impairment, which may be helpful to improve the current management of pulmonary TB in the elderly to save their lung function.

Frailty in older people living with HIV: current status and clinical management

This paper will update care providers on the clinical and scientific aspects of frailty which affects an increasing proportion of older people living with HIV (PLWH). The successful use of combination antiretroviral therapy has improved long-term survival in PLWH. This has increased the proportion of PLWH older than 50 to more than 50% of the HIV population. Concurrently, there has been an increase in the premature development of age-related comorbidities as well as geriatric syndromes, especially frailty, which affects an important minority of older PLWH. As the number of frail older PLWH increases, this will have an important impact on their health care delivery. Frailty negatively affects a PLWH's clinical status, and increases their risk of adverse outcomes, impacting quality of life and health-span. The biologic constructs underlying the development of frailty integrate interrelated pathways which are affected by the process of aging and those factors which accelerate aging. The negative impact of sarcopenia in maintaining musculoskeletal integrity and thereby functional status may represent a bidirectional interaction with frailty in PLWH. Furthermore, there is a growing body of literature that frailty states may be transitional. The recognition and management of related risk factors will help to mitigate the development of frailty. The application of interdisciplinary geriatric management principles to the care of older PLWH allows reliable screening and care practices for frailty. Insight into frailty, increasingly recognized as an important marker of biologic age, will help to understand the diversity of clinical status occurring in PLWH, which therefore represents a fundamentally new and important aspect to be evaluated in their health care.

Glucocorticoid Receptor Function and Cognitive Performance in Women With HIV

OBJECTIVE

Alterations in glucocorticoid receptor (GCR) function may be a risk factor for cognitive complications among older people with human immunodeficiency virus (HIV). We evaluated whether HIV serostatus and age modify the GCR function-cognition association among women.

METHODS

Eighty women with HIV ( n = 40, <40 years of age [younger]; n = 40, >50 years of age [older]) and 80 HIV-uninfected women ( n = 40 older, n = 40 younger) enrolled in the Women's Interagency HIV Study completed a comprehensive neuropsychological test battery. Peripheral blood mononuclear cells collected concurrent with neuropsychological testing were assessed for GCR function. Multivariable linear regression analyses were conducted to examine whether a) HIV serostatus and age were associated with GCR function, and b) GCR function-cognition associations are moderated by HIV serostatus and age adjusting for relevant covariates.

RESULTS

Among older women, higher baseline FKBP5 expression level was associated with lower attention/working memory performance among women with HIV ( B = 6.4, standard error = 1.7, p = .0003) but not in women without HIV infection ( B = -1.7, standard error = 1.9, p = .37). There were no significant HIV serostatus by age interactions on dexamethasone (DEX)-stimulated expression of the genes regulated by the GCR or lipopolysaccharide-stimulated tumor necrosis factor α levels (with or without DEX stimulation; p values > .13). HIV serostatus was associated with GC target genes PER1 ( p = .006) and DUSP1 ( p = .02), but not TSC22D3 ( p = .32), after DEX stimulation.

CONCLUSIONS

Collectively, these data suggest that HIV serostatus and age may modify the influence of the GCR, such that the receptor is likely engaged to a similar extent, but the downstream influence of the receptor is altered, potentially through epigenetic modification of target genes.

Persistent Inflammation and Non-AIDS Comorbidities During ART: Coming of the Age of Monocytes

Monocytes are innate immune cells that serve as the first line of defense against pathogens by engulfing and destroying pathogens or by processing and presenting antigens to initiate adaptive immunity and stimulate immunological responses. Monocytes are classified into three types: classical, intermediate, and non-classical monocytes, each of which plays a particular function in response to pathogens. Human immunodeficiency virus type 1 (HIV-1) infection disrupts the balance of monocyte subsets, and the quantity and function of monocytes will not fully recover even with long-term antiretroviral therapy (ART). Monocytes are vital for the establishment and maintenance of HIV-1 latent viral reservoirs and are closely related to immune dysfunction even after ART. Therefore, the present review focuses on the phenotypic function of monocytes and their functions in HIV-1 infection to elucidate their roles in HIV patients.

Reconstruction and repair, using mini-plate and bone graft for persons living with HIV with giant cell tumor of long bone: retrospective analysis of a single-center experience

Background

To evaluate the effect of reconstruction and repair, using a mini-plate and bone graft for HIV -positive patients with giant cell tumor of long bone.

Methods

We conducted a retrospective analysis of 12 HIV positive patients with giant cell tumor of long bone. A non-HIV-positive cohort of patients, matched for age, sex, and disease type, was selected as the control group. From June 2012 to August 2020, curettage by ultrasonic scalpel was performed in all patients, combined with min- plate and bone graft treatment. All patients were followed- up for 18 to 60 months. Limb function was evaluated, using the MSTS93 scoring system, and any examples of postoperative recurrence, distant metastasis, complications, MSTS93 score, and fracture prognosis were recorded.

Results

The mean age of HIV group was 43.5 years. The ratio of men to women was 11: 1. In all cases the histopathological diagnosis was clear, except the patients with primary malignant giant cell tumor of bone, including five, three, two, and two cases in the proximal tibia, distal femur, distal tibia, and talus, respectively. Following their surgery, all patients were followed up with an average of 31.24 ± 11.84 months. No local recurrence or pulmonary metastases were observed. Post-surgery, all the 12 patients showed good bone morphologic repair and reconstruction, good bone healing, good joint function, and no pathological fractures around their lesion. In the HIV group, one case of giant cell tumor in the proximal tibia showed mild articular surface collapse and mild valgus deformity of the knee joint but retained good joint function. The MSTS scores of excellent or good in the two groups comprised 83.3%, thus, there was no significant difference between them (P > 0.05). Compared with preoperatively, the MSTS scores in the HIV group were significantly improved, ranging from 7 to 11 points preoperatively to 24 to 27 points postoperatively; this difference was statistically significant (P < 0.05).

Conclusion

Reconstruction and repair, using a mini-plate and bone graft for HIV -positive patients with giant cell tumor of long bone can achieve satisfactory results. The mini- plate requires little space and is flexible during reconstruction and fixation, significantly reducing complications such as surgical site infection, as well as preserving joint function and avoiding amputation; therefore, it is a safe and effective treatment method.

Implications of Innate Immunity in Post-Acute Sequelae of Non-Persistent Viral Infections

Non-persistent viruses classically cause transient, acute infections triggering immune responses aimed at the elimination of the pathogen. Successful viruses evolved strategies to manipulate and evade these anti-viral defenses. Symptoms during the acute phase are often linked to dysregulated immune responses that disappear once the patient recovers. In some patients, however, symptoms persist or new symptoms emerge beyond the acute phase. Conditions resulting from previous transient infection are termed post-acute sequelae (PAS) and were reported for a wide range of non-persistent viruses such as rota-, influenza- or polioviruses. Here we provide an overview of non-persistent viral pathogens reported to be associated with diverse PAS, among them chronic fatigue, auto-immune disorders, or neurological complications and highlight known mechanistic details. Recently, the emergence of post-acute sequelae of COVID-19 (PASC) or long COVID highlighted the impact of PAS. Notably, PAS of non-persistent infections often resemble symptoms of persistent viral infections, defined by chronic inflammation. Inflammation maintained after the acute phase may be a key driver of PAS of non-persistent viruses. Therefore, we explore current insights into aberrant activation of innate immune signaling pathways in the post-acute phase of non-persistent viruses. Finally, conclusions are drawn and future perspectives for treatment and prevention of PAS are discussed.

Inflammation and kidney involvement in human viral diseases caused by SARS-CoV-2, HIV, HCV and HBV

Inflammation is closely related to renal diseases. This is particularly true for renal diseases caused by infections as in viral diseases. In this review, we highlight the inflammatory mechanisms that underlie kidney dysfunction in SARS-CoV-2, human immunodeficiency (HIV), hepatitis C (HCV), and hepatitis B (HBV) infections. The pathophysiology of renal involvement in COVID-19 is complex, but kidney damage is frequent, and the prognosis is worse when it happens. Virus-like particles were demonstrated mostly in renal tubular epithelial cells and podocytes, which suggest that SARS-CoV-2 directly affects the kidneys. SARS-CoV-2 uses the angiotensin-converting enzyme 2 receptor, which is found in endothelial cells, to infect the human host cells. Critical patients with SARS-CoV-2-associated acute kidney injury (AKI) show an increase in inflammatory cytokines (IL-1β, IL-8, IFN-γ, TNF-α), known as cytokine storm that favors renal dysfunction by causing intrarenal inflammation, increased vascular permeability, volume depletion, thromboembolic events in microvasculature and persistent local inflammation. Besides AKI, SARS-CoV-2 can also cause glomerular disease, as other viral infections such as in HIV, HBV and HCV. HIV-infected patients present chronic inflammation that can lead to a number of renal diseases. Proinflammatory cytokines and TNF-induced apoptosis are some of the underlying mechanisms that may explain the virus-induced renal diseases that are here reviewed.

New Insights into the Immune System Using Dirty Mice

The mouse (Mus musculus) is the dominant organism used to investigate the mechanisms behind complex immunological responses because of their genetic similarity to humans and our ability to manipulate those genetics to understand downstream function. Indeed, our knowledge of immune system development, response to infection, and ways to therapeutically manipulate the immune response to combat disease were, in large part, delineated in the mouse. Despite the power of mouse-based immunology research, the translational efficacy of many new therapies from mouse to human is far from ideal. Recent data have highlighted how the naive, neonate-like immune system of specific pathogen-free mice differs dramatically in composition and function to mice living under barrier-free conditions (i.e., "dirty" mice). In this review, we discuss major findings to date and challenges faced when using dirty mice and specific areas of immunology research that may benefit from using animals with robust and varied microbial exposure.

The effect of protease inhibitor-based dual antiretroviral regimens on CD4/CD8 ratio during the first year of therapy in ART-naïve patients with HIV-infection

OBJECTIVES

To assess the effect of protease inhibitor (PI)-based dual therapy on CD4/CD8 ratio during the first year of therapy in antiretroviral therapy (ART)-naïve patients using data from randomized controlled clinical trials.

METHODS

We pooled data from the GARDEL and ANDES studies, both randomized controlled clinical trials that recruited ART-naïve people living with HIV and randomly assigned them to receive PI-based dual therapy (DT) or triple therapy (TT) aiming to compare viral efficacy. We compared median CD4/CD8 ratios and the proportion of patients with CD4/CD8 ratio > 1 at 48 weeks after ART initiation in both treatment arms using the Mann-Whitney U-test and the χ² test. We performed subgroup analysis for patients > 50 years old, with baseline CD4 counts ≤ 200 cells/μL, viral load > 100 000 HIV RNA copies/mL, and ritonavir-boosted lopinavir-based therapy.

RESULTS

We analysed data from 571 patients: 292 on DT and 279 on TT. No differences were observed in CD4/CD8 ratio (0.632 vs. 0.617, P = 0.729) or in the proportion of patients with CD4/CD8 ratio > 1 (17.9% vs. 19.3%, P = 0.678) 48 weeks after ART initiation. Subgroup analysis showed no further differences.

CONCLUSION

The impact of PI-based DT regimens on the CD4/CD8 ratio during the first year of treatment for ART-naïve patients is similar to that of TT.

Impact of Aging and HIV Infection on the Function of the C-Type Lectin Receptor MINCLE in Monocytes

Both aging and HIV infection are associated with an enhanced pro-inflammatory environment that contributes to impaired immune responses and is mediated in part by innate immune pattern-recognition receptors. MINCLE is a C-type lectin receptor that recognizes trehalose-6,6'-dimycolate or "cord factor," the most abundant glycolipid in Mycobacterium tuberculosis. Here, we evaluated MINCLE function in monocytes in a cohort of HIV-infected and uninfected young (21-35 years) and older adults (≥60 years) via stimulation of peripheral blood mononuclear cells with trehalose-6,6-dibehenate, a synthetic analog of trehalose-6,6'-dimycolate and measurement of cytokine production (interleukin [IL]-10, IL-12, IL-6, tumor necrosis factor-α) by multicolor flow cytometry. Our studies show an age- and HIV-associated increase in cytokine multifunctionality of monocytes both at the population and single cell level that was dominated by IL-12, IL-10, and IL-6. These findings provide insight into the host response to M. tuberculosis and possible sources for the pro-inflammatory environment seen in aging and HIV infection.

Sensing of HIV-1 by TLR8 activates human T cells and reverses latency

During HIV infection, cell-to-cell transmission results in endosomal uptake of the virus by target CD4+ T cells and potential exposure of the viral ssRNA genome to endosomal Toll-like receptors (TLRs). TLRs are instrumental in activating inflammatory responses in innate immune cells, but their function in adaptive immune cells is less well understood. Here we show that synthetic ligands of TLR8 boosted T cell receptor signaling, resulting in increased cytokine production and upregulation of surface activation markers. Adjuvant TLR8 stimulation, but not TLR7 or TLR9, further promoted T helper cell differentiation towards Th1 and Th17. In addition, we found that endosomal HIV induced cytokine secretion from CD4+ T cells in a TLR8-specific manner. TLR8 engagement also enhanced HIV-1 replication and potentiated the reversal of latency in patient-derived T cells. The adjuvant TLR8 activity in T cells can contribute to viral dissemination in the lymph node and low-grade inflammation in HIV patients. In addition, it can potentially be exploited for therapeutic targeting and vaccine development.

Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults

The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.

Inflammation Strikes Again: Frailty and HIV

PURPOSE OF REVIEW

As a consequence of antiretroviral therapy, the proportion of older HIV-infected adults is increasing, with a concomitant shift in burden of illness to age-related syndromes and disease. Frailty is an age-related syndrome of increased vulnerability to stress, predictive of major adverse clinical outcomes among HIV-infected and uninfected persons alike. Understanding frailty pathogenesis is critical to developing interventions to improve health outcomes in HIV. Here, we review the current evidence for the relationship between inflammation and frailty in HIV, and the potential for novel, inflammation-targeted interventions.

RECENT FINDINGS

Dysregulated inflammation has been consistently associated with frailty in elderly HIV-uninfected persons. Dysregulated inflammation is also central to HIV pathophysiology and several recent studies have demonstrated the important association of inflammation with frailty in HIV. Some evidence suggests that anti-inflammatory therapies may be effective in ameliorating the adverse impact of frailty among aging HIV-infected adults, though further investigation is necessary. Inflammation has been implicated in frailty in HIV infection, and improved understanding of the role that inflammation plays in frailty pathogenesis is key to the development of effective therapies to slow or prevent frailty in the vulnerable HIV-infected population.

The Aging Brain With HIV Infection: Effects of Alcoholism or Hepatitis C Comorbidity

As successfully treated individuals with Human Immunodeficiency Virus (HIV)-infected age, cognitive and health challenges of normal aging ensue, burdened by HIV, treatment side effects, and high prevalence comorbidities, notably, Alcohol Use Disorders (AUD) and Hepatitis C virus (HCV) infection. In 2013, people over 55 years old accounted for 26% of the estimated number of people living with HIV (~1.2 million). The aging brain is increasingly vulnerable to endogenous and exogenous insult which, coupled with HIV infection and comorbid risk factors, can lead to additive or synergistic effects on cognitive and motor function. This paper reviews the literature on neuropsychological and in vivo Magnetic Resonance Imaging (MRI) evaluation of the aging HIV brain, while also considering the effects of comorbidity for AUD and HCV.

Chronic Inflammation: Accelerator of Biological Aging

Biological aging is characterized by a chronic low-grade inflammation level. This chronic phenomenon has been named "inflamm-aging" and is a highly significant risk factor for morbidity and mortality in the older persons. The most common theories of inflamm-aging include redox stress, mitochondrial dysfunction, glycation, deregulation of the immune system, hormonal changes, epigenetic modifications, and dysfunction telomere attrition. Inflamm-aging plays a role in the initiation and progression of age-related diseases such as type II diabetes, Alzheimer's disease, cardiovascular disease, frailty, sarcopenia, osteoporosis, and cancer. This review will cover the identification of pathways that control age-related inflammation across multiple systems and its potential causal role in contributing to adverse health outcomes.

Immunosenescence and hurdles in the clinical management of older HIV-patients

People living with HIV (PLWH) who are treated with effective highly active antiretroviral therapy (HAART) have a similar life expectancy to the general population. Moreover, an increasing proportion of new HIV diagnoses are made in people older than 50 y. The number of older HIV-infected patients is thus constantly growing and it is expected that by 2030 around 70% of PLWH will be more than 50 y old. On the other hand, HIV infection itself is responsible for accelerated immunosenescence, a progressive decline of immune system function in both the adaptive and the innate arm, which impairs the ability of an individual to respond to infections and to give rise to long-term immunity; furthermore, older patients tend to have a worse immunological response to HAART. In this review we focus on the pathogenesis of HIV-induced immunosenescence and on the clinical management of older HIV-infected patients.

Frailty in HIV: Epidemiology, Biology, Measurement, Interventions, and Research Needs

Frailty is a critical aging-related syndrome marked by diminished physiologic reserve and heightened vulnerability to stressors, predisposing to major adverse clinical outcomes, including hospitalization, institutionalization, disability, and death in the general population of older adults. As the proportion of older adults living with HIV increases in the era of antiretroviral therapy, frailty is increasingly recognized to be of significant clinical and public health relevance to the HIV-infected population. This article reviews current knowledge on the epidemiology and biology of frailty and its potential role as a target for reducing disparities in outcomes in HIV; conceptual frameworks and current approaches to frailty measurement; existing data on frailty interventions; and important areas for future research focus necessary to develop and advance effective strategies to prevent or ameliorate frailty and its marked adverse consequences among people living with HIV.

Untangling the Gordian knot of HIV, stress, and cognitive impairment

As individuals live longer with HIV, this "graying of the HIV epidemic" has introduced a new set of challenges including a growing number of age and inflammation-related diseases such as cardiovascular disease, type II diabetes, cancer, and dementia. The biological underpinnings of these complex and co-morbid diseases are not fully understood and become very difficult to disentangle in the context of HIV and aging. In the current review we examine the contributions and interactions of HIV, stress, and cognitive impairment and query the extent to which inflammation is the linchpin in these dynamic interactions. Given the inter-relatedness of stress, inflammatory mechanisms, HIV, and cognitive impairment, future work will either need to address multiple dimensions simultaneously or embrace the philosophy that breaking the aberrant cycle at any one point will subsequently remedy the other related systems and processes. Such a single-point intervention may be effective in early disease states, but after perpetuation of an aberrant cycle, adaptations in an attempt to internally resolve the issue will likely lead to the need for multifaceted interventions. Acknowledging that HIV, inflammation, and stress may interact with one another and collectively impact cognitive ability is an important step in fully understanding an individual's complete clinical picture and moving towards personalized medicine.

Paradoxical changes in innate immunity in aging: recent progress and new directions

Immunosenescence, describing alterations, including decline of immune responses with age, is comprised of inappropriate elevations, decreases, and dysregulated immune responses, leading to more severe consequences of bacterial and viral infections and reduced responses to vaccination. In adaptive immunity, these changes include increased proportions of antigen-experienced B and T cells at the cost of naïve cell populations. Innate immune changes in aging are complex in spanning multiple cell types, activation states, and tissue context. Innate immune responses are dampened in aging, yet there is also a paradoxical increase in certain signaling pathways and cytokine levels. Here, we review recent progress and highlight novel directions for expected advances that can lead the aging field to a new era of discovery that will embrace the complexity of aging in human populations.

CD4:CD8 ratio as a frontier marker for clinical outcome, immune dysfunction and viral reservoir size in virologically suppressed HIV-positive patients

Introduction

Absolute CD4 T cell count and plasma viral load have been established as predictors of HIV disease progression, and CD4 T cell count is used as an indicator for initiation of antiretroviral therapy. Following long-term therapy, patients generally present with significant CD4 T cell recovery contrasting with persistently elevated CD8 T cell counts, which leads to a partial restoration of CD4:CD8 ratio. This review focuses on the relevance of the CD4:CD8 ratio on clinical outcomes, immune dysfunction and HIV reservoir size in long-term treated patients.

Method

We conducted a comprehensive literature review of publications in English language using major electronic databases. Our search was focused on factors contributing to CD4:CD8 T cell ratio and clinical outcome in adult HIV-positive patients in the context of treated infection.

Discussion

Low CD4:CD8 ratio has been linked to ageing and acts as a predictor of mortality in the general population. This ratio may represent the combined effects of inflammation and immunological changes called “inflammaging.” Although the mechanisms underlying partial correction of the CD4:CD8 ratio and persistently elevated CD8 T cell count in long-term treated patients remain poorly understood, it has been recently indicated that patients with optimal CD4 T cell recovery and low CD4:CD8 ratio still harbour increased immune activation, an immune senescent phenotype and have a higher risk of non-AIDS morbidity and mortality. This review reconsiders CD4:CD8 ratio in the light of advances in the understanding of immune dysfunction and examines its pathophysiological features and implications on clinical outcome and HIV reservoir size in long-term treated HIV-positive adults.

Conclusion

The CD4:CD8 ratio can contribute to the immunological evaluation of treated patients in a long-term follow-up and may be applied for monitoring both immune dysfunction and viral reservoir size in immune-based clinical trials.

Immune aging, dysmetabolism, and inflammation in neurological diseases

As we age, the immune system undergoes a process of senescence accompanied by the increased production of proinflammatory cytokines, a chronic subclinical condition named as “inflammaging”. Emerging evidence from human and experimental models suggest that immune senescence also affects the central nervous system and promotes neuronal dysfunction, especially within susceptible neuronal populations. In this review we discuss the potential role of immune aging, inflammation and metabolic derangement in neurological diseases. The discovery of novel therapeutic strategies targeting age-linked inflammation may promote healthy brain aging and the treatment of neurodegenerative as well as neuropsychiatric disorders.

Mixed membership trajectory models of cognitive impairment in the multicenter AIDS cohort study

OBJECTIVE

The longitudinal trajectories that individuals may take from a state of normal cognition to HIV-associated dementia are unknown. We applied a novel statistical methodology to identify trajectories to cognitive impairment, and factors that affected the 'closeness' of an individual to one of the canonical trajectories.

DESIGN

The Multicenter AIDS Cohort Study (MACS) is a four-site longitudinal study of the natural and treated history of HIV disease among gay and bisexual men.

METHODS

Using data from 3892 men (both HIV-infected and HIV-uninfected) enrolled in the neuropsychology substudy of the MACS, a Mixed Membership Trajectory Model (MMTM) was applied to capture the pathways from normal cognitive function to mild impairment to severe impairment. MMTMs allow the data to identify canonical pathways and to model the effects of risk factors on an individual's 'closeness' to these trajectories.

RESULTS

First, we identified three distinct trajectories to cognitive impairment: 'normal aging' (low probability of mild impairment until age 60); 'premature aging' (mild impairment starting at age 45-50); and 'unhealthy' (mild impairment in 20s and 30s) profiles. Second, clinically defined AIDS, and not simply HIV disease, was associated with closeness to the premature aging trajectory, and, third, hepatitis-C infection, depression, race, recruitment cohort and confounding conditions all affected individual's closeness to these trajectories.

CONCLUSION

These results provide new insight into the natural history of cognitive dysfunction in HIV disease and provide evidence for a potential difference in the pathophysiology of the development of cognitive impairment based on trajectories to impairment.