Serum Neopterin, an Immune Activation Marker, Independently Predicts Disease Progression in Advanced HIV-1 Infection

Neopterin, the Cell-Mediated Immune Response Biomarker, in Inflammatory Periodontal Diseases: A Narrative Review of a More than Fifty Years Old Biomarker

Neopterin is a biomarker of the activation of cellular immunity. The purpose of this review is to summarise neopterin metabolism, methods of its detection, and its role in inflammation, focusing on periodontal inflammatory diseases. This derivative of guanosine is a non-enzymatic product of 7,8-dihydroneopterin oxidation caused by free radicals which protect activated macrophages from oxidative stress. Various methods, usually based on enzyme-linked immunosorbent essay, high-performance liquid chromatography, or radioimmunoassay were developed for the isolation of neopterin. A wide spectrum of diseases and conditions are known to affect neopterin levels, including cardiovascular, bacterial, viral, and degenerative diseases, as well as malignant tumours. Neopterin levels were found to increase in subjects with periodontitis, especially when the oral fluid and gingival crevicular fluid were evaluated. These findings confirm the role of activated macrophages and cellular immunity in periodontal inflammatory diseases. The gingival crevicular fluid and the oral fluid appear to be the most valuable biologic fluids for the evaluation of neopterin levels in periodontitis. For gingival crevicular fluid, neopterin can be determined as the concentration or the so-called total amount. Nonsurgical periodontal treatment was associated with a decrease in neopterin levels, but an increase was also reported, suggesting the possible role of macrophages in the resolution of the periodontal lesion.

Methadone use is associated with increased levels of sCD14, immune activation, and inflammation during suppressed HIV infection

Opioid use has negative effects on immune responses and may impair immune reconstitution in persons living with HIV (PLWH) infection undergoing antiretroviral treatment (ART). The effects of treatment with μ opioid receptor (MOR) agonists (e.g., methadone, MET) and antagonists (e.g., naltrexone, NTX) on immune reconstitution and immune activation in ART-suppressed PLWH have not been assessed in-depth. We studied the effects of methadone or naltrexone on measures of immune reconstitution and immune activation in a cross-sectional community cohort of 30 HIV-infected individuals receiving suppressive ART and medications for opioid use disorder (MOUD) (12 MET, 8 NTX and 10 controls). Plasma markers of inflammation and immune activation were measured using ELISA, Luminex, or Simoa. Plasma IgG glycosylation was assessed using capillary electrophoresis. Cell subsets and activation were studied using whole blood flow cytometry. Individuals in the MET group, but no in the NTX group, had higher plasma levels of inflammation and immune activation markers than controls. These markers include soluble CD14 (an independent predictor of morbidity and mortality during HIV infection), proinflammatory cytokines, and proinflammatory IgG glycans. This effect was independent of time on treatment. Our results indicate that methadone-based MOUD regimens may sustain immune activation and inflammation in ART-treated HIV-infected individuals. Our pilot study provides the foundation and rationale for future longitudinal functional studies of the impact of MOUD regimens on immune reconstitution and residual activation after ART-mediated suppression.

High seroprotection rates and geometric mean titre increases after repeated annual influenza vaccinations in a cohort of HIV-infected adults in Austria

INTRODUCTION

Vaccination against seasonal influenza is recommended for all HIV-infected persons. Few data have been reported on the effect of repeated annual vaccination in this population.

METHODS

We measured haemagglutination inhibition antibody responses and investigated seroprotection rates in 344 HIV-infected adults before and 12 weeks after influenza vaccination with a trivalent subunit vaccine.

RESULTS

68.3% of patients were male, the median age was 45 years. 83.7% had a viral load < 50 copies/mL. The median CD4 count was 604/µL. 304 patients (88.4%) had received influenza vaccinations in previous years. Seroprotection rates for A/H1N1 and B were over 90% in all age groups before vaccination and close to 100% after vaccination. For A/H3N2, seroprotection rates were lowest in individuals below 30 years both before and after vaccination (22.2% and 50.0%) and higher in older age groups (48.4% and 83.9% in people over 60 years). GMT fold increases were not significantly different across the age groups (3.0 to 4.2, p = 0.425). Previous influenza vaccinations were associated with higher seroprotection rates before and after vaccination (62.2% and 84.2% in patients with 8 or more previous vaccinations vs. 15.0% and 57.5% without previous vaccinations, respectively). Individuals with detectable viral load, elevated immune activation (urine neopterin ≥ 250 µmol/mol creatinine), and higher CD4 nadir (≥200 cells/µL) showed a trend towards inferior immune responses to vaccination, whereas gender and CD4 count did not have an effect.

CONCLUSION

The lower seroprotection rates observed in younger individuals may be explained by the higher proportion of patients without HIV treatment and with fewer previous encounters with influenza strains. Good seroprotection rates can be achieved in elderly HIV-infected patients and after repeated annual vaccinations.

Increased biomarkers of cardiovascular risk in HIV-1 viremic controllers and low persistent inflammation in elite controllers and art-suppressed individuals

HIV controllers (HICs) are models of HIV functional cure, although some studies have shown persistent inflammation and increased rates of atherosclerosis in HICs. Since immune activation/inflammation contributes to the pathogenesis of cardiovascular diseases (CVD), we evaluated clinical data and inflammation markers in HIV-1 viremic controllers (VC), elite controllers (EC), and control groups (HIV positive individuals with virological suppression by antiretroviral therapy—cART; HIV negative individuals—HIVneg) to assess whether they presented elevated levels of inflammation markers also associated with CVD. We observed the highest frequencies of activated CD8⁺ T cells in VCs, while EC and cART groups presented similar but slightly altered frequencies of this marker when compared to the HIVneg group. Regarding platelet activation, both HICs groups presented higher expression of P-selectin in platelets when compared to control groups. Monocyte subset analyses revealed lower frequencies of classical monocytes and increased frequencies of non-classical and intermediate monocytes among cART individuals and in EC when compared to HIV negative individuals, but none of the differences were significant. For VC, however, significant decreases in frequencies of classical monocytes and increases in the frequency of intermediate monocytes were observed in comparison to HIV negative individuals. The frequency of monocytes expressing tissue factor was similar among the groups on all subsets. In terms of plasma markers, VC had higher levels of many inflammatory markers, while EC had higher levels of VCAM-1 and ICAM-1 compared to control groups. Our data showed that VCs display increased levels of inflammation markers that have been associated with CVD risk. Meanwhile, ECs show signals of lower but persistent inflammation, comparable to the cART group, indicating the potential benefits of alternative therapies to decrease inflammation in this group.

The importance of neopterin in COVID-19: The prognostic value and relation with the disease severity

Coronavirus Disease 2019 [COVID-19], caused by severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2], has rapidly evolved into a global health emergency. Neopterin [NPT], produced by macrophages when stimulated with interferon [IFN-]gamma, is an essential cytokine in the antiviral immune response. NPT has been used as a marker for the early assessment of disease severity in different diseases. The leading cause of NPT production is the pro-inflammatory cytokine IFN-. Macrophage activation has also been revealed to be linked with disease severity in SARS-CoV-2 patients. We demonstrate the importance of NPT in the pathogenesis of SARS-CoV-2 and suggest that targeting NPT in SARS-CoV-2 infection may be critical in the early prediction of disease progression and provision of timely management of infected individuals.

Clues to Disease Activity in Juvenile Dermatomyositis: Neopterin and Other Biomarkers

Easily accessible biomarkers are urgently needed to evaluate immune activation in Juvenile Dermatomyositis (JDM). The goal of this retrospective study is to define immunological and clinical differences between untreated JDM patients with either normal or elevated (>10 mmol/L) levels of neopterin, a biomarker of macrophage activation. We included all JDM with neopterin data obtained before initiating medical therapy. We assessed T, B, NK cell populations, muscle enzymes, and disease activity scores for skin (sDAS), muscle (mDAS), total (tDAS), the duration of untreated disease, disease course, and myositis-specific antibody (MSA). Seventy-nine percent of 139 untreated JDM patients had elevated serum neopterin. The group with elevated neopterin had significantly more active disease: tDAS 11.9 vs. 8.1 (p < 0.0001), mDAS 5.8 vs. 3.1 (p < 0.0001), sDAS 6.1 vs. 4.9 (p = 0.0002), aldolase 24.0 vs. 7.6 U/L (p < 0.0001), von Willebrand factor antigen (p < 0.0001), and ESR 19.8 vs. 11.5 mm/hr (p = 0.01). The flow cytometry documented both reduced T cells (1494 vs. 2278/mm3, p = 0.008) and NK cells (145 vs. 240/mm3, p = 0.003). TNFα-308AA/AG polymorphism was more common in children with elevated neopterin than TNFα-308GG (p 0.05). We conclude that the availability of neopterin data will contribute to the rapid assessment of untreated JDM disease activity.

Neopterin: A Promising Candidate Biomarker for Severe COVID-19

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has rapidly spread across the world since its first emergence in China in late 2019. It is a major public health concern with no effective treatct 3ments. The immunopathology of SARS-CoV-2 is associated with an excessive inflammatory response. Macrophage activation syndrome (MAS) is also associated with the severity of the disease in SARS-CoV-2-infected patients. Neopterin is a macrophage activation marker produced by monocytes and macrophages upon activation by interferon-gamma (IFN-γ). Neopterin is a well-established marker in a variety of diseases, and recent evidence indicates that it could be helpful in early prediction of the severity of COVID-19 disease and serve as a prognostic marker. Here, we outline the role of macrophage activation syndrome in the pathogenesis of SARS-CoV-2 and suggest that neopterin could be used as a biomarker for progression of COVID-19.

Ecological, parasitological and individual determinants of plasma neopterin levels in a natural mandrill population

Investigating how individuals adjust their investment into distinct components of the immune system under natural conditions necessitates to develop immune phenotyping tools that reflect the activation of specific immune components that can be measured directly in the field. Here, we examined individual variation of plasma neopterin, a biomarker of Th1 immunity in wild mandrills (Mandrillus sphinx), who are naturally exposed to a suite of parasites, including simian retroviruses and malaria agents. We analyzed a total of 201 plasma samples from 99 individuals and examined the effect of sex, age, social rank, reproductive state and disease status on neopterin levels. We found higher neopterin concentrations in males than females, but were unable to disentangle this effect from possible confounding effects of retroviral infections, which affect nearly all adult males, but hardly any females. We further detected a non-linear age effect with heightened neopterin levels in early and late life. In addition, adult males that harbored very high parasitaemia for Plasmodium gonderi also showed high neopterin levels. There was no effect of social rank in either male or female mandrills, and no effect of female reproductive state. Taken together, these results indicate that plasma neopterin may prove useful to investigate individual variation in investment into specific immune components, as well as to monitor the dynamics of immune responses to naturally occurring diseases that elicit a Th1 immune response.

HIV-1 elite controllers present a high frequency of activated regulatory T and Th17 cells

HIV-1 infection is characterized by generalized deregulation of the immune system, resulting in increased chronic immune activation. However, some individuals called HIV controllers (HICs) present spontaneous control of viral replication and have a more preserved immune system. Among HICs, discordant results have been observed regarding immune activation and the frequency of different T cell subsets, including Treg and Th17 cells. We evaluated T cell immune activation, differentiation and regulatory profiles in two groups of HICs—elite controllers (ECs) and viremic controllers (VCs)—and compared them to those of cART-treated individuals (cART) and HIV-1-negative (HIV-neg) individuals. ECs demonstrated similar levels of activated CD4⁺ and CD8⁺ T cells in comparison to HIV-neg, while cART and VCs showed elevated T cell activation. CD4⁺ T cell subset analyses showed differences only for transitional memory T cell frequency between the EC and HIV-neg groups. However, VC individuals showed higher frequencies of terminally differentiated, naïve, and stem cell memory T cells and lower frequencies of transitional memory and central memory T cells compared to the HIV-neg group. Among CD8⁺ T cell subsets, ECs presented higher frequencies of stem cell memory T cells, while VCs presented higher frequencies of terminally differentiated T cells compared to the HIV-neg group. HICs showed lower frequencies of total Treg cells compared to the HIV-neg and cART groups. ECs also presented higher frequencies of activated and a lower frequency of resting Treg cells than the HIV-neg and cART groups. Furthermore, we observed a high frequency of Th17 cells in ECs and high Th17/Treg ratios in both HIC groups. Our data showed that ECs had low levels of activated T cells and a high frequency of activated Treg and Th17 cells, which could restrict chronic immune activation and be indicative of a preserved mucosal response in these individuals.

A high level of serum neopterin is associated with rapidly progressive interstitial lung disease and reduced survival in dermatomyositis

Neopterin is primarily synthesized and released by activated macrophages/monocytes upon stimulation with interferon-γ and is considered as a marker for macrophage activation. This study aimed to analyze the serum levels of neopterin in patients with dermatomyositis (DM) in association with clinical manifestations, laboratory data and patient prognosis. One hundred and eighty-two consecutive DM patients and 30 healthy controls were retrospectively enrolled into the study. Serum levels of neopterin were significantly increased in DM patients compared to healthy controls (P < 0·001). High serum neopterin levels were associated with anti-melanoma differentiation-associated gene (MDA5) antibody, rapidly progressive interstitial lung disease (RP-ILD) and characteristic DM cutaneous involvement. Longitudinal assessment of serum samples revealed that the serum neopterin levels were closely correlated with disease severity (β = 30·24, P < 0·001). In addition, a significant increase in serum neopterin concentration of non-survivors was observed when compared to that of survivors (P < 0·001). Receiver operator characteristic curves showed that serum neopterin could distinguish non-survivors and survivors at an optimal cut-off level of 22·1 nmol/l with a sensitivity and specificity of 0·804 and 0·625, respectively (P < 0·001). Kaplan-Meier survival curves revealed that DM patients with serum neopterin > 22·1 nmol/l had a significantly higher mortality compared to the patient group with serum neopterin < 22·1 nmol/l (log-rank P < 0·001). Multivariate regression analysis identified high serum neopterin concentration to be an independent risk factor for poor prognosis in DM (adjusted hazard ratio = 4·619, 95% confidence interval = 2·092-10·195, P < 0·001). In conclusion, increased serum levels of neopterin were significantly associated with RP-ILD and reduced survival in DM patients, suggesting it as a promising biomarker in disease evaluation of DM.

Assessment of neopterin and indoleamine 2,3-dioxygenase activity in patients with seasonal influenza: A pilot study

BACKGROUND

Seasonal influenza is an important cause of morbidity and mortality worldwide. Immune activation after stimulation with interferon-gamma leads to increased production of neopterin but also results in increased tryptophan catabolism through indoleamine 2,3-dioxygenase (IDO). Our pilot study determined neopterin serum levels and IDO activity in patients with influenza infection and investigated whether neopterin is linked to clinical outcome parameters (mortality ≤30 days, acute cardiac events (ACE) length of hospitalization, ICU admission).

METHODS

Neopterin concentrations were analyzed in serum samples of 40 patients with a confirmed diagnosis of influenza infection and in-hospital treatment for >24 hours. Data were compared to values of 100 healthy blood donors and 48 age-matched pneumonia patients. In a subgroup of 14 patients, tryptophan and kynurenine concentrations, as well as kynurenine-to-tryptophan ratio, were analyzed.

RESULTS

In all influenza patients, neopterin concentrations were increased and significantly higher compared to those determined in patients with pneumonia and healthy controls. Positive correlations between the duration of hospitalization and neopterin were found. Significantly higher levels of kynurenine, kynurenine-to-tryptophan ratio, and lower levels of tryptophan were seen in influenza patients compared to healthy controls.

CONCLUSIONS

Neopterin seems to be related to the course of the disease and could be a valuable biomarker to identify patients at an elevated risk of a worsened outcome; however, further prospective validation studies are needed to support the here presented preliminary results.

Systematic Review of Host-Mediated Activity of Miltefosine in Leishmaniasis through Immunomodulation

Host immune responses are pivotal for the successful treatment of the leishmaniases, a spectrum of infections caused by Leishmania parasites. Previous studies speculated that augmenting cytokines associated with a type 1 T-helper cell (Th1) response is necessary to combat severe forms of leishmaniasis, and it has been hypothesized that the antileishmanial drug miltefosine is capable of immunomodulation and induction of Th1 cytokines.

Host immune responses are pivotal for the successful treatment of the leishmaniases, a spectrum of infections caused by Leishmania parasites. Previous studies speculated that augmenting cytokines associated with a type 1 T-helper cell (Th1) response is necessary to combat severe forms of leishmaniasis, and it has been hypothesized that the antileishmanial drug miltefosine is capable of immunomodulation and induction of Th1 cytokines. A better understanding of the immunomodulatory effects of miltefosine is central to providing a rationale regarding synergistic mechanisms of activity to combine miltefosine optimally with other conventional and future antileishmanials that are currently under development. Therefore, a systematic literature search was performed to evaluate to what extent and how miltefosine influences the host Th1 response. Miltefosine’s effects observed in both a preclinical and a clinical context associated with immunomodulation in the treatment of leishmaniasis are evaluated in this review. A total of 27 studies were included in the analysis. Based on the current evidence, miltefosine is not only capable of inducing direct parasite killing but also of modulating the host immunity. Our findings suggest that miltefosine-induced activation of Th1 cytokines, particularly represented by increased gamma interferon (IFN-γ) and interleukin 12 (IL-12), is essential to prevail over the Leishmania-driven Th2 response. Differences in miltefosine-induced host-mediated effects between in vitro, ex vivo, animal model, and human studies are further discussed. All things considered, an effective treatment with miltefosine is acquired by enhanced functional Th1 cytokine responses and may further be enhanced in combination with immunostimulatory agents.

Serum neopterin as well as ferritin, soluble interleukin-2 receptor, KL-6 and anti-MDA5 antibody titer provide markers of the response to therapy in patients with interstitial lung disease complicating anti-MDA5 antibody-positive dermatomyositis

Objective: This study identified biomarkers that can be used to assess disease activity and response to therapy in patients with interstitial lung disease complicating anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab)-positive clinically amyopathic dermatomyositis (CADM). Methods: In 15 patients with interstitial lung disease complicating anti-MDA5 Ab-positive CADM, anti-MDA5 Ab, neopterin, interleukin (IL)-18, ferritin, and soluble interleukin 2 receptor (sIL-2R) levels were measured in cryopreserved serum specimens before and at multiple times after remission induction therapy, and their correlations were assessed. Results: Anti-MDA5 Ab, neopterin, IL-18, ferritin, and sIL-2R levels did not differ significantly between patients who survived and those who succumbed to the disease. In many cases, serum anti-MDA5 Ab titers were over the upper limit (over 150 index value) before treatment in the usual measuring method, and gradually decreased to the normal range at stable phase. Meanwhile, serum neopterin levels (21.6 [15.3-48.3] nmol/L) were significantly elevated in newly diagnosed patients and fell to 6.8 (5-11.4) nmol/L at 6 months after treatment introduction. Conclusions: Elevated serum neopterin as well as ferritin, sIL-2R, KL-6, and anti-MDA5 Ab titer might help identify patients with interstitial lung disease complicated with DM and might be useful in monitoring response to therapy.

The predictive value of serum neopterin for multiple organ dysfunction syndrome in severe burn patients

Objective To investigate the predictive value of serum neopterin for multiple organ dysfunction syndrome (MODS) in severe burn patients. Methods Seventy-six severe burn patients with burns covering a total body surface area (TBSA) above 70% were included in this study. Of the 76 patients, 29 cases developed MODS (MODS group) and the remaining 47 subjects did not (non-MODS group). From the MODS group, 12 patients died (Death group) and 17 patients survived (Survive group). The serum level of neopterin in the MODS and non-MODS groups were examined by radioimmunoassay on following 1, 3 , 7 , 14 , 21 and 28 post-burn days (PBDs). A receiver operating characteristic (ROC) curve was used to analyse the predictive value of serum neopterin for MODS and death. Results The serum neopterin level in the MODS group was significantly higher than that of non-MODS group between 3~28 PBDs (p<0.001). However, the serum neopterin levels between the MODS and non-MODS groups following 1 PBD were not statistically significant (p>0.05). The best diagnostic performance of serum neopterin for MODS occurred 14 PBDs with the prediction sensitivity and specificity of 75.86% (56.46%~89.70%) and 85.11% (71.69%~93.80%) respectively. However, serum neopterin levels had no clinical value in predicting the death of MODS patients. The area under the ROC curve (AUC) was 0.72 (0.58~0.85), 0.81 (0.71~0.92) and 0.83 (0.72~0.94) for serum neopterin as biomarker in the prediction of MODS after 3, 7 and 14 PBDs, respectively. The AUCs were 0.50 (0.27~0.73), 0.53 (0.30~0.76) and 0.56 (0.33~0.79) for serum neopterin as biomarker in prediction of death for MODS patients after 3, 7 and 14 PBDs, respectively. Conclusion The persistent and significant increase of serum neopterin level is closely related to the development of MODS in patients with severe burns. Serum neopterin is therefore a promising serological marker for MODS early diagnosis, but has little efficacy in the prediction of the likelihood of death in severe burn patients with MODS.

Neopterin, Inflammation, and Oxidative Stress: What Could We Be Missing?

Neopterin has been extensively used as a clinical marker of immune activation during inflammation in a wide range of conditions and stresses. However, the analysis of neopterin alone neglects the cellular reactions that generate it in response to interferon-γ. Neopterin is the oxidation product of 7,8-dihydroneopterin, which is a potent antioxidant generated by interferon-γ-activated macrophages. 7,8-Dihydroneopterin can protect macrophage cells from a range of oxidants through a scavenging reaction that generates either neopterin or dihydroxanthopterin, depending on the oxidant. Therefore, plasma and urinary neopterin levels are dependent on both macrophage activation to generate 7,8-dihydroneopterin and subsequent oxidation to neopterin. This relationship is clearly shown in studies of exercise and impact-induced injury during intense contact sport. Here, we argue that neopterin and total neopterin, which is the combined value of 7,8-dihydroneopterin and neopterin, could provide a more comprehensive analysis of clinical inflammation than neopterin alone.

Neopterin is associated with hippocampal subfield volumes and cognition in HIV

Objective

HIV infection sets off an immediate immune response and inflammatory cascade that can lead to neuronal injury and cognitive impairment, but the relationship between immune markers, regional brain volumes, and cognition remains understudied in HIV-infected adults.

Methods

Cross-sectional associations were examined between serum immune markers of activation (neopterin) and inflammation (interleukin [IL]-1β, IL-6, tumor necrosis factor alpha, and C-reactive protein) with regional brain volumes (cortical, subcortical, total gray matter, hippocampus, and subfields) and cognition in 66 HIV-infected, virally suppressed, adults who underwent 3.0-T MRI as part of the Research Core of the Rush Center of Excellence on Disparities in HIV and Aging. Immune markers were assayed from frozen plasma, values were entered into linear regression models as predictors of regional brain volumes, and interactive effects of immune response and regional brain volumes on cognition were examined.

Results

No inflammatory marker was associated with any regional brain volume. Higher neopterin level was associated with lower total hippocampal, presubiculum, and cornu ammonis (CA) subfield volumes. Higher neopterin level and lower total hippocampal volume were independently associated with lower episodic memory, and neopterin level fully mediated the effect of hippocampal atrophy on episodic memory. Higher neopterin levels were associated with lower presubiculum, CA1, and CA4/dentate volumes and lower semantic memory, working memory, and global cognition.

Conclusion

Immune activation in response to HIV infection, measured by neopterin, has a deleterious and targeted effect on regional brain structure, which can be visualized with clinically available MRI measures of hippocampus and its subfields, and this effect is associated with lower cognitive function.

Interferon-γ Mediated Pathways And Mitogen Stimulated Proliferation During And After An Acute Infection

Background: Interferon-γ (IFN- γ) regulates the degradation of tryptophan to kynurenine via induction of indoleamine- 2,3-dioxygenase (IDO). Local tryptophan depletion and accumulation of toxic metabolites might impair the proliferative capacity of lymphocytes. The aim of this study was to assess the actual status of immune system activation of patients with bacterial infection in the acute phase and during convalescence in vivo and in vitro. Parameters of systemic immune system activation were evaluated for associations with proliferative responsiveness of immune cells, and compared with healthy controls. Methods: 24 patients with various acute bacterial infections were included in the group of acutely ill patients. Sixteen patients participated in a follow-up examination after convalescence. The control group consisted of 6 healthy people. To assess the status of immune system activation in vivo, inflammation parameters C-reactive protein and differential blood counts were determined. Neopterin concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Tryptophan and kynurenine measurements were performed with high pressure liquid chromatography (HPLC). Peripheral blood mononuclear cells (PBMCs) were isolated from the patients’ blood and stimulated with concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) in vitro proliferation rates were evaluated by ³H-thymidine incorporation and neopterin production and tryptophan degradation were determined in supernatants of mitogen stimulated PBMCs. Results: Patients with acute bacterial infections showed reduced tryptophan and elevated neopterin concentrations, which did not normalize after convalescence period. Higher plasma neopterin values and increased IDO-activity were associated with reduced proliferative responses in vitro after stimulation with PHA. Associations were observed during acute infection as well as convalescence. Conclusions: Results of this study show that increased immune system activation in vivo is associated with impaired proliferative responsiveness of immune cells in vitro in acute bacterial infections as well as during convalescence.

Impact of HIV and Type 2 diabetes on Gut Microbiota Diversity, Tryptophan Catabolism and Endothelial Dysfunction

HIV infection and type 2 diabetes are associated with altered gut microbiota, chronic inflammation, and increased cardiovascular risk. We aimed to investigate the combined effect of these diseases on gut microbiota composition and related metabolites, and a potential relation to endothelial dysfunction in individuals with HIV-infection only (n = 23), diabetes only (n = 16) or both conditions (n = 21), as well as controls (n = 24). Fecal microbiota was analyzed by Illumina sequencing of the 16 S rRNA gene. Markers of endothelial dysfunction (asymmetric dimethylarginine [ADMA]), tryptophan catabolism (kynurenine/tryptophan [KT]-ratio), and inflammation (neopterin) were measured by liquid chromatography-tandem mass spectrometry. The combination of HIV and type 2 diabetes was associated with reduced gut microbiota diversity, increased plasma KT-ratio and neopterin. Microbial genes related to tryptophan metabolism correlated with KT-ratio and low alpha diversity, in particular in HIV-infected with T2D. In multivariate analyses, KT-ratio associated with ADMA (β = 4.58 [95% CI 2.53–6.63], p < 0.001), whereas microbiota composition per se was not associated with endothelial dysfunction. Our results indicate that tryptophan catabolism may be related to endothelial dysfunction, with a potentially detrimental interaction between HIV and diabetes. The potential contribution of gut microbiota and the impact for cardiovascular risk should be further explored in prospective studies powered for clinical end points.

Mass Spectrometric Identification of Urinary Biomarkers of Pulmonary Tuberculosis

Background

Tuberculosis (TB) is the leading infectious cause of death worldwide. A major barrier to control of the pandemic is a lack of clinical biomarkers with the ability to distinguish active TB from healthy and sick controls and potential for development into point-of-care diagnostics.

Methods

We conducted a prospective case control study to identify candidate urine-based diagnostic biomarkers of active pulmonary TB (discovery cohort) and obtained a separate blinded “validation” cohort of confirmed cases of active pulmonary TB and controls with non-tuberculous pulmonary disease for validation. Clean-catch urine samples were collected and analyzed using high performance liquid chromatography-coupled time-of-flight mass spectrometry.

Results

We discovered ten molecules from the discovery cohort with receiver-operator characteristic (ROC) area-under-the-curve (AUC) values >85%. These 10 molecules also significantly decreased after 60 days of treatment in a subset of 20 participants followed over time. Of these, a specific combination of diacetylspermine, neopterin, sialic acid, and N-acetylhexosamine exhibited ROC AUCs >80% in a blinded validation cohort of participants with active TB and non-tuberculous pulmonary disease.

Conclusion

Urinary levels of diacetylspermine, neopterin, sialic acid, and N-acetylhexosamine distinguished patients with tuberculosis from healthy controls and patients with non-tuberculous pulmonary diseases, providing a potential noninvasive biosignature of active TB.

Funding

This study was funded by Weill Cornell Medicine, the National Institute of Allergy and Infectious Diseases, the Clinical and Translational Science Center at Weill Cornell, the NIH Fogarty International Center grants, and the NIH Tuberculosis Research Unit (Tri-I TBRU).

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Urinary levels of small metabolites appear capable of distinguishing cases of active pulmonary tuberculosis from sick and healthy controls.

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Levels of these biomarkers decrease after 60 days of treatment in a longitudinal cohort of 20 participants.

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- Many of the identified biomarkers are known inflammatory intermediates that may reflect a specific immune response to tuberculosis.

Urine tests are commonly used to enable non-invasive, rapid and point-of-care diagnosis of various infectious diseases. We identified diacetylspermine, neopterin, sialic acid and N-acetylhexosamine as potential urine-based biomarkers for tuberculosis from two independent patient cohorts. These metabolites are known inflammatory intermediates and appear to decrease with anti-tuberculosis therapy in a subset of participants followed over 2 months. If validated, these metabolites have potential to both improve our understanding of the immune reaction to active tuberculosis and facilitate the development of a much-needed clinical biomarker for tuberculosis.

Multiple Homozygous Variants in the STING-Encoding TMEM173 Gene in HIV Long-Term Nonprogressors

Among HIV-infected individuals, long-term nonprogressor (LTNP) patients experience slow CD4 T cell decline and almost undetectable viral load for several years after primary acquisition of HIV. Type I IFN has been suggested to play a pathogenic role in HIV pathogenesis, and therefore diminished IFN responses may underlie the LTNP phenotype. In this study, we examined the presence and possible immunological role of multiple homozygous single-nucleotide polymorphisms in the stimulator of IFN genes (STING) encoding gene TMEM173 involved in IFN induction and T cell proliferation in HIV LTNP patients. We identified LTNPs through the Danish HIV Cohort and performed genetic analysis by Sanger sequencing, covering the R71H-G230A-R293Q (HAQ) single-nucleotide polymorphisms in TMEM173 This was followed by investigation of STING mRNA and protein accumulation as well as innate immune responses and proliferation following STING stimulation and infection with replication-competent HIV in human blood-derived cells. We identified G230A-R293Q/G230A-R293Q and HAQ/HAQ homozygous TMEM173 variants in 2 out of 11 LTNP patients. None of the 11 noncontrollers on antiretroviral treatment were homozygous for these variants. We found decreased innate immune responses to DNA and HIV as well as reduced STING-dependent inhibition of CD4 T cell proliferation, particularly in the HAQ/HAQ HIV LTNP patients, compared with the age- and gender-matched noncontrollers on antiretroviral treatment. These findings suggest that homozygous HAQ STING variants contribute to reduced inhibition of CD4 T cell proliferation and a reduced immune response toward DNA and HIV, which might result in reduced levels of constitutive IFN production. Consequently, the HAQ/HAQ TMEM173 genotype may contribute to the slower disease progression characteristic of LTNPs.

Differential Relationships among Circulating Inflammatory and Immune Activation Biomediators and Impact of Aging and Human Immunodeficiency Virus Infection in a Cohort of Injection Drug Users

As individuals with human immunodeficiency virus (HIV) infection live longer, aging and age-related chronic conditions have become major health concerns for this vulnerable population. Substantial evidence suggests that chronic inflammation and immune activation contribute significantly to chronic conditions in people aging with or without HIV infection. As a result, increasing numbers of inflammation and immune activation biomediators have been measured. While very few studies describe their in vivo relationships, such studies can serve as an important and necessary initial step toward delineating the complex network of chronic inflammation and immune activation. In this study, we evaluated in vivo relationships between serum levels of neopterin, a biomediator of immune activation, and four commonly described inflammatory biomediators: soluble tumor necrosis factor (TNF)-α receptor (sTNFR)-1, sTNFR-2, interleukin (IL)-6, and C-reactive protein (CRP), as well as the impact of HIV infection and aging in the AIDS Linked to the Intravenous Experience (ALIVE) study, a community-recruited observational study of former and current injection drug users (IDUs) with or at high risk for HIV infection in Baltimore, MD, USA. The study included 1,178 participants in total with 316 HIV-infected (HV+) and 862 HIV-uninfected (HIV−) IDUs. Multivariate regression analyses were employed, adjusting for age, sex, body mass index, smoking, hepatitis C virus co-infection, injection drug use, comorbidities, and HIV status (for all participants), and HIV viral load, CD4⁺ T-cell counts, and antiretroviral therapy (for HIV+ participants). The results showed significant impact of aging on all five biomediators and that of HIV infection on all but sTNFR-1. In the adjusted model, neopterin had positive associations with sTNFR-1 and sTNFR-2 (partial correlation coefficients: 0.269 and 0.422, respectively, for all participants; 0.292 and 0.354 for HIV+; and 0.262 and 0.435 for HIV−, all p < 0.0001). No significant associations between neopterin and IL-6 or CRP were identified. Such differential relationships between circulating neopterin and sTNFR-1, sTNFR-2, IL-6, and CRP may help inform their selection in future studies. These findings may also facilitate elucidation of underlying inflammatory and immune activation pathways that contribute to age-related chronic conditions, potentially leading to identification of key biomediators, particularly those upstream of CRP, as novel targets for intervention.

Heritability of plasma neopterin levels in the Old Order Amish

BACKGROUND

We examined the heritability of neopterin, a biomarker for cell-mediated immunity and oxidative stress, and potentially for psychiatric disorders, in the Old Order Amish.

METHODS

Plasma neopterin levels were determined in 2015 Old Order Amish adults. Quantitative genetic procedures were used to estimate heritability of neopterin.

RESULTS

Heritability of log-neopterin was estimated at 0.07 after adjusting for age, gender, and household (p=0.03). The shared household effect was 0.06 (p<0.02).

CONCLUSIONS

We found a low heritability of neopterin and small household effect, suggesting that non-household environmental factors are more important determinants of variance of neopterin levels in the Amish.

Neopterin and Soluble CD14 Levels as Indicators of Immune Activation in Cases with Indeterminate Pattern and True Positive HIV-1 Infection

Background

We aimed to evaluate the roles of the plasma immune activation biomarkers neopterin and soluble CD14 (sCD14) in the indirect assessment of the immune activation status of patients with the indeterminate HIV-1 (IHIV-1) pattern and a true HIV-1-positive infection (PCG).

Methods

This cross-sectional and descriptive study included eighty-eight patients with the IHIV-1 pattern, 100 patients in the PCG, and 100 people in a healthy control group (HCG). Neopterin and sCD14 levels were determined by competitive and sandwich ELISA methods, respectively.

Results

Mean neopterin and sCD14 levels among those with the IHIV-1 pattern were significantly lower than among the PCG (p < 0.001 and p = 0.001, respectively), but they were similiar to those in the HCG (p = 0.57 and p = 0.66, respectively. Mean neopterin and sCD14 levels among the PCG were found to be significantly higher than among those with the IHIV-1 pattern (p < 0.001 and p = 0.001, respectively) and among those in the HCG (p = 0.001, p < 0.001, respectively). Neopterin did not have adequate predictive value for identifying those in the PCG (area under the curve [AUC] = 0.534; 95% CI, 0.463–0.605; p = 0.4256); sCD14 also had poor predictive value but high specificity (100%) for identifying those in the PCG (AUC = 0.627; 95% CI, 0.556–0.694; p = 0.0036).

Conclusions

While low levels of these two biomarkers were detected among those with the IHIV-1 pattern, they were found in high levels among those in the PCG. These two markers obviously cannot be used as a sceening test because they have low sensitivies. Taken together, we suggest that neopterin and sCD14 may be helpful because they both have high specificity (92%-100%) as indirect non-specific markers for predicting the immune activation status of individuals, whether or not they have true positive HIV-1.

Tryptophan depletion in context of the inflammatory and general nutritional status of a low-income South African HIV-infected population

BACKGROUND

The essential amino acid tryptophan cannot be synthesised in the body and must be acquired through dietary intake. Oxidation of tryptophan, due to immune induction of the enzyme indoleamine 2,3-dioxygenase (IDO), is considered to be the main cause of tryptophan depletion in HIV infection and AIDS. We examined plasma tryptophan levels in a low-income sub-Saharan HIV-infected population and compared it to that of developed countries. Tryptophan levels were further examined in context of the general nutritional and inflammatory status.

METHODS

This cross-sectional study included 105 HIV-positive patients recruited from the Kalafong Hospital in Pretoria, South Africa, and 60 HIV-negative controls.

RESULTS

Patient tryptophan levels were in general markedly lower than those reported for developed countries. In contrast to reports from developed countries that showed tryptophan levels on average to be 18.8 % lower than their control values, tryptophan levels in our study were 44.1 % lower than our controls (24.4 ± 4.1 vs. 43.6 ± 11.9 μmol/l; p < 0.001). Tryptophan levels correlated with both CD4 counts (r = 0.341; p = 0.004) and with pro-inflammatory activity as indicated by neopterin levels (r = -0.399; p = 0.0001). Nutritional indicators such as albumin and haemoglobin correlated positively with tryptophan and negatively with the pro-inflammatory indicators neopterin, interleukin 6 and C-reactive protein. The most probable causes of the lower tryptophan levels seen in our population are food insecurity and higher levels of inflammatory activity.

CONCLUSIONS

We contend that inflammation-induced tryptophan depletion forms part of a much wider effect of pro-inflammatory activity on the nutritional profile of HIV-infected patients.

Correlation of (1→3)-β-D-glucan with other inflammation markers in chronically HIV infected persons on suppressive antiretroviral therapy

We evaluated associations between levels of BDG and other biomarkers of inflammation in blood from 41 virologically suppressed persons with chronic HIV-infection. We found a significant correlation between BDG and neopterin levels (r=0.68), and trends to significance for correlations with other inflammation markers (tumor-necrosis-factor-α: r=0.30; interleukin-8: r=0.30; interleukin-6: r=0.28). In conclusion, BDG levels correlated with inflammation markers in a cohort of virologically suppressed individuals with chronic HIV infection. Future studies are needed to evaluate whether BDG may be a marker for morbidity in chronic HIV infection.

Plasma Levels of Neopterin and C-Reactive Protein (CRP) in Tuberculosis (TB) with and without HIV Coinfection in Relation to CD4 Cell Count

Background

While the risk of TB is elevated in HIV-positive subjects with low CD4 cell counts, TB may in itself be associated with CD4 lymphocytopenia. We investigated markers of immune activation (neopterin) and inflammation (CRP) in TB patients with and without HIV coinfection and their association with CD4 cell levels, and determined their predictive capacity as alternative markers of advanced immunosuppression.

Methods

Participants selected from a cohort of adults with TB at Ethiopian health centers (195 HIV+/TB+, 170 HIV-/TB+) and 31 controls were tested for plasma levels of neopterin and CRP. Baseline levels of neopterin and CRP were correlated to CD4 cell count before and after anti-TB treatment (ATT). The performance to predict CD4 cell strata for both markers were investigated using receiver operating curves.

Results

Levels of both biomarkers were elevated in TB patients (neopterin: HIV+/TB+ 54 nmol/l, HIV-/TB+ 23 nmol/l, controls 3.8 nmol/l; CRP: HIV+/TB+ 36 μg/ml, HIV-/TB+ 33 μg/ml, controls 0.5 μg/ml). Neopterin levels were inversely correlated (-0.53, p<0.001) to CD4 cell count, whereas this correlation was weaker for CRP (-0.25, p<0.001). Neither of the markers had adequate predictive value for identification of subjects with CD4 cell count <100 cells/mm³ (area under the curve [AUC] 0.64 for neopterin, AUC 0.59 for CRP).

Conclusion

Neopterin levels were high in adults with TB, both with and without HIV coinfection, with inverse correlation to CD4 cell count. This suggests that immune activation may be involved in TB-related CD4 lymphocytopenia. However, neither neopterin nor CRP showed promise as alternative tests for immunosuppression in patients coinfected with HIV and TB.

Immune activation in the course of HIV-1 infection: Causes, phenotypes and persistence under therapy

Systemic immune activation is a striking consequence of HIV-1 infection. Even in virologically suppressed patients, some hyperactivity of the immune system and even of the endothelium and of the coagulation pathway may persist. Apart from immune deficiency, this chronic activation may contribute to various morbidities including atherothrombosis, neurocognitive disorders, liver steatosis and osteoporosis, which are currently main challenges. It is therefore of major importance to better understand the causes and the phenotypes of immune activation in the course of HIV-1 infection. In this review we will discuss the various causes of immune activation in HIV-1 infected organisms: the presence of the virus together with other microbes, eventually coming from the gut, CD4+ T cell lymphopenia, senescence and dysregulation of the immune system, and/or genetic factors. We will also describe the activation of the immune system: CD4+ and CD8+ T cells, B cells, NKT and NK cells, dendritic cells, monocytes and macrophages, and neutrophils of the inflammation cascade, as well as of the endothelium and the coagulation system. Finally, we will see that antiretroviral therapy reduces the hyperactivity of the immune and coagulation systems and the endothelial dysfunction, but often does not abolish it. A better knowledge of this phenomenon might help us to identify biomarkers predictive of non AIDS-linked comorbidities, and to define new strategies aiming at preventing their emergence.

The kynurenine pathway activities in a sub-Saharan HIV/AIDS population

BACKGROUND

Tryptophan is an essential amino acid for the synthesis of proteins and important metabolites such as serotonin, melatonin, tryptamine and niacin. After protein synthesis, more than 90 % of tryptophan catabolism occurs along the kynurenine pathway. The inflammation-inducible enzyme indoleamine 2,3 dioxygenase (IDO) is responsible for the first rate-limiting step in the kynurenine pathway, i.e., oxidation of tryptophan to kynurenine. Excessive IDO activity in conditions such as HIV/AIDS may lead to tryptophan depletion and accumulation of metabolites downstream from kynurenine. Little is known about the kynurenine pathway of HIV/AIDS patients in sub-Saharan regions. This study, in a low income sub-Saharan HIV/AIDS population, examined the effects of activities in the kynurenine pathway on plasma levels of tryptophan, kynurenine and the neurotoxin quinolinic acid, and on de novo synthesis of nicotinamide.

METHODS

Plasma samples were obtained from a cohort of 105 HIV patients and 60 controls. Kynurenine pathway metabolites were analysed using gas chromatography - mass spectrometry. ELISA and flow cytometry were used to assess plasma inflammatory markers.

RESULTS

IDO activity, depletion of tryptophan, as well as accumulation of kynurenine and the neurotoxin quinolinic acid, were not only significantly greater in the patients than in the controls, but also markedly greater than in HIV/AIDS patients from developed countries. Tryptophan levels were 12.3 % higher, kynurenine levels 16.2 % lower, quinolinic acid levels 43.2 % lower and nicotinamide levels 27,2 % lower in patients on antiretroviral treatment than in antiretroviral-naïve patients. Patients' kynurenine pathway metabolites correlated with the levels of inflammatory markers, including that of the major IDO-inducer, interferon-gamma. Indications are that the rate of de novo synthesis of nicotinamide in the kynurenine pathway correlates with increases in quinolinic acid levels up to a point where saturation of the enzyme quinolinate phosphoribosyl transferase occurs.

CONCLUSIONS

Higher levels of inflammatory activity in this low income sub-Saharan HIV/AIDS population than in patients from developed countries lead to greater tryptophan depletion and greater accumulation of metabolites downstream from tryptophan with quinolinic acid levels often reaching levels associated with the development of HIV/AIDS-associated neurocognitive dysfunction. De novo synthesis of nicotinamide from quinolinic acid contributes to the maintenance of nicotinamide, and by implication NAD levels, in HIV/AIDS patients from low income populations. Antiretroviral treatment partially corrects disturbances in the kynurenine pathway.

A non-specific biomarker of disease activity in HIV/AIDS patients from resource-limited environments

BACKGROUND

A general non-specific marker of disease activity that could alert the clinician and prompt further investigation would be of value in patients with HIV/AIDS, especially in resource limited environments.

OBJECTIVE

To investigate the potential of neopterin as non-specific biomarker in patients with advanced HIV/AIDS.

METHODS

Cross-sectional study in 105 HIV positive patients (75 on highly active antiretroviral treatment (HAART). Neopterin was assessed by enzyme linked immune-absorbent assay and cytokines by flow cytometry.

RESULTS

Neopterin levels were significantly higher (p<0.001) for the total patient than for the control group. Significant correlations between neopterin and plasma indicators of inflammation showed neopterin to be a good indicator of active inflammatory status and of the effect of HAART on the immune system. Neopterin was superior to C-reactive protein and to individual cytokines as indicator of immune deficiency. Increased neopterin levels were associated with a decline in albumin, haemoglobin and the albumin/globulin ratio, and with increases in red cell distribution width.

CONCLUSIONS

Plasma neopterin is a good non-specific biomarker of disease activity in HIV/AIDS patients. It is a good indicator of inflammatory activity, perpetuation of inflammation-associated co-morbidities, degree of immune deficiency and has predictive value for underlying disease, and for monitoring the HAART response.

Evaluation of Non-Viral Surrogate Markers as Predictive Indicators for Monitoring Progression of Human Immunodeficiency Virus Infection: An Eight-Year Analysis in a Regional Center

Suitable methods for clinical monitoring of HIV-infected patients are crucial in resource-poor settings. Demographic data, clinical staging, and laboratory findings for 112 asymptomatic subjects positive for HIV were assessed at the first admission and the last visit from 2002 to 2010. Cox regression analysis showed hemoglobin (Hb) (HR = 0.643, P = 0.021) to be a predictive indicator for disease progression, while CD4, CD8, and platelet counts showed low HRs, despite having significant probability values. Hb and total lymphocyte count (TLC) rapidly declined from stage II to III (10.9 and 29.6%, respectively). Reduced CD4 and platelet counts and Hb during stage I were associated with disease progression, and TLC was correlated with CD4 counts at the last follow-up (P < 0.001). However, WHO TLC cutoff of 1,200 cell/mm(3) had 26.1% sensitivity and 98.6% specificity. ROC curve analysis suggested that a TLC cutoff of 1,800 cell/mm(3) was more reliable in this region. Statistical analysis and data mining findings showed that Hb and TLC, and their rapid decline from stage II to III, in addition to reduced platelet count, could be valuable markers for a surrogate algorithm for monitoring of HIV-infected subjects and starting anti-viral therapy in the absence of sophisticated detection assays.

Utility of Serum Neopterin and Serum IL-2 Receptor Levels to Predict Absolute CD4 T Lymphocyte Count in HIV Infected Cases

A prospective study was carried out to evaluate the efficacy of serum neopterin and soluble IL-2 receptor (sIL-2R) concentrations in comparison to CD4 count to study the progression of HIV disease and monitor response to ART in HIV cases. One hundred newly diagnosed HIV seropositive subjects were recruited. CD4 counts were determined by FACS system. Serum neopterin and sIL-2R levels were measured using enzyme immunoassay. In our study, levels of neopterin and sIL-2R were significantly higher in subjects with CD4 <200 cells/ μ L (with S. neopterin levels of >25.1 nmol/L and sIL-2R levels of >47.1 pM as cutoff values for CD4 <200 cells/ μ L) compared to those in subjects with CD4 >200 cells/ μ L at baseline which indicate that these markers can be utilized for initiation of ART in HIV cases. The levels of these markers decreased significantly after initiation of ART. In patients with CD4 >200 cells/ μ L, these markers are helpful in predicting disease progression.

Approach to cerebrospinal fluid (CSF) biomarker discovery and evaluation in HIV infection

Central nervous system (CNS) infection is a nearly universal facet of systemic HIV infection that varies in character and neurological consequences. While clinical staging and neuropsychological test performance have been helpful in evaluating patients, cerebrospinal fluid (CSF) biomarkers present a valuable and objective approach to more accurate diagnosis, assessment of treatment effects and understanding of evolving pathobiology. We review some lessons from our recent experience with CSF biomarker studies. We have used two approaches to biomarker analysis: targeted, hypothesis-driven and non-targeted exploratory discovery methods. We illustrate the first with data from a cross-sectional study of defined subject groups across the spectrum of systemic and CNS disease progression and the second with a longitudinal study of the CSF proteome in subjects initiating antiretroviral treatment. Both approaches can be useful and, indeed, complementary. The first is helpful in assessing known or hypothesized biomarkers while the second can identify novel biomarkers and point to broad interactions in pathogenesis. Common to both is the need for well-defined samples and subjects that span a spectrum of biological activity and biomarker concentrations. Previously-defined guide biomarkers of CNS infection, inflammation and neural injury are useful in categorizing samples for analysis and providing critical biological context for biomarker discovery studies. CSF biomarkers represent an underutilized but valuable approach to understanding the interactions of HIV and the CNS and to more objective diagnosis and assessment of disease activity. Both hypothesis-based and discovery methods can be useful in advancing the definition and use of these biomarkers.

HIV-1 is not a major driver of increased plasma IL-6 levels in chronic HIV-1 disease

OBJECTIVE

Increased plasma IL-6 levels have been associated with HIV-1 disease progression risk, yet the drivers of IL-6 production in HIV-1 infection are not known. This study was designed to explore the relationship between HIV-1 replication and IL-6 induction.

DESIGN

Correlations between plasma levels of IL-6 and HIV-1 RNA were examined in 2 clinical studies. To more directly assess the induction of IL-6 by HIV-1, several cell and tissue types that support HIV-1 replication in vivo were infected with HIV-1, and expression of IL-6 was measured.

METHODS

Spearman rank correlations were used to examine the relationship between plasma levels of IL-6 and HIV-1 RNA. Macrophages and colonic and lymph node histocultures were infected with HIV-1 or stimulated with bacterial products, lipopolysaccharide (LPS) or flagellin, and IL-6 levels in supernatant were measured by enzyme-linked immunosorbent assay or multiplex bead assay.

RESULTS

In the clinical studies, there was weak or no correlation between plasma levels of IL-6 and HIV-1 RNA, but IL-6 levels were correlated with plasma levels of the LPS coreceptor CD14. Macrophages stimulated with LPS or flagellin showed robust production of IL-6, but there was no increase in IL-6 production after HIV-1 infection. IL-6 expression was not increased in lymph node histocultures obtained from HIV-1-infected subjects nor after productive HIV-1 infection of colonic or lymph node histocultures ex vivo.

CONCLUSIONS

We find no evidence that HIV-1 replication is an important driver of IL-6 expression in vivo or in in vitro systems.

Cognitive impairment in HIV infection is associated with MRI and CSF pattern of neurodegeneration

BACKGROUND AND PURPOSE

Biomarkers as indicators for the progression of human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain still elusive. We performed a cross-sectional study to analyze the correlation between cognitive impairment, abnormalities in magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) markers of neurodegeneration in HIV-infected patients.

METHODS

We enrolled 94 patients (82 men and 12 women; mean age 45 ± 10 years) with HIV infection, but without opportunistic infections of the CNS. All patients underwent MRI and CSF analysis. The global pattern of white matter signal intensity abnormalities, the index of atrophy, the severity of periventricular white matter abnormalities, and the severity of basal ganglia signal changes were analyzed. We measured CSF markers of neurodegeneration (total tau, phospho-tau, beta-amyloid). The findings of this evaluation were correlated with demographic and infection parameters of the patients in blood and CSF.

RESULTS

We found a highly significant correlation between the severity of global brain atrophy, basal ganglia signal changes, and cognitive impairment in HIV-infected patients. Furthermore, cognitive impairment was significantly correlated with total tau, but not with phospho-tau or A-beta-amyloid in CSF analysis.

CONCLUSIONS

Our results confirm the significant correlation between MRI changes and cognitive impairment in HIV infection. Furthermore, we could show that global brain atrophy and signal changes in basal ganglia are the typical MRI pattern in HAND. The correlation between cognitive impairment and total tau, but not phospho-tau, supports the hypothesis that HAND are not a subtype of Alzheimer's dementia.

Are plasma biomarkers of immune activation predictive of HIV progression: a longitudinal comparison and analyses in HIV-1 and HIV-2 infections?

Background

Chronic immune activation is a hallmark of HIV infection and has been associated with disease progression. Assessment of soluble biomarkers indicating immune activation provide clues into pathogenesis and hold promise for the development of point-of-care monitoring of HIV in resource-poor-settings. Their evaluation in cohort resources is therefore needed to further their development and use in HIV research.

Methodology/Principal Findings

Longitudinal evaluation of βeta-2 microglobulin (β-2 m), neopterin and suPAR soluble urokinase-type plasminogen activator receptor (suPAR) was performed with archived plasma samples to predict disease progression and provided the first direct comparison of levels in HIV-1 and HIV-2 infections. At least 2095 samples from 137 HIV-1 and 198 HIV-2 subjects with starting CD4% of ≥28 and median follow up of 4 years were analysed. All biomarkers were correlated negatively to CD4% and positively to viral load and to each other. Analyses in subjects living for ≥5 years revealed increases in median β-2 m and neopterin and decreases in CD4% over this period and the odds of death within 5 years were positively associated with baseline levels of β-2 m and neopterin. ROC analyses strengthened the evidence of elevation of biomarkers in patients approaching death in both HIV-1 and HIV-2 infections. Regression models showed that rates of biomarker fold change accelerated from 6–8 years before death with no significant differences between biomarker levels in HIV-1 and HIV-2 at equal time points prior to death.An ‘immune activation index’ analysis indicative of biomarker levels at equivalent viral loads also showed no differences between the two infections.

Conclusions/Significance

Our results suggest that β-2 m and neopterin are useful tools for disease monitoring in both HIV-1 and HIV-2 infections, whereas sUPAR performed less well. Levels of immune activation per amount of virus were comparable in HIV-1 and HIV-2 infected subjects.

Cumulative exposure to stimulants and immune function outcomes among HIV-positive and HIV-negative men in the Multicenter AIDS Cohort Study

We examined associations between stimulant use (methamphetamine and cocaine) and other substances (nicotine, marijuana, alcohol and inhaled nitrites) with immune function biomarkers among HIV-seropositive (HIV +) men taking highly active antiretroviral therapy (ART) and HIV-seronegative (HIV-) men in the Multicenter AIDS Cohort Study. Among HIV + men, cumulative adherence to ART (4.07, 95% confidence interval [CI]: 3.52, 4.71, per 10 years of adherent ART use), and recent cohort enrolment (1.38; 95% CI: 1.24, 1.55) were multiplicatively associated with increase in CD4+/CD8+ ratios. Cumulative use of methamphetamine (0.93; 95% CI: 0.88, 0.98, per 10 use-years), cocaine (0.93; 95% CI: 0.89, 0.96, per 10 use-years) and cumulative medical visits (0.99; 95% CI: 0.98, 0.99, per 10 visit-years), each showed small negative associations with CD4+/CD8+ ratios. Among HIV- men, cumulative medical visits (0.996; 95% CI: 0.993, 0.999), cumulative number of male sexual partners (0.999; 95% CI: 0.998, 0.9998, per 10 partner-years) and cigarette pack-years (1.10; 95% CI: 1.02, 1.18, per 10 pack-years) were associated with CD4+/CD8+ ratios over the same period. ART adherence is associated with a positive immune function independent of stimulant use, underscoring the influence of ART on immune health for HIV+ men who engage in stimulant use.

IL-6-independent association of elevated serum neopterin levels with prevalent frailty in community-dwelling older adults

BACKGROUND

neopterin is a monocyte/macrophage-derived immune activation marker and its levels increase with age. Frailty is an important clinical syndrome of old age. Previous studies have shown significant association between elevated interleukin-6 (IL-6) levels and frailty. The objective of this study was to evaluate IL-6-independent association of serum neopterin levels with prevalent frailty.

METHODS

this is a cross-sectional study in community-dwelling older adults recruited from residential and retirement communities in Baltimore, MD, USA. Frailty was determined using validated screening criteria. Serum neopterin and IL-6 levels were measured using standard enzyme-linked immunosorbent assay. Pearson correlation and multivariate linear regression analysis was performed to assess the relationship between log(neopterin) and log(IL-6). Odds ratios (ORs) for frailty were calculated using log(neopterin) and log(IL-6) as continuous measures and across tertiles of neopterin and IL-6 levels, adjusting for age, race, sex, education and body mass index.

RESULTS

one hundred and thirty-three individuals with a mean age of 84 years (range 72-97) completed the study. Neopterin levels were significantly higher in frail older adults than those in non-frail controls [median: 8.94 versus 8.35 nM, respectively, P < 0.001 t-test on log(neopterin)]. Log(neopterin) was significantly associated with prevalent frailty, adjusting for log(IL-6). Participants in the top tertile of neopterin had OR of 3.80 [95% confidence interval (CI) = 1.36-10.6, P < 0.01] for frailty. As expected, participants in the top tertile of IL-6 had OR of 3.29 (95% CI = 1.21-7.86, P < 0.05) for frailty. Log(neopterin) correlated with log(IL-6) (correlation coefficient = 0.19, P < 0.05). Moreover, OR for participants in the top neopterin tertile remained significant after adjusting for IL-6 (OR = 3.97, 95% CI = 1.15-13.72, P < 0.05).

CONCLUSION

elevated neopterin levels had IL-6-independent association with prevalent frailty, suggesting potential monocyte/macrophage-mediated immune activation in the frail elderly.

Resumption of HIV replication is associated with monocyte/macrophage derived cytokine and chemokine changes: results from a large international clinical trial

BACKGROUND

There is increasing interest in the role of immune activation and inflammation in HIV disease, but data on direct effects of HIV replication on immune cell activation are limited.

METHODS

High sensitivity multiplex bead array assays (MBAAs) were used to measure changes in plasma cytokines and chemokines [interleukin (IL)-1β, IL-2, IL-6, IL-7, IL-8, IL-12p70, IL-17, tumor necrosis factor-α (TNFα), interferon-γ, granulocyte macrophage colony-stimulating factor, IL-4, IL-5, IL-10, IL-13, CXCL10] from randomization (month 0) to month 2 in a random sample of 200 patients from both the drug conservation (DC) and viral suppression (VS) arms of the Strategies for Management of Antiretroviral Therapy (SMART) trial. IL-6 was also measured by ELISA. Data were evaluated using nonparametric correlation and censored parametric analysis of covariance and associations were declared as statistically significant when the Bonferroni-adjusted P-value was less than 0.003.

RESULTS

Compared with the VS arm, significant increases were seen in the DC arm for TNFα (+0.34 log(e) pg/ml, P = 0.0001), IL-10 (+0.33 log(e) pg/ml, P = 0.00001) and CXCL10 (+0.66 log(e) pg/ml, P = 0.00001). IL-6 ELISA poorly correlated with IL-6 MBAA (Spearman's rho = 0.29, P = 0.0001).

CONCLUSION

Resumption of HIV replication after ceasing antiretroviral therapy is associated predominantly with an increase of monocyte/macrophage-derived cytokines. Measurement of IL-6 levels may be affected by assay method and this should be considered in future studies of biomarkers.

Minocycline fails to modulate cerebrospinal fluid HIV infection or immune activation in chronic untreated HIV-1 infection: results of a pilot study

BACKGROUND

Minocycline is a tetracycline antibiotic that has been shown to attenuate central nervous system (CNS) lentivirus infection, immune activation, and brain injury in model systems. To initiate assessment of minocycline as an adjuvant therapy in human CNS HIV infection, we conducted an open-labelled pilot study of its effects on cerebrospinal fluid (CSF) and blood biomarkers of infection and immune responses in 7 viremic subjects not taking antiretroviral therapy.

RESULTS

There were no discernable effects of minocycline on CSF or blood HIV-1 RNA, or biomarkers of immune activation and inflammation including: CSF and blood neopterin, CSF CCL2, CSF white blood cell count, and expression of cell-surface activation markers on CSF and blood T lymphocytes and monocytes.

CONCLUSIONS

This pilot study of biological responses to minocycline suggests little potential for its use as adjunctive antiviral or immunomodulating therapy in chronic untreated HIV infection.

Serum neopterin levels as a diagnostic marker of hemophagocytic lymphohistiocytosis syndrome

The objective of this study was to retrospectively evaluate the utility of serum neopterin as a diagnostic marker of hemophagocytic lymphohistiocytosis (HLH). The medical records of patients diagnosed with HLH (familial and secondary) between January 2000 and May 2009 were reviewed retrospectively, and clinical and laboratory information related to HLH criteria, in addition to neopterin levels, was recorded. A group of 50 patients with active juvenile dermatomyositis (JDM) (who routinely have neopterin levels assessed) served as controls for the assessment of the accuracy, sensitivity, and specificity of neopterin as a diagnostic test for HLH. The Pearson correlation was used to measure the association between serum neopterin levels and established HLH-related laboratory data. Serum neopterin levels were measured using a competitive enzyme immunoassay. During the time frame of the study, 3 patients with familial HLH and 18 patients with secondary HLH were identified as having had serum neopterin measured (all HLH patients were grouped together). The mean neopterin levels were 84.9 nmol/liter (standard deviation [SD], 83.4 nmol/liter) for patients with HLH and 21.5 nmol/liter (SD, 10.13 nmol/liter) for patients with JDM. A cutoff value of 38.9 nmol/liter was 70% sensitive and 95% specific for HLH. For HLH patients, neopterin levels correlated significantly with ferritin levels (r = 0.76, P = 0.0007). In comparison to the level in a control group of JDM patients, elevated serum neopterin was a sensitive and specific marker for HLH. Serum neopterin has value as a diagnostic marker of HLH, and prospective studies are under way to further evaluate its role as a marker for early diagnosis and management of patients.

Soluble biomarkers and morbidity and mortality among people infected with HIV: summary of published reports from 1997 to 2010

PURPOSE OF REVIEW

Published articles from 1997 through May 2010 that reported findings on the relationship of soluble biomarkers with clinical outcomes among people infected with HIV were identified, and studies that examined the incremental value (over that of CD4 cell count and HIV RNA level) that biomarkers had for predicting clinical outcomes were summarized.

RECENT FINDINGS

Over 1500 articles were identified on MEDLINE databases that met selected medical subject heading terms. Thirty-eight met criteria for inclusion in the review. Fifteen of the articles were published since 2008. Most evaluated biomarkers reflecting inflammation and immune activation. For 25 studies, the relationship between the biomarker and all-cause mortality was evaluated. Samples stored in specimen repositories were used for many studies, and those that did not usually focused on biomarkers that are measured as part of routine care. Eight of the reports utilized a case-control design and most of these were nested within a cohort study or a clinical trial.

SUMMARY

Establishing the relationship between a biomarker and a clinical outcome is an important step in biomarker evaluation. To advance research on biomarkers relevant to people with HIV, large studies with long follow-up, carefully documented clinical events, and specimen repositories will be needed.

Microbial translocation in simian immunodeficiency virus (SIV)-infected rhesus monkeys (Macaca mulatta)

BACKGROUND

Chronic immune activation is a hallmark of HIV infection and has been postulated as major factor in the pathogenesis of AIDS. Recent evidence suggests that activation of immune cells is triggered by microbial translocation through the impaired gastrointestinal barrier.

METHODS

To determine the association between microbial translocation and disease progression, we have retrospectively analyzed microbial products, viral load and markers of immune activation in a cohort of 37 simian immunodeficiency virus-infected rhesus monkeys, divided in two groups with distinct disease courses.

RESULTS

As seen in HIV-infected patients, we found elevated levels of lipopolysaccharide (LPS) in infected animals. However, LPS levels or LPS control mechanisms like endotoxin core antibodies or LPS-binding protein did not differ between groups with different disease progression. In contrast, neopterin, a metabolic product of activated macrophages, was higher in fast progressors than in slow progressors.

CONCLUSION

Our data indicate that translocation of microbial products is not the major driving force of immune activation in HIV infection.

Cerebrospinal fluid neopterin: an informative biomarker of central nervous system immune activation in HIV-1 infection

HIV-1 invades the central nervous system (CNS) in the context of acute infection, persists thereafter in the absence of treatment, and leads to chronic intrathecal immunoactivation that can be measured by the macrophage activation marker, neopterin, in cerebrospinal fluid (CSF). In this review we describe our experience with CSF neopterin measurements in 382 untreated HIV-infected patients across the spectrum of immunosuppression and HIV-related neurological diseases, in 73 untreated AIDS patients with opportunistic CNS infections, and in 233 treated patients.

In untreated patients, CSF neopterin concentrations are almost always elevated and increase progressively as immunosuppression worsens and blood CD4 cell counts fall. However, patients with HIV dementia exhibit particularly high CSF neopterin concentrations, above those of patients without neurological disease, though patients with CNS opportunistic infections, including CMV encephalitis and cryptococcal meningitis, also exhibit high levels of CSF neopterin. Combination antiretroviral therapy, with its potent effect on CNS HIV infection and CSF HIV RNA, mitigates both intrathecal immunoactivation and lowers CSF neopterin. However, despite suppression of plasma and CSF HIV RNA to below the detection limits of clinical assays (<50 copies HIV RNA/mL), CSF neopterin often remains mildly elevated, indicating persistent low-level intrathecal immune activation and raising the important questions of whether this elevation is driven by continued CNS infection and whether it causes continued indolent CNS injury.

Although nonspecific, CSF neopterin can serve as a useful biomarker in the diagnosis of HIV dementia in the setting of confounding conditions, in monitoring the CNS inflammatory effects of antiretroviral treatment, and give valuable information to the cause of ongoing brain injury.

Pretreatment levels of soluble cellular receptors and interleukin-6 are associated with HIV disease progression in subjects treated with highly active antiretroviral therapy

BACKGROUND

To identify inflammatory pathways that may contribute to the pathogenesis of human immunodeficiency virus (HIV) disease, we explored associations between AIDS or death and different inflammatory markers, including selected soluble tumor necrosis factor superfamily receptors (sTNFRs) and ligands, interleukin (IL)-6, and CD8 T cell activation, in individuals treated with highly active antiretroviral therapy (HAART).

METHODS

A case-control study of subjects in AIDS Clinical Trials Group (ACTG) protocols 384 and 5015, who were matched according to the CD4 cell count and plasma viral load at baseline, was performed using conditional logistic regression.

RESULTS

Higher pretreatment concentrations of sTNFR-1, sCD27, sCD40L, and plasma IL-6 were associated with a new AIDS-defining illness or death in separate models adjusted for age, sex, hemoglobin, and the latest CD4 cell counts. In additional models that excluded case patients with opportunistic infections, sTNFR-1, sCD27, and sCD40L were each associated with a new AIDS-defining malignancy or death that developed at a median of 51 weeks after initiation of HAART, by which time the majority of subjects had a CD4 cell count of >200 cells/cm(3) and had achieved a plasma viral load of <50 copies/mL.

CONCLUSION

These data are compatible with a model in which these soluble inflammatory markers identify pathways that may contribute to the pathogenesis of HIV disease progression, pathways that might not be a direct consequence of ongoing HIV type 1 replication.

Plasma concentrations of the cardiovascular risk factor asymmetric dimethylarginine (ADMA) are increased in patients with HIV-1 infection and correlate with immune activation markers

OBJECTIVE

Higher concentrations of inflammation and immune activation markers as well as the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) are associated with an increased cardiovascular risk. In vitro, parallel formation of ADMA and macrophage marker neopterin was found in stimulated human peripheral blood mononuclear cells.

METHODS

In 112 HIV-1 infected patients, concentrations of ADMA, SDMA and arginine were compared to C-reactive protein and neopterin concentrations before they were referred to antiretroviral therapy. Disease activity was determined by viral load (qPCR), CD4(+) cell counts (FACS) and neopterin concentrations in plasma and urine (HPLC and ELISA). Additionally, concentrations of lipids were determined.

RESULTS

HIV-1 infected patients presented with increased neopterin, ADMA and SDMA concentrations, whereas CD4(+) counts and arginine and plasma lipid concentrations were low. ADMA and SDMA concentrations significantly correlated with markers of immune activation, but not with plasma lipids.

CONCLUSIONS

Results of this study indicate that increased ADMA and SDMA production may be related to an increased activity of immune activation pathways.

Immunopathogenesis of asymptomatic chronic HIV Infection: the calm before the storm

PURPOSE OF REVIEW

HIV and pathogenic simian immunodeficiency virus infection are characterized by chronic immune activation. This review addresses the factors that influence immune activation and may thus determine the rate of disease progression during the asymptomatic period of HIV.

RECENT FINDINGS

Immune activation stems from foreign antigen stimulation, including HIV, microbial products and coinfections and compensatory homeostatic mechanisms. Continuous immune stimulation creates a permissive environment for further viral replication, while temporarily allowing successful replenishment of the T-cell pool. Type I interferon, microbial translocation, activated (but ineffective) effector T cells, unruly regulatory T cells and inadequate T helper 17 cells all play important roles in the cycle of activation, functional exhaustion and T-cell death that leads to immunodeficiency.

SUMMARY

The asymptomatic chronic phase of HIV infection is a dynamic balance between host and virus, the outcome of which determines an individual's course of disease. Evaluation of the factors that determine the immunologic threshold of disease progression could assist in designing therapeutic strategies, including individualized timing of ART.