Pentraxin 3 as an Immune Recovery Marker in HIV Infection After Combination Antiretroviral Therapy

Abstract

Human immunodeficiency virus (HIV) infection causes chronic inflammation in affected individuals. Chronic inflammation may hinder immunological recovery. Treatment with combination antiretroviral therapy (cART) is insufficient to reduce inflammation. Pentraxin 3 (PTX3) is an inflammatory marker associated with cardiovascular disease, malignancy, and acute infection. This study evaluated the usefulness of serum PTX3 levels in measuring inflammation levels, which may be associated with the probability of immune recovery in people living with HIV (PLH). In this single-center prospective study, we measured serum PTX3 levels in PLH treated with cART. Clinical information on HIV status, type of cART administered, and CD4⁺ and CD8⁺ T cell counts at the initial diagnosis of HIV and at study enrollment was obtained from each participant. PLH were divided into good and poor responder groups according to their CD4⁺ T cell counts at enrollment. A total of 198 PLH were enrolled in this study. A total of 175 and 23 participants were assigned to the good and poor responder groups, respectively. The poor responder group exhibited higher PTX3 levels (0.53 ng/mL vs. 1.26 ng/mL, p = .032). Logistic regression analysis demonstrated that low body mass index [odds ratio (OR) = 0.8, p = .010], low initial CD4⁺ T cell counts at diagnosis (OR = 0.994, p = .001), and high PTX3 levels (OR = 1.545, p = .006) are clinical factors that were significantly associated with poor immune recovery in PLH. According to the Youden index, PTX3 levels >1.25 ng/mL are associated with poor immune recovery. PLH should be clinically, virologically, and immunologically evaluated. Serum PTX level is a useful inflammatory marker associated with immune recovery in PLH treated with cART.

Introduction

Pentraxin 3 (PTX3) is an acute-phase inflammatory biomarker similar to C-reactive protein (CRP) and the serum amyloid P component.¹ PTX3 is expressed in various cells involved in inflammation, is stored in neutrophil-specific granules,^2,3 and has prognostic value in malignancy, dengue virus infection, and leptospirosis.^4,5 Individuals with human immunodeficiency virus (HIV) infection are in a chronic state of inflammation despite the HIV being virologically suppressed. Comorbidities, such as cognitive decline, cardiovascular disease, and thrombotic disease, explain this inflammatory state induced by HIV infection.⁶ We hypothesized that an elevated systemic inflammation in people living with HIV (PLH) is associated with an incomplete reconstitution of CD4⁺ T cells, which are critical for defending the body from various opportunistic infections. To our knowledge, this is the first study to use serum PTX3 levels to assess the probability of immune recovery in PLH.

Methods

Study population

From October 2016 to November 2019, we prospectively enrolled Korean PLH aged ≥18 years who underwent combination antiretroviral therapy (cART) at Severance Hospital, a 2,000-bed tertiary teaching hospital with an HIV research institution in Seoul, South Korea. Written informed consent was obtained from all participants. This study was approved by the Institutional Review Board of Severance Hospital (4-2016-0596).

Study design and definitions

The CD4⁺ and CD8⁺ T cell counts, HIV-RNA titers, and serum PTX3 levels of the participants were measured at enrollment. Information on HIV-related profiles (initial CD4⁺ and CD8⁺ T cell counts and HIV-RNA titers) at the first diagnosis of HIV was retrospectively collected from electronic medical records. Basic clinical information, such as age, sex, weight, waist circumference, body mass index (BMI), underlying medical conditions, and type of cART administered, was collected.

The participants were classified into good and poor responder groups according to their CD4⁺ T cell counts at enrollment. Participants with a CD4⁺ T cell count of >300/μL, which means that they achieved the minimum level of immunologic recovery after undergoing treatment with cART, were classified into the good responder group. Participants with a CD4⁺ T cell count of <300/μL were assigned to the poor responder group. The participants were followed up for 2 years as part of their regular HIV clinic follow-ups.

Measurement of serum PTX3 levels

Each 0.5-cc blood sample was collected in a plasma tube. The samples were centrifuged and stored at −70°C. Serum PTX3 levels were measured using enzyme-linked immunosorbent assays (ELISA) with a TSG-24 ELISA kit (R&D Systems). The ELISA plates were analyzed using a SpectraMax190 plate reader (Molecular Devices; Sunnyvale, CA) at Seoul Clinical Laboratories in Yongin, Republic of Korea.

Statistical analysis

Statistical analysis was performed using Statistical Package for Social Sciences, version 26 (SPSS, Chicago, IL). The data were tested for normality. All values are presented as either the mean ± standard deviation or median with 25th percentile and 75th percentile values Statistical significance was defined as p < .05. Multivariable logistic regression analysis, receiver operating characteristic (ROC) curve analysis, and the Youden index were used to assess PTX3 as an inflammatory marker for immune recovery in PLH. The Youden index is calculated by finding the maximum value using the equation: Sensitivity + Specificity −1.

Results

A total of 198 participants were enrolled in the study, 175 and 23 of whom were classified into the good and poor responder groups, respectively. Table 1 shows a comparison of the baseline characteristics of participants in the two groups. The poor responders had a lower BMI (23.6 kg/m² vs. 21.9 kg/m², p = .024) and no dyslipidemia (24.0% vs. 0%, p = .005). The time from HIV diagnosis to the start of treatment was shorter in the poor responder group (31.0 days vs. 10.5 days, p = .001). The CD4⁺ T cell count at the first HIV diagnosis was lower in the poor responder group (291.4 vs. 150.3/μL, p = .001). PTX3 levels were higher in the poor responder group (0.53 ng/mL vs. 1.26 ng/mL, p = .032).

Table 1.

Baseline Characteristics of the Participants

	HIV-infected patients
	Good response to ART	Poor response to ART	p
	N = 175	N = 23
Baseline characteristic
Age, year	46.3 ± 13.2	44.9 ± 12.6	.626
Male	167 (95.4)	20 (87.0)	.121
Body mass index, kg/m²	23.6 ± 3.5	21.9 ± 2.5	.024
Smoking	78 (48.1)	8 (34.8)	.269
Medical history
Diabetes mellitus	22 (12.6)	1 (4.3)	.485
Hypertension	41 (23.4)	5 (21.7)	>.999
Dyslipidemia	42 (24.0)	0 (0.0)	.005
Chronic kidney disease	4 (2.3)	2 (8.7)	.145
Fatty liver	12 (6.9)	0 (0.0)	.367
Lipid profile
Total cholesterol (mg/dL)	183.0 [160.0, 208.3]	171.0 [142.0, 194.0]	.155
Triglyceride (mg/dL)	161.0 [114.5, 220.5]	132.0 [71.0, 177.0]	.054
LDL-C (mg/dL)	101.8 ± 29.8	101.4 ± 47.2	.969
HDL-C (mg/dL)	46.9 ± 12.3	42.5 ± 11.7	.143
HIV status
Known duration of HIV (days)	3443.6 ± 2240.9	2574.2 ± 2049.1	.079
Treatment duration with cART (days)	2947.3 ± 2029.6	2499.2 ± 1990.0	.320
Time from diagnosis to treatment (days)	31.0 [14.0, 372.0]	10.5 [3.5, 30.0]	.001
CD4⁺ T cell count at the initial diagnosis of HIV (/μL)	291.4 ± 185.0	150.3 ± 152.6	.001
CD4⁺ T cell count at the study enrollment (/μL)	630.4 ± 214.3	203.2 ± 80.2	<.0001
Antiretroviral therapy
Integrase inhibitor	141 (80.6)	20 (87.0)	.579
Nucleoside/nucleotide reverse transcriptase inhibitor	172 (98.3)	22 (95.7)	.148
Non-nucleoside/nucleotide reverse transcriptase inhibitor	20 (11.4)	0 (0.0)	.137
Protease inhibitor	23 (13.1)	7 (30.4)	.056
Pentraxin (ng/mL)	0.53 [0.31, 1.18]	1.26 [0.42, 1.83]	.032

Data are expressed as number (percent), average ± standard deviation, or median [25%, 75%].

p Values with statistical significance are shown in bold text.

cART, combinational antiretroviral therapy; HDL-C, high-density lipoprotein cholesterol; HIV, human immunodeficiency virus; LDL-C, low-density lipoprotein cholesterol.

Table 2 shows the univariable and multivariable logistic regression analyses performed to evaluate the clinical factors associated with poor immune recovery in PLH. The results demonstrate that a low BMI [odds ratio (OR) = 0.8, p = .010], low initial CD4⁺ T cell counts at diagnosis (OR = 0.994, p = .001), and high PTX3 levels (OR = 1.545, p = .006) were significant clinical factors associated with a poor immune recovery in PLH.

Table 2.

Risk Factors Associated with a Poor Immune Recovery in PLH Who Underwent Combination Antiretroviral Therapy

	Univariable		Multivariable
	OR (95% CI)	p	OR (95% CI)	p
Baseline characteristics
Age, years	0.992 (0.959–1.026)	.624
Gender, male	3.131 (0.768–12.769)	.111
Body mass index (kg/m²)	0.836 (0.718–0.974)	.022	0.800 (0.675–0.948)	.010
Underlying conditions
Diabetes mellitus	0.316 (0.041–2.464)	.272
Hypertension	0.908 (0.317–2.596)	.857
Chronic kidney disease	4.071 (0.703–23.590)	.117
Lipid profile
Total cholesterol (mg/dL)	0.992 (0.979–1.004)	.177
Triglyceride (mg/dL)	0.996 (0.991–1.001)	.142
LDL-C (mg/dL)	1.000 (0.985–1.015)	.956
HDL-C (mg/dL)	0.967 (0.924–1.012)	.147
HIV status
Known duration of HIV (days)	1.000 (1.000–1.000)	.082
Treatment duration with cART (days)	1.000 (1.000–1.000)	.320
Time from diagnosis to treatment initiation (days)	0.999 (0.997–1.000)	.149
CD4⁺ T cell count, initial (/μL)	0.994 (0.991–0.998)	.001	0.994 (0.990–0.998)	.001
Pentraxin (ng/mL)	1.355 (1.039–1.766)	.025	1.545 (1.133–2.107)	.006

p Values with statistical significance are shown in bold text.

CI, confidence interval; OR, odds ratio.

The ROC curve for assessing the association between PTX3 and immune recovery was 0.65 (95% confidence interval: 0.512–0.763, p = .032) (Fig. 1). According to the Youden index, PTX3 levels >1.25 ng/mL are associated with poor treatment outcomes. At this threshold, sensitivity and specificity were determined to be 52% and 77%, respectively. In the poor responder group, 12 of the 23 participants continued to exhibit a reduced CD4⁺ T cell count <300/μL at the 2-year follow-up. The pentraxin levels between the 12 participants who continued to show reduced CD4⁺ T cell counts and the remaining 11 participants who showed recovery of CD4⁺ T cell counts above 300/μL were not significantly different. The median CD4⁺ T cell counts of the 12 participants were 231/μL with a 134–288/μL 25%–75% interquartile range.

FIG. 1.

ROC curve analysis of pentraxin for assessing the association between PTX3 and immune recovery. PTX3, pentraxin 3; ROC, receiver operating characteristic.

Discussion

cART significantly enhanced the life expectancy of individuals with HIV infection and reduced the risk of associated comorbidities, but it was ineffective in reducing inflammation. HIV infection leads to selective CD4⁺ T cell depletion, which greatly affects the lymphocytes in the gastrointestinal tract. Bacterial translocation occurs because of the reduced integrity of the mucosal epithelium, which plays a key role in increasing the level of inflammation in PLH.⁶ Chronic infections caused by HIV are associated with accelerated aging and immunosenescence.

In this study, we compared different CD4⁺ T cell recovery levels in PLH who were treated with cART. We set the threshold of CD4⁺ T cells to be 300/μL according to clinical research data from the previous journals. In Mellors et al., CD4⁺ T cell counts lower than 300/μL are associated with poor prognosis, including a shorter time to develop AIDS or death.⁷ In addition, the British HIV Association also pointed out that CD4⁺ T cells below 200–300/μL are associated with increased risks of opportunistic infections.⁸ Some PLH achieved recovery of the CD4⁺ T cell count to a level of those without HIV infection. However, some PLH were unable to recover the number of CD4⁺ T cells.

The poor responder group exhibited a lower BMI and lower initial CD4⁺ T cell count at the time of HIV diagnosis. The low BMI in the poor responder group is indicative of HIV-associated cachexia.⁹ A low initial CD4⁺ T cell count at HIV diagnosis is another known risk factor for poor immune recovery in PLH.^10,11 We evaluated whether an elevated level of inflammation is associated with poor immune recovery in PLH who were treated with cART, in addition to analyzing previously known risk factors, such as old age and low CD4⁺ T cell counts at HIV diagnosis.¹²

Saracino et al. measured the level of inflammation using conventional inflammatory markers, such as interleukin-6, hs-CRP, and D-dimer.¹³ However, these inflammatory markers were unremarkable when comparing the group that did not achieve a normalized CD4:CD8 ratio with the group that did achieve a normalized CD4:CD8 ratio. In this study, we used serum PTX3 levels to identify PLH with elevated inflammation levels that were associated with recovery of CD4⁺ T cell counts. The poor responder group exhibited higher PTX3 levels, which demonstrates that greater inflammation may be associated with delayed immune recovery. Further studies should be conducted to determine the improvements in CD4⁺ T cell counts following the administration of anti-inflammatory agents. A limitation of this study is the absence of detailed data on the comorbidities of the participants associated with chronic inflammation.

Conclusions

The management of chronic inflammation and the augmentation of the immune function are key to successful HIV treatment in PLH. High serum PTX3 levels may be associated with poor immune recovery of PLH on cART.

Footnotes

Acknowledgment

We would like to thank the Seoul Medical Science Institute for providing technical support.

Authors' Contributions

E.H.L. performed the formal data analysis and validation, as well as the writing, reviewing, and editing of the original draft of the article. J.A.L. performed the data analysis. C.H.K. was involved in the investigation and validation. K.H.L., J.K., J.H.K., J.Y.A., N.S.K., J.Y.C., and J.-S.Y. supervised the project. S.J.J. was involved in the conceptualization, data curation, investigation, project administration, and supervision of the study.

Data Availability Statement

All clinical data are available upon request.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

This study was funded by Handok Inc., Seoul, Republic of Korea (HANDOK 2014-158). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the article.

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