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Abstract

Background:

High prevalence of vitamin D deficiency among HIV-infected individuals has been reported in many studies. Increasing evidence for vitamin D’s role in innate and cell-mediated immunity suggests that vitamin D insufficiency or deficiency is worrisome particularly for HIV-infected individuals who are already at increased risk of infection. It is unknown whether vitamin D deficiency and supplementation will have any effects on HIV infection, including CD4 counts/CD4% and HIV plasma RNA.

Method:

Serum vitamin D levels, 25-hydroxyvitamin D (25-(OH)D), were obtained from 160 HIV-infected youth, aged 2 to 26 years as part of routine care. The HIV plasma RNA and CD4 counts were compared between patients with normal vitamin D and vitamin D insufficiency/deficiency. Individuals whose vitamin D level was ≤35 ng/mL received vitamin D₃ supplementation. We compared the HIV plasma RNA, absolute CD4 counts, and CD4% in pre– and post–vitamin D supplementation. Categorical comparisons between the groups were examined using a nonparametric Fisher exact test, while continuous variables, pre– and post–vitamin D supplementation, were examined using a parametric paired samples t test.

Results:

The majority (152 of 160; 95%) of our patients were African American. Only 8 (5%) of 160 had normal vitamin D. Of the 160 patients with HIV, 37 (23.1%) had vitamin D insufficiency (25-(OH)D level between 21 and 35 ng/mL) and 11 of 160 (71.9%) had vitamin D deficiency (25-(OH)D level ≤20 ng/mL). Absolute CD4 counts averaged lower in patients who have severe vitamin D deficiency (25-(OH)D ≤10 ng/mL; mean 574.41 ± 306.17 cells/mm³) compared to those who had higher vitamin D level (mean 701.15 ± 444.19 cells/mm³). The CD4% were also lower (mean 25.12% ± 12.5%) in those who have severe vitamin D deficiency compared to those whose vitamin D level was ≥11 ng/mL (mean 29.47% ± 11.62%). The HIV plasma RNA was similar in all the groups. Our patients who were prescribed tenofovir (TDF) and/or efavirenz (EFV) did not have different vitamin D levels than patients who were prescribed other antiretroviral (ARV) medications. Only 60 (39.5%) of the 152 patients who received vitamin D supplement showed improvement in vitamin D level. Of the 60 patients, 10 (16.7%) had normalized vitamin D level (25-(OH)D level > 35 ng/mL). We did not see any significant change in the absolute CD4 counts or CD4%.

Conclusions:

A higher prevalence of vitamin D insufficiency/deficiency was found in our study compared to the previous large cohorts. However, patients who were prescribed TDF/EFV did not have lower vitamin D levels. Inadequate sunlight exposure in temperate latitudes and the cloud effect of the Great Lakes as well as large number of African American participants who live in the inner city area with poverty and poor diet may combine to explain these results. The effect of ARV medications on vitamin D may be washed out by the numerous other factors affecting vitamin D in our patients. Severe vitamin D deficiency seemed to be related to lower CD4 counts and CD4% but not related to HIV plasma RNA. Vitamin D supplementation did not increase CD4 counts/CD4% in our study.

Keywords

vitamin D insufficiency vitamin D deficiency CD4 counts HIV viral load HIV inner city

Introduction

A high prevalence of vitamin D insufficiency/deficiency in HIV-infected individuals has been reported in many cohort studies.¹ The Study to Understand the Natural History of HIV and AIDS in the ERA of Effective Therapy from the US Centers for Disease Control and Prevention reported that 72% of a large cohort (n = 672) of HIV-infected individuals have vitamin D insufficiency.² The prevalence of low vitamin D level in HIV-infected individuals was reported as 61% (n = 856) in Italy and 92% (n = 1077) in England.^3,4 It is of interest, however, that in at least 2 studies in the United States^2,5 the prevalence of vitamin D insufficiency/deficiency was similar in the general population.

Antiretroviral therapy for HIV is well known to affect vitamin D metabolism. Protease inhibitors are known to inhibit 25-hydroxylase and 1-α-hydroxylase, the major enzymes in vitamin D metabolism, in a reversible and dose-dependent manner. This can lead to decrease in active vitamin D (1,25-dihydroxyvitamin D [1,25-(OH)₂D₃]) production.⁶ Nonnucleoside reverse transcriptase inhibitor efavirenz (EFV) induces 24-hydroxylase enzyme to metabolize active vitamin D to its inactive form, 24,25-dihydroxyvitamin D, and is associated with vitamin D deficiency.^2,7 Probably, the most problematic is the nucleoside inhibitor tenofovir (TDF), which increases phosphate loss from proximal renal dysfunction and increases median parathyroid hormone level.^8,9 This can worsen osteomalacia, particularly in HIV-infected individuals whose vitamin D is insufficient. This is particularly problematic in young persons with HIV who may be looking at a prolonged burden of medication toxicity and, often, have poor dietary habits.

We sought to not only learn the prevalence of vitamin D deficiency in our population of young persons with HIV who are predominantly dark skinned in a low sunlight area (Detroit, Michigan) but also learn whether vitamin D supplementation in HIV improves the disease markers, particularly HIV plasma RNA, CD4 counts, and CD4%, in those HIV-infected patients with low vitamin D level.

Method

Serum vitamin D levels (25-hydroxyvitamin D; 25-(OH)D) were obtained from 160 HIV-infected patients, aged 2 to 26 years during a clinic visit in 2010 to 2011 as part of routine care. The study was a retrospective study (chart review) of vitamin D in HIV-infected children and youth. All HIV-infected patients in our clinic were eligible. The vitamin D levels ≤20 ng/mL were considered as vitamin D deficiency. The levels between 21 and 35 ng/mL were considered as vitamin D insufficiency. The HIV plasma RNA, absolute CD4 counts, and CD4% were evaluated at the same time and compared between patients with normal vitamin D and low vitamin D. Antiretroviral (ARV) medications prescribed, race, gender, and season that the vitamin D levels were obtained were all recorded and compared using SPSS (Version 20.0; IBM Corp, Armonk, New York).

All the patients whose vitamin D level was ≤35 ng/mL received vitamin D₃ supplementation as part of routine care (cholecalciferol 1000 units/day).^10,11 The dosing was referenced from the European AIDS Clinical Society as 800 to 2000 units/day. The vitamin D level was repeated every 3 months. We compared the HIV plasma RNA, absolute CD4 counts, and CD4% in pre– and post–vitamin D supplementation. The study was approved by the institutional review board of Wayne State University/Children’s Hospital of Michigan.

Statistical Analyses

Continuously scaled data were reported as mean, standard deviation, median, and interquartile range values. Categorically scaled variables were reported using proportions and ratios. Categorical comparisons between the groups were examined using a nonparametric Fisher's exact test, while continuous variables, pre– and post–vitamin D supplementation, were examined using a parametric paired samples t test. If assumptions of normality were violated, a nonparametric Wilcoxon Sum Rank test was substituted. Statistically significant differences were considered achieved at a P value of ≤.05, 2-tailed. All statistical procedures were conducted using IBM SPSS version 20.0.

Results

Demographic Data

Of the 160 participants, 122 (76.3%) were male and 38 (23.7%) were female. The majority (152 of 160; 95%) of our patients were African American. Of the 160 patients, 5 (3%) were caucasian and 3 (2%) were of mixed ethnicity. Of 160 patients, 75 (46.9%) were aged 21 to 26 years, 72 (45%) were aged 11 to 20 years, and 13 (8.1%) were aged ≤10 years. Of the 160 participants, 45 (28.1%) were not prescribed ARV medication, 67 (41.9%) were prescribed regimens containing TDF and/or EFV, and 48 (30%) were prescribed ARV medications other than TDF and/or EFV. Overall, 39 (24.4%) participants had undetectable HIV plasma RNA (see Table 1).

Table 1.

Demographic Data.

Characteristic	No. (N = 160)	%
Gender, male	122	76.3
Race
African American	152	95
Caucasian	5	3
Mixed ethnicity	3	2
Age, year
≤10	13	8.1
11-20	72	45
21-26	75	46.9
ARV medication
Prescribed tenofovir and/or efavirenz	67	41.9
Other ARV medications	48	30
No ARV medication prescribed	45	28.1
Undetectable HIV plasma RNA	39	24.4

Abbreviation: ARV, antiretroviral.

Vitamin D Level

Of the 160 HIV-infected patients, 37 (23.1%) had vitamin D insufficiency (25-(OH)D level between 21 and 35 ng/mL) and 115 (71.9%) had vitamin D deficiency (25-(OH)D level ≤20 ng/mL). Only 8 (5%) of the 160 patients had normal vitamin D level (25-(OH)D level ≥36 ng/mL). Of the 160 patients, 31 (19.4%) had severe vitamin D deficiency (25-(OH)D level ≤10 ng/mL). Vitamin D levels were lower during the winter months (November through February) than those of other months with more sunlight exposure (March through October), but the difference was insignificant. The HIV-infected children, aged ≤10 years, had higher vitamin D level (mean 24.8 ng/mL) compared to young adults, aged between 21 and 26 years, (mean 17.6 ng/mL) and adolescent, aged between 11 and 20 years, (mean 16.9 ng/mL). African American individuals had lower vitamin D level (mean 17.8 ng/mL) compared to caucasian (mean 24.2 ng/mL). Vitamin D levels were not different among gender.

Antiretroviral Medications and Vitamin D Level

Of 160 patients, 67 (41.9%) were prescribed TDF- and/or EFV-containing regimens. Of the 67 patients, 38 (56.7%) who were prescribed TDF and/or EFV had HIV plasma RNA <1000 copies/mL (utilized as a surrogate marker for adherence with medication). In our study, these patients had mean vitamin D level of 20.3 ± 18.1 ng/mL, compared to those who were prescribed TDF and/or EFV but had HIV plasma RNA >1000 copies/mL (29 of 160, 18.1%; mean 14.4 ± 6.5 ng/mL, P value .49) and those who were not on ARV medications (45 of 160, 28.1%; mean 14.6 ± 7.3 ng/mL, P value .37). Patients who were prescribed other ARV medications not containing TDF and/or EFV had mean vitamin D level of 21.2 ± 16.8 ng/mL, but the differences between the groups are not statistically significant (P value 1.0).

Vitamin D Level, CD4, and HIV plasma RNA

Absolute CD4 counts averaged lower in patients who have severe vitamin D deficiency (25-(OH)D ≤10 ng/mL; mean absolute CD4 count 574.41 ± 306.17 cells/mm³) compared to those who had higher vitamin D level (mean absolute CD4 count 701.15 ± 444.19 cells/mm³; P value .09). The CD4% were also lower (mean 25.12% ± 12.5%) in those who have severe vitamin D deficiency compared to those whose vitamin D level was ≥11 ng/mL (mean 29.47% ± 11.62%; P value .19). The HIV plasma RNAs were similar in all groups.

After Vitamin D Supplementation

In all, 152 patients with vitamin D level ≤35 ng/mL received vitamin D supplement. However, only 60 (39.5%) of the 152 showed improvement in vitamin D level. Of these 60 patients, only 10 (16.7%) had vitamin D level normalized (25-(OH)D level >35 ng/mL), 27 (45%) had 25-(OH)D level between 21 and 35 ng/mL, and as much as 23 (38.3%) still had 25-(OH)D ≤20 ng/mL although increased from their previous level (see Figure 1).

Figure 1.

Vitamin D levels; pre– and post–vitamin D supplementation, absolute CD4 counts, CD4%, and HIV plasma RNA. VL, viral load.

Subgroup analyses were performed in patients who showed improvement in their serum vitamin D level (n = 60), mean vitamin D level 13.7 ± 7.0 ng/mL presupplementation versus mean vitamin D level 25.0 ± 13.3 ng/mL postsupplementation. We did not see any difference in the absolute CD4 counts (CD4 counts 734.0 ± 496.9 cells/mm³ presupplementation versus CD4 counts 702.3 ± 446.7 cells/mm³ postsupplementation, P value .26) or CD4% (CD4% 29.1% ± 13.4% presupplementation versus CD4% 28.7% ± 12.6% postsupplementation, P value .60). Mean HIV plasma RNA presupplementation was 22 310.77 ± 98 793.34 copies/mL versus 10 209.65 ± 25 015.93 copies/mL postsupplementation. (P value .31).

Discussion

The vast majority of our HIV-infected individuals had vitamin D insufficiency/deficiency (152 of 160; 95%), particularly in adolescents and young adults more so than in children aged ≤10 years. This prevalence of low vitamin D in our study is even higher compared to the high prevalence reported by the previous large cohorts.^2
–4 Perhaps other factors had contributed to this lower vitamin D level in our population. These included inadequate sunlight exposure in temperate latitudes and a large number of African American participants who live in the inner city area with poverty and poor diet.

In contrast to previous studies,^2,6

–9 our patients who were prescribed TDF and/or EFV did not have different vitamin D levels than patients who were prescribed other ARV medications. This finding is against the known fact that these ARV medications interfere with vitamin D metabolism. It is possible that some unknown or confounding factors have been involved, but perhaps the effect of the medication is washed out by the stronger effect of low sunlight and dark skin and low vitamin D intake.

We found that the absolute CD4 counts and CD4% were lower in those with severe vitamin D deficiency (25-(OH)D) level ≤10 ng/mL). The HIV plasma RNA was also found to be almost twice higher in this group of patients. The low CD4 counts in this group of patients is likely the result of uncontrolled viremia, but vitamin D may also play some role.

As previously reported by Kakalia et al,¹² we did not find improvement in absolute CD4 counts or CD4% in those whose vitamin D level improved after vitamin D supplementation. Similarly, HIV plasma RNA did not decrease significantly with vitamin D supplementation. It is to be noted that the majority of our patients’ serum vitamin D level was not normalized to the level of >35 ng/mL. Perhaps with aggressive vitamin D supplementation, we may find the different direction of CD4 counts and HIV plasma RNA in the future studies. On the other hand, if poor adherence to vitamin D supplementation related to the lack of normalization of vitamin D level and poor adherence to the ARV medications, the insignificant decrease in HIV plasma RNA observed in our study may be explained by the poor adherence to the ARV medications rather than the effect of the vitamin D.

The fact that many of our patients (57 of 60; 95%) still continue to have insufficient vitamin D (25-(OH)D level <35 ng/mL) after vitamin D supplementation may reflect issues of poor adherence to vitamin D supplement, inadequate dose of the vitamin D supplement, poor diet, poor sun exposure or, perhaps, some defects in vitamin D metabolism from ARV medications or HIV disease itself. The optimum dose of vitamin D supplementation in HIV-infected individual is still being actively investigated.

We remain concerned about the vitamin D deficiency/insufficiency in our HIV-infected patients, as there is increasing evidence for vitamin D role in innate and cell-mediated immunity. T cell proliferation and function are affected by vitamin D.¹ The vitamin D receptor (VDR) is implicated in antigen receptor signaling.^13,14 Vitamin D and VDR are involved in multiple pathways of innate immunity including macrophage function, dendritic cell antigen presentation, and antimicrobial peptide secretion.¹⁴ Extra renal production of active vitamin D (1,25-(OH)₂D₃) is found in human monocytes and dendritic cells in vitro.^15
–17

Vitamin D appears to inhibit T-helper (Th) 1 and Th17 responses and their cytokines production and so modulate autoimmune disease.^15,18
–20 Further positive regulatory effects of 1,25-(OH)₂D₃ are also found on T regulatory cells and invariant natural killer T cells.^21,22 This decrease in inflammatory cytokines may have an effect on HIV infection/AIDS where inflammation is an important disease mediator.

The limitations in our study are that it is a small study and involved only a single site. The majority of our participants are African American, and the results may not reflect the whole population. Our data on participants with normal vitamin D level after the vitamin D supplement is still insufficient. Larger, multicenter prospective studies are required to evaluate the effect of vitamin D in HIV disease progression.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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Vitamin D Insufficiency/Deficiency in HIV-Infected Inner City Youth

Abstract

Background:

Method:

Results:

Conclusions:

Keywords

Introduction

Method

Statistical Analyses

Results

Demographic Data

Vitamin D Level

Antiretroviral Medications and Vitamin D Level

Vitamin D Level, CD4, and HIV plasma RNA

After Vitamin D Supplementation

Discussion

Footnotes

Declaration of Conflicting Interests

Funding

References