HIV-specific IgA antibodies in tears of children with AIDS or at risk of AIDS

Smart Contact Lenses as Wearable Ophthalmic Devices for Disease Monitoring and Health Management

The eye contains a complex network of physiological information and biomarkers for monitoring disease and managing health, and ocular devices can be used to effectively perform point-of-care diagnosis and disease management. This comprehensive review describes the target biomarkers and various diseases, including ophthalmic diseases, metabolic diseases, and neurological diseases, based on the physiological and anatomical background of the eye. This review also includes the recent technologies utilized in eye-wearable medical devices and the latest trends in wearable ophthalmic devices, specifically smart contact lenses for the purpose of disease management. After introducing other ocular devices such as the retinal prosthesis, we further discuss the current challenges and potential possibilities of smart contact lenses.

The Multifaceted Nature of Immunoglobulin A and Its Complex Role in HIV

IgA is the most abundant immunoglobulin in mucosal secretions, and understanding the role of IgA in both protection from HIV acquisition and modulation of HIV disease progression is a field of considerable controversy and renewed research interest. Analysis of the RV144 clinical trial associated plasma HIV envelope-specific monomeric IgA from vaccines with reduced vaccine efficacy. The RV144 trial, however, only assessed for plasma IgA, which was not further subclassed, and the role of mucosal IgA was not addressed as mucosal samples were not collected. On the other hand, several studies have detected envelope-specific IgA in mucosal secretions of highly exposed persistently seronegative cohorts, while recent macaque simian-HIV passive immunization studies have suggested a potentially protective role for mucosal IgA. It is well established that total IgA in serum appears to correlate with HIV disease progression. In contrast, a selective deficit of anti-HIV IgA responses in HIV infection is apparent, with a number of recent studies beginning to elucidate the mechanisms behind these dysfunctional IgA responses. In this review, we highlight the dichotomy that exists in the literature as to whether anti-HIV IgA is protective or harmful to the host. Herein, we emphasize the importance of distinguishing between monomeric, multimeric, and isoforms of IgA and review what is known about the complex and diverse interactions of various molecular forms of IgA with HIV in both the systemic circulation and mucosal compartments.

Contact lens sensors in ocular diagnostics

Contact lenses as a minimally invasive platform for diagnostics and drug delivery have emerged in recent years. Contact lens sensors have been developed for analyzing the glucose composition of tears as a surrogate for blood glucose monitoring and for the diagnosis of glaucoma by measuring intraocular pressure. However, the eye offers a wider diagnostic potential as a sensing site and therefore contact lens sensors have the potential to improve the diagnosis and treatment of many diseases and conditions. With advances in polymer synthesis, electronics and micro/nanofabrication, contact lens sensors can be produced to quantify the concentrations of many biomolecules in ocular fluids. Non- or minimally invasive contact lens sensors can be used directly in a clinical or point-of-care setting to monitor a disease state continuously. This article reviews the state-of-the-art in contact lens sensor fabrication, their detection, wireless powering, and readout mechanisms, and integration with mobile devices and smartphones. High-volume manufacturing considerations of contact lenses are also covered and a case study of an intraocular pressure contact lens sensor is provided as an example of a successful product. This Review further analyzes the contact lens market and the FDA regulatory requirements for commercialization of contact lens sensors.

Paucity of antigen-specific IgA responses in sera and external secretions of HIV-type 1-infected individuals

This study was undertaken to resolve existing controversies with respect to the detection of IgA HIV-1-specific mucosal antibodies in infected individuals. External secretions, including tears, nasal, rectal, and vaginal washes, saliva, semen, urine, and sera were obtained from 50 HIV-1-infected individuals and 20 controls using collection procedures that minimize the irritation of mucosal surfaces. Levels of total and antigen (gp120 and gp160)-specific antibodies of the IgG and IgA isotypes were measured by assays that proved reliable in a large multicenter study: quantitative ELISA and chemiluminescence-enhanced Western blot analyses. Although the levels of total IgG and IgA were increased or remained unchanged in body fluids of HIV-1-infected individuals as compared to the controls, HIV-1-specific IgA antibodies were either absent or present at low levels even in secretions with characteristically high relative contents of total IgA vs. IgG (saliva, tears, and rectal and nasal washes). In these secretions, HIV-1-specific IgG antibodies dominated. In assessing levels and frequency of detection of IgG antibodies, both female and male genital tract secretions, urine, and nasal wash were preferable to parotid saliva and especially to rectal wash. External secretions contained IgG antibodies to gp160> gp120> gp41 and p24; when present, IgA antibodies were predominantly directed at gp160. Analyses of peripheral blood antibody-secreting cells (ASC) isolated from the same individuals paralleled these serological findings: gp160-specific IgG-secreting ASC were dominant. Therefore, in striking contrast to other mucosally encountered microbial infections, HIV-1 does not induce vigorous specific IgA responses in any body fluid examined or in ASC in peripheral blood.

Plasma and salivary IgA subclasses and IgM in HIV-1-infected individuals

We examined IgA and IgM responses in parotid saliva from human immunodeficiency virus-1 (HIV-1)-infected individuals. Compared to the uninfected controls, levels of salivary secretory IgA2 were significantly increased in HIV-1-infected subjects, with higher levels in those who displayed oral manifestations of HIV- I infection. Assessed by enzyme immunoassay, about two thirds of the HIV-1-infected individuals tested positive for salivary HIV-1-specific IgA antibodies but not for salivary IgM. No clear correlations between the amount of HIV-1-specific IgA and CD4 counts or plasma viral loads were found. The proportions of HIV-1-specific IgA did not correlate with the levels of total IgA. Determined by Western blot, IgA1 accounted for the majority of anti-HIV-1 IgA antibodies in saliva. Comparisons between the specificities of plasma and salivary IgA directed to HIV-1 proteins revealed the absence of salivary anti-gp41 IgA antibodies, and lower HIV-1-specific reactivity of IgA and IgM were determined in saliva than in plasma.

Plasma and salivary IgG subclasses in HIV type 1 infection: evidence of both transudation and local synthesis of IgG in parotid saliva

In this study we measured the levels of plasma and salivary IgG subclasses in 81 HIV-1-infected individuals and 30 uninfected controls. Salivary IgG1 was increased in HIV-1-infected patients, while salivary IgG2 and IgG4 were decreased. Patients with high levels of plasma anti-HIV-1 IgG antibodies presented a higher CD4+ cell count and lower viral load. High levels of anti-HIV-1 IgG antibodies in plasma were also associated with high levels of anti-HIV-1 IgG antibodies in parotid saliva. In comparing the HIV-1 recognition patterns of salivary IgG with plasma IgG, we determined that plasma and salivary IgG antibodies had similarities as well as differences in their reactivity to HIV-1 antigens. The present study demonstrates that HIV-1 infection affects both plasma and salivary IgG and provides evidence that the origin of HIV-1-specific IgG antibodies in parotid saliva is primarily transudated from plasma; however, some local synthesis of IgG in parotid saliva also occurs.

Compartmentalization of the IgG immune response to HIV-1 in breast milk

OBJECTIVE

To evaluate the IgG immune response to HIV-1 in colostrum.

METHODS

Paired serum and colostrum were collected from 16 asymptomatic HIV-1-infected women. IgG to gp160 and to four peptides (gp41 immunodominant DI domain, gp41/Id; EDLKWA epitope of DIII domain, gp41/K; gp120 C-terminus, gp120/Ct; V3 loop, gp120/V3) were evaluated in all samples. Functional activity of purified IgG was assessed for the ability to block transcytosis of cell-associated HIV-1 through a tight monolayer of endometrial epithelial cell line HEC1.

RESULTS

IgG antibody to gp160 and to the four env-encoded synthetic peptides were detected in all specimens. The mean specific activity of IgG to gp41/K was 4.2 fold higher in colostrum than in paired serum. In contrast, mean specific activities of IgG to gp160 and gp41/Id were twofold higher in serum than in paired colostrum. Mean specific activities of IgG to gp120/V3 and to gp120/Ct were similar in systemic and milk compartments. Functional activity of IgG was evaluated in six paired serum and colostrum: in two women, serum IgG was 3.0 and 7.6 fold more efficient in blocking transcytosis than colostrum IgG; in one patient, colostrum IgG exhibited a 28 fold higher inhibitory capacity than serum IgG; in the remaining patients, serum and colostrum IgG demonstrated similar inhibitory activities against transcytosis of HIV.

CONCLUSION

These features are consistent with a compartmentalization of the humoral IgG immune response to HIV within the mammary gland. Some HIV-1 antigens are able to induce a strong humoral mucosal immune response which may be of relevance for the design of a mucosal vaccine against HIV-1.

IgA immunity in HIV type 1-infected chimpanzees. II. Mucosal immunity

Vaginal wash fluids from chimpanzees cervically infected with HIV-1 and saliva from intravenously and cervically infected chimpanzees were analyzed for total IgA, IgA1, IgA2, IgG, and albumin concentrations and for reactivity against HIV-1. No overt abnormalities were detected in salivary immunoglobulin or albumin concentrations in either group of animals. Anti-HIV IgA and IgA subclass antibodies were demonstrated in saliva from five of six intravenously infected chimpanzees and in two of four cervically infected animals, with titers ranging from 1:5 to 1:20. HIV-specific IgG antibodies could be detected in saliva from half of the systemically infected group, the highest titer being 1:2560, whereas the highest anti-HIV IgG titer in the mucosally infected group was 1:20. Western blot analyses of the first saliva samples obtained after initial virus exposure revealed IgG, IgA, and IgA subclass antibodies directed at the env, gag, or pol gene products in both groups of chimpanzees. Examination of IgG, IgA, IgA1, and IgA2 concentrations in vaginal washes from cervically infected animals showed that IgG levels were highest, but IgA and IgA subclass reactivities against HIV-1 were more prominent than that of IgG. These results demonstrate that systemic infection of chimpanzees with HIV-1 elicits mucosal responses specific for HIV, and vaginal infection of chimpanzees induces a common mucosal immune response reminiscent of that in humans.

Rapid and constant detection of HIV antibody response in saliva of HIV-infected patients; selective distribution of anti-HIV activity in the IgG isotype

Anti-HIV antibodies can be specifically detected with a sensitivity and a specificity of 100% in the saliva of all HIV-infected patients. A saliva collection device facilitates the sampling procedure, and if a rapid test is used, the diagnosis of infection can be established in as little as 10 min. The analysis of a group of CDC stage IV AIDS patients showed a decrease in lactoferrin (produced by the oral mucosa) in comparison with HIV-negative controls, associated with an increase in albumin (filtering from plasma), indicating an alteration of the mucosal barrier. The salivary anti-HIV-gp160 activity was largely carried by the IgG isotype whereas the salivary antibacterial activity (anti-Streptococcus sobrinus; anti-LPS from Escherichia coli) remained located in the IgA isotype as usually observed with all infectious agents. Salivary IgG carried a specific anti-gp160 activity 25-fold higher than that of serum IgG. Thus, significant local synthesis of specific IgG by oral mucosa was revealed as a characteristic of HIV infection.

Antibodies to recombinant gp160 in mucosal secretions and sera of persons infected with HIV-1 and seronegative vaccine recipients

An enzyme immunoassay (EIA) was developed to detect secretory IgA (sIgA) antibodies to HIV-1 envelope glycoprotein, using a mouse monoclonal antibody and a highly purified, baculovirus-expressed recombinant gp160 (rgp160) as antigen. Detection of sIgA was enhanced by prior immunoprecipitation of IgG. IgG and sIgA rgp160 antibodies were measured in parotid saliva and nasal wash samples of 18 HIV-1-seropositive volunteers and 14 HIV-1-seronegative adult volunteers immunized 3 times with HIV-1 IIIB rgp160 vaccine at 1 of 4 dosage levels: 40 micrograms (N = 3), 80 micrograms (N = 3), 160 micrograms (N = 4), and 640 micrograms (N = 4). We detected rgp160-specific IgG antibody in the nasal wash samples of all HIV-1-seropositive volunteers and 4/8 vaccinees (50%) immunized with the two highest doses of rgp160 vaccine. All infected volunteers tested had rgp160-specific sIgA in their nasal wash samples. None of the vaccinees and very few of infected volunteer specimens had detectable antibody in the parotid saliva samples (5/8 had IgG and 1/8 had sIgA). We also detected IgG antibody to rgp160 in the sera of all infected volunteers and 13/14 vaccinees (93%). With this EIA, sIgA antibody can be measured in mucosal secretions of recipients of appropriate candidate HIV-1 vaccines.

Detection of anti-HIV IgA in tears of children born to seropositive mothers is highly specific

In order to improve the diagnosis of HIV infection in children born to seropositive mothers, 86 children were previously tested by Western blotting for anti-HIV IgA in tears and IgG in serum, at a median age of 9.2 months. To determine the exact value of the assay, 68/86 children of the same cohort were retested 9 months later. Nine children (13.4%) were seropositive and all had anti-HIV IgA in tears. Eight of them had possessed lachrymal antibodies 9 months earlier. The ninth child was seronegative when 9 months old and then seroconverted. Four children (6%), known to be seronegative, had an indeterminate Western blot pattern and no HIV IgA in tears. Fifty four (80.6%) were seronegative at 18 months; none of them had ever had anti-HIV IgA in tears. This highlights the fact that only the children without lachrymal HIV IgA at the age of 9 months became seronegative at the age of 18 months. Our results clearly show that the detection of anti-HIV IgA in tears is a highly specific and reliable diagnostic test in children aged less than 15 months, born to seropositive mothers.