Researchers at the University of Illinois at Chicago are the first to identify the presence of a specific type of antibody, called anti-citrullinated protein autoantibodies, or ACPAs, in human tear fluid.
They are also the first to demonstrate that patients with dry eye disease experienced reduced signs and symptoms of the condition in response to a new eye drop treatment —made from pooled human antibodies – that targets ACPAs.
The findings from their early stage clinical trial are reported in the journal The Ocular Surface.
Dry eye disease is caused by abnormalities in the tear fluid and results in dry areas over the cornea, the transparent outer layer of the eye, which can lead to disabling eye pain and sensitivity to light in severe cases.
“The burden of autoimmune dry eye is much greater than just having an occasional feeling of dryness,” said Dr. Sandeep Jain, senior author of the study and UIC professor of ophthalmology and visual sciences at the College of Medicine.
“It can severely compromise quality of life to the point of disability and can compromise a person’s vision.”
In previous research, Jain and his colleagues discovered that strands of DNA extrude from neutrophils, a type of white blood cell, to form webs on the surface of eyes affected by severe dry eye disease and cause inflammation.
In the new study, the researchers identified ACPAs as another cause of eye inflammation that also contributes to the development of these webs, which Jain calls “a vicious cycle of inflammation.”
The new eye drops treat dry eye disease by knocking the immune system out of this cycle, at least partially.
The drops are formulated using pooled antibodies – which are made from immune globulins processed from the donated blood of thousands of individuals, all containing varied types of antibodies – that counteract the negative effects of ACPAs.
The phase I/II drug trial compared the antibody-based eye drops with eye drops without the antibodies.
“There are currently only two approved drugs to treat dry eye, and they don’t work for everyone, especially those with severe disease, so having a new drug that can treat the disease by targeting a different mechanism, in this case, an autoimmunity, is very important,” Jain said.
Twenty-seven participants with severe dry eye disease participated in the trial.
The participants were randomized into two groups.
One group was given eye drops made from pooled antibodies and instructed to administer one drop to each eye twice daily for eight weeks.
The control group was given the same instructions with eye drops made without antibodies.
The researchers evaluated patients’ symptoms through questionnaires and measured the extent of corneal damage and the amount of pro-inflammatory biomarkers on the surface of the eye before and for the duration of the study.
They found that people using antibody-based eye drops had a statistically significant and clinically meaningful reduction in corneal damage at eight weeks compared with the control group.
Questionnaire scores related to symptoms also reflected significant improvement among patients using the new antibody-based eye drops when compared with the eye drops without antibodies.
In the test group, the amount of pro-inflammatory biomarkers—or dry areas—also was reduced on the surface of the eye.
“Participants in the trial who used the drops with pooled antibodies reported less eye discomfort and their corneas were healthier,” Jain said.
“The data from this early clinical trial suggests that eye drops containing pooled antibodies may be safe and effective for treating dry eye disease, and we look forward to conducting larger randomized trials to definitively prove its efficacy.”
More information: Jieun Kwon et al, Pathological consequences of anti-citrullinated protein antibodies in tear fluid and therapeutic potential of pooled human immune globulin-eye drops in dry eye disease, The Ocular Surface (2019). DOI: 10.1016/j.jtos.2019.10.004
Provided by University of Illinois at Chicago
Dry eye syndrome (DES) is currently defined as a multifactorial disease of the eye surface characterized by the loss of homeostasis – instability and hyperosmolarity – of the tear film and secondary inflammation, with eye symptoms such as blurred vision, eye pain, and irritation and difficulty performing daily activities such as driving or using a computer in a sustained manner. Its high and increasing prevalence in the aged population (affecting 40% of people over 70s), chronic nature, and capacity to affect quality of daily life make it an important disease.1,2
The usual treatment strategies such as lubrication and hydration of the eye surface with artificial tears of different compositions (hyaluronic acid, carmellose, etc.) and densities (gel, etc.), associated measures to directly or indirectly increase surface lubrication (tear plugs, nasal neurostimulation), as well as use of anti-inflammatory drugs (corticoids, cyclosporine, tacrolimus) make treating DES a frustrating experience, often only resulting in brief, temporary, and mild relief of discomfort.3–5
Through its alkaline pH, high concentrations of bicarbonate, potassium, and magnesium, and low level of sodium, seawater has proved effective in relieving skin and nasal mucosal symptoms, dermatitis, and dry, atrophic, and atopic rhinitis through different mechanisms, such as surface-moisturizing effect, anti-inflammatory effect, and washing of detritus and pro-inflammatory molecules by dragging and sweeping them away.6–8
The present study evaluated the efficacy and safety of this isotonic seawater in reducing the signs and symptoms of moderate-to-severe DES compared to standard treatment with carmellose artificial tears eyedrops.
Patients and methods
The study was conducted in accordance with the ethical principles set forth in the Declaration of Helsinki and the Good Clinical Practice Guidelines. The study protocol and informed consent were reviewed and approved by the institutional review board of the University of Valencia before study initiation. Written informed consent was obtained from each patient before the start of the study, and power analysis was performed to justify the number of patients enrolled in the study. The study processes, including recruitment of patients, collection of patients’ data, and Ocular Surface Disease Index (OSDI) evaluation, was conducted at multiple clinical sites in Valencia (Spain). All the examinations were conducted by the same examiner (MD), under standardized conditions of room illumination and temperature (between 20°C and 25°C). The measurements of parameters were carried out after a period of 2–3 hours from the last application of the treatment.
Study population and inclusion criteria
Eligible patients were those aged 55–75 years, who had been diagnosed with DES within the preceding 3 months, and had dry eye-related symptoms that were present for >3 months before the screening examination, or who had a minimum OSDI score of 23 with moderate or severe DES. Other inclusion criteria were as follows: 1) tear film breakup time (TBUT) of ≥5 seconds, 2) fluorescein corneal staining (FCS) score of ≤4 on National Eye Institute (NEI) scale, and 3) Schirmer I test score at 5 minutes of ≥10 mm. These criteria needed to be met at both the screening and baseline examination.
Exclusion criteria included the following: 1) presence of anterior ocular disease (such as neurotrophic keratitis or keratoconus); 2) continued use of eye drops; 3) presence of a punctal plug or its removal within 1 month before the screening examination; 4) surgery on the ocular surface or intraocular surgery within 3 months before the screening period; 5) use of drugs or therapies that were prohibited from the screening examination to the end of study treatment (steroids, immunosuppressants, antihistamines, any prescription or over-the-counter ophthalmic drugs, contact lenses, and any other treatment agent affecting the dynamics of tear fluid, including its nasolacrimal drainage process), and 6) presence of systemic disease including allergy, Sjögren’s syndrome, or ocular graft-vs-host disease.
Results
Demographic data of the population studied
A total of 193 participants were recruited into the trial. Sixty patients in Group I (seawater) and 60 patients in Group II (artificial tears) completed the entire protocol. The difference between the two groups in sex distribution was not significant (P=0.447). The mean age of the participants in Group I and Group II was 68.08±6.29 and 66.83±8.42 years, respectively, and there was no significant difference between the groups (P=0.379) (Table 1).
Table 1
Demographic data
| Group I (seawater) | Group II (artificial tears eyedrops) | P-value | |
|---|---|---|---|
| Age, mean ± SD | 68.08±6.29 | 66.83±8.42 | 0.379 |
| Female:male | 1.60:1 | 1.56:1 | 0.447 |
| Severity, n | 0.829 | ||
| Moderate | 37 | 39 | |
| Severe | 23 | 21 | |
| Hypertension, n | 14 | 12 | 0.238 |
| Cholesterol >260 mg/dL, n | 19 | 17 | 0.658 |
| Diabetes, n | 13 | 18 | 0.051 |
| Osteoarthritis, n | 13 | 15 | 0.324 |
| Smoking history, n | 16 | 14 | 0.287 |
| Cardiovascular disease, n | 19 | 20 | 0.376 |
OSDI questionnaire
The OSDI scores after the intervention showed a significant decrease compared to those before the intervention in both groups (P<0.001). In addition, there was a significant difference in the efficacy of the two products (P<0.001), with seawater spray wash being much more effective. The mean score improvement was 68% in the seawater spray group compared to 42% in the carmellose artificial tears eyedrops group; in other words, the mean score improvement was 26% higher than in the artificial tears group (Table 2).
Table 2
Comparison of the clinical efficacy of seawater and artificial tears eyedrops
| Type of test | Group I (seawater) | Group II (artificial tears eyedrops) | ||||||
|---|---|---|---|---|---|---|---|---|
| Baseline | 12-week visit | P-value (1) | Baseline | 12-week visit | P-value (1) | P-value (2) | P-value (3) | |
| OSDI score | 42.58±16.96 | 23.94±15.19 | <0.001 | 40.52±15.77 | 28.5±16.19 | <0.001 | 0.339 | <0.001 |
| ConjScore | 7.67±2.98 | 5.03±2.27 | <0.001 | 7.43±2.20 | 5.68±1.69 | <0.001 | 0.334 | 0.822 |
| CornScore | 1.23±1.43 | 0.49±0.78 | <0.001 | 1.15±1.18 | 0.44±0.57 | <0.001 | 0.807 | 0.793 |
| TMH (mm) | 0.26±0.15 | 0.28±0.13 | 0.289 | 0.29±0.16 | 0.27±0.09 | 0.318 | 0.542 | 0.459 |
| TO (mOsm/L) | 293.9±10.57 | 296.4±9.50 | 0.456 | 298.3±13.7 | 295.6±7.2 | 0.348 | 0.711 | 0.251 |
| TBUT (seconds) | 7±2.2 | 7.64±2.60 | 0.127 | 7.15±2.35 | 8.09±2.74 | 0.113 | 0.64 | 0.497 |
| ST score (mm) | 6.14±5.35 | 6.36±5.66 | 0.129 | 6.34±6.42 | 7.10±6.20 | 0.115 | 0.676 | 0.441 |
Notes: Group I: patients treated using seawater spray (Quinton®); Group II: patients treated using carmellose artificial tears eyedrops (Viscofresh® 0.5%). P-value (1) indicates the significance level of paired t-test within Group I or II between baseline and 12 weeks after intervention; P-value (2) indicates the significance level of independent t-test for comparing between Groups I and II before intervention; P-value (3) indicates the significance level of independent t-test for comparing between Groups I and II after 12 weeks.
Abbreviations: ConjScore, conjunctival score; CornScore, corneal score; OSDI, Ocular Surface Disease Index; TBUT, tear breakup time; TMH, tear meniscus height; TO, tear osmolarity; ST, Schirmer test.
Corneal and conjunctival staining
The corneal and conjunctival staining scores after the intervention also showed a significant decrease compared to those before the intervention (P<0.001). However, although the improvement of the seawater group was superior, the two products – seawater and artificial tears – did not show statistically significant differences (FCS score: P=0.793; LGCS score: P=0.822; Table 2).
The rest of the parameters studied were Schirmer I test (without anesthesia) score, tear osmolarity (TearLab®), TBUT, and TMH (meniscography OCT) (Table 2).
There were no significant differences before and after the administration of the two products in any of the other parameters tested.
Multiplex analysis of inflammatory molecules in tears
With the assayed amounts of tears utilized in the present study (mean 14±8 μL), it was possible to detect the majority of molecules related to inflammation (as in the human cytokine panel utilized herein) in 95% of the samples (Table 3). Polystyrene beads coupled covalently to specifically directed antibodies (cytokines) were allowed to react with each tear sample containing an unknown amount of the molecules, or with a standard solution containing a known amount of these molecules, at room temperature for 1 hour, following the manufacturer’s instructions. Detection data of the inflammation molecules (expressed in pg/μL) from the tear samples are summarized in Table 3. When comparing Group I (seawater) vs Group II (carmellose eyedrops), the results showed statistically significant differences in the tear expression of IL-1 beta and IL-6. Levels of IL-1 beta and IL-6 in tears decreased significantly more in the seawater group compared to the carmellose artificial tears group (19% IL-1 beta/17% IL-6 vs 52% IL-1 beta/51% IL-6) (P<0.001).
Table 3
Levels of the inflammatory molecules IL-1 beta and IL-6 in tears in Group I treated with isotonic seawater (Quinton®) and in Group II treated with carmellose artificial tears eyedrops (Viscofresh® 0.5%)
| IL-1 beta (pg/μL) | IL-6 (pg/μL) | |
|---|---|---|
| Before starting/applying treatment | ||
| Seawater spray | 43.6±8 | 32.5±6 |
| Carmellose artificial tears | 38.9±12 | 36.4±8 |
| After treatment | ||
| Seawater spray | 8.3±3 (19%) | 5.6±2 (18%)** |
| Carmellose artificial tears | 20.4±7 (52%) | 18.6±6 (51%)* |
Notes: Data are presented as mean ± SD for all participants in each group, with decrease in levels shown in parentheses. Comparative analysis between groups: significance levels were taken at P<0.01 (*) and P<0.001 (**).
Adverse events
No cases of intolerance or side effects were observed in either of the two treatment groups.
Discussion
DES is the most frequent and prevalent ophthalmological disease worldwide and is likely to increase exponentially with the progressive aging of the population pyramid in the coming years and decades. Its degree of impact on quality of life is very high due to the continuity of discomfort caused throughout the day, year after year, and the consequent difficulties carrying out everyday activities (driving, reading, watching television, using computers, coping with air conditioning and heating in commercial and/or domestic interiors, street wind, and kitchens, etc.). The standard treatment is the frequent application of artificial tears to the eye surface. However, this only offers a very limited degree of effectiveness in relieving symptoms – especially the need for immediate relief understood as a “feeling of freshness” – and durability – a maximum of a few minutes – thus generating a permanent and generalized feeling of frustration in patients receiving this treatment. It merely prevents the disease from getting worse, without offering any sensation of improvement. Therefore, one of the main issues to be resolved is the need to find a truly gratifying treatment that generates a feeling of immediate and lasting relief in patients.
Another of the main issues to be solved is the chronification and the appearance of periodic inflammatory episodes secondary to the accumulation of inflammatory molecules – IL-1 beta, IL-6, etc. – on the conjunctival surface due to the lack of their neutralization, dilution, and entrainment (dragging), which generate an intense increase in the patient’s discomfort, accompanied by itching, redness, and photophobia, and are also responsible for corneal complications (eg, secondary keratitis). Permanent maintenance treatment with corticoids, immunosuppressants, or autologous serum solutions in the form of eye drops is complex and can cause side effects (eg, bacterial superinfections). Given the necessary high frequency of application and low degree of efficacy of the current treatment options, as well as the potential side effects of anti-keratitis treatments, the introduction of new treatments is necessary. Ideally, new treatments should be easily and frequently attainable, and easy for the patients to get hold of and self-administer, as would be the case with seawater.
Seawater has been used for years for the relief of mucosal and skin symptoms, especially dry, atrophic, psoriatic, and atopic dermatitis, chronic nonhealing trophic skin wounds and ulcers, and atrophic and allergic rhinitis, due to its documented therapeutic effects. There is also traditional nonscientific cultural information on its effectiveness in treating dryness and eye irritation – the classic technique of washing with water and salt, etc. Having reviewed the data on PubMed from the last 50 years, there is no documented scientific research on the efficacy of seawater in any ophthalmic disease in general, or in DES in particular. All the above data supported the initiation and performance of a scientific study to establish the probable efficacy of isotonic seawater in DES and the safety of its application and to establish its comparative efficacy vs standard treatment with carmellose artificial tears eyedrops.
In the group treated with seawater spray, the clinical symptoms of dry eye improved on average by 68%, and the improvement was 26% more than in the group treated with carmellose artificial tears eyedrops, demonstrating the superiority of the seawater treatment. It should be noted that not all dry eye symptoms responded equally, with maximum efficacy shown on the gritty sensation, foreign body sensation, dryness, itching, burning, irritation, and redness, and with much less impact on the sensation of pain, need to blink and keep the eyes closed, or severe difficulty opening them in the morning. In addition, the perfect tolerance and complete absence of even minimal side effects supports the inclusion of seawater washing as the first basic therapeutic step in the initial treatment of dry eye. And this important fact is due to its special ability to achieve a sensation of freshness and immediate relief of symptoms, as well as the reduction of mucous secretions after its application as reported by the patients.
All the objective parameters related to changes or improvements in the production and quantity of tear film – osmolarity, TBUT, and the results of Schirmer I test, Schirmer II test, and OCT meniscography – did not change when applying either the seawater or artificial tears treatments, as there is no pathophysiological mechanism to influence their production. It is therefore clear that the great efficiency demonstrated by seawater spray has other fundamental mechanisms to explain its effectiveness.
The fact that there is a direct relationship in the decrease of pro-inflammatory molecules in the tears of patients with dry eye, and that there is a proven correlation between greater or lesser clinical efficacy in the improvement of symptoms with a greater or lesser decrease in the high pathological levels of these molecules, clearly indicates that this may be the main mechanism of action of seawater on DES. The documented 26% (OSDI score) greater clinical efficacy of seawater compared to artificial tears statistically correlated with the greater decrease in IL-1 beta and IL-6 levels (by 19%/17% with seawater compared to 52%/51% with artificial tears).
Seawater has been shown to reduce the presence of IL-1 beta and IL-6 by nearly half, and to levels virtually similar to those of the normal population without dry eye, and this lays the biochemical foundation for why it is so effective in the clinic, as well as the need for long-term studies that continuously demonstrate its ability to break the vicious circle of the pathogenesis of the disease, using its continuous and long-term administration to interrupt the episodes of exacerbation (keratitis, red eye, etc.) and end its chronicity.21,22 In addition, one should not forget that in these multiple mechanisms of seawater including neutralization, dilution, and entrainment, entrainment is unique and differentiates seawater from any other dry eye treatment and could explain much of its effectiveness. Lubricating, which is what artificial tears do, is not the same as washing by dragging (entrainment), which is what seawater does, just as it is not the same to wash your hands as it is to shower or to bathe in seawater. This would explain why the seawater spray has that special capacity to provide a sensation of freshness and immediate relief of symptoms, as well as reduce mucous secretions, which is not documented with any other treatment.
The fact that the microulcerations of the conjunctival and corneal surface (keratitis), documented by staining with sodium and lissamine green fluorescein stain, are reduced with isotonic seawater, and in a manner similar to that demonstrated by artificial tears, corroborates and confirms their healing and restoring capacity for the normalization of the ocular surface. The efficacy of seawater has already been documented in other dry and inflammatory diseases of other mucous membranes of the human body (dermatitis, trophic skin ulcers, rhinitis), but until the present study it had not been documented in any ophthalmological diseases, such as dry eye.
Among the therapeutic mechanisms of seawater that make it effective are:23–28 1) its alkaline pH and higher bicarbonate level, which, by decreasing the acidification of the inflammatory damaged surface, would promote tropism, healing, and restoration of mucosal integrity through increased levels of EGF; 2) its restoration of the electrolyte balance of the surface through its low sodium levels, eliminating or reducing the electrolyte imbalance that is at the origin of the pathophysi-ological chain of dry eye; 3) its anti-inflammatory effect due to its high concentration of potassium and magnesium, as it is able to reduce the levels of TNF and IL-8 already known, and from the present study, of IL-1 beta and IL-6, and thus end the vicious circle chronically perpetuating the dry eye; 4) its hydrating effect, preventing hyperosmolarity from the outset, provided that it is applied in a sufficiently frequent and maintained manner; and 5) its washing and cleaning effect by “dragging” and removing from the surface much of the cellular debris, hyperosmolarizing electrolytes, and pro-inflammatory molecules and cells (IL-1 beta, IL-6, IL-8, and MMP-3 and MMP-9, TNF, and macrophages and T-lymphocytes) through a mechanical sweeping mechanism, or “showering/bathing in seawater” effect.
