Evaluation of a novel dry eye model induced by oral administration of finasteride

Ocular side effects of oncological therapies: Review

With the advance of cancer therapy in recent years, the knowledge of the mechanisms involved in this disease has increased, which has meant an increase in the quality of life and survival of patients with tumor pathologies previously considered incurable or refractory to treatment. The number of drugs used has increased exponentially in number, and although the implicit toxicity is lower than that of conventional antineoplastic therapy, they lead to the appearance of new associated adverse effects that the ophthalmologist must recognize and manage.

The post-finasteride syndrome: possible etiological mechanisms and symptoms

Finasteride and dutasteride, synthetic 5α-reductase inhibitors (5ARIs) are recommended in many guidelines for the treatment of benign prostatic hyperplasia/lower urinary tract symptoms and alopecia despite a variety of side effects like sexual, neurological, psychiatric, endocrinological, metabolic and ophthalmological dysfunctions and the increased incidence of high grade prostate cancer. The sexual side effects are common during the use of the drug but in a small subgroup of patients, they can persist after stopping the drug. This so-called post-finasteride syndrome has serious implications for the quality of life without a clear etiology or therapy. Three types of 5α-reductases are present in many organs in- and outside the brain where they can be blocked by the two 5ARIs. There is increasing evidence that 5ARIs not only inhibit the conversion of testosterone to 5α-dihydrotestosterone (DHT) in the prostate and the scalp but also in many other tissues. The lipophilic 5ARIs can pass the blood-brain barrier and might block many other neurosteroids in the brain with changes in the neurochemistry and impaired neurogenesis. Further research and therapeutic innovations are urgently needed that might cure or relieve these side effects. More awareness is needed for physicians to outweigh these health risks against the benefits of 5ARIs.

Effects of systemic anti-androgen drugs on the ocular surface

PURPOSE

To investigate the effect of systemic anti-androgen drugs on tear function tests and the ocular surface.

METHODS

Sixty-four male subjects were included in this study. Subjects who were on anti-androgen treatment for prostate cancer (Group A, n: 31) and those who had received only surgical treatment for prostate cancer (Group B, n: 17) were recruited from the department of urology. Age-matched subjects who had never received anti-androgen treatment (Group C, n: 16) constituted the control group. Group A was divided into two subgroups according to the number of anti-androgen drugs used (Group A1: one drug, Group A2: two drugs). All cases underwent a complete ocular examination, including tear film break up time (TBUT), corneal and conjunctival staining, Schirmer 1 test, conjunctival impression cytology, and ocular surface disease index (OSDI) questionnaire.

RESULTS

The mean Schirmer's values were 6.87mm, 11.41mm, and 13.03mm in Groups A, B, and C, respectively (P=0.001). TBUT was 5.45±2.01, 9.85±2.52 and 9.81±1.96seconds in Groups A, B, and C, respectively (P=0.001). Schirmer and TBUT were significantly lower, and corneal staining and OSDI questionnaire scores were higher in Group A compared to groups B and C (P<0.01). Conjunctival impression cytology results according to the Nelson grading system revealed no statistically significant difference between the groups (P=0.422).

CONCLUSION

Anti-androgen drugs alter tear function tests, cause increased corneal and conjunctival staining scores and worsen complaints of dry eye in patients with prostate cancer.

Application of Animal Models in Interpreting Dry Eye Disease

Different pathophysiologic mechanisms are involved in the initiation, development, and outcome of dry eye disease (DED). Animal models have proven valuable and efficient in establishing ocular surface microenvironments that mimic humans, thus enabling better understanding of the pathogenesis. Several dry eye animal models, including lacrimal secretion insufficiency, evaporation, neuronal dysfunction, and environmental stress models, are related to different etiological factors. Other models may be categorized as having a multifactorial DED. In addition, there are variations in the methodological classification, including surgical lacrimal gland removal, drug-induced models, irradiation impairment, autoimmune antibody-induced models, and transgenic animals. The aforementioned models may manifest varying degrees of severity or specific pathophysiological mechanisms that contribute to the complexity of DED. This review aimed to summarize various dry eye animal models and evaluate their respective characteristics to improve our understanding of the underlying mechanism and identify therapeutic prospects for clinical purposes.

The use of androgen deprivation therapy for prostate cancer and its effect on the subsequent dry eye disease: a population-based cohort study

This study aimed to investigate the influence of androgen deprivation therapy (ADT) for the development of dry eye disease (DED) in subjects with prostate cancer via the use of national health insurance research database (NHIRD) of Taiwan. A retrospective cohort study was conducted and patients were selected as prostate cancer with ADT according to diagnostic and procedure codes. Each participant in that group was then matched to one patient with prostate cancer but without ADT and two subject s without prostate cancer and ADT. And a total of 1791, 1791 and 3582 participants were enrolled in each group. The primary outcome was set as the DED development according to the diagnostic codes. Cox proportional hazard regression was applied to calculate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) of ADT and other parameters for DED development. There were 228, 126 and 95 new events of DED developed in the control group, the prostate cancer without ADT group and the prostate cancer with ADT group. The rate of DED in the prostate cancer with ADT group (aHR: 0.980, 95% CI: 0.771-1.246, P= 0.8696) and Prostate cancer without ADT group (aHR: 1.064, 95% CI: 0.855-1.325, P= 0.5766) were not significantly different compared to the control group. In addition, the patients aged 70-79 years old demonstrated a significantly higher incidence of developing DED compared to those aged 50-59 years old (aHR: 1.885, 95% CI: 1.188-2.989, P= 0.0071). In conclusion, the use of ADT did not alter the incidence of subsequent DED.

Experimental Models, Induction Protocols, and Measured Parameters in Dry Eye Disease: Focusing on Practical Implications for Experimental Research

Dry eye disease (DED) is one of the major ophthalmological healthcare challenges worldwide. DED is a multifactorial disease characterized by a loss of homeostasis of the tear film, and its main pathogenesis is chronic ocular surface inflammation related with various cellular and molecular signaling cascades. The animal model is a reliable and effective tool for understanding the various pathological mechanisms and molecular cascades in DED. Considerable experimental research has focused on developing new strategies for the prevention and treatment of DED. Several experimental models of DED have been developed, and different animal species such as rats, mice, rabbits, dogs, and primates have been used for these models. Although the basic mechanisms of DED in animals are nearly identical to those in humans, proper knowledge about the induction of animal models is necessary to obtain better and more reliable results. Various experimental models (in vitro and in vivo DED models) were briefly discussed in this review, along with pathologic features, analytical approaches, and common measurements, which will help investigators to use the appropriate cell lines, animal, methods, and evaluation parameters depending on their study design.

L-carnosine mitigates interleukin-1α-induced dry eye disease in rabbits via its antioxidant, anti-inflammatory, antiapoptotic, and antifibrotic effects

OBJECTIVE

To elucidate the implications of L-carnosine on interleukin-1α (IL-1α)-induced inflammation of lacrimal glands (LGs).

MATERIALS AND METHODS

Forty rabbits were divided equally into four groups: control group (G1), IL-1α (G2), L-carnosine (G3), and L-carnosine plus IL-1α (G4). Several clinical, histopathological, immunohistochemical, morphometric, and biochemical investigations were performed, followed by statistical analysis to diagnose the presence of dry eye disease (DED).

RESULTS

The LGs of G2 rabbits showed degeneration of the acinar cells, increased deposition of collagen fibers, and marked immunoexpression of FasL; elevated levels of interferon-γ, tumor necrosis factor-α, transforming growth factor-β1, and malondialdehyde; and decreased levels of glutathione peroxidase, superoxide dismutase, catalase, and reactive oxygen species compared with those of G1 rabbits. In contrast, administration of L-carnosine to G4 rabbits revealed marked improvement of all previously harmful changes in G2 rabbits, indicating the cytoprotective effects of L-carnosine against IL-1α-induced inflammation of LGs.

CONCLUSIONS

IL-1α induced inflammation of LGs and eye dryness via oxidative stress, proinflammatory, apoptotic, and profibrotic effects, whereas L-carnosine mitigated DED through antioxidant, anti-inflammatory, antiapoptotic, and antifibrotic effects on LGs. Therefore, this work demonstrates for the first time that L-carnosine may be used as adjuvant therapy for the preservation of visual integrity in patients with DED.HighlightsIL-1α induced dry eye disease through its oxidative stress, proinflammatory, apoptotic and profibrotic effects on the lacrimal glands of rabbit.L-carnosine has antioxidant, anti-inflammatory, antiapoptotic and antifibrotic effects.L-carnosine mitigated IL-1α induced dry eye disease via elevating the levels of FasL, IFN-γ, TNF-α, TGFβ1 and MDA as well as reducing the levels of antioxidants (GPx, SOD, and catalase) and ROS in the lacrimal glands of rabbit.L-carnosine could be used as a novel adjuvant therapy for the treatment of dry eye disease.

Metabolomics approach to biomarkers of dry eye disease using 1H-NMR in rats

Dry eye disease (DED) is a chronic and progressive lesion on the ocular surface and induces symptoms, such as burning sensation, itchy eyes, heavy eyes, tired eyes, dry feeling, facial flushing, and blurred vision. The present study was performed to develop DED biomarkers using metabolomics in a rat model. DED was induced by injecting scopolamine and exposing rats to a dry condition. Scopolamine (12 mg/kg/day for 7 days) was subcutaneously injected to male Sprague-Dawley rats. The rats were placed in dry condition with air-flow and dehumidifier. Tear volume and tear breakup time (TBUT) were measured, and eyes were examined through fluorescein staining to assess DED. Mucosal damage and immune reactions were also determined. Plasma and urinary endogenous metabolites were determined using ¹H-NMR analysis. Compared with control tear and TBUT levels were significantly decreased in the DED group whereas corneal damage was significantly increased. The levels of interleukins (IL-6) and IL-1β significantly elevated in the cornea and lacrimal glands in the DED group. TNF-α was numerically increased but not significantly different between groups. Pattern recognition using principal component analysis (PCA) and orthogonal projections to latent structure-discriminant analysis (OPLS-DA) of the NMR spectra in global profiling revealed different clusters between DED and control groups. Target profiling demonstrated that PCA and OPLS-DA score plots were separated between DED and controls in plasma and urine. Subsequently, 9 plasma metabolites were selected to examine different clustering between groups, and 26 urinary metabolites were also selected. Plasma metabolites showed a non-significant rising tendency in the DED group. Urinary phenylalanine, phenylacetate, pantothenate, glycine, succinate, methanol, valine, propylene glycol, histidine, threonine, lactate, and acetate were significantly different between control and DED rats. These results may contribute to understanding the metabolic regulation that is involved in DED and might be useful for potential biomarkers related to DED in rats.

Health Risks Associated with Long-Term Finasteride and Dutasteride Use: It's Time to Sound the Alarm

5α-dihydrotestosterone (5α-DHT) is the most potent natural androgen. 5α-DHT elicits a multitude of physiological actions, in a host of tissues, including prostate, seminal vesicles, hair follicles, skin, kidney, and lacrimal and meibomian glands. However, the physiological role of 5α-DHT in human physiology, remains questionable and, at best, poorly appreciated. Recent emerging literature supports a role for 5α-DHT in the physiological function of liver, pancreatic β-cell function and survival, ocular function and prevention of dry eye disease and kidney physiological function. Thus, inhibition of 5α-reductases with finasteride or dutasteride to reduce 5α-DHT biosynthesis in the course of treatment of benign prostatic hyperplasia (BPH) or male pattern hair loss, known as androgenetic alopecia (AGA) my induces a novel form of tissue specific androgen deficiency and contributes to a host of pathophysiological conditions, that are yet to be fully recognized. Here, we advance the concept that blockade of 5α-reductases by finasteride or dutasteride in a mechanism-based, irreversible, inhabitation of 5α-DHT biosynthesis results in a novel state of androgen deficiency, independent of circulating testosterone levels. Finasteride and dutasteride are frequently prescribed for long-term treatment of lower urinary tract symptoms in men with BPH and in men with AGA. This treatment may result in development of non-alcoholic fatty liver diseases (NAFLD), insulin resistance (IR), type 2 diabetes (T2DM), dry eye disease, potential kidney dysfunction, among other metabolic dysfunctions. We suggest that long-term use of finasteride and dutasteride may be associated with health risks including NAFLD, IR, T2DM, dry eye disease and potential kidney disease.

Post-finasteride syndrome - does it really exist?

Inhibitors of 5α-steroid reductase are drugs used to treat androgen-dependent conditions including prostate diseases and androgenic alopecia. Finasteride was the first on the market and is currently the most widely used inhibitor. Dutasteride was the second inhibitor to be approved and has a similar safety profile. Common adverse events of treatment consist of sexual disorders and a negative affect balance. It was described that the prolonged use of 5α-steroid reductase inhibitors in patients with alopecia can cause persistent side effects called a post-finasteride syndrome (PFS), that is not just a simple coexistence of events, but rather a definite syndrome with an iatrogenic background. PFS occurs in susceptible individuals even after small doses of the drug and can last for a long time after the discontinuation of treatment. A deterioration in the quality of life in affected individuals does not justify use of the drug. Wider recognition of PFS symptoms, its incidence, course, prevention, and treatment possibilities will allow the indications for drug use to be reconsidered and treatment to be more personalized. Knowledge about PFS will also help to provide the best treatment for affected individuals and to properly educate patients before obtaining an informed consent for therapy with 5α-steroid reductase inhibitors.