Functional relationship between cationic amino acid transporters and beta-defensins: implications for dry skin diseases and the dry eye

Ocular complications in adults with psoriasis: a cross-sectional study in a referral center in Brazil

PURPOSE

There is limited literature on the ocular manifestations in patients with psoriasis. Therefore, this study aimed to identify the prevalence of and factors associated with ocular manifestations in adults with psoriasis.

METHODS

This cross-sectional study included Brazilian adults with psoriasis. The dermatological evaluation included diagnosis, clinical form, Psoriasis Area and Severity Index (PASI) measurement, and location of the lesions. Patients underwent a full ophthalmological examination, including the Schirmer I test, Rose Bengala staining, and tear breakup time tests. The results were analyzed using chi-square and Pearson's linear correlation tests.

RESULTS

Of the 130 patients assessed, 118 (90.8%) exhibited ocular abnormalities, with meibomian gland dysfunction (MGD) being the most prevalent (59.2%), followed by dry eye disease (DED) (56.2%). A significant correlation was observed between MGD and PASI (p = 0.05), and between MGD and certain treatment modalities. DED was significantly associated with PASI (p < 0.05). Concurrent use of acitretin was identified as an independent predictor of MGD (odds ratio [OR] = 3.5, p < 0.05), whereas PASI was a protective factor against DED (OR = 0.39, p < 0.01).

CONCLUSION

Given the high prevalence of eye disease among individuals with psoriasis, routine ophthalmological assessments are recommended to prevent possible ocular complications.

Psoriasis beyond the skin: Ophthalmological changes (Review)

Psoriasis is a chronic, immune-mediated inflammatory disease of unknown etiology that may be associated with abnormal T-lymphocyte function. Ocular manifestations associated with psoriasis, particularly artropathic or pustular psoriasis, usually affect men, often during exacerbations of the disease. It has been reported that eye damage tends to occur later compared with cutaneous or joint manifestations, blindness being the most disabling complication. Previous studies have focused on ophthalmic manifestations and identified several etiopathogenic mechanisms. Psoriasis may be associated with eye complications such as lesions of the eyelids, conjunctiva and others, with systemic inflammation being the main contributor. In addition, the treatment used for psoriasis may cause ocular changes. The main ophthalmic manifestations associated with psoriasis are keratoconjunctivitis sicca, blepharitis, conjunctivitis and uveitis. The treatment of uveitis, perceived as one of the most serious eye conditions, is controversial and has yet to be clearly determined. Thus, the aim of the present review was to emphasize the importance of regular eye examination for patients with psoriasis, either those receiving biological treatment or those not receiving treatment, in order to diagnose and manage the disease appropriately.

Emerging potential of niosomes in ocular delivery

INTRODUCTION

Niosomes have recently grabbed attention as one of the best tools for various site-specific drug delivery systems, including ophthalmic drug delivery. Surfactants (nonionic; tweens and spans) of different HLB values and cholesterol are the fundamental components for these formulations. It is an alternative controlled ocular drug delivery system to liposomes to overcome the problems associated with sterilization, large-scale production, and stability. It also enhances the adhesion or retention ability of drug at the ocular site. Hydrophilic or lipophilic or amphoteric drugs can be easily encapsulated in niosomes. Besides, niosomes are a leading vesicular system compatible with most of the drugs for site-specific delivery.

AREAS COVERED

This article reveals challenges and barriers for ocular drug delivery, various transporters and receptors present in the ocular region for the transportation of therapeutics as well as nutrients, and various method of preparations, loading methods and application potential of niosomes in ocular drug delivery.

EXPERT OPINION

Niosomes, a vesicular system offers numerous advantages and applicability because of its good stability, non-immunogenicity, permeation potential, and controlled release ability etc. This drug delivery system has been efficiently used in the treatment of many ocular diseases.

Identification and characterization of three novel antimicrobial peptides from Acipenser dabryanus

Antimicrobial peptides (AMPs) play essential roles in the innate immune system to protect against a wide variety of pathogens in aquatic environments. In this study, three very important AMPs, cathelicidin, hepcidin and defensin, were identified in the critically endangered Acipenser dabryanus. The full-length cDNA sequences of these three AMPs were identified from transcriptome sequencing and the rapid amplification of cDNA ends (RACE) technique. Phylogenetic analysis showed that cathelicidin formed a clade with the other members of the cathelicidin family, and similar results were obtained for hepcidin. The A. dabryanus β-defensin belonged to the fish class 2 β-defensins. A tissue distribution study showed that the three AMP transcripts could be detected constitutively in various tissues. The highest expression levels of cathelicidin and hepcidin were found in the liver, while defensin was primarily expressed in the skin. Bacterial challenge in vivo revealed significant changes in the gene expression of the three AMPs at both mucosal sites and systemic sites. Striking upregulation of cathelicidin and hepcidin was observed in the skin at 12 h post-challenge, with increases of more than 7000-fold and 1000-fold, respectively, compared to the control, and the expression of defensin mRNA was remarkably elevated in the hindgut (by 230-fold at 6 h post-challenge). Moreover, according to the expression profiles of the AMPs post-challenge, we found that the mucosal immune response occurred earlier than the systemic immune response following bacterial infection. Our results suggest that these three novel AMPs may play important roles in the innate immune system of A. dabryanus to protect against invading pathogens, especially during the mucosal immune response.

Identification, expression and bioactivity of Paramisgurnus dabryanus β-defensin that might be involved in immune defense against bacterial infection

β-defensins are a large family of multi-disulfide-bonded peptides with broad-spectrum antimicrobial activities that contribute to innate host defense in many organisms, but little information is available about β-defensins produced by freshwater fish lacking scales. We therefore cloned and identified a β-defensin gene from Chinese loach (Paramisgurnus dabryanus) by designing degenerate primers and using thermal asymmetric interlaced PCR. This gene is the first defensin gene ever identified in a non-scaled freshwater fish. Annotation of the protein domain architecture showed that the putative Chinese loach β-defensin contains the signature motif of six conserved cysteines within the mature peptide, an aspect similar to β-defensins of other marine fish. We also used quantitative real-time PCR to investigate the expression pattern of the Chinese loach β-defensin gene, mRNA of which could be observed in various tissues. After challenge with the pathogenic bacterium Aeromonas hydrophila, β-defensin expression was induced in the eye, gill, skin, and spleen of the adult loach. The bioactivity of the recombinant P. dabryanus β-defensin was examined against pathogenic bacteria, and the results suggest that this class 2 β-defensin has potential applications for treatment of bacterial infections.

In vitro evidence of involvement of the epithelial y+ transporter in β-defensin production on the ocular surface

To analyse the hypothesis as to whether there is a functional relationship between human cationic amino acid transporters (hCATs, y(+) transporter, the main transporter of L-arginine and L-lysine) and human β-defensin (important components of immune function) production on the ocular surface, arginase and nitrate monoxide synthase (NOS), enzymes that compete for L-arginine, were inhibited by norNOHA (N(omega)-hydroxy-nor-L-arginine) and/or L-NAME (NG-nitro-L-arginine methyl ester) in cultured human corneal epithelial cells. In addition, the transport activity of hCAT proteins was inhibited or activated through α-tocopherol or PMA (phorbol myristate acetate), respectively. Concentrations of the human inducible β-defensins (hBD) 2 and 3 were determined by ELISA experiments. The basic expression of hBD3 in non-stimulated HCE cells significantly exceeded that of hBD2. Both β-defensins also differed as to how readily their excretion could be stimulated. HBD2 excretion rate was 3.5 time more by L-NAME, whereas norNOHA had no effect. In contrast, hBD3 excretion was increased by norNOHA by a factor of 1.5 but L-NAME alone had no effect. The excretion of both β-defensins was increased 3- and 6-fold by combined administration of L-NAME, norNOHA and interleukin (IL)-1β. Administration of α-tocopherol increased hBD2 excretion twofold. No effect was observed for hBD3. With PMA, on the other hand, a reduction in secretion for both β-defensins was observed. These in vitro findings provide evidence of a functional association between CAT proteins and β-defensins 2 and 3 opening up a new field of research with pharmacological perspectives for treatment of inflammatory diseases such as keratitis or dry eye disease.

Role of host-defence peptides in eye diseases

The eye and its associated tissues including the lacrimal system and lids have evolved several defence mechanisms to prevent microbial invasion. Included among this armory are several host-defence peptides. These multifunctional molecules are being studied not only for their endogenous antimicrobial properties but also for their potential therapeutic effects. Here the current knowledge of host-defence peptide expression in the eye will be summarised. The role of these peptides in eye disease will be discussed with the primary focus being on infectious keratitis, inflammatory conditions including dry eye and wound healing. Finally the potential of using host-defence peptides and their mimetics/derivatives for the treatment and prevention of eye diseases is addressed.