Expression of prostaglandin E2 receptor 3 in the eyelid epidermis of patients with Stevens-Johnson syndrome/toxic epidermal necrolysis

Altered Prostaglandin E Receptor Subtype 3 Expression in Lacrimal Glands of Patients with Chronic Stevens-Johnson Syndrome

PURPOSE

To compare the prostaglandin E2 receptor subtype 3 (EP3) distribution in the lacrimal glands of normals, non-specific dacryoadenitis, and chronic Stevens-Johnson syndrome (SJS) patients.

METHODS

Biopsies from lacrimal glands of four chronic SJS patients with severe dry eye disease, four dacryoadenitis patients, and five fresh body donors were assessed for EP3 expression using immunohistochemistry.

RESULTS

In normal main and accessory lacrimal glands, EP3 is expressed strongly in nuclei and cytoplasm of majority (>75%) of acini with no ductular expression. In dacryoadenitis, EP3 expression was similar to normal glands. However, lacrimal glands from SJS patients (5-20/HPF mononuclear cells) showed a weak and reduced (<10% acini) EP3 expression within acinar cells. The reduction in intensity was more in glands with higher mononuclear cell infiltration (>10/HPF).

CONCLUSION

There is downregulation of EP3 expression in the lacrimal glands of SJS patients, whereas EP3 expression is preserved in non-specific lacrimal gland inflammations.

Lid margin keratinization in Stevens-Johnson syndrome: Review of pathophysiology and histopathology

Lid margin keratinization (LMK) is a chronic ocular sequela of Stevens-Johnson syndrome (SJS), which causes lid wiper epitheliopathy and progressive ocular surface damage. The exact etiopathogenesis of LMK, however, remains elusive. This review summarizes the potential pathophysiological mechanisms of LMK and describes its histopathological features. A literature search of articles discussing the pathophysiology of LMK in SJS was performed. The possible pathophysiologic mechanisms contributing to LMK, as identified on the literature review, included loss of the muco-cutaneous junction barrier leading to epidermalization, dyskeratosis involving the meibomian gland orifices, altered lid margin microbiome, and de novo squamous metaplasia of the marginal conjunctival epithelium. Based on these mechanisms, the possible sources of keratinized epithelium at the posterior lid margin in SJS could be the adjacent anterior eyelid skin, hyperkeratinized epithelium from the meibomian gland ductal orifices, or the inflamed marginal conjunctiva. The epithelial, sub-epithelial, and stromal changes seen in keratinized posterior lid margins in SJS patients undergoing mucous membrane grafting were also investigated. The findings revealed keratinizing squamous metaplasia of the posterior lid margin accompanied by subepithelial infiltration of helper T cells predominantly on the conjunctival side. The visible meibomian gland orifices had ductal hyperkeratinization and plugging. These findings support a role for inflammation in the pathogenesis of LMK in SJS. Future research can be directed at delineating the pathways that lead to LMK by studying the changes in the lid margin microbiome, and the molecular mechanisms regulating keratinization in the conjunctiva and the meibomian gland orifices in eyes affected by SJS.

The complex role of prostaglandin E2-EP receptor signaling in wound healing

Prostaglandins are critical lipid mediators involved in the wound healing response, with prostaglandin E₂ (PGE₂) being the most complex and exhibiting the most diverse physiological outputs. PGE₂ signals via four G protein-coupled receptors, termed EP-receptors 1-4 that induce distinct signaling pathways upon activation and lead to an array of different outputs. Recent studies examining the role of PGE₂ and EP receptor signaling in wound healing following various forms of tissue damage are discussed in this review.

Association of HLA polymorphisms and acetaminophen-related Steven-Johnson syndrome with severe ocular complications in Thai population

Background/aims

To investigate the association of genetic polymorphisms of human leucocyte antigens (HLA) class I and II genes with acetaminophen-related Steven-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) who developed severe ocular complications (SOC) in the Thai population.

Methods

A prospective case–control study including 20 unrelated Thai acetaminophen-related SJS/TEN patients with SOC and 60 Thai healthy volunteers, recruited at three university hospitals in Bangkok, Thailand, from September 2014 to August 2019. HLA genes were analysed using PCR amplification followed by hybridisation with sequence-specific oligonucleotide (SSO) probes with bead-based typing kits. The carrier and gene frequencies of individual HLA alleles in patients were compared with those in control volunteers based on dominant assumption using Fisher’s exact test.

Results

Among HLA class I polymorphisms, HLA-A*33:03, HLA-B*44:03 and HLA-C*07:01 were significantly associated with acetaminophen-related SJS/TEN and SOC with high ORs (95% CI, corrected p value; Pc) in carrier frequency of 5.4 (1.8 to 16.3, Pc=0.0274), 9.0 (95% CI 2.7 to 30.4, Pc=0.0034), and 9.3 (2.8 to 30.2, Pc=0.0022), respectively. There were no significant HLA class II associations with the disease after corrected for a total number of alleles tested.

Conclusion

HLA-B*44:03 was strongly associated with acetaminophen-related SJS/TEN patients who developed SOC in Thai population. In addition, we also found moderate to strong associations with HLA-A*33:03 and HLA-C*07:01 suggesting their potential roles in the pathogenesis of SOC in acetaminophen-related SJS/TEN.

International Union of Basic and Clinical Pharmacology. CIX. Differences and Similarities between Human and Rodent Prostaglandin E2 Receptors (EP1-4) and Prostacyclin Receptor (IP): Specific Roles in Pathophysiologic Conditions

Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.

Integrated transcriptome expression profiling reveals a novel lncRNA associated with L-DOPA-induced dyskinesia in a rat model of Parkinson's disease

Levodopa-induced dyskinesia (LID) is a common complication of chronic dopamine replacement therapy in the treatment of Parkinson's disease (PD). Long noncoding RNAs regulate gene expression and participate in many biological processes. However, the role of long noncoding RNAs in LID is not well understood. In the present study, we examined the lncRNA transcriptome profile of a rat model of PD and LID by RNA sequence and got a subset of lncRNAs, which were gradually decreased during the development of PD and LID. We further identified a previously uncharacterized long noncoding RNA, NONRATT023402.2, and its target genes glutathione S-transferase omega (Gsto)2 and prostaglandin E receptor (Ptger)3. All of them were decreased in the PD and LID rats as shown by quantitative real-time PCR, fluorescence in situ hybridization and western blotting. Pearson's correlation analysis showed that their expression was positively correlated with the dyskinesia score of LID rats. In vitro experiments by small interfering RNA confirmed that slicing NONRATT023402 inhibited Gsto2 and Ptger3 and promoted the inflammatory response. These results demonstrate that NONRATT023402.2 may have inhibitive effects on the development of PD and LID.