Downregulation of TLR-7 receptor in hepatic and non-hepatic patients with lichen planus

Demystifying Esophageal Lichen Planus: A Comprehensive Review of a Rare Disease You Will See in Practice

Lichen planus (LP) is a chronic inflammatory disorder that often affects the skin, hair, nails, and mucus membranes. Although esophageal involvement has traditionally been felt to be rare, recent reports suggest that it is often unrecognized or misdiagnosed. The diagnoses of esophageal lichen planus can be challenging and is suspected based on patients' endoscopic and histologic findings and in the context of their clinical history and physical examination. Physicians must have an index of suspicion, particularly in older white women and in those patients with an atypical esophagitis or stricturing disease, which do not respond to traditional treatment. Currently, there are limited data on esophageal lichen planus patients, and no formal management guidelines for this disease, which all gastroenterologists will see in practice. This article reviews the etiology and histopathology of LP and provides a comprehensive discussion of the clinical features, diagnosis, and management of esophageal disease from the gastroenterologist's perspective. Finally, we address the esophageal complications of LP.

Potential pathogenic mechanisms involved in the association between lichen planus and hepatitis C virus infection

Lichen planus (LP) is an immune-mediated inflammatory disease that particularly affects the skin and mucous membranes. Its etiology remains elusive, however some trigger factors, including viral or bacterial antigens, drugs and metals, have been postulated. There is a higher prevalence of hepatitis C virus (HCV) infection among patients with LP, with some geographical variations. HCV is an enveloped RNA virus that belongs to the Flaviviridae family and in most instances causes chronic liver infections. It has been hypothesized that HCV may contribute to LP development, but the link between the two disorders is not fully understood. It is still debatable whether HCV leads to the occurrence of LP lesions directly by replication inside the infected cells or indirectly by activating immunological pathways. Molecular studies have revealed HCV RNA in specimens collected from patients with LP. The autoimmune theory was also suggested given that several studies have revealed viral replication and immune response activation associated with autoantibody synthesis. The aim of this review is to summarize the main potential mechanisms involved in the association between LP and HCV infection. Understanding the link between the two disorders may shed some light on the pathogenesis of LP, which is a challenging issue.

Increased infiltration of CD11 c+/CD123+ dendritic cell subsets and upregulation of TLR/IFN-α signaling participate in pathogenesis of oral lichen planus

OBJECTIVE

Investigation of dendritic cell (DC) subsets and expression patterns of Toll-like receptors (TLRs) was conducted to understand the pathogenesis in oral lichen planus (OLP).

STUDY DESIGN

Blood, OLP lesion, and control samples were collected. Four DC subsets (CD11c⁺CD123^-myeloid DC1 [mDC1], CD141⁺mDC2, CD11c^-CD123⁺plasmacytoid DC [pDC], and CD1a⁺CD207⁺Langerhans cells [LC]) were investigated via flow cytometry (FCM) and immunohistochemical staining. Expression patterns of TLRs and their downstream molecules were analyzed via quantitative real-time polymerase chain reaction and immunohistochemistry in situ.

RESULTS

Thirty-two samples were collected (9 controls and 23 OLP patients). FCM results found that the percentages of LC, mDC1, mDC2, and pDC in situ were 0.0119 ± 0.0251%, 0.0064 ± 0.0134%, 0.0005 ± 0.0011%, and 0.0022 ± 0.0019% in control mucosa, respectively. The mDC1 (0.0300 ± 0.0276%) and pDC (0.0204 ± 0.0186%) subsets were significantly increased in OLP lesions (P < .01). No marked differences were evident, when comparing all 4 DC subsets from blood, between control and OLP groups. Significant upregulation of TLR7, TLR8, and TLR9 were disclosed in OLP (P < .01), along with their downstream interferon-α (IFN-α) signaling molecules (IRF7 and IFN-α, P < .01).

CONCLUSION

Our findings of increased infiltration of pDC and mDC1, along with upregulation of TLR/IFN-α signaling, provide valuable information for further understanding the immunity in OLP.

Assessment of systemic inflammation with neutrophil-lymphocyte ratio in lichen planus

Introduction

Lichen planus (LP) is a papulosquamous eruption of the skin and mucous membranes. Although the exact pathogenesis of the disease remains unclear, it is believed that LP represents an inflammatory disorder. Neutrophil-lymphocyte (N/L) ratio is considered a systemic inflammatory marker that correlated with severity of the diseases.

Aim

To investigate whether N/L ratio increases in LP and may be an independent severity marker for LP lesions.

Material and methods

White blood cell (WBC), neutrophil and lymphocyte counts, N/L ratio, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were statistically compared between the patient (n = 55) and the control group (n = 48). The relationship of N/L ratio and the body surface area (BSA) was assessed.

Results

Erythrocyte sedimentation rate and CRP were statistically higher in patients with LP than in controls (p < 0.0001). Our analysis revealed a significantly higher level of N/L ratio in patients with LP compared with controls, respectively (2.5 ±1.1 (1.2–7.3) vs. 1.4 ±0.4 (0.8–2.7), p < 0.0001). Body surface area (p = 0.001), CRP (p = 0.006), and ESR (p = 0.003) were identified as possible predictors of N/L ratio, but only BSA (p = 0.002) and ESR (p = 0.003) were found as significant independent predictors in a multiple linear regression model.

Conclusions

The inflammatory process in LP was supported by our results. N/L ratio may have an impact to show the inflammatory status in patients with LP as an inexpensive, simple and effective predictor. It may be used for the severity and treatment option of LP. But, N/L ratio and LP relationship could be confirmed by other large prospective studies.

The early induction of suppressor of cytokine signaling 1 and the downregulation of toll-like receptors 7 and 9 induce tolerance in costimulated macrophages

Toll-like receptors (TLR) 7 and 9 transduce a cellular signal through the MyD88-dependent pathway and induce the production of inflammatory mediators against microbial nucleotide components. The repeated stimulation of TLR4 leads to endotoxin tolerance, but the molecular mechanisms of tolerance induced through the costimulation of individual TLR has not yet been established, although endosomal TLRs share signaling pathways with TLR4. In the present study, mouse macrophages were simultaneously stimulated with the TLR7 agonist, gardiquimod (GDQ), and the TLR9 agonist, CpG ODN 1826, to examine the mechanism and effector functions of macrophage tolerance. Compared with individual stimulation, the costimulation of both TLRs reduced the secretion of TNF-α and IL-6 through the delayed activation of the NF-κB pathway; notably, IL-10 remained unchanged in costimulated macrophages. This tolerance reflected the early induction of suppressor of cytokine signaling-1 (SOCS-1), according to the detection of elevated TNF-α secretion and restored NF-κB signaling in response to the siRNA-mediated abrogation of SOCS-1 signaling. In addition, the restimulation of each TLRs using the same ligand significantly reduced the expression of both TLRs in endosomes. These findings revealed that the costimulation of TLR7 and TLR9 induced macrophage tolerance via SOCS-1, and the restimulation of each receptor or both TLR7 and TLR9 downregulated TLR expression through a negative feedback mechanisms that protects the host from excessive inflammatory responses. Moreover, the insufficient and impaired immune response in chronic viral infection might also reflect the repeated and simultaneous stimulation of those endosomal TLRs.