Pattern-recognition receptors in endometriosis: A narrative review

Endometriosis is closely associated with ectopic focal inflammation and immunosuppressive microenvironment. Multiple types of pattern recognition receptors (PRRs) are present in the innate immune system, which are able to detect pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) in both intracellular and external environments. However, the exact role of PRRs in endometriosis and the underlying molecular mechanism are unclear. PRRs are necessary for the innate immune system to identify and destroy invasive foreign infectious agents. Mammals mainly have two types of microbial recognition systems. The first one consists of the membrane-bound receptors, such as toll-like receptors (TLRs), which recognize extracellular microorganisms and activate intracellular signals to stimulate immune responses. The second one consists of the intracellular PRRs, including nod-like receptors (NLRs) and antiviral proteins retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA-5) with helix enzyme domain. In this review, we mainly focus on the key role of PRRs in the pathological processes associated with endometriosis. PRRs recognize PAMPs and can distinguish pathogenic microorganisms from self, triggering receptor ligand reaction followed by the stimulation of host immune response. Activated immune response promotes the transmission of microbial infection signals to the cells. As endometriosis is characterized by dysregulated inflammation and immune response, PRRs may potentially be involved in the activation of endometriosis-associated inflammation and immune disorders. Toll-like receptor 2 (TLR2), toll-like receptor 3 (TLR3), toll-like receptor 4 (TLR4), nod-like receptor family caspase activation and recruitment domain (CARD) domain containing 5 (NLRC5), nod-like receptor family pyrin domain containing 3 (NLRP3), and c-type lectin receptors (CLRs) play essential roles in endometriosis development by regulating immune and inflammatory responses. Absent in melanoma 2 (AIM2)-like receptors (ALRs) and retinoic acid-inducible gene I-like receptors (RLRs) may be involved in the activation of endometriosis-associated immune and inflammation disorders. PRRs, especially TLRs, may serve as potential therapeutic targets for alleviating pain in endometriosis patients. PRRs and their ligands interact with the innate immune system to enhance inflammation in the stromal cells during endometriosis. Thus, targeting PRRs and their new synthetic ligands may provide new therapeutic options for treating endometriosis.

Evaluation of Toll-like receptor 3 (TLR3) signaling pathway genes and its genetic polymorphisms in ectopic and eutopic endometrium of women with endometriosis

OBJECTIVE

Toll-like receptors (TLRs, as members of the innate immune system) are expressed in the human endometrium and their aberrant regulation and expression are involved in the pathogenesis of endometrial diseases. This study is aimed at evaluation of TLR3 signaling pathway genes and its genetic changes in endometriosis patients.

MATERIALS AND METHODS

Blood samples were collected from 83 endometriosis patients and 93 healthy fertile women and PCR was performed in blood-derived DNA for detection of SNP of TLR3. Also, ectopic (EC) and eutopic (EU) endometrial biopsies were obtained from endometriosis patients (n = 20), as well as endometrium from healthy women (n = 16, CE). Q-PCR was performed for determination of mRNA expression level of TLR3 signaling pathway genes (TLR3, TICAM, NF-kB1A, CXCL10, IRF3, IFN-B1, IL-6 and IL-8). Also, serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were determined using ELISA.

RESULTS

The mRNA expression levels of TLR3, NF-kB1A, IFN-B1, IRF3, TICAM1, IL-6 and IL-8 were significantly higher in EU compared to ectopic ones and also compared to CE. SNPs frequency (rs3775291 and rs3775290) was not significantly different between patients and controls. Serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were significantly increased in endometriosis patients.

CONCLUSION

Significant changes were observed in the expression of IL-6 and IL-8 cytokines and other genes in TLR3 cascade in diseased EU, demonstrating that EU similarly to EC is in an intensive inflammatory state. These fundamental alterations in the concept of immune response in EU may lead to its activation, escapes from apoptosis, and displaced implantation of the endometrium.

Activation of HMGB1-TLR4 Pathway and Inflammasome Contribute to Enhanced Inflammatory Response in Extended Criteria and Kidneys With KDPI ≥85

BACKGROUND

Metrics for evaluating low-quality kidneys have failed to predict outcomes or reduce the kidney refusal and discard rates. Kidneys from extended-criteria donors (ECDs) and kidneys with ≥85% kidney donor profile indexes (KDPIs) might have different sensitivities to the proinflammatory milieu generated by brain death. We aimed to identify gene expression profile differences in innate immunity pathways between low-quality and ideal kidneys.

METHODS

Preimplantation kidney biopsies from ECD (n = 41) and standard-criteria donor (n = 39) were evaluated for real-time quantitative polymerase chain reaction gene expression using the TaqMan Gene Expression Array Plates system for genes Toll-like receptor-4 (TLR4), high-mobility group box 1, nuclear factor kappa beta, myeloid differentiation primary response 88, interferon (IFN)-γ, interleukin (IL)1-β, tumor necrosis factor alpha, caspase-1 (CASP1), intercellular adhesion molecule 1, IL-10, heme oxygenase 1 hypoxia-inducible factor 1 (HIF-1), monocyte chemotactic protein 1, transforming growth factor beta 1, TIR-domain containing adapter inducing interferon-β (TRIF), TRIF-related adaptor molecule, interferon regulatory factor 3 (IRF-3), receptor-interacting protein 1, IFNβ-1, and nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin protein 3 complex. Gene expression was also evaluated in kidneys with KDPI ≥85.

RESULTS

ECD biopsies showed significantly higher expression of IL-10, TLR4, high-mobility group box 1, IFN-γ, TRIF-related adapter molecule, IRF-3, HIF-1, nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin protein 3 complex, CASP1, and IL-1β (P < 0.05) compared with standard-criteria donor biopsies. IRF-3, HIF-1, and CASP1 were exclusively upregulated in ECD kidneys. Compared with kidneys with KDPIs <85%, kidneys with KDPIs ≥85% had very similar gene transcripts as those observed in ECD kidneys, except that tumor necrosis factor alpha and monocyte chemotactic protein 1 expression was only elevated in kidneys with KDPIs ≥85%. Significant positive correlations were found between the different genes upregulated and the increase in KDPIs.

CONCLUSIONS

Our results showed that TLR4 and inflammasome pathways are enhanced in low-quality kidneys and suggest that blocking of some targets might improve transplant outcomes and reduce discard rates.

Human closed and open apex premolar teeth express different toll-like receptor

Background

The innate immune activation which promotes inflammation responses in the dental pulp tissue leads to the progression of dentin caries. Accordingly, toll‐like receptors (TLRs) are key molecules of the innate immune system that identify pathogen‐associated molecular patterns (PAMPs) on microorganisms and may have a critical role in a dental injury. Therefore, this study aimed to investigate the expression of TLR2, TLR3, and TLR4 in the human dental pulp of opened and closed apex teeth.

Methods

Human dental pulps were derived from the healthy opened and closed apex premolar, in which extraction was indicated for orthodontic reasons. The extraction of RNA was performed and the gene expression determined by real‐time polymerase chain reaction (RT‐PCR). The result from real‐time PCR was confirmed using western blot analysis.

Results

Real‐time PCR data analysis showed that the expression TLR2 and TLR4 were significantly increased in closed apex premolar teeth compared to open apex teeth, whereas TLR3 expression was not significantly different in these two groups (p < .05).

Conclusion

The results of the present study suggested increased expression of TLR2 and TLR4 by the maturation of the apex, which may be due to the presence of microorganisms in the normal or destructed dental pulp tissue. Thus, identifying the expression of TLRs molecules in dental pulp tissue helps to develop a deeper knowledge of the immune responses in the oral cavity.

Efficacy of Corticosteroid Injection for Treatment of Trigger Finger: A Meta-Analysis of Randomized Controlled Trials

Purpose: To determine the efficacy and safety of corticosteroid injection for trigger finger by performing a meta-analysis of all relevant studies. Methods: PubMed, EMBASE, and Cochrane Library databases were searched for randomized controlled trials (RCTs) comparing corticosteroid injection with other treatments for trigger finger. Pooled summary estimates for outcomes, including success rate, relapse rate, visual analogue score (VAS) and complications, were calculated as standardized mean difference (SMD) or relative risk (RR) either on a fixed- or random-effect model via Stata 12.0 software. Results: Ten literatures involving 806 patients (387 in corticosteroid injection group and 419 in control group) were included. Pooled analysis showed there were no differences in the success rate, VAS and complications between patients undergoing corticosteroid injection and others. However, the relapse rate was significantly higher in patients treated with corticosteroid injection than that of other treatments (RR = 19.53, 95% CI = 6.23-61.19). Subgroup analysis indicated the efficacy of corticosteroid injection was superior to other non-surgical treatments (success rate: RR = 1.54, 95% CI = 1.01-2.35), but inferior to surgery (success rate: RR = 0.55, 95% CI = 0.48-0.63; relapse rate: RR = 21.15, 95% CI = 6.06-73.85; VAS: SMD = 3.49, 95% CI = 2.84-4.14). Conclusions: Corticosteroid injection may be an effective strategy for management of trigger finger, although surgery may be needed for some patients due to recurrence.