Dysregulation of lncRNAs in autoimmune neuropathies

Molecular mechanism of lncRNAs in pathogenesis and diagnosis of auto-immune diseases, with a special focus on lncRNA-based therapeutic approaches

Autoimmune diseases are a diverse set of conditions defined by organ damage due to abnormal innate and acquired immune system responses. The pathophysiology of autoimmune disorders is exceedingly intricate and has yet to be fully understood. The study of long non-coding RNAs (lncRNAs), non-protein-coding RNAs with at least 200 nucleotides in length, has gained significant attention due to the completion of the human genome project and the advancement of high-throughput genomic approaches. Recent research has demonstrated how lncRNA alters disease development to different degrees. Although lncRNA research has made significant progress in cancer and generative disorders, autoimmune illnesses are a relatively new research area. Moreover, lncRNAs play crucial functions in differentiating various immune cells, and their potential relationships with autoimmune diseases have received growing attention. Because of the importance of Th17/Treg axis in auto-immune disease development, in this review, we discuss various molecular mechanisms by which lncRNAs regulate the differentiation of Th17/Treg cells. Also, we reviewed recent findings regarding the several approaches in the application of lncRNAs in the diagnosis and treatment of human autoimmune diseases, as well as current challenges in lncRNA-based therapeutic approaches to auto-immune diseases.

Significant up-regulation of lncRNAs in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an immune-related demyelinating defect. Long non-coding RNAs (lncRNAs) might influence the pathobiology and progression of NMOSD. The current study assessed expression level of NEAT1, PANDAR, MEG3 and TUG1 lncRNAs in the peripheral blood of NMOSD patients compared with healthy individuals. All mentioned lncRNAs were shown to be over-expressed in total NMOSD cases, male NMOSD cases and female NMOSD cases compared with the matching control subgroups. MEG3 had the most robust over-expression in patients subgroups compared with normal subjects. There was no noteworthy difference in the expression of any of lncRNAs between female and male patients. MEG3 had an ideal performance in the differentiation of NMOSD cases from healthy persons (Sensitivity and specificity values = 100%). Other lncRNAs could also efficiently separate NMOSD cases from control subjects (AUC values = 0.97, 0.89 and 0.88 for PANDAR, NEAT1 and TUG1, respectively). Cumulatively, NEAT1, PANDAR, MEG3 and TUG1 lncRNAs can be considered as appropriate disease markers for NMOSD.

Lnc-HULC, miR-122, and sirtulin-1 as potential diagnostic biomarkers for psoriasis and their association with the development of metabolic syndrome during the disease course

Psoriasis is a persistent inflammatory skin disorder driven by T cells. The disease is characterized by aberrant keratinocytes (KCs) differentiation, epidermal proliferation, and excessive hyperplasia of veins and arteries. The purpose of the study was to identify the levels of circulating lnc-HULC, miR-122, and Sirtuin 1 (SIRT-1) in psoriatic patients, evaluate their possible roles as diagnostic biomarkers, and link their levels with the development of metabolic syndrome during psoriasis progression. This study included 176 participants. The subjects were divided into four groups, with 44 participants in each group. All patients have undergone a complete history taking and clinical examination. Laboratory investigations included Low-density lipoprotein (LDL), High-density lipoprotein (HDL), Triglycerides (TG), Fasting blood sugar (FBS), and cholesterol plasma levels. Serum levels of miR-122 and lnc-HULC were examined by qRT-PCR. Serum levels of SIRT-1 were examined by ELISA. The serum concentrations of lnc-HULC and miR-122 were significantly higher in psoriatic participants compared to controls. Psoriatic patients' serum concentrations of SIRT-1 were much lower than those of healthy individuals. There was a negative association between SIRT-1 concentration and BMI, disease duration, PASI score, LDL, and cholesterol levels. The blood levels of lnc-HULC, miR-122, and SIRT-1 in psoriasis patients provide a promising role as diagnostic biomarkers in patients with and without metabolic syndrome.

A review on the importance of LINC-ROR in human disorders

Long Intergenic Non-Protein Coding RNA, Regulator Of Reprogramming (LINC-ROR) is a long non-coding RNA with diverse physiological functions. The gene encoding this transcript resides on 18q21.31. Expression levels of LINC-ROR have been reported to be dysregulated in patients with diverse disorders, including cancer, autoimmune disorders and neurodegenerative and neurodevelopmental disorders. Moreover, polymorphisms within this lncRNA have been shown to be associated with a variety of disorders, such as some kinds of cancer and some aspects of systemic lupus erythematous. Abnormal expression of LINC-ROR in some other human disorders is not yet understood. Emerging evidence suggests that LINC-ROR exerts pivotal roles in most types of human disorders as an oncogene. Differentially expressed LINC-ROR contributes in the development of diseases by changing the expression of genes that control the cell cycle. It can also exert its role by affecting the activity of some cancer-related signaling pathways and sponging tumor suppressor miRNAs. Expanding our understanding of LINC-ROR functions will pave the way for developing efficient therapeutic strategies against cancer and related disorders. The current review aims at providing a concise overview of the role of LINC-ROR in diverse human disorders through providing a summary of association studies and expression assays.

miR-31-5p as a Potential Circulating Biomarker and Tracer of Clinical Improvement for Chronic Inflammatory Demyelinating Polyneuropathy

Background

MicroRNAs are endogenous, small noncoding RNA molecules that play a pivotal role in the regulation of gene expression. MicroRNAs are involved in many biological processes such as proliferation, cell differentiation, neovascularization, and apoptosis. Studies on microRNA expression may contribute to a better understanding of the pathomechanism of chronic inflammatory demyelinating polyneuropathy (CIDP) and consequently enable the development of new therapeutic measures using antisense miRNAs (antagomirs). In this study, we evaluated the level of miR-31-5p in the serum of patients with CIDP and its correlation with the miR-31-5p level and clinical presentation and electrophysiological and biochemical parameters.

Methods

The study group consisted of 48 patients, mean age 61.60 ± 11.76, who fulfilled the diagnostic criteria of a typical variant of CIDP. The expression of miR-31-5p in patient serum probes was investigated by droplet digital PCR. The results were correlated with neurophysiological findings and the patient's clinical and biochemical parameters.

Results

The mean copy number of miRNA-31 in 100 μl serum was 1288.64 ± 2001.02 in the CIDP group of patients, while in the control group, it was 3743.09 ± 4026.90. There was a significant positive correlation (0.426) between IgIV treatment duration and miR-31-5p expression. Patients without IgIV treatment showed significantly lower levels of miR-31 compared to the treated group (259.44 ± 304.02 vs. 1559.48 ± 2168.45; p = 0.002). The group of patients with body weight > 80 kg showed statistically significantly lower levels of miRNA-31-5p than the patients with lower body weight (934.37 ± 1739.66 vs. 1784.62 ± 2271.62, respectively; p = 0.014). Similarly, the patients with elevated cerebrospinal fluid (CSF) protein levels had significantly higher miRNA-31-5p expression than those with normal protein levels (1393.93 ± 1932.27 vs. 987.38 ± 2364.10, respectively; p = 0.044).

Conclusion

The results may support the hypothesis that miR-31-5p is strongly involved in the autoimmune process in CIDP. The positive correlation between higher miR-31-5p levels and duration of IVIg treatment may be an additional factor explaining the efficacy of prolonged IVIg therapy in CIDP.

Analysis of expression of regulatory T cell related lncRNAs in inflammatory demyelinating polyneuropathies

Long non-coding RNAs that regulate function of regulatory T cells can affect pathoetiology of autoimmune disorders, such as inflammatory demyelinating polyneuropathies. In the current case-control study, we compared expression of four of these lncRNAs, namely FLICR, NEST, RMRP and TH2-LCR between patients with inflammatory demyelinating polyneuropathies and healthy subjects. Expressions of RMRP, NEST and FLICR were higher in total patients compared with controls. However, there was no significant difference in their expressions between acute and chronic demyelinating polyneuropathies. In addition, interaction of gender and disease factors had significant effect on expression levels of RMRP and TH2-LCR genes in subgroups. RMRR was superior to other lncRNAs in terms of AUC, sensitivity and specificity values in total patients and both subgroups of patients. This lncRNA could separate total patients, female patients and male patients from corresponding controls with AUC values (±SD) of 0.9 ± 0.03, 0.86 ± 0.07 and 0.93 ± 0.03, respectively. FLICR ranked second in this regard, since it could separate total patients, female patients and male patients from corresponding controls with AUC values (±SD) of 0.81 ± 0.03, 0.72 ± 0.07 and 0.87 ± 0.04, respectively. Therefore, our study provides evidence for participation of regulatory T cells-related lncRNAs in the pathoetiology of inflammatory demyelinating polyneuropathies.

Parkinson's Disease Is Associated With Dysregulation of Circulatory Levels of lncRNAs

Long non-coding RNAs (lncRNAs) have been recently reported to be involved in the pathoetiology of Parkinson’s disease (PD). Circulatory levels of lncRNAs might be used as markers for PD. In the present work, we measured expression levels of HULC, PVT1, MEG3, SPRY4-IT1, LINC-ROR and DSCAM-AS1 lncRNAs in the circulation of patients with PD versus healthy controls. Expression of HULC was lower in total patients compared with total controls (Expression ratio (ER)=0.19, adjusted P value<0.0001) as well as in female patients compared with female controls (ER=0.071, adjusted P value=0.0004). Expression of PVT1 was lower in total patients compared with total controls (ER=0.55, adjusted P value=0.0124). Expression of DSCAM-AS1 was higher in total patients compared with total controls (ER=5.67, P value=0.0029) and in male patients compared with male controls (ER=9.526, adjusted P value=0.0024). Expression of SPRY4-IT was higher in total patients compared with total controls (ER=2.64, adjusted P value<0.02) and in male patients compared with male controls (ER=3.43, P value<0.03). Expression of LINC-ROR was higher in total patients compared with total controls (ER=10.36, adjusted P value<0.0001) and in both male and female patients compared with sex-matched controls (ER=4.57, adjusted P value=0.03 and ER=23.47, adjusted P value=0.0019, respectively). Finally, expression of MEG3 was higher in total patients compared with total controls (ER=13.94, adjusted P value<0.0001) and in both male and female patients compared with sex-matched controls (ER=8.60, adjusted P value<0.004 and ER=22.58, adjusted P value<0.0085, respectively). ROC curve analysis revealed that MEG3 and LINC-ROR have diagnostic power of 0.77 and 0.73, respectively. Other lncRNAs had AUC values less than 0.7. Expression of none of lncRNAs was correlated with age of patients, disease duration, disease stage, MMSE or UPDRS. The current study provides further evidence for dysregulation of lncRNAs in the circulation of PD patients.