Effect of Conbercept on serum lncRNA MALAT1 levels and central macular thickness in patients with diabetic macular edema

Abstract?AIM: To investigate the effect of Conbercept on serum lncRNA MALAT1 levels, central macular thickness (CMT) and best corrected visual acuity (BCVA) in patients with diabetic macular edema (DME), and to observe its efficacy and safety.

?KEYWORDS:Conbercept; Ranibizumab; injections; injection for diabetic macular edema; lncRNA; MALAT1; central macular thickness

INTRODUCTION

Diabetes mellitus (DM) is a common chronic metabolic disorder caused by abnormal blood glucose levels[1]. With the development of the social economy and changes in lifestyle, DM affects about 10% of the world’s population[2-3]. The incidence rate of the disease is expected to continue to increase significantly in the near future. Besides the abnormal physiological conditions caused by DM itself, complications from the disease also seriously affect human health[4]. Diabetic retinopathy (DR) is one of the common microvascular complications of diabetes. Diabetic macular edema (DME) is the main cause of blindness in DR patients[5]. It is reported that 28.8% of DM patients develop DR, while 22.2% of DM patients do not develop DR regardless of blood glucose levels. These studies indicate that genetic factors play an important role in the pathogenesis of DR[6].

Long noncoding RNA (lncRNA) is a group of noncoding transcriptional RNA with more than 200 nucleotides. It regulates gene expression through epigenetic, transcriptional, and post transcriptional levels and plays an important role in regulating the physiological and pathological processes of the cardiovascular system. Metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is an evolutionarily conserved lncRNA. It was initially shown to be associated with lung metastasis of cancer, but the latest research has shown that it can regulate the proliferation, migration and vascular growth of vascular endothelial cells in heart failure, myocardial infarction and congenital heart disease. DR plays an important role in vascular diseases[7].

Ranibizumab and Conbercept are two kinds of commonly used anti-VEGF drugs[8-13]. Conbercept injections can competitively bind VEGF receptors and inhibit VEGF activation from preventing the formation of pathological neovascularisation[14-17]. In this study, DME patients treated with Ranibizumab and Conbercept were assessed. The clinical effects of the two drugs were retrospectively analysed and compared.

METHODS

SubjectsA total of 300 DME patients (300 eyes, all monocular lesions) treated in the Eye Center of Suining Central Hospital from January 2021 to October 2021 were included in the study. One hundred cases (100 eyes) were recruited in the non-injection group, including 55 males and 45 females, aged 46-61 years, with an average age of (53.56±7.03) years. The duration of diabetes was (10.61±4.52) years. According to a random numbers table, 100 cases (100 eyes) were assigned to a control group and were treated with Ranibizumab injections, including 53 males and 47 females, aged from 45 to 60 years, with an average age of (53.03±7.01) years. The duration of diabetes in this group was 10.63±4.54 years. In the study group, 100 patients (100 eyes) were treated with Conbercept, including 55 males and 45 females, aged 47～63 years, with an average age of 55.79±7.21 years. The duration of diabetes was 10.57±4.51 years. The general characteristics of the two groups were comparable. The design of this study was in line with the Helsinki Declaration and the informed consent of the patients was obtained.

The inclusion criteria were in accord with the 2014 Guidelines for Clinical Diagnosis and Treatment of Diabetic Retinopathy in China. Ophthalmoscopy, fundus photography, optical coherence tomography (OCT), and fundus fluorescein angiography were performed to diagnose nonproliferative DR combined with DME. The central macular thickness (CMT) was >250μm. The preoperative BCVA(LogMAR) was 0.9～0.4 and CMT was 321.04～451.73 μm. The average CMT was 320.33±130.81μm. The exclusion criteria were fundus diseases, such as retinal vein occlusion or age-related macular degeneration, glaucoma, optic neuritis and other eye diseases. Patients with a history of retinal laser photocoagulation, intravitreal drug injection and internal eye surgery were also excluded. Patients with turbid quality and poor coordination that affected imaging clarity, failure to follow the treatment plan, or were lost to follow-up were also excluded.

MethodsOperation method: Vitreous cavity injection was performed according to the internal eye operation standard, which included routine disinfection and laying of towels, surface anaesthesia with promecaine hydrochloride eye drops, flushing of the conjunctival sac with iodophor and normal saline, special filtering of the drug with, removal of liquid with an 18G blunt needle, inserting the needle into the eye at 3.5 mm behind the corneal limbus above the temporal area, slowly injecting 0.05 mL of the drug into the vitreous cavity, and pressing the puncture point for 30s after pulling the needle out to prevent reflux. The intraocular pressure was stabilised as normal, tobramycin dexamethasone eye ointment was applied to the operated eyes, and the operated eyes were bandaged. Levofloxacin eye drops were given after the operation. Patients in both groups were injected once a month for 3mo. All operations were performed by the same operator.

The control group was treated with Ranibizumab injections (Novartis Pharma Stein AG, Switzerland, Registration No.s20140003) and the study group was treated with Conbercept injections (Chengdu Kanghong Biotechnology Co., Ltd., National Drug Standard s20130012).

Index observation: The same examination equipment and methods as used previously were used for measurements during the 3mo after treatment. The changes in BCVA(LogMAR), serum lncRNA MALAT1 and CMT were observed during the 3mo after treatment. All measurements were completed by the same researcher.

BCVA:According to the low visual acuity grading standard formulated by the World Health Organization, patients were examined with the international standard visual acuity chart before treatment and during the 3mo after treatment. Tropicamide eye drops were used for mydriasis, and measurement values were converted to the minimum visual angle logarithm (LogMAR) for visual acuity analysis. The visual acuity evaluation criteria were divided into three levels: BCVA increase ≥2, behavioural visual acuity improvement, BCVA decrease ≥2, behavioural visual acuity decreased, fluctuated up and down and behavioural visual acuity was stable.

Serological indexes: A total of 5 mL of elbow vein blood of all subjects were taken on an empty stomach before and for 3mo after treatment. After centrifugation, serum samples were stored in a refrigerator at -70℃. The level of lncRNA MALAT1 in serum was measured with a double antibody sandwich enzyme-linked immunosorbent assay.

Anatomical indexes:The CMT was measured with OCT before treatment and in during the 3mo after treatment.

Observation of adverse reactions:We observed the general situation, adverse reactions and complications in the eyes.

RESULTS

BaselineCharacteristicsThree hundred eyes of patients were randomly divided into the non-injection group (n=100), control group (n=100) and study group (n=100). There was no significant difference among the three groups (P>0.05; Table 1).

Table 1 Baseline data for the three groups before treatment

ComparisonofLogMARBCVAamongthethreegroupsaftertreatmentThe BCVA(LogMAR) of patients in the non-injection group before treatment and 1, 2 and 3 mo after treatment were 0.69±0.21, 0.71±0.18, 0.70±0.23 and 0.69±0.31 respectively, and there was no statistical significance (P>0.05). The BCVA(LogMAR) of patients in the control group before treatment and during the 3mo after treatment were 0.67±0.23, 0.46±0.12, 0.41±0.14, and 0.38±0.09, respectively,

BCVA was significantly higher after treatment compared to before treatment (P<0.05). The BCVA(LogMAR) of patients in the study group before treatment and for 3mo after treatment were 0.71±0.13, 0.41±0.22, 0.41±0.35, and 0.36±0.17, respectively. After treatment, compared with before treatment, the BCVA was significantly improved (P<0.05). However, there was no significant difference between the study group and the control group (P>0.05; Table 2).

Table 2 Comparison of best corrected visual acuity among the three groups before and after treatment LogMAR)

ComparisonofserumlncRNAMALAT1amongthethreegroupsbeforeandaftertreatmentThe serum levels of lncRNA MALAT1 in the non-injection group before treatment and 1, 2 and 3mo after treatment, were 156.31±13.96 ng/L, 156.40±14.01 ng/L, 156.41±13.99 ng/L, and 156.36±13.98 ng/L, respectively. There was no statistically significant change in the level of serum lncRNA MALAT1 (P>0.05). The levels of serum lncRNA MALAT1 in the control group were 158.21±14.36 ng/L, 103.26±11.21 ng/L, 103.31±12.53 ng/L and 100.48±9.53 ng/L before treatment and during the 3mo after treatment, respectively. The levels of lncRNA MALAT1 after treatment were significantly lower than those before treatment (P<0.05). The levels of serum lncRNA MALAT1 in the study group before treatment and for 3mo after treatment were 155.67±22.01ng/L, 81.14±13.01ng/L, 79.69±11.54ng/L and 77.26±10.32ng/L, respectively. The level of lncRNA MALAT1 after treatment was significantly lower than that before treatment (P<0.05). Compared with the control group, the level of lncRNA MALAT1 decreased significantly in the study group (P<0.05; Table 3).

Table 3 Comparison of serum lncRNA MALAT1 levels among the three groups before and after treatment ng/L)

ComparisonofcentralmacularthicknessamongthethreegroupsbeforeandaftertreatmentThe CMT of patients in the non-injection group before treatment and 1, 2 and 3mo after treatment were (324.81±130.90)μm, (324.86±131.06) μm, (324.75±130.87)μm and (324.83±130.66)μm respectively. There was no significant difference in CMT (P>0.05). The CMT of patients in the control group before treatment and 1, 2 and 3mo after treatment were (322.89±131.62)μm, (289.74±101.24)μm, (277.68±102.52)μm, and (264.49±100.71)μm, respectively. As such, CMT decreased significantly after treatment compared with that before treatment (P<0.05). The CMT of patients in the study group before treatment and at 1, 2 and 3mo after treatment were (320.71±129.87)μm, (221.47±90.01)μm, (220.69±92.58)μm and (209.26±87.52)μm respectively. Similarly, CMT decreased significantly after treatment compared with that before treatment (P<0.05).In addition, compared with the control group, CMT decreased more significantly in the study group (P<0.05). (Table 4; Figure 1 A-L).

Figure 1 Changes of central macular thickness before and after treatment. A-D: Changes of central macular thickness in non-injection group before treatment and 1, 2 and 3mo after treatment; E-H: Changes of central macular thickness in control group before treatment and 1, 2 and 3mo after treatment; I-L: Changes of central macular thickness in study group before treatment and 1, 2 and 3mo after treatment.

AdverseEventsThere were no mental diseases, nervous system diseases, allergies and other adverse reactions in the two groups during treatment observation and follow-up. The adverse reaction rate of patients in the control group during follow-up was 11.0% (11/100). Eight cases and 8 eyes had different degrees of the subconjunctival haemorrhage, which was absorbed within 10d, and 3 cases (3 eyes) had mild inflammatory reactions in the anterior chamber on the second day after the operation, which recovered within 3d. The adverse reaction rate in the study group was 2.0% (2/100). Two subjects (2 eyes) had different degrees of the subconjunctival haemorrhage, which was absorbed within 7d without other adverse reactions. The incidence of adverse eye reactions in the study group was significantly lower than that in the control group.

DISCUSSION

Due to continuous hyperglycemia and insulin metabolism disorder, DM may be associated with increased blood viscosity and abnormal vascular endothelial function, resulting in blood retinal barrier damage, microvascular leakage and finally DR with microaneurysms, hard exudation, cotton wool spots and macular edema as the main manifestations. Thus, due to DME in DR, patients can have a serious visual impairment or even blindness[18-19]. DR is a complex process involving various internal and external factors. The lncRNA is a group of RNA transcripts composed of more than 200 nucleotides and it has no protein coding ability. MALAT1 is an evolutionarily conserved lncRNA. It has been reported that some lncRNAs are involved in the occurrence and development of DR[20]. In addition, many studies have shown that MALAT1 also plays an important role in the occurrence and development of DR[21-22]; for example, yes-associated protein-1 (YAP1) may promote the occurrence and development of DR by regulating the MALAT1/miR/200b-30p/VEGFA axis and regulating the miR-125b/VE-CaALAN1 axis can promote angiogenesis of DR[23]. Previous studies have shown that some lncRNAs are involved in the development of retinal injury caused by hyperglycemia. The expression of lncRNA MALAT1 is up-regulated in high glucose-induced retinal injury. The expression of lncRNA MALAT1 was positively correlated with the severity of DM[24]. In addition, studies have found that the expression of lncRNA MALAT1 is up-regulated in DR, resulting in an increase in the expression of serine enriched splicing factor (ASF/SF2), which leads to the development of the disease[25]. In addition, studies have shown that lncRNA MALAT1 is continuously up-regulated in DR renal tissue. The level of lncRNA MALAT1 in HK-2 cells is time-dependent, and the knockout of MALAT1 can inhibit renal tubular epithelial cell fibrosis[26]. In addition, an increase in lncRNA MALAT1 was observed in the retinal tissues of DR patients and Hg exposed human renal glomerular endothelial cells[27]. Therefore, the study of lncRNA MALAT1 will help provide new ideas for the prevention and treatment of DR.

Table 4 Comparison of central macular thickness among the three groups before and after treatment

At present, great progress has been made in research on the treatmentof DME, and this new progress is due to the emergence of anti-VEGF drugs, such as Conbercept and Ranibizumab, which can reduce the concentration of VEGF and prevent angiogenesis[28-34]. Therefore, selecting reasonable anti-VEGF drugs and employing standardised treatment is an important means to treat DME and delay the development of the disease. In this study, Ranibizumab were selected for the control group and Conbercept were chosen for the research group to treat DME patients. There were no significant changes in LogMAR BCVA, serum lncRNA MALAT1 and CMT in the non-injection group (P>0.05).The serum lncRNA MATAL1 level, CMT and BCVA were measured before and during the 3mo after treatment. The results showed that the LogMAR BCVA of the control group was significantly higher than that before treatment (P<0.05). The LogMAR BCVA of patients in the study group for 3mo after treatment was significantly higher than that before treatment (P<0.05), but there was no significant difference between the study group and the control group (P<0.05). The level of serum lncRNA MALAT1 in the control group decreased during the 3mo after treatment, and the level of serum lncRNA MALAT1 in the study group decreased significantly in the 3mo after treatment. The level of serum lncRNA MALAT1 in the study group was significantly lower than that of the control group (P<0.05). The CMT of patients in the control group decreased during the 3mo after treatment, and the CMT of patients in the study group decreased significantly during the 3mo after treatment. The CMT of the study group was significantly lower than that of the control group (P<0.05).The incidence of adverse reactions in the study group (2.0%) was significantly lower than that in the control group (11.0%). Therefore, our study showed that Conbercept injections can more effectively reduce the level of lncRNA MATAL1 in serum, inhibit neovascularisation, reduce CMT, reduce DME, inhibit disease progression, improve vision and significantly reduce the risk of blindness in patients with DME.

In conclusion, Conbercept injections can significantly reduce the level of serum lncRNA MALAT1, reduce CMT, reduce DME and improve vision in patients with DME. The therapeutic effectiveness and safety of Conbercept are significantly better than Ranibizumab.