The glomerular GCR expression, MEST score and clinical progression in patients with IgAN

Ala Tekin B^*, Paydas S, Kaya B, Eren Erdogan K, Binokay H, Sertdemir Y, Balal M and Gonlusen G
^*Correspondence: Ala Tekin B, Department Internal Medicine Nephrology, Pathology and Biostatistics, Cukurova University, Adana, Turkey, Email:

Received: 23-Mar-2023, Manuscript No. IJUN-23-92520; Editor assigned: 27-Mar-2023, Pre QC No. IJUN-23-92520 (PQ); Reviewed: 10-Apr-2023, QC No. IJUN-23-92520; Revised: 30-May-2023, Manuscript No. IJUN-23-92520 (R); Published: 07-Jun-2023

Keywords

IgA nephropathy, Glucocorticoid receptor, MEST score, High blood pressure, Creatinine

Introduction

IgAN, Berger’s disease (described in 1968), is the most common primary glomerulonephritis worldwide [1]. The disease is characterized by episodic hematuria accompanied by IgA deposition in the mesengium on immunofluorescence [2]. Unfavorable prognostic factors for future development of end stage renal disease include impaired renal function at the time of diagnosis [3].

The Oxford classification described 4 lesions with Mesangial proliferation (M0 or M1), absence or presence of any degree of endocapillary hypercellularity (E0 and E1), any glomerulosclerotic lesion (S0 or S1) and tubular atrophy/interstitial fibrosis severity of interstitial fibrosis (T0: 1-25%; T1: 26-50%; T2: >50%) [4,5]. VALIGA has also confirmed the association between renal outcomes with some lesions such as M1, S1, T1/2 and the association of M1 and E1 with subsequent increase in proteinuria [6]. Corticosteroids exert their actions by binding to the intracellular Glucocorticoid Receptors (GCRs) to form the glucocorticoid-GCR complexes [7]. Previous studies have shown that GCR expression is correlated with the extent of steroid response in several diseases [8,9]. However, few studies have reported on this association in patients with IgAN. In this study, we evaluate the glomerular GCR expression, MEST score and clinical progression in patients with IgAN evaluated.

Materials and Methods

This study included 103 patients with pathological diagnosis of IgA nephropathy who were also followed up in our nephrology outpatient clinic. Between 2002 and 2019, 200 patients with IgAN were identified from our hospital records. Patients who were followed for less than 3 months or who did not regularly follow-up, patients with recurrence IgAN in the transplant kidney, and patients whose consent could not be obtained for participation in the study were excluded from the study.

In the post-biopsy period, patients receiving Angiotensin Converting Enzyme Inhibitor/ Angiotensin Receptor Blocker (ACEI/ARB) for at least 3 months; according to the KDIGO guidelines, methylprednisolone 0.5-0.7 mg/kg/day, maximum 64 mg/day was given in patients with eGFR>30 ml/min and proteinuria >1 g/day. The steroid dose was reduced according to clinical response and administered as 4 mg/day maintenance. At the beginning of the treatment and at the 3rd, 6th, 12th months; complete blood count, BUN, creatinine, eGFR, albumin, PTH, total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride, proteinuria values were recorded. The MEST score was calculated by the nephropathologist in kidney biopsy samples of patients diagnosed with IgAN. Kidney biopsy samples were immunohistochemically stained according to the recommendations of the GCR expression commercial kit (rabbit polyclonal antibody anti-glucocorticoid receptor antibody-ChIP Grade ab 3671).

The rate of staining of the glomeruli in the samples, the rate of staining in the glomeruli in which staining was detected and the intensity of staining were evaluated semi quantitatively. The 6^th and 12^th month progression indexes of the patients were calculated according to the international IgAN prediction tool.
This study approved by Cukurova university faculty of medicine “clinical research ethics committee” on 28 August 2019 (meeting no: 3) and Cukurova university “department of scientific research projects” on 19 November 2019 (Project number: TTU-2019-12465).

Statistical analysis

Categorical variables were expressed as numbers and percentages, whereas continuous variables were summarized as mean and standard deviation and as median and minimum-maximum where appropriate. Chi-square test was used to compare categorical variables between the groups. For comparison of continuous variables between two groups, the Student's t-test or Mann-Whitney U test was used depending on whether the statistical hypotheses were fulfilled or not. To evaluate the change in the measurements obtained in the time interval, the repeated measurements analysis was applied. All analyses were performed using IBM SPSS Statistics Version 20.0 statistical software package. The statistical level of significance for all tests was considered to be 0.05.

Results

103 patients with IgA nephropathy were included in the study. The demographic characteristics and some biochemical parameters of the patients presented in Tables 1 and 2.

Table 1. Demographic characteristics and some laboratory parameters of patients at baseline.

Table 2. Laboratory parameters at baseline, 3 Month, 6 Month and 12 month.

The comparisons glucucorticoid receptor staining intensity with MEST score summarised in Table 3. Statistically significant difference was found only M0 and M1 for GCR staining intensity.

Table 3. Comparison of Glucocorticoid Receptor (GCR) staining rate and MEST score.

As seen in Table 3, while there were statistical difference in BUN, albumin, uric acid, values, over time, for GCR staining intensity statistically significant difference were found for serum albumin and uric acid over time (Table 4).

Table 4. Correlation between changes in BUN, creatinine, uric acid, albumin, Glomerular Filtration Rate (GFR), proteinuria values over time and Glucocorticoid Receptor Staining (GCR)

Patients with M0 or M1 lesion were similar for GFR, BP and proteinuria at baseline, 3, 6, 12 Month (Table 5).

The patients classified into 2 groups according to the presence of endocapillary proliferation (E0 and E1) in the glomeruli and tubular injury (T0, T1 and T2). The GFR and daily proteinuria of the patients at 3 months, 6 months with endocapillary proliferation were found to be statistically significant lower and higher than the patients without endocapillary proliferation respectively. Also systolic blood pressure has been found to be statistically significantly higher in patients with endocapillary proliferation. Diastolic blood pressure was nonsignificantly higher in patients with endocapillary proliferation (Table 6).

Table 5. The relationship glomerular meningeal proliferation Glomerular Filtration Rate (GFR) (ml/dk/1,73 m²), proteinuria (mg/day) and Blood Pressure (BP) (mmHg).

Table 6. Comparison of endocapillary proliferation the glomeruli and tubular injury in with GFR, proteinuria, and Blood Pressure (BP).

Patients were classified into 3 groups according to the rate of tubular lesion. GFR was found to be lower as the degree of tubular atrophy increased statistically at 0, 3, and 6 months, but it was not statistically significant at 12 months. When proteinuria and tubular atrophy were compared, a statistically significant difference was found at month 0 and 3. No statistically significant difference was found between the degree of tubular atrophy and blood pressure.

Demographic data, laboratory and biopsy results of the patients at the time of diagnosis compared between groups of patients who achieved remission at 12 months and those who did not (Table 7). In the remission group, which formed by the sum of the partial remission (proteinuria 300 mg/day-3,5 g/day) and the complete remission group (proteinuria <300 mg/day), 80 people who achieved remission in the 12^th month and 4 people who did not achieved remission determined. No significant difference observed between the two groups in terms of age, MEST score and GCR staining. When examined in terms of GFR, proteinuria, systolic blood pressure, and diastolic blood pressure, there was a statistically significant difference between the groups in remission and those who did not.

Table 7. Comparison of the demographic data of the patients at the time of diagnosis, laboratory and biopsy results between the patient groups in remission and non-remission at 12 months.

At the time of diagnosis although demographic characteristics, comorbidities, MEST scores and GCR expression were similar, serum total protein (↑), uric acid (↑), PTH (↑), WBC and neutrophyl count (↑), systolic and diastolic blood pressure (↑), GFR (↓) were found significantly different in patients with those with proteinuria ≥1 g/day at 12 months comparing to patient with proteinuria <1 g/day at 12 months (p<0,05 for all). Also in patients with those with GFR < 60 mL/min/1,73 m² at 12 months comparing to patient with GFR ≥ 60 mL/min/1,73 m² 12 months at the time of diagnosis although gender, MEST score, GCR expression, levels of trygliseride, HDL and LDL were similar but PTH, total cholestrol (↑), GFR (↓), creatinine (↑), BUN (↑), systolic and diastolic BP (↑) were found significantly different (p<0,05 for all).

Discussion

Corticosteroids exert their effects by binding to intracellular Glucocorticoid Receptors (GCRs) to form glucocorticoid-GCR complexes [10]. Previous studies have shown that GCR expression correlates with steroid response in a variety of diseases [11]. However, few studies have been reported on this relationship in the literature. In this study, we evaluated whether the response to steroids in IgAN patients is dependent on GCR expression.

No significant results were obtained in the comparison of demographic and laboratory data according to the GCR staining rate. In comparison of GCR with MEST score, the rate of GCR staining was found to be higher in patients with Mesangial proliferation (M1) than in those without (M0). Although there was a statistically significant difference in BUN, proteinuria over time but no significant difference has shown between the groups comparing to the rate of GCR staining there was a statistically significant difference in uric acid, albumin over time and according to the GCR staining rate. In a study GCR mRNA expression measured by RT-PCR was compared with steroid response and it was found that GCR mRNA expression was 2.5 fold higher in the group with complete remission compared to the group without complete remission. This finding was confirmed by immunohistochemical studies, which showed that the complete remission group had more cells with positive staining for GCRs. Mean semi-quantitative scores for glomerular GCR were significantly higher in the CR group compared to the non-CR group [12]. In our study, patients with a GCR staining rate >80% had a higher rate of remission, but no statisticallysignificant difference determined. We can explain this situationwith the small number of patients.

In our study, eGFR and proteinuria have been shown to be higherin M1 patients with meningeal proliferation according to theOxford MEST classification than in M0 patients withoutmeningeal proliferation, but no statistically significant differencewas found for both. Interestingly, the eGFR level at 3, 6 monthhas been shown to be statistically significantly higher in patientswithout endocapillary proliferation (E0) than in patients withendocapillary proliferation (E1). In patients with E1; systolicblood pressure and proteinuria have been shown to bestatistically significantly higher. Diastolic blood pressure has alsobeen shown to be higher in patients with E1, but it was notstatistically significant. In patients with segmental sclerosis (S1),eGFR values at 3^th month and 6^th month were lower andproteinuria at 0,3,6 month was found to be higher than thosewithout segmental sclerosis, which were statistically significant.Systolic and diastolic blood pressures were found to benonsignificantly higher in S1 patients compared to S0 patients. Inpatients with T0 compared to patients with T1 eGFR values at 0.3, 6 month were found to be higher and proteinuria at 0. 3 monthstatisticaly significantly lower and these differences werestatistically significant.

Pathological findings are accepted as an important factor for theprognosis of IgAN. According to the Oxford classification, M, E,S, T and C lesions are partially associated with prognosis.Barbour reported that M/T lesions were independently associatedwith renal outcome. The results of Bellur, et al. support theOxford classification S-score in non-immunosuppressed patients.Coppo R analyzed 1147 IgAN patients in the VALIGA cohortand suggested that M/S/T independently predicted renal outcome(50% reduction in renal function and/or ESRD) [13,14].However, in a subgroup of 219 patients with minimal proteinuria,no MEST score predicted renal outcome in multivariate analysis,these findings were similar to our results. Another reviewconducted by Coppo R failed to confirm a predictive value ofMEST scores in a subgroup of 174 children (<18 years) in theVALIGA cohort. These results showed that the evaluation of theOxford classification should be stratified. In a study by Shu et al.,the pathological indicator M1 lesion was found to be anindependent factor in predicting ESRD [15]. In our study, theinitial pathological values of the patients and the eGFR values at12 months were compared. Those with S1 lesions in the biopsy atthe time of diagnosis were more patients with eGFR <60mL Found to be higher in patients with E1 than those with E0, but itwas not statistically significant.

Interestingly at the time of diagnosis although demographic characteristics, comorbidities, MEST scores and GCR expession 60mL/min/1.73 m² at 12 months compared to those with eGFR ≥60 mL/min/1.73 m² but it was not statistically significant. Again, the number of patients with T1 on biopsy was higher in patients with eGFR <60 mL/min/1.73 m² compared to those with eGFR ≥60 mL/min/1.73 m², and it was not significant.

In this retrospective analysis, the patients were evaluated as remission and non-remission groups. In the KDIGO guideline, the criteria for remission in IgA nephropathy have not been clearly defined [16]. It is observed that many different remission criteria have been determined in the literature studies. In a clinical trial; Having 0.3 g/day proteinuria is similar to 0.3 to 1.0 g/day, but for each gram above 1 g/day (reference group) ESRD has worse renal survival, 1 to 2 g/day found a 3.5 fold risk for a day, 5-fold a risk for 2 to 3 g/day, and a 10-fold risk for ESRD above 3 g/day [17]. In our study our criteria for complete remission was proteinuria <0.3 g/day, as studies have shown that the optimal goal in treatment is to keep proteinuria below 0.3 g/day. We determined partial remission between 0.3 g/day and 3.5 g/day. Since the loss of kidney function was approximately 25 times higher in patients with proteinuria >3.5 g/day compared to patients with proteinuria <1 g/day in studies, we determined the criterion for non-remission as proteinuria >3.5 g/day. Eighty five (78.7%) patients at 3 months, 80 (74.1%) at 6 months, and 75 (74.3%) patients at 12 months were considered in partial remission. Patients in complete remission were 77 (6.5%) at the 3rd month, 17 (15.7%) at the 6^th month, and 20 (19.8%) at the 12^th month. There were 6 (5.9%) patients who did not go into remission at the end of the 12^th month. In another study protienuria >1 g/day in IgA nephropathy has been associated with a rapid decline in eGFR and progression to ESRD [18].

Confirmed prognostic markers for IgA nephropathy include eGFR and proteinuria. Low eGFR at diagnosis or at follow-up is an indicator of poor prognosis. In a large scale cohort study of 1155 patients with IgA nephropathy in China, eGFR <60 ml/min/1.73 m² at the time of diagnosis 50% reduction in eGFR or ESRD. Also in our study it has been shown to be an independent risk factor for progression. It was found to be statistically significant higher than those with 60 mL/min/1.73 m², consistent with another study. Another independent risk factor in patients with IgA nephropathy is proteinuria. Proteinuria >1 g/day was found to be associated with rapid decline in kidneyfunctions and progression to ESRD. In this study, we alsoidentified 57 (60%) patients with proteinuria <1 g/day at the endof the 12th month. those in remission; we considered it as the sumof patients with complete remission and partial remission.Consistent with the literature, we found that proteinuria waslower in patients with remission, both at the time of diagnosisand at 3 month follow-up [19].

Another parameter of the prognostic factor in IgA nephropathy isthe levels of blood pressure at the time of diagnosis and follow-up period. High blood pressure; it is associated with increasedprotein excretion and a faster eGFR decline. In our study,systolic and diastolic blood pressure was found to be statisticallysignificant lower in the remission group comparing to non-remission group [20]. Also systolic blood pressure in patientswith endocapillary proliferation (E1) in the glomeruli wassignificantly higher than in patients with E0. We did not foundsimilar finding earlier study. Diastolic blood pressure was also were similar, significantly higher levels of serum total protein,uric acid, parathormon, systolic and diastolic blood pressure andincreased white blood cell and neutrophil count, and lower GFRwere in patients with those with proteinuria ≥ 1 g/day at 12 month comparing to patient with proteinuria <1 g/day at 12 Month. Similarly significantly higher levels of PTH, total cholestrol, creatinine, BUN, systolic and diastolic BP were in patients with GFR<60 mL/min/1,73 m² at 12. Month comparing to patient with GFR ≥ 60 mL/min/1,73 m² 12 Month. Similarly our finding in a study conducted in China, it was found that hypercholesterolemia played a role in 50% reduction in eGFR and progression to ESRD in univariate analyses, but lost its significance in multivariate analyses. In the univariate survival analysis of 1151 patients with IgA nephropathy in China, it was found that the count of white blood cell and neutrpohil showed significant associations with IgAN progression.

Conclusion

In conclusion, although no correlation was found between the rate of GCR expression showing glucocorticoid receptor activation and steroid response, and progression in patients with IgA nephritis, M1 was higher in those with high GCR staining. However, patients with high proteinuria, low GFR, and high blood pressure at baseline and 6 month, had higher MEST scores for E, S, and T. Larger studies are needed to evaluate the effect of GCR expression in the treatment or clinical course of IgA nephropathy.

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