Abstract
Objective
Glucocorticoids are key drugs used in remission induction therapy for IgG4-related disease (IgG4-RD). However, the therapeutic outcomes vary widely, with some patients requiring long-term maintenance therapy and others relapsing repeatedly, whereas still others can tolerate withdrawal. These variations underscore the need for personalized treatment strategies for IgG4-RD. We examined the relationship between human leukocyte antigen (HLA) genotypes and the response to glucocorticoid treatment in patients with IgG4-RD.
Methods
Eighteen IgG4-RD patients visiting our hospital were included in the study. Peripheral blood samples were collected, HLA genotypes were determined, and the response to glucocorticoid treatment (maintenance dose at the time of last observation, glucocorticoid dose when the serum IgG4 level was the lowest after remission induction therapy, and occurrence of relapse) was examined retrospectively.
Results
The DQB1*12:01 genotypes were associated with a prednisolone maintenance dose of ＜7 mg/day. A prednisolone dose ≥10 mg with a minimum serum IgG4 level was significantly more common in B*40:01 and DRB1-GB-7-Val (DRB1*04:01, *04:03, *04:05, *04:06, and *04:10) patients than other alleles. Relapse also tended to be more common in DRB1-GB-7-Val carriers than other alleles.
Conclusion
These data suggest that HLA-DRB1 is associated with glucocorticoid treatment responsiveness and is important for follow-up monitoring of serum IgG4 levels during glucocorticoid tapering. We believe that these data will contribute to the future development of personalized medicine for IgG4-RD.
Keywords: glucocorticoid, human leucocyte antigen, IgG4-related disease, relapse, valine
Introduction
Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibro-inflammatory condition that was newly identified in the 21st century (1). IgG4-RD is associated with a variety of immune abnormalities and can cause lesions in many organs. The disease is characterized by hyper-IgG4emia and marked infiltration of IgG4-positive plasma cells in affected organs (2). Diagnostic criteria (3) and classification criteria (4) have recently been developed to facilitate the diagnosis of IgG4-RD in daily practice. IgG4-RD is typically treated by remission induction therapy using primarily glucocorticoids, but the response to glucocorticoid treatment varies (5). Therefore, optimized treatment regimens for individual cases are needed. In actual clinical practice, we are attempting to determine the degree to which we can reduce the dose of steroids while avoiding relapse.
The association between human leukocyte antigen (HLA) alleles and disease susceptibility has been examined for many immune disorders. In IgG4-RD, a genome-wide association study identified HLA-DRB1 as a disease susceptibility gene, in which the seventh amino acid residue (DRB1-GB-7) in the Gβ domain (the antigen presentation site of the HLA-DRB1 protein) is substituted with a valine residue (DRB1-GB-7-Val) (6). The genotype consists of HLA-DRB1*04:01, *04:03, *04:04, *04:05, *04:06, *04:07, *04:09, *04:10, and *10:01.
In the present study, we examined the relationship between the HLA genotype and responsiveness to glucocorticoid treatment in IgG4-RD patients.
Materials and Methods
Subjects
Eighteen consecutive patients with IgG4-RD who were registered in the TOMORROW registry established by the Department of Rheumatology and Allergy, IMSUT Hospital, Institute of Medical Science, The University of Tokyo, and who visited the hospital between January and April 2022 were included in the analysis. The diagnosis of IgG4-RD was made based on the revised comprehensive diagnostic criteria for IgG4-RD (3). Remission induction therapy consisted of an initial dose of prednisolone ≥0.5 mg/kg for at least 4 weeks, with dose tapering of 10% every 2 weeks, regardless of the type of organ damage. Only follow-up data from patients who had been in the study for at least six months were included in the analysis. For patients receiving concomitant immunosuppressants, data from immediately before the concomitant medications were used.
Analyses and endpoints
The HLA genotypes HLA-A, B, DRB1, and DQB1 were typed using the Luminex method with 2 mL of peripheral blood. The following endpoints were analyzed retrospectively: [1] maintenance dose of prednisolone at the time of last observation (≥7 mg/day); [2] prednisolone dose when the serum IgG4 level was the lowest, before it began to increase again during glucocorticoid tapering (≥10 mg/day); and [3] occurrence of relapse during the follow-up period. For each of the above endpoints, the allele frequencies were analyzed for each group that met or did not meet the endpoint. Conversely, whether or not treatment outcomes differed between carriers and noncarriers of the extracted alleles was also determined.
The significance of differences in the frequency of positive endpoints for each item in each allele was evaluated using the chi-squared test. Pearson's correlation coefficient was used to evaluate correlations. Statistical significance was set at p＜0.05.
Results
Patient characteristics
The study included 10 men and 8 woman, with a mean age at the onset for all subjects of 51.9±14.7 [standard deviation (SD)] years old. The mean number of affected organs was 2.4±0.9, as follows: salivary glands in 13 cases; lacrimal glands in 12 cases; pancreas in 6 cases; retroperitoneum in 6 cases; lungs in 4 cases; and kidneys in 2 cases. Pre-treatment levels of serum IgG and serum IgG4 were 2,110.8±746.0 mg/dL and 723.6±551.3 mg/dL, respectively (Table 1).
Table 1.
Patient Profiles and Therapeutic Outcomes.
| Gender | Male 10, female 8 |
|---|---|
| Age at the onset (years) | 51.9±14.7 |
| Duration of illeness (years) | 3.4±5.0 |
| Number of the involved organs | 2.4±0.9 |
| Salivary gland | 13 |
| Lacrimal gland | 12 |
| Pancreas | 6 |
| Retroperitoneum | 6 |
| Lung | 4 |
| Kidney | 2 |
| Serum IgG (mg/dL) | 2,110.8±746.0 |
| Serum IgG4 (mg/dL) | 723.6±551.3 |
| Maintenance dose of prednisolone (mg/day) | 7.1±2.0 |
| Dose of prednisolone at min serum IgG4 (mg/day) | 10.5±3.7 |
| Number of relapse cases | 6 |
Treatment outcomes
The mean duration of observation in our department was 3.4±5.0 (SD) years. The mean glucocorticoid maintenance dose at the time of the last observation was 7.1±2.0 mg/day. The mean glucocorticoid dose at which the IgG4 level was the lowest was 10.5±3.7 mg/day. Six patients (33.3%) experienced relapse (Table 1).
Endpoints and allele
1. Maintenance dose
Eleven patients (61.1%) were on a maintenance prednisolone dose of ≥7 mg/day. No significantly different allele was extracted for HLA-A, HLA-B, or HLA-DQB1. HLA-DRB1*12:01 (p=0.030) was significantly more prevalent in the ＜7 mg/day group than other alleles (Table 2A).
Table 2.
Distribution of Alleles.
| A. Maintenance dose | B. Dose at lowest serum IgG4 level | C. Relapse rate | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≥7mg/day | <7mg/day | p value | ≥10mg/day | <10mg/day | p value | Relapse | Remission | p value | ||||||||
| n=11 | n=7 | n=12 | n=6 | n=6 | n=12 | |||||||||||
| HLA-A | 02:01 | 1 | 2 | 0.324 | HLA-A | 02:01 | 3 | 0 | 0.221 | HLA-A | 02:01 | 1 | 2 | 1.000 | ||
| 02:06 | 4 | 1 | 0.386 | 02:06 | 4 | 1 | 0.527 | 02:06 | 3 | 2 | 0.206 | |||||
| 02:07 | 1 | 0 | 0.425 | 02:07 | 1 | 0 | 0.480 | 02:07 | 0 | 1 | 0.480 | |||||
| 02:10 | 1 | 0 | 0.425 | 02:10 | 1 | 0 | 0.480 | 02:10 | 0 | 1 | 0.480 | |||||
| 11:01 | 2 | 2 | 0.649 | 11:01 | 3 | 1 | 0.724 | 11:01 | 2 | 2 | 0.480 | |||||
| 11:02 | 1 | 0 | 0.425 | 11:02 | 1 | 0 | 0.480 | 11:02 | 0 | 1 | 0.480 | |||||
| 24:02 | 8 | 5 | 0.975 | 24:02 | 6 | 7 | 0.117 | 24:02 | 4 | 9 | 0.845 | |||||
| 26:02 | 1 | 2 | 0.324 | 26:02 | 2 | 1 | 1.000 | 26:02 | 1 | 2 | 1.000 | |||||
| 26:03 | 1 | 0 | 0.425 | 26:03 | 1 | 0 | 0.480 | 26:03 | 1 | 0 | 0.157 | |||||
| 31:01 | 1 | 2 | 0.324 | 31:01 | 1 | 2 | 0.221 | 31:01 | 0 | 3 | 0.221 | |||||
| 33:03 | 1 | 0 | 0.425 | 33:03 | 1 | 0 | 0.480 | 33:03 | 0 | 1 | 0.480 | |||||
| HLA-B | 07:02 | 1 | 0 | 0.425 | HLA-B | 07:02 | 0 | 1 | 0.157 | HLA-B | 07:02 | 1 | 0 | 0.157 | ||
| 15:01 | 3 | 2 | 0.959 | 15:01 | 4 | 1 | 0.527 | 15:01 | 2 | 3 | 0.752 | |||||
| 15:18 | 1 | 0 | 0.425 | 15:18 | 1 | 0 | 0.480 | 15:18 | 1 | 0 | 0.157 | |||||
| 27:04 | 1 | 0 | 0.425 | 27:04 | 1 | 0 | 0.480 | 27:04 | 0 | 1 | 0.480 | |||||
| 35:01 | 1 | 2 | 0.324 | 35:01 | 3 | 0 | 0.221 | 35:01 | 1 | 2 | 1.000 | |||||
| 39:01 | 1 | 1 | 0.747 | 39:01 | 2 | 0 | 0.317 | 39:01 | 1 | 1 | 0.617 | |||||
| 40:01 | 3 | 2 | 0.959 | 40:01 | 1 | 4 | 0.027 | 40:01 | 0 | 5 | 0.114 | |||||
| 40:06 | 1 | 2 | 0.324 | 40:06 | 2 | 1 | 1.000 | 40:06 | 2 | 1 | 0.221 | |||||
| 44:03 | 2 | 1 | 0.844 | 44:03 | 2 | 1 | 1.000 | 44:03 | 0 | 3 | 0.221 | |||||
| 46:01 | 1 | 1 | 0.747 | 46:01 | 1 | 1 | 0.617 | 46:01 | 0 | 2 | 0.317 | |||||
| 51:01 | 2 | 0 | 0.259 | 51:01 | 2 | 0 | 0.317 | 51:01 | 2 | 0 | 0.046 | |||||
| 52:01 | 2 | 1 | 0.844 | 52:01 | 1 | 2 | 0.221 | 52:01 | 1 | 2 | 1.000 | |||||
| 54:01 | 3 | 1 | 0.569 | 54:01 | 4 | 0 | 0.157 | 54:01 | 0 | 4 | 0.157 | |||||
| 55:02 | 0 | 1 | 0.210 | 55:02 | 0 | 1 | 0.157 | 55:02 | 1 | 0 | 0.157 | |||||
| HLA-DRB1 | 01:01 | 1 | 0 | 0.425 | HLA-DRB1 | 01:01 | 0 | 1 | 0.157 | HLA-DRB1 | 01:01 | 1 | 0 | 0.157 | ||
| 04:01 | 1 | 0 | 0.425 | 04:01 | 1 | 0 | 0.480 | 04:01 | 1 | 0 | 0.157 | |||||
| 04:03 | 1 | 0 | 0.425 | 04:03 | 1 | 0 | 0.480 | 04:03 | 1 | 0 | 0.157 | |||||
| 04:05 | 6 | 2 | 0.420 | 04:05 | 7 | 1 | 0.211 | 04:05 | 4 | 4 | 0.317 | |||||
| 04:06 | 3 | 1 | 0.569 | 04:06 | 4 | 0 | 0.157 | 04:06 | 2 | 2 | 0.480 | |||||
| 04:10 | 0 | 1 | 0.210 | 04:10 | 1 | 0 | 0.480 | 04:10 | 0 | 1 | 0.480 | |||||
| 08:03 | 0 | 1 | 0.210 | 08:03 | 0 | 1 | 0.157 | 08:03 | 0 | 1 | 0.480 | |||||
| 09:01 | 3 | 0 | 0.167 | 09:01 | 1 | 2 | 0.221 | 09:01 | 0 | 3 | 0.221 | |||||
| 11:01 | 0 | 1 | 0.210 | 11:01 | 0 | 1 | 0.157 | 11:01 | 0 | 1 | 0.480 | |||||
| 12:01 | 0 | 3 | 0.030 | 12:01 | 1 | 2 | 0.221 | 12:01 | 1 | 2 | 1.000 | |||||
| 12:02 | 1 | 0 | 0.425 | 12:02 | 1 | 0 | 0.480 | 12:02 | 0 | 1 | 0.480 | |||||
| 13:02 | 2 | 1 | 0.844 | 13:02 | 2 | 1 | 1.000 | 13:02 | 0 | 3 | 0.221 | |||||
| 14:06 | 1 | 1 | 0.747 | 14:06 | 2 | 0 | 0.317 | 14:06 | 0 | 2 | 0.317 | |||||
| 15:01 | 1 | 2 | 0.324 | 15:01 | 2 | 1 | 1.000 | 15:01 | 1 | 2 | 1.000 | |||||
| 15:02 | 2 | 1 | 0.844 | 15:02 | 1 | 2 | 0.221 | 15:02 | 1 | 2 | 1.000 | |||||
| HLA-DQB1 | 03:01 | 3 | 5 | 0.171 | HLA-DQB1 | 03:01 | 5 | 3 | 0.803 | HLA-DQB1 | 03:01 | 2 | 6 | 0.617 | ||
| 03:02 | 4 | 1 | 0.386 | 03:02 | 5 | 0 | 0.114 | 03:02 | 3 | 2 | 0.206 | |||||
| 03:03 | 4 | 0 | 0.111 | 03:03 | 2 | 2 | 0.480 | 03:03 | 0 | 4 | 0.157 | |||||
| 04:01 | 5 | 2 | 0.576 | 04:01 | 6 | 1 | 0.285 | 04:01 | 4 | 3 | 0.181 | |||||
| 04:02 | 0 | 1 | 0.210 | 04:02 | 1 | 0 | 0.480 | 04:02 | 0 | 1 | 0.480 | |||||
| 05:01 | 1 | 0 | 0.425 | 05:01 | 0 | 1 | 0.157 | 05:01 | 1 | 0 | 0.157 | |||||
| 06:01 | 2 | 2 | 0.649 | 06:01 | 1 | 3 | 0.077 | 06:01 | 1 | 3 | 0.724 | |||||
| 06:02 | 1 | 2 | 0.324 | 06:02 | 2 | 1 | 1.000 | 06:02 | 1 | 2 | 1.000 | |||||
| 06:04 | 2 | 1 | 0.844 | 06:04 | 2 | 1 | 1.000 | 06:04 | 0 | 3 | 0.221 | |||||
| HLA-DRB1 | GB-7-Val | 11 | 4 | 0.332 | HLA-DRB1 | GB-7-Val | 14 | 1 | 0.028 | HLA-DRB1 | GB-7-Val | 8 | 7 | 0.100 | ||
2. Dose at lowest serum IgG4 level
In 12 patients (66.7%), the prednisolone dose was ≥10 mg/day when the serum IgG4 level was at its lowest point after remission induction therapy. No significantly different alleles were extracted for HLA-A, HLA-DRB1, or HLA-DQB1; HLA-B*40:01 exhibited a strong toward an increased prevalence at a prednisolone dose of ＜10 mg/day (p=0.027). However, HLA-DRB1-GB-7-Val carriers were significantly more common in the ＞10 mg/day group than other alleles (p=0.028) (Table 2B).
3. Relapse
Six patients (33.3%) experienced relapse. However, no significantly different alleles were extracted for HLA-A, HLA-B, HLA-DRB1, or HLA-DQB1 in this study. A trend toward an increased frequency of HLA-DRB1-GB-7-Val carriers was observed among patients with a prednisolone dose of ≥10 mg/day (p=0.100) (Table 2C).
4. Validation
Focusing on the presence/absence of HLA-DRB1-GB-7-Val, the above three items were validated (Table 3). In patients harboring at least one of the four alleles, the glucocorticoid maintenance dose was 7.4±2.4 mg/day, whereas the dose was 8.8±1.6 mg/day in patients harboring 2 of the 4 alleles and 6.0±2.3 mg/day in patients harboring only one of the alleles. In contrast, in patients lacking all four of the alleles, the glucocorticoid maintenance dose was 6.7±1.5 mg/day. A similar trend was observed in terms of the glucocorticoid dose at the lowest serum IgG4 level after remission induction therapy. In patients with the HLA-DRB1-GB-7-Val allele, the glucocorticoid dose was 12.0±3.3 mg/day, which was higher than the 8.8±3.3 mg/day dose in patients lacking the alleles. A significant positive correlation was observed between the number of relevant alleles and glucocorticoid dose at the lowest serum IgG4 level (r=0.913). The rate of relapse was 50.0% among patients who harbored at least 1 of the 4 alleles and 12.5% among those who did not harbor any of the alleles.
Table 3.
Frequency of Each Endpoint According to the Presence or Absence of HLA-DRB1-GB-7-Val.
| Number of GB-7-Val alleles | Maintenance dose of prednisolne (mg/day) | Dose of prednisolone at min. serum IgG4 (mg/day) | Cases of relapse (%) | |
|---|---|---|---|---|
| DRB1-GB-7-Val carrier | 7.4±2.4 | 12.0±3.3 | 50.0 | |
| 2 | 8.8±1.6 | 14.5±3.3 | 60.0 | |
| 1 | 6.0±2.3 | 9.4±1.3 | 40.0 | |
| Non-carrier | 0 | 6.7±1.5 | 8.8±3.3 | 12.5 |
Discussion
The present study showed that the HLA-DRB1 allele may be associated with responsiveness to glucocorticoid treatment in patients with IgG4-RD.
HLA-DRB1-GB-7-Val, which is reportedly a disease susceptibility variant, was significantly extracted at a prednisolone dose ≥10 mg with a minimum serum IgG4 level. Studies examining genes associated with the risk of relapse in patients with autoimmune pancreatitis have identified HLA-A, HLA-C, and DQB1 (7,8). However, both the glucocorticoid maintenance dose and risk of relapse are greatly affected by the treatment regimen, as a lower initial glucocorticoid dose or more rapid rate of tapering increases the risk of relapse (9). Fluctuations in serum IgG4 levels during tapering of glucocorticoids can affect the attending physician's maintenance dose decision. However, the glucocorticoid dose at the lowest serum IgG4 level is generally independent of the attending physician's intent if the treatment is fixed. Therefore, we consider this factor to be the most important of the three examined in this study. Even in terms of carriers of HLA-DRB1-G7-Val, the glucocorticoid dose at the lowest serum IgG4 level exhibited a positive correlation with the number of relevant alleles, which we believe reflects the pathogenesis of IgG4-RD.
The HLA-DRB1 allele plays a role in a wide range of immunity-related diseases in addition to IgG4-RD. For example, in rheumatoid arthritis, the HLA-DRB1 allele is associated with not only the risk of developing rheumatoid arthritis but also various clinical parameters, such as disease activity, response to therapy, bone destruction, and even the prognosis (10). HLA-DRB1 alleles encoding QKRAA, QRRAA, or RRRAA sequences at positions 70-74 of the HLA-DR beta chain are significantly associated with the onset and severity of rheumatoid arthritis in diverse populations worldwide. These sequences are recognized as the most well-established disease susceptibility genes for rheumatoid arthritis and are collectively referred to as the shared epitope (11). The shared epitope has been identified as a predictor of response to abatacept therapy (12). Thus, differences in even a single amino acid residue can significantly affect disease susceptibility and treatment response. Based on these data, we speculate that the HLA-DRB1-GB-7-Val allele extracted in the present study also plays a major role in the onset and pathophysiology of IgG4-RD.
One major limitation of the present study is that the number of cases was small. We therefore plan to conduct a larger study including a disease activity index at the initial visit to validate the present results. In the future, as treatments for IgG4-RD are expected to diversify to include biologic agents and molecular-targeted drugs, large-scale validation studies to predict the therapeutic response to each new drug will be required. It is our hope that the results of the present study will be useful for the development of personalized medicine approaches for IgG4-RD.
Conclusion
In this study, we analyzed the association between various HLA genotypes and therapeutic response in patients with IgG4-RD. Our research identified HLA-DRB1-GB-7-Val (*04:01, *04:03, *04:04, *04:05, *04:06, *04:07, *04:09, *04:10, and *10:01) as risk alleles for resistance to glucocorticoid treatment.
The authors state that they have no Conflict of Interest (COI).
Financial Support
This study was funded by the JSPS KAKENHI Grant Numbers JP20K08770 and Ministry of Health, Labour and Welfare Research Program on Rare and Intractable Diseases (Grant Number JPMH20FC1040).
notes
Informed consent from the patients involved was obtained for the publication of this article.
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