Pathophysiological lessons from rare associations of immunological disorders

The multidisciplinary approach to diagnosing inborn errors of immunity: a comprehensive review of discipline-based manifestations

INTRODUCTION

Congenital immunodeficiency is named primary immunodeficiency (PID), and more recently inborn errors of immunity (IEI). There are more than 485 conditions classified as IEI, with a wide spectrum of clinical and laboratory manifestations.

AREAS COVERED

Regardless of the developing knowledge of IEI, many physicians do not think of IEI when approaching the patient's complaint, which leads to delayed diagnosis, misdiagnosis, serious infectious and noninfectious complications, permanent end-organ damage, and even death. Due to the various manifestations of IEI and the wide spectrum of associated conditions, patients refer to specialists in different disciplines of medicine and undergo - mainly symptomatic - treatments, and because IEI are not included in physicians' differential diagnosis, the main disease remains undiagnosed.

EXPERT OPINION

A multidisciplinary approach may be a proper solution. Manifestations and the importance of a multidisciplinary approach in the diagnosis of main groups of IEI are discussed in this article.

An Updated Review of Membranous Nephropathy

Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in adults. The discovery of phospholipase A2 receptor (PLA2R) as a target antigen has led to a paradigm shift in the understanding and management of MN. At present, serum PLA2R antibodies are used for diagnosis, prognostication, and guiding treatment. Now, with the discovery of more than 20 novel target antigens, antigen mapping is almost complete. The clinical association of certain antigens provides clues for clinicians, such as the association of nerve epidermal growth factor-like 1 with malignancies and indigenous medicines. Serum antibodies are detected for most target antigens, except exostosin 1 and 2 and transforming growth factor-beta receptor 3, but their clinical utility is yet to be defined. Genome-wide association studies and studies investigating environmental factors, such as air pollution, shed more light on the underpinnings of MN. The standard therapy of MN diversified from cyclical cyclophosphamide and steroids to include rituximab and calcineurin inhibitors over the past decades. Here, we provide a cutting-edge review of MN, focusing on genetics, immune system and environmental factors, novel target antigens and their clinical characteristics, and currently available and emerging novel therapies in MN.

Significance of thyroid dysfunction in the patients with primary membranous nephropathy

BACKGROUND

Thyroid dysfunction is common in patients with nephrotic syndrome, especially patients with primary membranous nephropathy (pMN). In view of both MN and thyroid dysfunction are associated with autoimmunity, the current study aimed to elucidate the significance of thyroid dysfunction in patients with pMN.

METHODS

Four hundred and twenty patients with biopsy-proven pMN from 2018-2021 were retrospectively enrolled. Clinical and pathological parameters, and treatment response of patients with and without thyroid dysfunction were analyzed.

RESULTS

Ninety-one (21.7%) patients with pMN suffered from thyroid dysfunction, among which subclinical hypothyroidism (52.7%) was the main disorder. Compared to patients with normal thyroid function, patients with thyroid dysfunction presented with a higher level of proteinuria, a lower level of serum albumin, a higher level of serum creatinine and more severe tubulointerstitial injury at the time of biopsy. But the positive rate and level of circulating anti-phospholipase A2 receptor (PLA2R) antibody were comparable between these two groups. Though following the similar treatment, the percentage of no response to treatment were significantly higher in the patients with thyroid dysfunction (38.6 vs. 20.0%, P = 0.003). Similar to the urinary protein and the positivity of anti-PLA2R antibody, multivariate COX analysis showed thyroid dysfunction was also identified as an independent risk factor for the failure to remission (HR = 1.91, 95%CI, 1.07-3.40, P = 0.029).

CONCLUSION

In conclusion, thyroid dysfunction is common in the patients with pMN and might predict a severe clinical manifestation and a poor clinical outcome, which indicated that the thyroid dysfunction might be involved in the disease progression of pMN.

The association between albuminuria and thyroid antibodies in newly diagnosed type 2 diabetes mellitus patients with Hashimoto's thyroiditis and euthyroidism

BACKGROUND

Microalbuminuria is a prognostic marker of diabetes kidney disease. It is generally diagnosed as the ratio of urinary albumin to creatinine (UACR) of 30-300 mg/g. Hashimoto's thyroiditis is a common disease in the endocrinology and the thyroid antibodies may associated with kidney disease. We investigated the UACR in the newly diagnosed T2DM with Hashimoto's thyroiditis and tried to detect the relationship between the UACR and thyroid antibodies.

METHODS

One hundred twenty newly diagnosed T2DM patients with Hashimoto's thyroiditis and euthyroidism and 50 sex and age-matched T2DM with non-Hashimoto's and other thyroid disease were recruited. T2DM patients were divided into 2 groups by the titer of TPOAb: (1). TPOAb (+) group: T2DM with positive TPOAb (n = 105); (2). TPOAb (-) group: T2DM with negative TPOAb (n = 65).

RESULTS

T2DM with positive TPOAb group had higher UACR than T2DM with negative TPOAb group (21.55 ± 7.28 vs 15.13 ± 5.69 mg/g, P < 0.01). UACR were positively related to BMI (r = 0.255, P < 0.05), FPG (r = 0.285, P < 0.05), HbA1c (r = 0.260, P < 0.05) and TPOAb (r = 0.349, P < 0.05). HbA1c (β = 0.793, P < 0.05), BMI (β = 0.342, P < 0.05) and lnTPOAb (β = 1.207, P < 0.05) were independently associated with UACR.

CONCLUSIONS

In the newly diagnosed T2DM patients, Hashimoto's thyroiditis with TPOAb positive had higher UACR levels. TPOAb titer, BMI and HbA1c were independent associated with UACR in these patients.

Juvenile dermatomyositis with IgA nephropathy: case-based review

Juvenile dermatomyositis (JDM) is the most common childhood idiopathic inflammatory myopathy (IIM). It is characterized by the classic skin rash in the form of Gottron papules and heliotrope rash, and symmetric proximal muscle weakness. Renal involvement in JDM is rare which includes acute kidney injury and glomerulonephritis. We report a 10-year-old boy with juvenile dermatomyositis and IgA nephropathy. Child responded dramatically to the conventional therapy with steroids and methotrexate for the primary disease, and did not require any additional treatment for his renal disease. Child's primary disease is in remission and has normal urinalysis with normal renal function at 6-month follow-up. We reviewed the literature and found 11 cases of IIMs with renal involvement. Four patients (one JDM, two polymyositis, and one dermatomyositis) had IgA nephropathy out of which three patients responded to the conventional therapy of primary disease and only one patient with polymyositis needed hiking immunosuppression targeted for renal condition. Therapy targeting the underlying disorder is usually sufficient in patients with JDM and secondary IgA nephropathy.

A Case of Concomitant Pemphigus Foliaceus and Oral Pemphigus Vulgaris

Pemphigus is a chronic autoimmune condition that can affect multiple areas of the body. The two main subtypes of pemphigus are pemphigus vulgaris (PV) and pemphigus foliaceus (PF) which can rarely occur concurrently or even transition from one to the other. The process of transition may be explained by qualitative changes in desmoglein autoantibody profile. We present a rare case of concomitant PF and oral PV and explore the literature on transitions between pemphigus subtypes and whether this case could represent a transition from PF to PV. Furthermore, the realities of multidisciplinary patient management are discussed.

Autoimmune Thyroiditis and Glomerulopathies

Autoimmune thyroiditis (AIT) is generally associated with hypothyroidism. It affects ~2% of the female population and 0.2% of the male population. The evidence of thyroid function- and thyroid autoantibody-unrelated microproteinuria in almost half of patients with AIT and sometimes heavy proteinuria as in the nephrotic syndrome point to a link of AIT with renal disease. The most common renal diseases observed in AIT are membranous nephropathy, membranoproliferative glomerulonephritis, minimal change disease, IgA nephropathy, focal segmental glomerulosclerosis, antineutrophil cytoplasmic autoantibody (ANCA) vasculitis, and amyloidosis. Different hypotheses have been put forward regarding the relationship between AIT and glomerulopathies, and several potential mechanisms for this association have been considered. Glomerular deposition of immunocomplexes of thyroglobulin and autoantibodies as well as the impaired immune tolerance for megalin (a thyrotropin-regulated glycoprotein expressed on thyroid cells) are the most probable mechanisms. Cross-reactivity between antigens in the setting of genetic predisposition has been considered as a potential mechanism that links the described association between ANCA vasculitis and AIT.

Rheumatologic manifestations of primary immunodeficiency diseases

In the last 5 years, several hundred articles have been published concerning the link between primary immunodeficiency disease (PID) and rheumatologic diseases. Although rheumatologic complications were originally thought to be at the opposite ends of the spectrum of immunopathologic manifestations, they are now all being considered secondary manifestations of a causative primary "immune derangement." For the rheumatologist, it is important to be able to identify patients who may present with typical rheumatologic findings but who have an underlying PID. In a systematic manner, this overview addresses both the systemic and organ-based rheumatologic diseases which have known associations with primary immunodeficiencies, and explores how immunodeficiency may actually cause these clinical manifestations.

Onset of Graves' disease during long-term immunosuppressive therapy in a patient with membranous nephropathy

A 67-year-old man was referred to our department for thyrotoxicosis with intermittent palpitation and 4-kg weight loss during the previous month. At the first visit, the patient was treated with cyclosporine A (CyA) for membranous nephropathy during the last 3 years and 8 months. Laboratory studies revealed that the serum TSH level was <0.005 μU/ml, and free thyroxine (fT₄) and triiodothyronine (fT₃) levels were elevated at 2.76 ng/dl and 5.96 pg/ml respectively. Anti-TSH receptor antibody (TRAb) level was increased at 26.4%. A clinical diagnosis of Graves' hyperthyroidism was given, and then thyrostatic treatment with thiamazole (MMI) at a dose of 10 mg daily was initiated after CyA withdrawal. After the initiation of MMI therapy, serum fT₄ and fT₃ attained the normal level within 1.5 months, with relief of symptoms followed by a remarkable decrease in urinary protein excretion from 2.0–5.2 g/day to ≤0.03 g/day. The patient maintained euthyroid with a low titre of TRAb for the succeeding 2 years and then MMI was finally stopped. Neither a relapse of hyperthyroidism nor a flare-up of nephrotic syndrome was observed for 3 years after MMI discontinuation. CyA has conflicting effects on immunologic self-tolerance by modulation of self-reactive T cells and natural CD4⁺CD25⁺Foxp3⁺ regulatory T cell (Treg) functions, and possibly becomes a triggering factor in the development of autoimmune disorders. This case may be interesting when considering the effect of each T cell subset on the development of Graves' disease.

Membranous nephropathy: a review on the pathogenesis, diagnosis, and treatment

In adults, membranous nephropathy (MN) is a major cause of nephrotic syndrome. However, the etiology of approximately 75% of MN cases is idiopathic. Secondary causes of MN are autoimmune diseases, infection, drugs, and malignancy. The pathogenesis of MN involves formation of immune complex in subepithelial sites, but the definite mechanism is still unknown. There are three hypotheses about the formation of immune complex, including preformed immune complex, in situ immune-complex formation, and autoantibody against podocyte membrane antigen. The formation of immune complex initiates complement activation, which subsequently leads to glomerular damage. Recently, the antiphospholipase A2 receptor antibody was found to be associated with idiopathic MN. This finding may be useful in the diagnosis and prognosis of MN. The current treatment includes best supportive care, which consists of the use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, lipid-lowering agents, and optimal control of blood pressure. Immunosuppressive agents should be used for patients who suffer from refractory proteinuria or complications associated with nephrotic syndrome. Existing evidence supports the use of a combination of steroid and alkylating agents. This article reviews the epidemiology, pathogenesis, diagnosis, and the treatment of MN.

Depletion of B lymphocytes in idiopathic membranous glomerulopathy: results from patients with extended follow-up

Aims

To assess the long-term therapeutic benefit of temporary depletion of B lymphocytes in patients with idiopathic membranous glomerulopathy (MGN) and search for potential predictors of response.

Patients and Methods

The patients included had been diagnosed with biopsy-proven MGN in the absence of secondary causes. Estimated glomerular filtration rate should be above 30 ml/min/1.73 m² and 24-hour proteinuria 3 g/day or more. Patients who had been treated with cyclosporine or cytotoxic agents the year prior to study entry were excluded. Depletion of B cells was achieved with rituximab, which was administered intravenously for 4 consecutive weeks. Partial remission was defined as a >50% decrease in proteinuria with absolute proteinuria <3 g/day, while complete remission was defined as a >50% decrease in proteinuria and an absolute protein excretion <0.3 g/day.

Results

Twelve patients were studied (4 females/8 males) with a mean age of 51.3 years. No major adverse effects were observed. During a median follow-up time of 48 months, 11/12 (91.6%) patients achieved remission [7/12 (58.3%) complete remission and 4/12 (33.3%) partial remission], while 1 patient did not respond to therapy. Twelve months after therapy, 68.8% (p = 0.003) of cases had achieved partial and 28.4% complete remission. Measurements of lymphocyte subpopulations did not reveal any changes except for the B cell depletion. B cell infiltrates captured per mm³ of renal tissue in the diagnostic biopsy did not correlate with subsequent response.

Conclusion

Depletion of B cells in idiopathic MGN was well tolerated and resulted in significant and long-lasting response rates in a series of 12 patients.

Coexistent findings of renal glomerular disease with Hashimoto's thyroiditis

AIM AND BACKGROUND

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disease with a female preponderance. Renal involvement in HT is not uncommon. In the present study, we aimed to define the frequency and characteristics of the glomerular diseases associated with HT and further the understanding of any common pathogenesis between HT and glomerular disease.

MATERIALS AND METHODS

We reviewed retrospectively 28 patients with HT who were referred to our Department because of unexplained haematuria, proteinuria or renal impairment from 2007 to 2011. Routine laboratory investigations including blood count, serum biochemistry, urinalysis and 24-h urinary protein excretion were performed on all patients. Renal biopsy was performed in 20 patients with HT, and the specimens were examined by light microscopy and immunofluorescence staining.

RESULTS

We detected four cases of focal segmental glomerulosclerosis (FSGS), four membranous glomerulonephritis (MGN), two minimal-change disease (MCD), three immunoglobulin A nephritis (IgAN), three chronic glomerulonephritis (CGN) and one amyloidosis. In three patients, the renal biopsy findings were nonspecific. Daily urinary protein excretion and glomerular filtration rates were found to be independent of the level of thyroid hormone and thyroid-specific autoantibodies.

CONCLUSION

Glomerular pathologies associated with HT are similar to those in the general population, the most common lesions being MGN, FSGS and IgA nephritis.

Correlation between B Lymphocyte Abnormality and Disease Activity in Patients with Idiopathic Membranous Nephropathy

This study investigated the relationship between peripheral blood B lymphocytes, regulatory T-cells and T lymphocyte subsets, the distribution of B lymphocytes in the kidney, and the pathogenesis of idiopathic membranous nephropathy (IMN). Lymphocyte subsets were measured using flow cytometry in 66 patients with clinically-confirmed IMN and in 40 healthy control subjects. Compared with healthy subjects, the number of peripheral blood B lymphocytes was significantly increased in IMN patients and that of regulatory T-cells was significantly decreased, accompanied by an increased CD4+/CD8+ T-cell ratio. There was no relationship between the number of peripheral blood B lymphocytes and markers of kidney function. Although the number of infiltrating B lymphocytes in the kidney of IMN patients was higher, there was no relationship with the number of peripheral blood B lymphocytes. In conclusion, there was no relationship between peripheral blood B lymphocytes and disease activity, suggesting that peripheral blood B lymphocytes are not a biomarker of disease activity and therapeutic efficacy in IMN.

Monoclonal antibodies for podocytopathies: rationale and clinical responses

The podocytopathies, including minimal-change nephropathy, focal segmental glomerulosclerosis, collapsing glomerulopathy, and diffuse mesangial sclerosis, involve diverse types of injury to podocytes. These injuries can have genetic causes, or can be caused by viral infection, mechanical stress, medication or-probably-immunologic injury. Several lines of evidence-including the immunosuppressive effects of standard therapies-suggest a role for immunologic injury in some cases, but the precise pathologic mechanisms are far from clear. Despite this uncertainty, newly available biologic therapies that target immune cells and cytokines have been used to treat a number of patients with different podocytopathies. Of these therapies, the greatest experience has been gained with rituximab. The data on all such therapies remain too fragmentary to provide firm conclusions, but further clinical research with such agents might help to define pathogenetic pathways and could potentially contribute to new therapies.