DNAJB9 and the treatment option with rituximab

The identification of DNAJB9 is a crucial tool for the diagnosis of atypical fibrillary glomerulonephritis. Rituximab can assist in preserving kidney function for certain human beings with fibrillary glomerulonephritis.¹ To summarise, FGN is an uncommon glomerular disease defined by randomly orientated, non-branching fibrils. According to the current research, the fibrils include IgG, complementing parts, and DNAJB9, allowing for FGN diagnosis without electron microscopy. Patients with FGN have a poor prognosis, with inadequate data to support successful treatment. As therapeutic choices are limited, the appropriate therapy has yet to be determined. These limited data are not sufficient for us to draw any conclusions about immunosuppressive therapy for FGN, although rituximab may be beneficial in those with FGN, particularly those with relatively normal baseline renal function.²

The definition of glomerulonephritis disease

Fibrillary glomerulonephritis is a complex illness that has a high risk of end-stage renal failure and death.³ Fibrillary glomerulonephritis (FGN) is a very uncommon kind of glomerulonephritis distinguished by the presence of deposits of randomly aligned microfibrils ranging in size from 10 to 30 nanometers in the glomeruli, which may be observed under an electron microscope. In most cases, the prognosis is poor, with progression to ESRD; nevertheless, remission may occur in a small percentage of people. Age, severity of renal impairment at diagnosis, and degree of glomerular scarring are among the factors that influence renal survival.⁴

Renin-angiotensin inhibition andimmunosuppression and glomerulonephritis

Fibrillary glomerulonephritis is commonly linked with autoimmune disorders, cancer, or hepatitis. In most cases, the prognosis is poor with progression to ESRD; nevertheless, remission may occur in a small number of individuals. Age, severity of renal impairment at diagnosis, and degree of glomerular scarring are all variables that affect renal survival. A regimen of renin-angiotensin inhibition and immunosuppression is commonly used in FGN, however it is not particularly beneficial.⁴ Fibrillary glomerulonephritis and immunotactoid microtubular glomerulopathy have distinctive immunological characteristics.⁵

The importance of electron microscopy and a case explanation

In this case, electron microscopy results are important for FG since certain FGN patient biopsy samples may not stain in immunofluorescence studies. Furthermore, it is stated that if neurologic symptoms are present in conjunction with Bence-Jones proteinuria, the patient should be investigated for paraproteinemic demyelinating neuropathy.⁶ A patient was reported to have developed nephrotic syndrome, which comprised impaired renal function and microscopic haematuria. An ultrastructural examination of a kidney biopsy sample revealed fibrils consistent with fibrillary glomerulonephritis. In addition, the patient had bilateral intraretinal haemorrhages and purpura. This is a new set of results in a cystic fibrosis patient.⁷

Immunohistochemistry

Fibrillary glomerulonephritis (FGN) is a rare glomerular illness with a poor prognosis, defined by the deposition of randomly distributed fibrillar material. Furthermore, ultrastructurally, the fibrillary material in this entity may be mistaken for diabetic fibrillosis, which occurs in diabetic nephropathy.⁸

Antibodies and pathophysiology

Immunoglobulin negativity in FGN occurs when the deposited fibrils do not interact with the polyclonal or monoclonal antibodies used for labelling due to mutations or structural epitope alterations caused by an immunologically active underlying disease state. Other pathophysiologic possibilities exist, and further research is needed to explore these concepts.8 FGN and diabetic nephropathy both produce increased proteinuria, and a high level of suspicion is required for FGN, which I would like to list some points:⁸

• Due to the fact that immunoglobulin-negative FGN is rare, we use electron microscopy, nonargyophilia on silver staining, and DNAJB9 positive to establish the diagnosis⁸
• HCV has been linked to both FGN and immunoglobulin-negative FGN, and it may increase immunoglobulin synthesis. Appropriate antiviral therapy may reduce antigenic stimulation, prevent immunoglobulin and DNAJB9 deposition, and result in the generation of this entity⁸
• A research paper found that DNAJB9 protein synthesis in FGN is not induced by glomerular transcriptional activation of DNAJB9⁹

Monotypic and Polytypic FGN

Interestingly, in a paper, the two cases of FGN that tested negative for DNAJB9 were unique in that they solely stained for IgG (without k or l light chains) on IF. Clinical evidence of monoclonal gammopathy was observed in both cases, while only 17% of monotypic FGN patients and 1% of polytypic FGN patients showed it.¹⁰

Prospective treatment options

The occurrence of similar ultrastructural abnormalities in the kidney and lung in this patient suggests that fibrillary material deposition might be caused by a circulating component. Although corticosteroid therapy appeared to provide a brief remission of our patient's pulmonary bleeding, postmortem examination indicated that alveolar haemorrhage may have been ongoing in a slow way, since there were signs of pulmonary hemosiderosis and fibrosis. Cyclophosphamide treatment and plasmapheresis might be utilised to treat future cases.¹¹

Unidentification

It is also possible that FGN is not a single, homogeneous substance and that, like amyloid, it has a variety of antecedents, such as immunoglobulins and other, as of yet unidentified compounds. the purported bulins and other as-yet-unidentified chemicals. While some of the reported variations in the fibrils' width (10 to 22 nm) may be due to variations in their composition.¹²

Rituximab and a case

A chimeric monoclonal antibody targeting CD20+ B cells, rituximab (RTX) is being utilized more and more to treat renal diseases. Patients receiving treatment for haematological illnesses have been shown to have RTX-induced pulmonary disease in one research, and a small number of patients with underlying rheumatological problems have also shown signs of this syndrome. They report a case of a 49-year-old patient with primary (fibrillary) glomerulonephritis who developed non-infectious interstitial pneumonitis as a result of using RTX. As is usually seen, the pulmonary symptoms resolved once the medication was stopped and glucocorticoids were started right away. On the other hand, deaths have been documented, thus, nephrologists who treat patients with glomerulonephritis with RTX should be aware of this potentially deadly side effect.¹³

Causes of glomerulonephritis

Infections, autoimmune diseases, vasculitis and sclerotic conditions can be listed as causes of glomerulonephritis syndrome.¹⁴

Infections can cause glomerulonephritis. These can be listed as:¹⁴

• Post-streptococcal glomerulonephritis¹⁴
• Bacterial endocarditis¹⁴
• Viral kidney infections¹⁴
• HIV¹⁴

Autoimmune ailments:

IgA nephropathy, Goodpasture’s syndrome and lupus are among the autoimmune diseases that can have the capability to cause glomerulonephritis.¹⁴

Polyarteritis and Granulomatosis with polyangiitis (Wegener's granulomatosis) are two distinctive types of vasculitis that can cause glomerulonephritis. Polyarteritis can affect both medium and small blood vessels. Focal segmental glomerulosclerosis is a type of sclerotic condition which is either caused by another disease or developed due to an unknown reason. It can be defined as a scattered scar on glomeruli. High blood pressure and diabetic kidney disease (known as diabetic nephropathy) are also other sclerotic conditions which can cause glomerulonephritis.¹⁴

Side effects of glomerulonephritis

The potential adverse effects of glomerulonephritis are:¹⁴

• Acute kidney failure¹⁴
• Chronic kidney disease¹⁴
• High blood pressure¹⁴
• Nephrotic syndrome¹⁴

Glomerulonephritis diagnosis tests

• Urine tests that determine if you have protein or blood in your urine
• blood tests that measure the level of creatinine in a sample of your blood
• kidney biopsy and imaging tests such as ultrasound, X-ray or CT scan can be used in prognosis¹⁵

Treatment options

In some cases, treating the hidden cause can be sufficient. If the underlying reason for a patient to develop glomerulonephritis is infections, then prescribing the patient antibiotics would be a great action to take. In other cases, immunosuppressants, angiotensin-converting enzyme (ACE) inhibitors or angiotensin blockers (ARBs), corticosteroids, plasmapheresis, dialysis, or diuretics can be used and be utilised in the treatment process of glomerulonephritis. To prevent glomerulonephritis, implementing a healthy lifestyle in a routine is recommended as general advice.¹⁵

FAQs

How can I manage glomerulonephritis, can you explain this in a brief sentence?

The goal of managing glomerulonephritis is to have regular renal evaluations.¹⁵

Is glomerulonephritis a serious disease?

In some individuals, it may progress into chronic kidney disease or even kidney failure; these are life-threatening conditions. Such an approach to preventive care will help in the early identification of disorders like glomerulonephritis, which, sometimes, remains asymptomatic in some cases.¹⁵

When should I see my healthcare provider?

You should call your doctor if you have one or more from the provided list:

• Hematuria or other changes in the appearance of urine.¹⁵
• Change in frequency of urination¹⁵
• Joint pain¹⁵
• Leg or facial swelling¹⁵
• Shortness of breath¹⁵

Summary

Fibrillary glomerulonephritis (FGN) is a rare kidney disease marked by the buildup of randomly arranged fibrils in the glomeruli, often leading to end-stage renal disease. The discovery of DNAJB9 as a highly specific marker has improved diagnostic accuracy, reducing the need for electron microscopy in many cases.

FGN has a poor prognosis and limited treatment options. While immunosuppressive therapy has shown mixed results, rituximab—a monoclonal antibody targeting B cells—has shown potential in preserving kidney function, particularly in patients with mild baseline impairment. However, it carries risks, including rare cases of lung toxicity.

FGN can be associated with autoimmune diseases, cancer, or infections like hepatitis C, and can present in monotypic or polytypic forms. Some rare cases test negative for DNAJB9, often linked to monoclonal gammopathy. Diagnosis may involve biopsy, immunostaining, and electron microscopy when needed.

Treatment strategies include managing underlying causes and using supportive therapies such as ACE inhibitors, corticosteroids, or plasmapheresis. Research is ongoing, as the exact mechanisms and optimal treatments for FGN remain unclear.