Immune-mediated kidney diseases like glomerulonephritis and tubulointerstitial nephritis are not the most common cause of chronic kidney disease in the population, however the difficulties in their management, as well as a more rapid deterioration of kidney function, compared to diabetes mellitus and hypertension, justify the importance of this problem for internal medicine. Due to the fundamental discoveries in pathology and to the introduction of various methods of laboratory and instrumental investigation in the second half of the XX century substantial progress was made in the diagnostic approaches and treatment of these conditions. State-of-the-art diagnostic approach requires complex evaluation of the clinical, laboratory and morphological data to identify the nosological form of the disease. The accumulation of knowledge in the field of diseases\' pathogenesis led to the revision of the current classification of glomerulonephritis that should be based on the immunopathogenesis of these conditions. The following phenotypes were suggested: autoimmunity-related, autoinflammation-related, alloimmunity-related, infections-related, and monoclonal gammopathy-related. The assessment of disease activity and chronicity in the kidney tissue should be mandatory. Personalized selection of the optimal treatment modality on the basis of the diagnosis, severity, and individual features of the patient is currently possible. The leading trends include rational prescription of glucocorticoids (steroid-sparing regimens) and cytotoxic agents, e.g. cyclophosphamide, as well as the introduction of multitarget regimens that include biologic agents or small molecules selectively suppressing B-cells or various complement pathways. Another mandatory component of treatment on par with immune suppression is nephroprotective therapy, which currently comprises not only traditional renin-angiotensin-aldosterone antagonists, but also endothelin receptor antagonists and sodium-glucose cotransporter-2 inhibitors. Current guidelines emphasize the importance of the non-pharmacological interventions for the implementation of the nephroprotective strategy. Rational combination of the aforementioned approaches allows for the optimization of the management of patients with immune-mediated kidney diseases, although it requires high competencies and strict adherence to the principles of the evidence-based medicine from the healthcare providers.
Гломеруло- и тубулоинтерстициальные нефриты – не ведущая причина развития хронической болезни почек в популяции, но сложности их диагностики и лечения, а также более быстрые по сравнению с сахарным диабетом и артериальной гипертензией темпы прогрессирования почечной дисфункции обосновывают актуальность решения этой проблемы для внутренней медицины. Благодаря фундаментальным открытиям в области морфологии и патофизиологии, а также внедрению различных методов лабораторного и инструментального обследования во второй половине XX в. стал возможным существенный прогресс в диагностике и лечении этой группы заболеваний. Современные стандарты диагностики подразумевают комплексную оценку клинико-лабораторных и гистологических данных с целью верификации нозологической формы заболевания. Накопление знаний о патогенезе этой группы нозологий привело к очередному пересмотру подхода к классификации гломерулонефритов, в основе которого должен лежать патогенетический принцип с выделением фенотипов, ассоциированных с инфекциями, аутоиммунными, аутовоспалительными и аллоиммунными реакциями, а также моноклональной гаммапатией, с обязательной оценкой активности иммунного воспаления и склеротических изменений (хронизация) в ткани почки. Стал возможным персонализированный выбор оптимальной тактики лечения на основании не только нозологической формы, но и тяжести течения заболевания, а также индивидуальных особенностей пациента. При этом ведущими тенденциями становятся рациональное применение глюкокортикостероидов (стероид-сберегающие схемы) и неселективных цитостатиков, в первую очередь циклофосфамида, а также внедрение мультитаргетных схем лечения, в том числе с использованием биологических препаратов и малых молекул, избирательно подавляющих B-лимфоциты или различные пути активации системы комплемента. Помимо иммуносупрессивной терапии обязательным компонентом лечения стала нефропротективная терапия, основанная на применении не только традиционных антагонистов ренин-ангиотензин-альдостероновой системы, но и антагонистов эндотелиновых рецепторов, а также ингибиторов натрийглюкозного котранспортера 2-го типа. Не меньшее значение придается немедикаментозным компонентам нефропротективной стратегии. Рациональная комбинация этих подходов позволяет оптимизировать подходы к ведению пациентов с иммуновоспалительными заболеваниями почек, однако требует от врача глубокой подготовки и приверженности зафиксированным в рекомендациях принципам.

OBJECTIVE: Tubulointerstitial nephritis and uveitis (TINU) syndrome is an uncommon disease. We present a confirmed case of TINU syndrome, and a systematic review of epidemiological characteristics, clinical manifestations, management, and outcomes in Chinese patients.
METHODS: A systematic search was carried out using defined terms and updated up to September 2022, in PubMed, Web of Science, Wanfang, CNKI, and VIP, to identify reported cases of TINU in China, according to PRISMA guidelines.
RESULTS: An 18-year-old boy presented with elevated serum creatinine and 24-h urine protein level of > 2 g. Inspection result revealed acute tubulointerstitial nephritis, and bilateral uveitis. The patient was diagnosed with TINU syndrome and received treatment with methylprednisolone sodium succinate, which resulted in a significant decrease in creatinine and urinary protein levels. Systematic review identified 35 publications that met the inclusion criteria. A total of 71 cases were included in this article, of which 70 were from publications and 1 was from our hospital. The median age at onset was 42 years and was significantly lower in males than females (P < 0.05). The symptoms of uveitis often occurred after kidney injury (54%) and most uveitis was anterior (55%) and bilateral (75%). Among the 51 patients who were followed up for more than 6 months, 24 had recurrent ocular symptoms or progression to chronic uveitis. Twenty patients experienced chronic or progressive kidney disease.
CONCLUSIONS: TINU syndrome is prone to misdiagnosis because kidney damage may not occur simultaneously with uveitis. The incidence of kidney sequelae in children is lower than that in adults, and glucocorticoids are the preferred treatment.
UNASSIGNED: INPLASY202350050.

Inflammatory bowel diseases are autoimmune disorders affecting the gastrointestinal tract and producing a wide variety of extraintestinal manifestations. Kidneys are a rare target organ of their extraintestinal activity, but if affected, renal function could deteriorate to end-stage kidney disease, which is curable only by organ transplantation. Renal calculi are the most common pathological kidney manifestation in IBD patients, followed by tubulointerstitial nephritis, glomerulonephritis, and other kidney pathologies. The liver is the most commonly transplanted organ in IBD patients (primary sclerosing cholangitis and autoimmune hepatitis), and a scarcity of literature on kidney recipients is present to date regarding the incidence of renal insufficiency, kidney transplantations, post-transplant IBD course and further complications such as graft rejection or infections in this specific group of patients. De novo IBD is a paradoxical entity in the setting of rigorous post-transplant immunosuppression. In this case series, we present three patients who underwent kidney transplantation with a history of an IBD and one patient who developed de novo Crohn\'s disease after the deceased donor organ transplant was performed.

BACKGROUND: Despite much research on chronic kidney disease of uncertain etiology (CKDu) in Sri Lanka and the Mesoamerican nephropathy, the etiology and pathogenesis of this disease remains elusive. The pathology has broadly been described as chronic tubulointerstitial nephritis and no specific signature lesions have been identified.
METHODS: A scoping review was conducted through MEDLINE and Google Scholar databases for peer-reviewed publications on biopsy studies related to CKDu - Sri Lanka and Mesoamerican nephropathy to develop a comparative and critical analysis of the renal pathology found in these patients.
RESULTS: Thirteen studies met the selection criteria. Interstitial fibrosis was the predominant lesion in all the studies. Tubulointerstitial and glomerular abnormalities showed a more variable distribution. No characteristic histopathological feature was reported other than a proximal tubular lysosomal inclusion body which was claimed to indicate a toxic etiology. Three main pathogenetic mechanisms were postulated: repeated acute insults leading to scarring, low-grade chronic insults leading to non-inflammatory fibrosis, and tubulointerstitial damage in combination with glomerular injury. The main limitations in the interpretation and comparative analysis of these studies were the heterogeneity in case selection and biopsy reporting.
CONCLUSIONS: Although no characteristic histopathological feature could be found in CKDu-Sri Lanka or Mesoamerican nephropathy, there are noticeable differences between these two groups in the frequency and severity of the glomerular and tubulointerstitial changes which warrant more explorative studies preferably on kidneys in early stages of the disease. Future strategies should ensure that more uniform selection criteria and reporting methods are used.

Tubulointerstitial nephritis and uveitis (TINU) syndrome is defined as the occurrence of tubulointerstitial nephritis (TIN) and uveitis in the absence of other systemic diseases. The most comprehensive review on this condition was published in 2001.
We conducted a systematic review of the literature for cases of TINU syndrome. MEDLINE and Embase databases were screened. Full-length articles or letters reporting cases with both TIN and uveitis were selected. We investigated differences between males and females and paediatric and adult cases. Multivariate analysis was performed to identify potential risk factors for chronic kidney disease (CKD) development.
A total of 233 articles reporting 592 TINU cases were retained for the analysis. The median age of the included subjects was 17 years (interquartile range 13-46) with a female predominance (65%). Uveitis most frequently (52%) followed renal disease and was mostly anterior (65%) and bilateral (88%). Children tended to have more ocular relapses, while they were slightly less likely than adults to suffer from acute kidney injury and to develop CKD. Adult age as well as posterior or panuveitis were associated with an increased risk of developing CKD.
TINU affects both children and adults, with some differences between these two categories. Adult age and the presence of a posterior uveitis or panuveitis appear to be associated with the development of CKD.

Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibrosing inflammatory systemic disorder that has been recognized relatively recently in the medical literature. Little is known about the exact disease pathogenesis and epidemiology. IgG4-RD may be asymptomatic or may have minimal symptoms or involve multiple organs with overt symptoms. The different phenotypes of IgG4-RD can lead to delayed or incorrect diagnosis. We report the case of a 66-year-old male with coal worker\'s pneumoconiosis who presented with progressive kidney disease and was diagnosed with tubulointerstitial nephritis due to IgG4-RD. The patient was noted to have progressive kidney disease, skin involvement, worsening interstitial lung disease, complete vision loss in the left eye, and retroperitoneal fibrosis. Serologic workup revealed elevated inflammatory markers, IgG4 and IgG1 levels, and hypocomplementemia. A tissue biopsy helped us establish a definitive diagnosis of IgG4-RD and initiate treatment with glucocorticoids to prevent further progression of kidney disease and other end-organ damage.

BACKGROUND: There is a growing base of literature describing BK nephropathy (BKVN) in patients outside of the setting of kidney transplant. Previous systematic reviews of the literature have been limited by methodology or by the scope of patients included.
METHODS: Systematic Review (Prospero # CRD42018088524).
METHODS: Patients without kidney transplant who had biopsy-proven BKVN.
METHODS: Full-text articles that describe native BKVN patient cases.
UNASSIGNED: Descriptive synthesis.
RESULTS: The search identified 630 unique articles of which 51 were included in the final review. Sixty-five cases (including two new cases presented in this review) were identified, all but one occurred in the setting of known immunosuppression.
CONCLUSIONS: The primary limitation was the exclusion of studies that did not fulfill the stringent review criteria. We excluded reports with only a clinical diagnosis of BKVN, such as those with viruria and/or viremia without biopsy.
CONCLUSIONS: As of May 2018, there are 65 reported cases of BKVN in native kidneys. This represents the most comprehensive description of biopsy-proven BKVN in native kidneys to date. Evaluation for BK nephropathy should be considered in immunocompromised patients who exhibit unexplained renal failure.

IgG4-related disease (IgG4-RD) is a newly recognized immune-mediated multisystemic disease characterized by a fibro-inflammatory condition with tissue infiltration of IgG4-positive plasma cells and often associated with elevated serum IgG4 levels. Typical renal involvement of IgG4-RD presents as tubulointerstitial nephritis (TIN), membranous or membranoproliferative nephropathy. We are presenting a case with combined IgG4 membranous nephropathy and TIN, as well as a literature review on pathophysiology, diagnosis and treatment of IgG4-RD. A 62-year-old man presented with weight loss and fatigue. Labs showed significant proteinuria and hematuria with elevated serum creatinine (2.5 mg/dL). CT/PET scan found scattered lymphadenopathy without increased FDG uptake. Kidney biopsy showed glomerular lesions as well as severe interstitial fibrosis and tubular atrophy. Immunohistochemistry study was negative for anti-phospholipase A2 receptor antibodies and showed interstitial lymphocytic infiltration with IgG4 positive plasma cells. Patient also had elevated serum IgG4 level and IgG4 to total IgG ratio. Prednisone treatment was initiated soon after the diagnosis was made, patient responded well with proteinuria and hematuria both resolved. IgG4-related disease (IgG4-RD) is a newly increasingly recognized immune-mediated multisystemic disease; IgG4-related membranous nephropathy should be included in the differential diagnosis for patients with proteinuria.

This review will encompass definition, pathogenesis, renal clinical manifestations and treatment of immunoglobulin G4-related diseases (IgG4-RDs). IgG4-RD is a recently recognized clinical entity that often involves multiple organs and is characterized by high levels of serum immunoglobulins G4, dense infiltration of IgG4+ cells and storiform fibrosis. Cellular immunity, particularly T-cell mediated immunity, has been implicated in the pathogenesis of IgG4-RDs. The most frequent renal manifestations of IgG4-RD are IgG4-related tubulointerstitial nephritis, membranous glomerulopathy and obstructive nephropathy secondary to urinary tract obstruction due to IgG4-related retroperitoneal fibrosis. IgG4-RD diagnosis should be based on specific histopathological findings, confirmed by tissue immunostaining, typical radiological findings and an appropriate clinical context. The first line treatment is the steroids with two warnings: Steroid resistance and relapse after discontinuation. In the case of steroid resistance, B cell depleting agents as rituximab represent the second-line treatment. In the case of relapse after discontinuation, steroid treatment may be associated with steroid sparing agents. Since the disease has been only recently identified, more prospective, long-term studies are needed to an improved understanding and a more correct and safe treatment.

Sjögren\'s syndrome (SS) is a chronic autoimmune inflammatory disease that typically affects the salivary and lacrimal glands. Renal involvement is relatively uncommon and may precede other complaints. Tubulointestitial nephritis (TIN) is the most common renal involvement in SS. Osteomalacia occurring as the first manifestation of renal tubular disorder due to SS is very rare. We report a 39-year-old male who presented with polydipsia, polyuria, and multiple bone pain. Bone density test showed severe osteoporosis, and laboratory findings suggested hypokalemia, hypophosphatemia, and vitamin D deficiency, which supported the diagnosis of hypophosphatemic osteomalacia. He had nephrogenic loss of phosphate and potassium, tubular acidification, and concentration dysfunction. And, the diagnosis of chronic TIN was subsequently confirmed by renal biopsy. The patient reported dry mouth and physical examination showed multiple dental caries. Xerophthalmia, abnormal morphology, and function of the salivary glands by sonography and scintigraphy, together with positive anti-SSA and anti-SSB, confirmed the diagnosis of SS. The TIN indicated SS as the underlying cause of osteomalacia. After taking supplements of potassium, phosphate, vitamin D, and sodium bicarbonate for 1 month, bone pain was alleviated and serological potassium and phosphorus were also back to normal. In conclusion, renal involvement in SS may be latent and precede the typical sicca symptoms. Osteomalacia can be the first manifestation of renal disorder due to SS. Therefore, autoantibody investigations as well as the lacrimal and salivary gland examinations for SS should be considered and performed for suspected patients.