Understanding how intestinal immune cells contribute to the development and activity of IgA nephropathy

ISRCTN	ISRCTN11448420
DOI	https://doi.org/10.1186/ISRCTN11448420
Sponsor	Fundamental and Applied Research Projects in Latvia
Funder	Fundamental and Applied Research Projects in Latvia

Submission date: 22/03/2026
Registration date: 22/04/2026
Last edited: 11/05/2026

Recruitment status: Recruiting
Overall study status: Ongoing
Condition category: Urological and Genital Diseases

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Mikus Saulīte
Scientific, Public

Pilsonu str. 13
Riga
LV-1002
Latvia

ORCID ID	0000-0001-5383-0129
Phone	+371 (0)67069286
Email	mikus.saulite@stradini.lv

Dr Kārlis Rācenis
Principal investigator

Pilsonu str. 13
Riga
LV-1002
Latvia

ORCID ID	0000-0001-7123-4048
Phone	+371 (0)67069286
Email	karlis.racenis@stradini.lv

Study information

Primary study design	Observational
Observational study design	Cohort study
Scientific title	The role of intestinal mucosal B cells in the pathogenesis and activity of IgA nephropathy
Study objectives	The aim of this study is to investigate the role of intestinal mucosal B cells in the pathogenesis and activity of IgA nephropathy by identifying the origin, phenotype, and molecular characteristics of GdIgA1-producing B cells in intestinal lymphoid tissue and peripheral blood.
Ethics approval(s)	Approved 20/06/2025, Central Medical Ethics Committee of Latvia (72 k-1 Brīvības Street, Riga, LV-1002, Latvia; +371 (0)67876182; pasts@vm.gov.lv), ref: 01-29.1.2/3696
Health condition(s) or problem(s) studied	IgA nephropathy
Intervention	This is an observational quantitative cross-sectional study including patients with biopsy-proven IgA nephropathy and controls from the general population. Blood, urine, and intestinal biopsy samples (Peyer’s patches) will be collected during colonoscopy. Peripheral blood mononuclear cells and intestinal immune cells will be isolated and analyzed using flow cytometry, ELISA, and RNA sequencing (bulk RNA-seq and single-cell RNA sequencing) to characterize B cell subpopulations and GdIgA1 production. In vitro B cell stimulation and co-culture models will be used to evaluate mechanisms of GdIgA1 production and B cell activation. Immunofluorescence microscopy will be used to analyze intestinal lymphoid tissue. Clinical and laboratory data will be collected and compared between study groups. Statistical analysis will be performed to identify differences between groups and associations between immunological markers and disease activity.
Intervention type	Other
Primary outcome measure(s)	Frequency and molecular characterization of GdIgA1-producing B cells measured using flow cytometry, ELISA measurement of GdIgA1, and RNA sequencing (bulk RNA-seq and single-cell RNA sequencing) of B cells isolated from peripheral blood and intestinal Peyer’s patches at the time of sample collection during study visit (single timepoint)
Key secondary outcome measure(s)
Completion date	31/12/2027

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	99 Years
Sex	All
Target sample size at registration	60
Key inclusion criteria	Cases – IgAN group: 1. Adults (≥18 years) 2. Biopsy-proven IgA nephropathy 3. eGFR ≥45 ml/min/1.73 m² 4. Proteinuria <1 g/day 5. Indication for colonoscopy (anemia, change in bowel habits, abdominal pain, positive fecal occult blood test) Controls: 1. Adults (≥18 years) 2. Individuals from general population undergoing screening colonoscopy 3. Positive fecal occult blood test 4. No pathological findings in colonoscopy (no polyps, tumors, inflammation)
Key exclusion criteria	1. Age <18 years 2. Pregnancy or breastfeeding 3. Secondary IgA nephropathy 4. IgA vasculitis 5. Liver disease 6. Alcoholism 7. Type 1 or type 2 diabetes mellitus 8. Chronic inflammatory diseases 9. Malignancy 10. Acute myocardial infarction or stroke within the last 6 months 11. Active gastrointestinal bleeding For control group: polyps, tumors, or inflammatory changes detected during colonoscopy
Date of first enrolment	01/04/2026
Date of final enrolment	01/05/2027

Locations

Countries of recruitment

Latvia

Study participating centres

Pauls Stradiņš Clinical University Hospital

Department of Nephrology
Riga
LV-1002
Latvia

Rīga Stradiņš University

-
Riga
LV-1007
Latvia

Results and Publications

Individual participant data (IPD) Intention to share	No

Editorial Notes

11/05/2026: Study contacts were updated.
28/04/2026: Observational study design was changed from Case control to Cohort study, and study centres were added.
02/04/2026: Study's existence confirmed by the Central Medical Ethics Committee of Latvia.