Table 2.
Clinical studies on OPN and kidney diseases (2010–2024).
| Study identifier | Disease type | Promote or inhibit immune environment | Sampling | Source of OPN | Changes in immune cells | Role and mechanisms of OPN |
|---|---|---|---|---|---|---|
| Xu et al. (181) | Tumor | Inhibit | Tissue | Tumor tissue | Reduction in CD8+ T-lymphocytes/increase in Tregs | OPN promotes tumor immune evasion by inhibiting CD8+ T lymphocyte infiltration and enhancing Tregs cell infiltration. |
| Zhang et al. (182) | Tumor | Inhibit* | Tissue | Tumor cells | – | OPN binds to integrin receptors on the surface of target cells in renal cell carcinoma, activating signaling pathways such as JAK/STAT, which in turn facilitates disease progression. |
| Chen et al. (185) | ORG | Promote | Tissue | Increased expression of OPN in T-lymphocytes and B-lymphocytes | Decreased number of T lymphocytes and B lymphocytes | Although lymphocyte infiltration is reduced, the increased expression of OPN in lymphocytes suggests that OPN may promote inflammatory responses and disease progression in ORG. |
| Ye et al. (186) | FSGS | Promote | Tissue/urine | TECs, podocytes, and macrophages | Increased macrophage infiltration and M2 polarization | OPN is positively correlated with the accumulation and M2 polarization of macrophages. |
| Steinbrenner et al. (210) | CKD | – | Urine | – | – | Higher OPN levels are associated with a higher risk for adverse outcomes. |
| Kim et al. (266) | AKI | – | Blood | – | – | – |
| Armstrong et al. (183) | Tumor | Promote | Blood | – | Enhancement of T-cell differentiation toward Th17 cells | OPN promotes the differentiation of T cells into Th17 cells and induces IL-17 production. |
| Xu et al. (232) | AR | Promote* | Blood | – | – | OPN promotes endothelial cell proliferation. |
| Owens et al. (211) | CKD | – | Urine | – | – | OPN can serve as a predictive marker for the prognosis of CKD. |
| Almaani et al. (267) | LN | Promote* | Tissue | Kidney tissue | – | – |
| Wang et al. (35) | Tumor | – | Tissue | Tumor tissue | – | OPN enhances the migration and invasion of tumor cells by upregulating NF-κB expression. |
| Kaleta et al. (187) | IgAN | Promote* | Urine | Kidney tissue* | – | Due to genetic polymorphisms of OPN, urinary excretion of the rs1126616 and rs9138 subtypes of OPN is significantly elevated in patients with IgAN. |
| Spinelli et al. (188) | LN | Promote* | Blood/urine | Kidney tissue* | – | Plasma levels of OPN are significantly higher in patients with active LN (lupus nephritis) and in those with LN remission than in healthy normal controls. |
| Ibrahim et al. (191) | AKI | Promote* | Urine | – | – | Drug-induced kidney injury can increase the level of OPN in urine. |
| Choueiri et al. (184) | Tumor | Inhibit* | Blood | – | – | Lower levels of OPN in the blood can enhance the therapeutic efficacy for RCC patients. |
| Sobotke et al. (268) | Tumor | Inhibit* | Blood | – | – | The serum levels of OPN in RCC (renal cell carcinoma) patients are significantly higher than those in controls, and they correlate with the size and stage of the tumor. High levels of OPN are associated with poorer overall survival (OS) rates and cancer-specific survival (CSS). |
| Berti et al. (269) | AAV | Promote* | Blood | – | – | High levels of OPN may be associated with disease activity and prognosis in MPA patients. |
| Zurita et al. (270) | Tumor | Inhibit* | Blood | – | – | High levels of OPN are correlated with poorer overall survival. |
| Trojanowicz et al. (271) | Hemodialysis | Promote* | Blood | – | – | – |
| Taguchi et al. (213) | Urolithiasis | Promote | Tissue | RPs, TECs, and interstitial cells | Increased infiltration of macrophages, plasma cells, and neutrophils | High expression of OPN can promote calcium salt deposition and crystallization, thereby facilitating the formation and progression of RP. |
| Brooks et al. (272) | Urolithiasis | Promote* | Urine | – | Increased MIP-1α in urine (secreted by macrophages) | OPN can protect the kidneys from oxalate crystal-induced injury. |
| Ma et al. (273) | LN | Promote | Tissue | Kidney tissue | Increased infiltration of T-lymphocytes and macrophages | OPN facilitates macrophage infiltration within the kidney and induces injury to podocytes, leading to proteinuria. |
| Rabjerg et al. (274) | Tumor | Inhibit* | Tissue | Kidney tissue | – | High expression of OPN is associated with poorer survival outcomes. |
| Al-Malki (209) | DN | Promote* | Urine | – | – | There is a positive correlation between the number of podocytes in urine and the level of OPN. |
| Okumura et al. (275) | Urolithiasis | – | Stone | – | Kidney stones contain a variety of proteins enriched with neutrophils | OPN protein is present in most kidney stones. |
| Righi et al. (276) | Tumor | Inhibit* | Tissue | Tumor tissue and TECs | Increased infiltration of macrophages in tumor tissue | OPN may indirectly contribute to the mechanisms driving RCC progression and impact patient survival by influencing aspects such as the invasiveness, proliferation, and treatment resistance of tumors. |
| Jin et al. (231) | AR | Promote* | Blood | – | – | During acute rejection episodes, the levels of OPN in the blood increase, and they decrease following anti-rejection therapy. |
| Sim et al. (277) | Tumor | Inhibit* | Blood | – | – | Higher concentrations of OPN in the blood are associated with poorer survival outcomes in patients with RCC. |
| Papworth et al. (278) | Tumor | Inhibit* | Blood | – | – | Blood OPN levels are an independent prognostic factor for RCC-specific survival. |
| Zurita et al. (279) | Tumor | – | Blood | – | – | Patients with higher concentrations of OPN in the blood tend to derive greater benefits from targeted treatments. |
AAV, antineutrophil cytoplasmic antibody-associated vasculitis; AKI, acute kidney injury; AR, acute rejection; DN, diabetic nephropathy; FSGS, focal segmental glomerulosclerosis; IgAN, IgA nephropathy; LN, lupus nephritis; OPN, osteopontin; ORG, obesity-related glomerulopathy; OS, overall survival; RP, Randall plaques; TEC, tubular epithelial cell. *Not explicitly stated in the original study but inferred from cytokines and medical changes.