Decreased absolute number of peripheral regulatory T cells in patients with idiopathic retroperitoneal fibrosis.

Objective: In order to determine whether the immune balance of T helper 17(Th17)/regulatory T(Treg) is related to the pathogenesis of idiopathic retroperitoneal fibrosis (IRPF), we analyzed the differences in peripheral blood lymphocytes, CD4+T cell subsets and cytokines between patients with IRPF and healthy people to clarify the CD4+T cell subsets, especially Treg cell subsets, and the role of cytokines in the pathogenesis of IRPF. Methods: This study included 22 patients with IRPF, 36 patients with IgG4-related diseases (IgG4-RD) without retroperitoneal fibrosis (RPF), and 28 healthy controls. The absolute numbers and percentage of peripheral blood lymphocyte subsets and CD4+T cell subsets in each group were detected by flow cytometry, and the serum cytokine level was detected by flow cytometric bead array (CBA). Results: Compared with the healthy group, the absolute value of B cells in peripheral blood of IRPF patients was significantly decreased, and T, natural killer (NK), CD4+ and CD8+ were not significantly abnormal. The absolute numbers of Th2 cells were lower than healthy group(p=0.043). In particular, the absolute numbers of Treg cells were significantly lower than healthy group(p<0.001), while the absolute numbers of Th17 cells increased(p=0.682). Th17/Treg was significantly higher than healthy group (p< 0.001). Cytokine analysis showed that the level of interleukin (IL)-4 in IRPF patients was higher than healthy group(p=0.011), IL-6, IL-10, IL-17, TNF-α and IFN-γ were significantly higher than healthy group (all p<0.001). Receiver operating characteristic (ROC) curves showed that IL-10 and TNF-α could distinguish bilateral ureteral dilatation in IRPF patients, with areas under the ROC curve (AUCs) of 0.813 (95% CI:0.607-1.000, p=0.026) and 0.950 (95% CI:0.856-1.000, p=0.001), respectively. IL-6 could distinguish bilateral ureteral obstruction, with an AUC of 0.861 (95% CI: 0.682-1.000, p=0.015). Conclusions: Our study showed that IRPF patients had reduced Treg cells and indeed had Th17/Treg imbalance, which may be related to the pathogenesis of the disease. The levels of IL-6, IL-10 and TNF-α appear to be associated with the progression of IRPF.

Bile Acids Elevated in Chronic Periaortitis Could Activate Farnesoid-X-Receptor to Suppress IL-6 Production by Macrophages.

Chronic periaortitis (CP) is a rare autoimmune disease without effective treatment. By analyzing the serum bile acid spectrum in 28 CP patients with the ultra-performance liquid chromatography-tandem mass spectrometry, we found that the bile acids were significantly altered in CP patients, with significant increases in chenodeoxycholic acid (CDCA) and glycochenodeoxycholic acid (GCDCA) and decrease in deoxycholic acid (DCA). Signaling pathway enrichment analysis from the RNA sequencing results suggested that the altered gene sets in PBMC of CP patients were associated with bile acid metabolism. Furthermore, we found that pathological concentration of CDCA could significantly inhibited IL-6 expression in RAW 264.7 cells after LPS stimulation. Since CDCA is a well-known natural high-affinity ligand for the bile acid receptor farnesoid-x-receptor (FXR) while GW4064 is the synthetic specific agonist of this receptor, we then revealed that GW4064 significantly decreased IL-6 expression in RAW 264.7 cells and bone marrow-derived macrophages but not in FXR-/- macrophages upon LPS stimulation. The western blot results with the anti-FXR antibody showed significantly increased expression in the nuclear proportion, suggesting that FXR agonist promoted the transportation of FXR into the nucleus but did not increase the FXR expression in macrophages. Dual-luciferase report assay and ChIP assay demonstrated that upon activation, FXR could directly bind to the promoter site of IL-6, leading to the decreased expression of IL-6. Thus, bile acids, especially CDCA, may operate to damp inflammation via FXR-mediated downregulation of IL-6 in mononuclear cells and provide a protective mechanism for CP patients.

Idiopathic Retroperitoneal Fibrosis With Intense Uptake of 68Ga-Fibroblast Activation Protein Inhibitor and 18F-FDG.

ABSTRACT: A 26-year-old man presented with a retroperitoneal mass with left urinary tract obstruction and hydronephrosis recently. 18F-FDG PET/CT showed the retroperitoneal mass had intense and homogeneous FDG avidity. In 68Ga-FAPI PET/CT, the retroperitoneal mass showed intense radioactivity without other organ involvements. The patient was finally diagnosed with idiopathic retroperitoneal fibrosis. After treatment, the follow-up CT showed significant decrease in size of the retroperitoneal mass. The current case indicated that idiopathic retroperitoneal fibrosis had active uptake of 68Ga-FAPI.

Large Tumefactive IgG4-related Disease: Histologic, Cytologic, and Immunohistochemical Features of a Very Unusual Case.

Immunoglobulin G4-related disease (IgG4-RD) is a regional or systemic multiorgan lymphoplasmacytic inflammatory disease of unknown etiology. It has been described in numerous organs and anatomic locations. Review of the literature shows that when the disease involves the retroperitoneum it causes retroperitoneal fibrosis. Tumefactive IgG4-RD of the retroperitoneum has not been previously reported. In this report, we describe the first case of a large retroperitoneal tumefactive IgG4-RD along with its histologic, cytologic, and immunohistochemical characteristics.

Fibrocytes in Chronic Periaortitis: A Novel Mechanism Linking Inflammation and Fibrosis.

OBJECTIVE: Chronic periaortitis (CP) is a rare disease characterized by periaortic and periiliac fibroinflammatory tissue. The pathogenic mechanisms leading to tissue accumulation and activation of fibroblasts are unclear. This study was undertaken to explore the role of fibrocytes, circulating precursors of tissue fibroblasts, in patients with CP. METHODS: We studied 44 patients with newly diagnosed CP and 30 healthy controls. Circulating fibrocytes were identified as Col1+CD45+ cells using flow cytometry. Retroperitoneal tissue biopsy samples from 9 CP patients were stained with anti-type I procollagen, anti-CXCR4, and anti-CD45 antibodies and analyzed by confocal microscopy to detect tissue-infiltrating fibrocytes. Circulating levels and tissue expression of CXCL12, a CXCR4 ligand that promotes fibrocyte homing, were investigated using enzyme-linked immunosorbent assay and immunohistochemistry, respectively. We also characterized T helper polarization in biopsy samples from CP patients and measured serum levels of a panel of cytokines that are hallmarks of T helper responses and capable of influencing fibrocyte differentiation. RESULTS: The frequency of circulating Col1+CD45+ fibrocytes was higher in patients than in controls (P = 0.0371). CD45+proCol1+ and CXCR4+proCol1+ cells were detected in all examined biopsy samples from CP patients. Serum levels of CXCL12 were also higher in CP patients than controls (P = 0.0056), and tissue-infiltrating inflammatory cells intensely expressed CXCL12. Increased serum levels of Th2 cytokines (e.g., interleukin-13 [IL-13] and IL-10) were found in patients, and immunohistochemistry revealed a dominant infiltration of GATA-3+ cells, also indicating Th2 polarization; Th2-skewed responses are known to promote fibrocyte differentiation. CONCLUSION: Our findings indicate that fibrocytes are enriched in the peripheral blood of CP patients and infiltrate target lesions. The accumulation of fibrocytes in the pathologic tissue might be driven by CXCL12, and Th2-skewed immune responses are likely to facilitate their differentiation.

Interleukin-6 as an inflammatory mediator and target of therapy in chronic periaortitis.

OBJECTIVE: Chronic periaortitis (CP) usually responds to glucocorticoids, but some patients have glucocorticoid-refractory disease or contraindications to glucocorticoid therapy. This study was undertaken to evaluate treatment with the anti-interleukin-6 receptor (anti-IL-6R) antibody tocilizumab in 2 patients with CP, one with refractory disease and the other with contraindications to glucocorticoids, and to assess IL-6 levels in an additional cohort of patients with CP. METHODS: Both patients were given intravenous tocilizumab (8 mg/kg) once every 4 weeks for 6 months. Serum IL-6 was measured in 22 patients with active CP and 16 healthy controls. Tissue IL-6 expression was assessed by confocal microscopy in biopsy specimens obtained from 6 patients with CP. RESULTS: In the first patient, whose disease was refractory to various immunosuppressive treatments, tocilizumab added to ongoing therapy with prednisone and methotrexate allowed prednisone withdrawal and induced resolution of symptoms, acute-phase reactant normalization, and reduction in (18) F-fluorodeoxyglucose ((18) F-FDG) uptake on positron emission tomography. The patient experienced a relapse 7 months later and was successfully retreated with tocilizumab. In the second patient, who was unable to tolerate glucocorticoids because of psychiatric side effects, tocilizumab monotherapy induced sustained clinical and laboratory remission, (18) F-FDG uptake disappearance, and CP shrinkage. Serum IL-6 levels were significantly higher in patients with active CP than in controls (P < 0.0001), and IL-6 was abundantly expressed in biopsy specimens from CP patients, particularly by T cells, B cells, histiocytes, fibroblasts, and vascular smooth muscle cells. CONCLUSION: Tocilizumab may be a therapeutic option for CP. The systemic and tissue up-regulation of IL-6 in CP, together with the clinical benefit of IL-6R blockade observed in our 2 patients, suggest that IL-6 may contribute to CP pathogenesis.

IgG4-related disease: nomenclature, clinical features, and treatment.

Concepts about IgG4-related disease (IgG4-RD) are now emerging swiftly. The condition has been identified in virtually every organ system, and its features are often excellent mimickers of malignancies, infections, and other immune-mediated disorders. Recommendations for nomenclature were proposed by the Organizing Committee of the 2011 International IgG4-related disease Symposium, and guidelines for the pathologic diagnosis of this condition have been published by an international group of experts. Experience with treatment regimens is growing. Glucocorticoids and B-cell depletion strategies both appear to be effective and are the subject of ongoing studies. This article reviews the current thought and understanding of this disease with regard to nomenclature, organ system involvement, and approaches to therapy.

Retroperitoneal and aortic manifestations of immunoglobulin G4-related disease.

Retroperitoneal fibrosis is one of the prototypic manifestations of immunoglobulin G4 (IgG4)-related disease (IgG4-RD), but there is growing evidence that the aorta is also involved. These 2 conditions are closely linked, and based on the epicenter of the disease, the clinical manifestations can be classified as retroperitoneal fibrosis, inflammatory abdominal aortic aneurysm (including a combination of the 2), and thoracic aortitis. IgG4-RD is responsible for only a subset (∼50%) of cases of retroperitoneal fibrosis and inflammatory aortic aneurysms. Histological features include an extensive lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, fibrosis arranged in a storiform pattern, moderate tissue eosinophilia, and partially or completely obliterated veins. Among the 3 layers comprising the aorta, the adventitia is most susceptible to IgG4-related inflammation. The inflammatory process can also disrupt the lamellar elastic fibers in the media, which is seemingly a critical event leading to aneurysmal transformation. Steroid therapy is effective for both retroperitoneal and aortic lesions, as it is for the other manifestations of IgG4-RD. The risk of rupture appears to be low in patients with IgG4-related aortic aneurysms, but immunosuppressive therapy may trigger this critical complication by reducing the wall thickness.

Characterization of a hemophore-like protein from Porphyromonas gingivalis.

The porphyrin auxotrophic pathogen Porphyromonas gingivalis obtains the majority of essential iron and porphyrin from host hemoproteins. To achieve this, the organism expresses outer membrane gingipains containing cysteine proteinase domains linked to hemagglutinin domains. Heme mobilized in this way is taken up by P. gingivalis through a variety of potential portals where HmuY/HmuR of the hmu locus are best described. These receptors have relatively low binding affinities for heme. In this report, we describe a novel P. gingivalis protein, HusA, the product of PG2227, which rapidly bound heme with a high binding constant at equilibrium of 7 × 10(-10) M. HusA is both expressed on the outer membrane and released from the organism. Spectral analysis indicated an unusual pattern of binding where heme was ligated preferentially as a dimer. Further, the presence of dimeric heme induced protein dimer formation. Deletional inactivation of husA showed that expression of this moiety was essential for growth of P. gingivalis under conditions of heme limitation. This finding was in accord with the pronounced increase in gene expression levels for husA with progressive reduction of heme supplementation. Antibodies reactive against HusA were detected in patients with chronic periodontitis, suggesting that the protein is expressed during the course of infection by P. gingivalis. It is predicted that HusA efficiently sequesters heme from gingipains and fulfills the function of a high affinity hemophore-like protein to meet the heme requirement for growth of P. gingivalis during establishment of infection.

Tc-99m MDP uptake in retroperitoneal fibrosis.

A 60-year-old man with a history of surgical resection of leiomyosarcoma of the right kidney had a bone scan to evaluate possible metastatic osseous disease. The bone scan showed significantly increased Tc-99m MDP activity in the right abdomen, corresponding to a heterogeneous mass in the right retroperitoneal region on the subsequent abdominal CT scan. These findings were initially interpreted as recurrent malignancy. However, the surgical pathology examination demonstrated that the lesion was retroperitoneal fibrosis, which was not previously known to have increased MDP uptake.

Hypermetabolic activity in patients with active retroperitoneal fibrosis on F-18 FDG PET: report of three cases.

Idiopathic retroperitoneal fibrosis is an uncommon disease characterized by periaortic inflammation with gradual fibrosis and distortion of retroperitoneal structures such as the ureter. Several earlier case reports have documented hypermetabolic retroperitoneal activity on fluorodeoxyglucose positron emission tomography (FDG PET) in patients with active disease, and a decrease in the activity following immunosuppressive therapy. We report FDG PET positive findings in three patients presenting with active retroperitoneal fibrosis. In two cases, enhancing periaortic soft tissue seen on computed tomography (CT) markedly diminished following immunosuppressive therapy. In one patient, repeat FDG PET was performed following immunosuppressive therapy, with complete resolution of the retroperitoneal FDG avidity. We suggest that FDG PET may play a useful adjunct to anatomic imaging and serum inflammatory markers in assessing the severity of inflammation in retroperitoneal fibrosis, and in assessing the likelihood of response to immunosuppressive therapy. FDG PET may also be used in follow-up to assess therapeutic response if CT findings are unclear.

Post-treatment residual tissue in idiopathic retroperitoneal fibrosis: active residual disease or silent "scar" ? A study using 18F-fluorodeoxyglucose positron emission tomography.

OBJECTIVE: Medical treatment is often effective in idiopathic retroperitoneal fibrosis (IRF) but frequently leads to residual retroperitoneal masses that may represent active disease or simply consist of inactive fibrotic tissue. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is a functional imaging modality that reliably assesses disease activity in a number of inflammatory diseases including IRF. We used 18F-FDG PET to evaluate the metabolic activity of residual masses in a series of IRF patients. METHODS: We studied 7 consecutive IRF patients, all of whom presented constitutional symptoms and/or pain, and had high acute-phase reactant levels; 6 had ureteral involvement. IRF was diagnosed by means of computed tomography (CT), which revealed a peri-aortoiliac mass in all cases. Three patients underwent surgical ureterolysis and 2 received ureteral stents. Subsequently, 5 patients received prednisone, one sequential treatment with prednisone and tamoxifen, and one prednisolone plus methotrexate. All of the patients underwent 18F-FDG PET at varying times after the end of treatment. RESULTS: The presenting signs/symptoms improved in all patients and the levels of acute-phase reactants significantly decreased or normalised. Ureteral obstructive disease resolved in all cases. Post-treatment CT revealed a considerable reduction in the amount of IRF but all of the patients had a residual retroperitoneal mass. PET revealed slight aorto-iliac 18F-FDG uptake in only one patient; all of the others were negative. No patient relapsed during the follow-up. CONCLUSIONS: Post-treatment residual masses are frequent in IRF patients but, in most cases, probably represent metabolically inactive tissue.

Chronic sclerosing sialadenitis of the submandibular gland associated with idiopathic retroperitoneal fibrosis.

We report a case of a 57-year-old man who developed a fibrosclerosing lesion in the submandibular gland and idiopathic retroperitoneal fibrosis (IRF) involving the unilateral periureteral region within a year. Both lesions were resected surgically because of the suspicion of neoplasm. Pathologic examination revealed similar histologic and immunohistochemical features for both lesions, namely, fibrosclerosis with prominent hyalinizing collagen bundles and proliferation of myofibroblastic cells, and a non-neoplastic reactive nature. There was infiltration by lymphocytes with prominent lymph follicles, plasma cells and macrophages. The histologic and immunohistochemical findings suggest that the two lesions were of a similar pathogenesis, which was possibly mediated by macrophages. We think that the present case may be an unusual form of multifocal fibrosclerosis. Although sialolithiasis is thought to be a major pathogenic factor for chronic sclerosing sialadenitis of the submandibular gland, the present case suggests that certain cases might have an etiology similar to IRF.

Crystal-storing histiocytosis and immunocytoma associated with multifocal fibrosclerosis.

AIMS: Crystal-storing histiocytosis is a rare disorder described in patients with lymphoproliferative diseases, mainly in cases of multiple myeloma but also in lymphoplasmacytic lymphoma (immunocytoma). Most cases involve one single organ which, in the majority, is related directly to the presence of tumour. We describe a 44-year-old man with a clinical picture of multifocal fibrosclerosis (with mesenteric panniculitis, peritoneal, mediastinal and orbital fibrosis) in which the autopsy showed a systemic infiltrate of crystal-storing histiocytes and functional alteration of the organs involved, associated with IgG-kappa type immunocytoma. METHODS AND RESULTS: Histology showed a systemic infiltration, with a predilection for adipose tissue, by a diffuse cellular infiltrate composed of small lymphocytes, plasmacytoid lymphocytes and plasma cells, admixed with large number of crystal-storing histiocytes. Intracytoplasmic crystals were not identified either in the plasma cells or plasmacytoid lymphocytes. The neoplastic cells and the crystalline inclusions displayed reactivity with antibodies for IgG and the kappa light chain. A polymerase chain reaction study for the IgH gene showed a monoclonal rearrangement. Ultrastructural studies showed needle-shaped crystals surrounded by a single unit membrane. CONCLUSION: This case is, to the authors' knowledge, the first to be described in which crystal-storing histiocytosis is associated with a clinical picture of multifocal fibrosclerosis, which suggests that lymphoproliferative processes should be considered in the differential diagnosis of the various conditions associated with multifocal fibrosclerosis.

Idiopathic sclerosing inflammation of the orbit: immunohistologic analysis and comparison with retroperitoneal fibrosis.

Idiopathic sclerosing inflammation of the orbit is clinically characterized by an insidious, chronic and progressive fibrosing process damaging orbital structures through entrapment and mass effect. Histologically, desmoplasia and a sparse infiltrate of lymphocytes, histiocytes, plasma cells, and occasional neutrophils and eosinophils are seen. An immune pathogenesis is suspected but presently poorly understood. To characterize the inflammatory infiltrate and to compare orbital and other inflammatory fibrosing lesions, immunoperoxidase studies using the streptavidin method were performed on 16 formalin or Bouins' fixed, paraffin-embedded orbital biopsy specimens and six specimens of retroperitoneal fibrosis. Positive staining of orbital tissue occurred as follows: T-cells (UCHL-1) 94% of cases, B-cells (L26) 40%, tissue macrophages (KP-1) 56%, HLA Dr positive antigen presenting cells and activated T-cells (LN3) 44%, and immunoglobulins (kappa, 80%; lambda, 63%, IgG, 73%, IgA, 44% and IgM, 31%). Results were strikingly similar for retroperitoneal fibrosis. These findings imply a cell mediated pathogenesis in idiopathic sclerosing inflammation of the orbit that is similar to retroperitoneal fibrosis and suggest therapeutic potential for agents modifying this facet of the immune system.

Characterisation of inflammatory cells associated with "idiopathic retroperitoneal fibrosis".

During ureterolysis in a patient with "idiopathic retroperitoneal fibrosis", fresh samples of peri-ureteric and peri-aortic tissue were obtained. An abdominal CT scan confirmed the peri-aortic distribution of the inflammation associated with advanced abdominal aortic atherosclerosis. Histology confirmed the presence of fibrosis and a variable chronic inflammatory cell infiltrate. Monoclonal antibodies were used to identify the inflammatory cells. B and T lymphocytes were present with the majority of T lymphocytes of the T helper phenotype. The majority of lymphocytes and macrophages and most vascular endothelial cells were HLA-DR positive. Ki67 and BerH2 staining was found in B cells and T helper cells, indicating that these cells were proliferating and activated. These findings compare with the characterisation of inflammatory cells associated with "inflammatory aneurysms" and with the inflammatory cells present in the spectrum of inflammation seen as a complication of advanced atherosclerosis--conditions known as "chronic peri-aortitis". It is suggested that our findings support the view that idiopathic retroperitoneal fibrosis represents clinical chronic peri-aortitis seen in an undilated aorta.

Retroperitoneal fibroses--an association with hyperuricaemia.

A review of a small series of cases with idiopathic retroperitoneal fibrosis revealed that two of the patients had been under treatment for gout prior to developing retroperitoneal fibrosis. Investigation showed that other patients in the series had hyperuricaemia. Examination of the retroperitoneal fibrotic tissue demonstrated the presence of urate crystals in unusually high numbers. It is suggested that the pathological process of retroperitoneal fibrosis in these cases may have been initiated by the deposition of urate crystals in the retroperitoneal connective tissue and that the same process may be related to the causation of idiopathic hydrocoele.