Intratumoral metastasis of sigmoid colon cancer to chromophobe renal cell carcinoma: a case report

We herein report an extremely rare case of intratumoral metastasis of colon cancer to chromophobe renal cell carcinoma. A 71-year-old woman was diagnosed with lung metastasis of sigmoid colon cancer and underwent sigmoid colon resection with D3 lymph node dissection. Preoperative contrast-enhanced computed tomography (CT) revealed a left renal tumor; however, colon resection was prioritized, and the renal tumor was placed under observation. Two years later, CT revealed enlargement of the left renal tumor, and laparoscopic partial left nephrectomy was performed 1 month later. Histopathologic examination showed that the resected renal tumor was a chromophobe renal cell carcinoma with intratumoral metastasis of colon cancer to the renal tumor center, and adjuvant chemotherapy with bevacizumab plus SOX (L-OHP + S-1) was initiated. Because of severe chemotherapy-induced fatigue and nausea, the patient was switched to bevacizumab + S-1. However, the patient's nausea did not improve after this change, and postoperative adjuvant chemotherapy was discontinued at the patient's request 4 months after the partial nephrectomy. Two months after discontinuation of chemotherapy, CT showed no renal recurrence; however, increased lung metastases and a new bone metastasis in the left sciatic bone were observed. Palliative treatment was then initiated because of severe adverse events that made it difficult to continue treatment. In patients who have multiple cancers and an increase in renal tumor size, the possibility of intratumoral metastasis to the renal tumor should be considered.

SAT0527 COMBINED EFFECT OF COMMON VARIANTS IN EXON 2 OR EXON 3 AND A PATHOGENIC MUTATION IN EXON 10 OF THE MEDITERRANEAN FEVER GENE ON INFLAMMASOME ACTIVATION IN JAPANESE PATIENTS WITH FAMILIAL MEDITERRANEAN FEVER

Background:

Familial Mediterranean fever (FMF) is an autoinflammatory disease that is caused by Mediterranean fever (MEFV) gene mutations. It is characterized by recurrent and self-limiting febrile attacks within a short period. Although the pathologic significance ofMEFVexon 2 or exon 3 common variants in patients with FMF is modest and these variants are usually associated with less severe clinical presentations of FMF (1, 2), their combined effects with pathogenic mutation in exon 10 remain to be evaluated.

Objectives:

To determine the combined effect of common variants on clinical manifestations and inflammasome activity, we compared the clinical and laboratory characteristics between the coexistence and non-coexistence ofMEFVexon 2 or exon 3 variants in patients with FMF that had a heterozygousMEFVexon 10 mutation.

Methods:

We excluded patients with FMF that had twoMEFVexon 10 mutations in one or more alleles and those withMEFVvariants in exons other than in exons 2, 3, or 10. Finally, we reviewed 131 Japanese patients with FMF that had a heterozygousMEFVexon 10 mutation, and they were divided into the groups with and withoutMEFVexon 2 or exon 3 variants of 34 and 97, respectively. All enrolled patients had only a heterozygous M694I mutation in exon 10 of theMEFVgene. We measured serum IL-18 levels at remission without febrile attacks in the groups with and withoutMEFVexon 2 or exon 3 variants of 9 and 31, respectively.

Results:

In the univariate analysis, the group with variants in exon 2 or exon 3 had significantly earlier onset (16.0 years v.s. 20.5 years, p = 0.04), a higher percentage of thoracic pain with febrile attacks (68% v.s. 44%, p = 0.02), a higher frequency of attack (1.0/month v.s. 0.5/month, p = 0.02), and a higher IL-18 level in the serum at remission (606.3 pg/ml v.s. 168.4 pg/ml, p = 0.04, Figure 1) compared to the group without these variants. Importantly, multivariate analyses showed that the coexistence ofMEFVexon 2 or exon 3 variants and an exon 10 mutation was independently and significantly associated with earlier onset of FMF (p = 0.049) and thoracic pain (p = 0.03).

Figure 1.

Conclusion:

Our results suggest that the coexistence ofMEFVexon 2 or exon 3 variants and aMEFVexon 10 mutation has combined effects on inflammasome activation in the Japanese population.

References:

[1]Migita K, Uehara R, Nakamura Y, et al. Familial Mediterranean fever in Japan. Medicine (Baltimore). 2012 Nov;91(6):337-43.

[2]Shinar Y, Livneh A, Langevitz P, Genotype-phenotype assessment of common genotypes among patients with familial Mediterranean fever. J Rheumatol. 2000;27(7):1703.

Disclosure of Interests:

None declared

Prognostic significance of the prognostic nutritional index in esophageal cancer patients undergoing neoadjuvant chemotherapy

Nutritional status is one of the most important issues faced by cancer patients. Several studies have shown that a low preoperative nutritional status is associated with a worse prognosis in patients with various types of cancer, including esophageal cancer (EC). Recently, neoadjuvant chemotherapy (NAC) and/or radiotherapy have been accepted as the standard treatment for resectable advanced EC. However, NAC has the potential to deteriorate the nutritional status of a patient. This study aimed to evaluate the prognostic significance of the nutritional status for EC patients who underwent NAC. We retrospectively reviewed 66 squamous cell EC patients who underwent NAC consisting of docetaxel, cisplatin, and 5-fluorouracil followed by subtotal esophagectomy at Nara Medical University Hospital between January 2009 and August 2015. To assess the patients' nutritional status, the prognostic nutritional index (PNI) before commencing NAC and prior to the operation was calculated as 10 × serum albumin (g/dl) + 0.005 × total lymphocyte count in the peripheral blood (per mm3). The cutoff value of the PNI was set at 45. A multivariable analysis was performed to identify prognostic factors for overall survival (OS) and relapse-free survival (RFS). The mean pre-NAC and preoperative PNI were 50.2 ± 5.7 and 48.1 ± 4.7, respectively (P = 0.005). The PNI decreased following NAC in 44 (66.7%) patients. Before initiating NAC, 9 (13.6%) patients had a low PNI, and 12 (18.2%) patients had a low PNI prior to the operation. The pre-NAC PNI and preoperative PNI were significantly associated with the OS (P = 0.013 and P = 0.004, respectively) and RFS (P = 0.036 and P = 0.005, respectively) rates. The multivariable analysis identified the preoperative PNI as an independent prognostic factor for poor OS and RFS, although the pre-NAC PNI was not an independent predictor. Our results suggest that the preoperative PNI is a useful marker for predicting the long-term outcomes of EC patients undergoing NAC and subsequent subtotal esophagectomy. Therefore, patients with a low preoperative nutritional status may be at a higher risk of EC recurrence.

Increased prevalence of MEFV exon 10 variants in Japanese patients with adult-onset Still's disease

Autoinflammatory diseases include a large spectrum of monogenic diseases, e.g. familial Mediterranean fever (FMF), as well as complex genetic trait diseases, e.g. adult-onset Still's disease (AOSD). In populations where FMF is common, an increased MEFV mutation rate is found in patients with rheumatic diseases. The aim of this study was to examine MEFV mutations in Japanese patients with AOSD. Genomic DNA was isolated from 49 AOSD patients and 105 healthy controls, and exons 1, 2, 3 and 10 of the MEFV gene genotyped by direct sequencing. MEFV mutation frequencies in AOSD patients were compared with controls. We found no significant difference in overall allele frequencies of MEFV variants between AOSD patients and controls. However, MEFV exon 10 variants (M694I and G632S) were significantly higher in AOSD patients than controls (6.1 versus 0%). In addition, there was no significant difference between MEFV variant carriers and non-carriers with clinical manifestations, but the monocyclic clinical course of the AOSD disease phenotype was observed less frequently in patients without MEFV variants. AOSD patients had significantly higher frequencies of MEFV exon 10 mutations, suggesting that low-frequency variants of MEFV gene may be one of the susceptibility factors of AOSD.

MEFV gene polymorphisms and TNFRSF1A mutation in patients with inflammatory myopathy with abundant macrophages

Inflammatory myopathy with abundant macrophages (IMAM) has recently been proposed as a new clinical condition. Although IMAM shares certain similarities with other inflammatory myopathies, the mechanisms responsible for this condition remain unknown. Patients with familial Mediterranean fever (FMF) and tumour necrosis factor receptor-associated periodic syndrome (TRAPS) also often develop myalgia. We therefore investigated the polymorphisms or mutations of MEFV and TNFRSF1A genes in patients with IMAM to identify their potential role in this condition. We analysed the clinical features of nine patients with IMAM and sequenced exons of the MEFV and TNFRSF1A genes. The patients with IMAM had clinical symptoms such as myalgia, muscle weakness, erythema, fever and arthralgia. Although none of the patients were diagnosed with FMF or TRAPS, seven demonstrated MEFV polymorphisms (G304R, R202R, E148Q, E148Q-L110P and P369S-R408Q), and one demonstrated a TNFRSF1A mutation (C43R). These results suggest that MEFV gene polymorphisms and TNFRSF1A mutation are susceptibility and modifier genes in IMAM.

Effects of Janus kinase inhibitor tofacitinib on circulating serum amyloid A and interleukin-6 during treatment for rheumatoid arthritis

The Janus kinase inhibitor tofacitinib is currently being investigated as a disease-modifying agent in rheumatoid arthritis (RA). We investigated the in-vivo effects of tofacitinib treatment for 4 weeks on elevated circulating acute-phase serum amyloid (SAA) levels in 14 Japanese patients with RA. SAA levels fell from 110·5 ± 118·5 μg/ml (mean ± standard deviation) at treatment initiation to 15·3 ± 13·3 μg/ml after 4 weeks treatment with tofacitinib. The reduction in SAA levels was greater in patients receiving tofacitinib plus methotrexate compared with those receiving tofacitinib monotherapy. Tofacitinib was also associated with reduced serum interleukin (IL)-6, but had no effect on serum levels of soluble IL-6 receptor. Patients were divided into groups with adequate (normalization) and inadequate SAA responses (without normalization). Serum IL-6 levels were reduced more in the group with adequate SAA response compared with those with inadequate SAA response. These results suggest that tofacitinib down-regulates the proinflammatory cytokine, IL-6, accompanied by reduced serum SAA levels in patients with active RA. The ability to regulate elevated serum IL-6 and SAA levels may explain the anti-inflammatory activity of tofacitinib.

Inhibition of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway in rheumatoid synovial fibroblasts using small molecule compounds

Janus kinase (JAK) inhibitors have been developed as anti-inflammatory agents and have demonstrated clinical efficacy in rheumatoid arthritis (RA). We investigated if JAK-3-selective inhibition alone could disrupt cytokine signalling in rheumatoid synovial fibroblasts. In-vitro studies were performed using synovial fibroblasts isolated from patients with RA. Levels of activated JAK and signal transducer and activator of transcription (STAT) proteins were detected by immunoblot analysis. Target-gene expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR) or real-time PCR. The JAK inhibitors CP-690,550 and INCB028050 both suppressed activation of JAK-1/-2/-3 and downstream STAT-1/-3/-5, as well as the expression levels of target proinflammatory genes (MCP-I, SAA1/2) in oncostatin-M (OSM)-stimulated rheumatoid synovial fibroblasts. In contrast, the JAK-3-selective inhibitor, PF-956980, suppressed STAT-1/-5 activation but did not affect STAT-3 activation in OSM-stimulated rheumatoid synovial fibroblasts. In addition, PF-956980 significantly suppressed MCP-1 gene expression, but did not block SAA1/2 gene expression in OSM-stimulated rheumatoid synovial fibroblasts. These data suggest that JAK-3-selective inhibition alone is insufficient to control STAT-3-dependent signalling in rheumatoid synovial fibroblasts, and inhibition of JAKs, including JAK-1/-2, is needed to control the proinflammatory cascade in RA.

Atypical mycobacteriosis in two patients with rheumatoid arthritis

Abstract We report two cases of rheumatoid arthritis (RA) with atypical mycobacteriosis. Opportunistic infections are critical complications for rheumatic diseases. The use of steroids or immunosuppressants may increase the risk of opportunistic infections. However, these reports are rare in that they demonstrate atypical mycobacterial infections as complications of RA, even though no immunosuppressive agents were used. We discuss the characteristics of atypical mycobacterial infections of the lung in RA.

Endothelin B receptor expression correlates with tumour angiogenesis and prognosis in oesophageal squamous cell carcinoma

Background:

The endothelin axis has been shown to have a pivotal role in several human malignancies. The aim of this study was to clarify the clinical importance of endothelin receptor type B (ETBR) in human oesophageal squamous cell carcinoma (OSCC).

Methods:

We evaluated ETBR expression in 107 patients with OSCC by immunohistochemistry. Microvessel density (MVD) and lymphatic vessel density were assessed by CD31 and D2-40 immunostaining, respectively. Furthermore, CD4, CD8, and CD45RO+ tumour-infiltrating lymphocytes (TILs) were immunohistochemically analysed.

Results:

Sixty-one (57%) cases showed high expression of ETBR. Endothelin receptor type B expression was correlated with several clinicopathological factors including tumour differentiation, tumour depth, and lymph node metastasis. The overall and disease-specific survival rates were significantly lower in patients with high ETBR expression than patients with low expression. Furthermore, multivariate analysis revealed that ETBR status was an independent prognostic factor for patient survival. Mechanistic analysis indicated that MVD was significantly higher in tumour tissues with high ETBR expression compared with those with low expression, suggesting that angiogenesis may be a key mechanism in tumour progression and metastasis of OSCC mediated by ETBR expression. By contrast, there were no significant correlations between TILs and ETBR expression.

Conclusion:

Endothelin receptor type B has a pivotal role in oesophageal cancer and may be therapeutic target for this intractable malignancy.

Prognostic importance of tumour-infiltrating memory T cells in oesophageal squamous cell carcinoma

Memory T cells survive for many months and years and are critically important for host defence in humans. In tumour immunity, they have been also suggested to play a significant role in tumour progression and metastasis. However, the role of memory T cells in actual human cancer remains largely unknown. In this study, the clinical importance of tumour-infiltrating CD45RO(+) memory T cells was investigated in human oesophageal squamous cell carcinoma (OSCC). CD45RO(+) T cells were evaluated by immunohistochemistry in primary OSCC tumours from 105 patients. Patients were classified into two groups as CD45RO(+hi) or CD45RO(+lo) based on the number of cells stained positively for CD45RO. No significant difference was observed between CD45RO status and several clinicopathological prognostic factors. However, the postoperative overall and disease-free survival for CD45RO(+hi) patients was significantly better than for CD45RO(+lo) patients. Furthermore, there were significant correlations of CD45RO status in the primary tumour with postoperative lymph node and pulmonary recurrence, suggesting that memory T cells may control postoperative metastatic recurrence. Most importantly, CD45RO(+) memory T cell status has a significant prognostic value for OSCC independently of conventional tumour-node-metastasis (TNM) classification. Our study may provide a rationale for developing a novel immunotherapy in intentional induction of memory T cells for the treatment of oesophageal cancer.

A comparison of surgery and radiation therapy for cT1 esophageal squamous cell carcinoma

Surgery and radiation therapy have been used to treat esophageal squamous cell carcinoma. However, treatment outcomes have not yet been extensively investigated. The aim of this study was to compare surgery and radiation therapy for clinical T1 esophageal squamous cell carcinoma. A total of 67 clinical T1 esophageal squamous cell carcinoma patients were treated between January 1997 and December 2005; 29 had undergone radical esophagectomy (surgery group) and 38 were treated with definitive radiation therapy (radiation group). The mean patient age was lower in the surgery group than in the radiation group. In surgery group, respiratory complications, anastomotic leaks, recurrent nerve palsies, and anastomotic stenosis occurred in 7, 8, 6, and 5 patients, respectively. In radiation group, leucopenia, esophagitis, pericarditis were observed in 15, 3, and 3 patients, respectively. The 5-year overall survival rate for the surgery group was 68.9%, and 74.3% for the radiation group. There were no significant difference between groups (P= 0.3780). The 5-year relapse-free survival rate in the surgery group was 61.8% and 38.8% in the radiation group. The relapse-free survival rate was significantly higher in the surgery group than in the radiation group (P= 0.0051). The 5-year overall and relapse-free survival rates for tumors invaded into but not through the muscularis mucosa were 83.3% and 75.0%, respectively, in the surgery group and 78.8% and 33.3%, respectively, in the radiation group. There were no significant differences. The 5-year overall survival rates for patients with tumors that invaded the submucosal layer was 64.9% in the surgery group and 66.5% in the radiation group. This difference was not significant (P= 0.8712). The 5-year relapse-free survival rate in the surgery group (56.0%) was significantly higher than that in the radiation group (41.8%; P= 0.0219). In conclusion, surgery may become a standard treatment for cT1 esophageal cancer that can offer longer relapse-free survival, particularly for patients with tumors that invade the submucosa.

Expression of CD64 on polymorphonuclear neutrophils in patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is an autoinflammatory disease characterized by recurrent episodes of fever and serosal or synovial inflammation. We examined the utility of CD64 (FcγRI) expression in polymorphonuclear neutrophils (PMNs) as clinical and biological parameters in patients with FMF. We studied 12 Japanese FMF patients (mean age; 22·8 ± 15·5 years, male/female: 2/10), along with rheumatoid arthritis patients (RA, n = 38 male/female: 6/32, mean age; 52·2 ± 15·3 years), systemic lupus erythematosus (SLE, n = 15 male/female: 0/15, mean age; 38·5 ± 15·9 years) and 12 healthy subjects (male/female: 3/9, mean age; 37·9 ± 17·2 years). CD64 expression on PMNs was determined using flow cytometry. The quantitative expression of CD64 in patients with FMF (2439·6 ± 2215·8 molecules per PMN) was significantly higher than in healthy subjects (547·8 ± 229·5, P = 0·003) or in patients with RA (606·5 ± 228·2, P < 0·0001) and SLE (681·3 ± 281·1, P = 0·004). The increased CD64 expression on PMNs isolated from untreated FMF patients was down-regulated by colchicine treatment. NACHT-LRR-PYD-containing protein 3 (NLRP3) activation using MurNAc-L-Ala-D-isoGln (MDP) resulted in increased CD64 expression on PMNs from healthy subjects. Our results suggest that quantitative measurement of CD64 expression on PMNs can be a valuable tool to discriminate between FMF and autoimmune diseases.

Induction of interleukin-23 p19 by serum amyloid A (SAA) in rheumatoid synoviocytes

In this study, we investigated the roles of serum amyloid A (SAA) in T helper 17 (Th17)-related cytokine induction in rheumatoid arthritis (RA) synoviocytes. Synoviocytes isolated from rheumatoid arthritis (RA) patients were stimulated with recombinant SAA and IL-23 expression was investigated using reverse transcriptase-polymerase chain reaction and Western blot. The involvement of mitogen-activated protein kineases (MAPKs) and nuclear factor (NF)-κB in SAA-induced interleukin (IL)-23 p19 expression was investigated using pharmacological inhibitors. In RA synoviocytes, SAA induced the expression of IL-23 p19 and p40 mRNA expression. The SAA-stimulated expression of p19 was rapid (< 3 h), and insensitive to polymyxin B treatment. This SAA-stimulated expression of IL-23 p19 was inhibited completely by inhibitors of NF-κB, p38MAPK and dexamethasone. Interestingly, the SAA-induced IL-23, p19 and p40 production was accompanied by enhanced expression of IL-1β, but not transforming growth factor-β. These results indicate that SAA is a significant inducer of IL-23 and IL-1β in RA synoviocytes and potentially activates the IL-23/IL-17 pathway in the RA synovium. Our data present a novel interaction between inflammation and autoimmunity by an acute-phase protein.

Potentiation of glucocorticoid receptor (GR)-mediated signaling by the immunosuppressant tacrolimus in rheumatoid synoviocytes

OBJECTIVE

The immunosuppressant tacrolimus is known to enhance many aspects of glucocorticoid. In this study, we investigated the effects of tacrolimus on glucocorticoid receptor (GR) signaling using rheumatoid fibroblast-like synoviocytes (RA-FLS).

METHODS

The nuclear translocation of GR was analyzed by immunocytochemistry. The DNA binding activity of p65 was assayed by a functional ELISA kit using nuclear extracts. GR-associated FK506-binding protein-51 (FKBP-51) was analyzed by Western blotting following immunoprecipitation of glucocorticoid receptor (GR) complexes.

RESULTS

High concentrations (10-7M) of Dexamethasone (Dex) induced GR translocation to the nucleus in RA-FLS. However, the nuclear GR translocation did not occur with low concentrations of Dex (10-9M). Tacrolimus treatment of RA-FLS results in potentiation of GR translocation to the nucleus even in the presence of a low concentration of Dex (10-9M). GR-associated FKBP-51 decreased after tacrolimus treatment. Furthermore, tacrolimus also decreased the IL-1Beta-induced DNA binding activity of p65, a subunit of NF-KappaB, in the presence of 10-9 M of Dex.

CONCLUSION

These data suggest that tacrolimus exerts anti-inflammatory properties by potentiating the GR signaling through the GR-immunosuppressant-binding proteins (immunophilins) interaction and its nuclear transport in rheumatoid synovium.

MEFV mutations in Japanese rheumatoid arthritis patients

OBJECTIVE

Familiar Mediterranean Fever (FMF) is common among Mediterranean populations, while other populations are rarely affected. The aim of this study was to assess the involvement of MEFV gene mutations among Japanese rheumatoid arthritis patients with or without amyloid A (AA) amyloidosis.

METHODS

The frequency of the MEFV mutations, which were identified in Japanese FMF patients, was determined in 126 Japanese RA patients and 76 Japanese healthy subjects.

RESULTS

The M694I mutation was not observed among RA patients and healthy subjects. Allele frequency of R408Q, P369S, E148Q, L110P mutations account respectively for 3.3%, 3.9%, 23.7%, 9.2% in healthy subjects and 5.6%, 6.7%, 24.2%, 9.5% in RA patients. The overall mutation rate was comparable between the RA patients and healthy subjects, as well as between the RA patients with and without amyloidosis.

CONCLUSION

This study shows the high prevalence of mutations of the MEFV genes in Japanese RA patients. However, our data suggest that the MEFV gene mutations may not be a genetic factor affecting the susceptibility of RA or the development of amyloidosis in a Japanese population.

Determination of anti-cyclic citrullinated peptide antibodies in the sera of patients with liver diseases

OBJECTIVE

To determine the frequency of anti-cyclic citrullinated peptide (anti-CCP) antibodies in patients with HCV infection, primary biliary cirrhosis (PBC) and type-I autoimmune hepatitis (AIH) to assess the specificity of anti-CCP antibodies.

METHODS

Rheumatoid factor (RF) and anti-CCP antibodies were measured in the sera from patients with HCV infection (n=45), PBC (n=73), AIH (n=55) and rheumatoid arthritis (n=48), and also from the sera of healthy subjects (n=23). Anti-CCP antibodies were measured using a second generation enzyme-linked immunosorbent assay (ELISA).

RESULTS

No sera with elevated anti-CCP were found in the patients with HCV infection. Two PBC patients (2.7%) and six AIH patients (10.5%) had anti-CCP antibodies. The seropositivity for anti-CCP in these autoimmune disease patients was associated with a high frequency of RA association [PBC; 100% (2/2), AIH; 86.4% (5/6)].

CONCLUSIONS

Although anti-CCP antibodies may be present in patients with autoimmune liver diseases, almost seropositive patients had concomitant RA. As a result, the measurement of anti-CCP antibodies may therefore be helpful for accurately diagnosing RA in patients with these liver diseases.

The serum levels of resistin in rheumatoid arthritis patients

OBJECTIVE

Adipocyte-derived resistin is a circulating protein implicated in insulin resistance, but the role of human resistin is uncertain because it is produced largely by macrophages. The aim of this study was to analyze serum resistin concentrations in rheumatoid arthritis (RA) patients to determine the role of resistin in human inflammatory diseases.

MATERIALS AND METHODS

Resistin concentrations were assessed by ELISA in serum samples from 42 patients with RA. Serum samples from 38 healthy subjects acted as controls. We also evaluated the circulating levels of tumor necrosis factor- alpha (TNF-alpha) and disease activity markers in RA patients.

RESULTS

In RA patients, serum resistin levels were significantly higher than those in healthy subjects. Serum resistin levels in RA patients were correlated with the RA disease activity markers, CRP and ESR. Furthermore, resistin levels in RA patients were significantly correlated with circulating levels of TNF-alpha.

CONCLUSION

Serum resistin levels were significantly increased in RA patients and correlated with inflammatory markers and TNF-alpha, suggesting that resistin may play a role in the rheumatoid inflammatory process.

Reduced blood BDCA-2+ (lymphoid) and CD11c+ (myeloid) dendritic cells in systemic lupus erythematosus

Type 1 IFN is thought to be implicated in the autoimmune process of SLE. Plasmacytoid dendric cells (DC), which are natural IFN-alpha producing cells, play a pivotal epipathogenic role in SLE. The present study was undertaken to investigate the phenotypic characteristics of peripheral blood DC in SLE patients in comparison with those of healthy controls. Samples from 20 SLE patients and 18 healthy controls were studied. Three-colour flow cytometry was performed to identify myeloid DC, as CD11c(+) lineage marker(-), and HLA-DR(+) cells and plasmacytoid DC, as BDCA-2(+) linage marker(-), and HLA-DR(+) cells. We used the whole blood 'lyse/no-wash' procedure, which allows precise counting of peripheral blood DC. BDCA-2(+) plasmacytoid DC and CD11c(+) myeloid DC were reduced in SLE patients compared with controls. Similarly, BDCA-3(+) DC were reduced in SLE patients. These results indicated that SLE patients had a reduced number of both BDCA-2(+) plasmacytoid DC and CD11c(+) myeloid DC. These alternations of the DC subset may drive the autoimmune response in SLE.

A rare case of shunt malfunction attributable to a broken Codman-Hakim programmable shunt valve after a blow to the head

We report a rare case of shunt malfunction resulting from breakage of the Codman-Hakim programmable shunt valve system following a blow to the head. Originally, the patient had suffered intraventricular hemorrhage a month after birth; ventriculoperitoneal shunt was performed at 7 months. After that, the shunt valve functioned well for 7 years. The patient presented with headaches after receiving a blow behind the right ear. The headache became exacerbated with activity and improved with rest. Damage to the shunt valve was identified during surgery, with a crack at the top of the valve housing. Symptoms resolved following a change of the complete shunt system. The possibility of damage to the shunt valve following a blow should be considered in shunt patients presenting with headaches.

An active metabolite of leflunomide, A77 1726, inhibits the production of serum amyloid A protein in human hepatocytes

OBJECTIVE

Cytokine-induced hepatic serum amyloid A (SAA) synthesis is the critical step in the pathogenesis of AA amyloidosis secondary to rheumatoid arthritis (RA). This study was conducted to provide more insight into the mechanism of SAA production in hepatocytes and its regulation.

METHODS

Primary cultured normal human hepatocytes were stimulated with cytokines (IL-1beta, TNF-alpha and IL-6) and the culture supernatants were analysed for the production of SAA. Human hepatocytes, treated or not treated with A77 1726, were stimulated with IL-1beta and the cellular lysates were analysed by immunoblot using anti-phospho-specific mitogen-activated protein kinase (MAPK) and IkappaB-alpha. Acute phase-SAA (SAA1) mRNA expression was analysed by reverse transcription-polymerase chain reaction.

RESULTS

IL-1beta is a most potent inducer of SAA in normal hepatocytes. A77 1726 suppressed the production of SAA in human hepatocytes activated by IL-1beta in a dose-dependent manner (0-50 microM). A77 1726 inhibited IL-1beta-induced p38 and c-Jun N-terminal kinase 1/2 (JNK1/2) activation, whereas A77 1726 did not affect IL-1beta-induced NF-kappaB activation in hepatocytes.

CONCLUSION

These results indicate that MAPK signalling pathways are critical in IL-1beta-induced hepatic SAA synthesis. Leflunomide may suppress SAA synthesis by affecting these pathways and may therefore have some beneficial effect on AA amyloidosis secondary to RA.

Cytomegalovirus-associated hemophagocytic syndrome in a patient with adult onset Still's disease

Reactive hemophagocytic syndrome (HPS) is characterized by hemophagocytosis by activated histiocytes, resulting in pancytopenia and liver dysfunction. We describe a patient with adult onset Still's disease (AOSD) in whom HPS developed. An 80-year-old Japanese woman with high fever, arthralgia, skin rash, and pleuritis was admitted to our hospital for further examination. She was diagnosed with AOSD and steroid therapy was initiated. During the course of steroid therapy, a re-elevation of serum ferritin levels and a marked increase in serum transaminase were observed. Bone marrow aspiration revealed an increase in the number of histiocytes with hemophagocytosis and cytomegalovirus (CMV)-positive leukocytes were detected. At this time we diagnosed the patient as having virus-associated hemophagocytic syndrome (VAHS) and elevated levels of trasaminase and ferritin were normalized by ganciclovir treatment. Reactive HPS occurs in cases of active AOSD. However, it should be noted that HPS may be accompanied by opportunistic infections during immunosuppressive therapy requiring prompt antibiotic therapy.

Suppressive effect of leflunomide metabolite (A77 1726) on metalloproteinase production in IL-1beta stimulated rheumatoid synovial fibroblasts

Leflunomide, an isoxazol derivative structurally unrelated to other immunomodulatory drugs, has proven to be efficacious in the treatment of rheumatoid arthritis (RA). This study was conducted to elucidate the mechanism by which leflunomide mediated antirheumatic effects. We investigated the effects of A77 1726, leflunomide's active metabolite, on mitogen-activated protein kinase (MAPK) activation in IL-1beta-stimulated rheumatoid synovial fibroblasts. The effects of A77 1726 on the secretion of matrix metalloproteinases (MMPs) from rheumatoid synovial fibroblasts were also examined. A77 1726 partially suppressed IL-1beta-induced ERK1/2 and p38 kinase activation. In contrast, A77 1726 efficiently suppressed IL-1beta-stimulated JNK1/2 kinase activation. Although no suppressive effect was demonstrated on MMP-2, A77 1726 markedly inhibited MMP-1, 3, and 13 secretions from IL-1beta-stimulated rheumatoid synovial fibroblasts. Tissue inhibitor of metalloproteinases-1 (TIMP-1) was constitutively produced from rheumatoid synovial fibroblasts and the suppressive effects of A77 1726 on TIMP-1 production were minimal. Our results suggest that the suppression of the MAPK signalling pathway and MMP synthesis in rheumatoid synovial fibroblasts is a possible mechanism for the inhibitory activity of leflunomide against rheumatoid arthritis.

Osteoprotegerin (OPG) acts as an endogenous decoy receptor in tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis of fibroblast-like synovial cells

We examined the role of osteoprotegerin (OPG) on tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in rheumatoid fibroblast-like synovial cells (FLS). OPG protein concentrations in synovial fluid from patients with rheumatoid arthritis (RA) correlated with those of interleukin (IL)-1beta or IL-6. A similar correlation was present between IL-1beta and IL-6 concentrations. Rheumatoid FLS in vitro expressed both death domain-containing receptors [death receptor 4 (DR4) and DR5] and decoy receptors [decoy receptor 1 (DcR1) and DcR2]. DR4 expression on FLS was weak compared with the expression of DR5, DcR1 and DcR2. Recombinant TRAIL (rTRAIL) rapidly induced apoptosis of FLS. DR5 as well as DR4 were functional with regard to TRAIL-mediated apoptosis induction in FLS; however, DR5 appeared be more efficient than DR4. In addition to soluble DR5 (sDR5) and sDR4, OPG administration significantly inhibited TRAIL-induced apoptogenic activity. OPG was identified in the culture supernatants of FLS, and its concentration increased significantly by the addition of IL-1beta in a time-dependent manner. Neither IL-6 nor tumour necrosis factor (TNF)-alpha increased the production of OPG from FLS. TRAIL-induced apoptogenic activity towards FLS was reduced when rTRAIL was added without exchanging the culture media, and this was particularly noticeable in the IL-1beta-stimulated FLS culture; however, the sensitivity of FLS to TRAIL-induced apoptosis itself was not changed by IL-1beta. Interestingly, neutralization of endogenous OPG by adding anti-OPG monoclonal antibody (MoAb) to FLS culture restored TRAIL-mediated apoptosis. Our data demonstrate that OPG is an endogenous decoy receptor for TRAIL-induced apoptosis of FLS. In addition, IL-1beta seems to promote the growth of rheumatoid synovial tissues through stimulation of OPG production, which interferes with TRAIL death signals in a competitive manner.

A novel mutation (T61I) in the gene encoding tumour necrosis factor receptor superfamily 1A (TNFRSF1A) in a Japanese patient with tumour necrosis factor receptor-associated periodic syndrome (TRAPS) associated with systemic lupus erythematosus

OBJECTIVE

To identify potential mutations in the tumour necrosis factor receptor superfamily 1A gene (TNFRSF1A) in a Japanese female patient with recurrent fever complicated by systemic lupus erythematosus (SLE), and in her family members.

METHODS

DNA sequencing of exons 1-10 of the TNFRSF1A gene was performed to determine mutations that might be associated with the tumour necrosis factor receptor-associated periodic syndrome (TRAPS). Moreover, the TNFRSF1A gene was examined in Japanese patients with autoimmune diseases, including SLE, rheumatoid arthritis (RA), mixed connective tissue disease (MCTD) and Behçet's disease, and in healthy Japanese controls. Enzyme-amplified sensitivity immunoassay (EASIA) analysis was used to assess serum levels of TNF, the 55-kDa TNF receptor (TNFRSF1A) and the 75-kDa TNF receptor (TNFRSF1B). Membrane TNFRSF1A expression was analysed on the surface of peripheral blood mononuclear cells by flow cytometry.

RESULTS

A novel mutation, a heterozygous C to T transition in exon 3 which substitutes an isoleucine for a threonine at position 61 (T61I) was detected in the TNFRSF1A gene derived from the genomic DNA of a Japanese female TRAPS patient. Two nieces and one nephew, all with a similar clinical phenotype, also possessed the same TNFRSF1A mutation. We further demonstrated the same mutation in five of 60 SLE patients (8.3%) and in five of 120 healthy individuals (4.2%), with no significant differences. Although high titres of serum TNF and soluble TNFRSF1B protein were observed in this patient, low titres of soluble TNFRSF1A protein were detected. However, a defect in TNFRSF1A shedding in vitro was not observed in monocytes derived from this patient.

CONCLUSION

This is the first report of a TRAPS patient associated with SLE with a novel TNFRSF1A mutation (T61I).

Cytokines regulate fibroblast-like synovial cell differentiation to adipocyte-like cells

OBJECTIVES

Our recent work showed that fibroblast-like synovial cells (FLS) could differentiate into adipocyte-like cells in vitro in response to stimulation with peroxisome proliferator-activated receptor gamma (PPAR gamma) ligand. The aim of the present study was to determine the role of cytokines in the regulation of FLS differentiation to adipocyte-like cells.

METHODS

FLS isolated from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and from normal synovial tissues were incubated with the synthetic PPAR gamma ligand troglitazone to induce adipocyte-like differentiation of the cells.

RESULTS

Production of interleukin (IL)-6, IL-8 and matrix metalloproteinase-3 was reduced in adipocyte-like cells compared with FLS. DNA binding activity of nuclear factor kappa B (NF-kappa B) was clearly inhibited in adipocyte-like cells. Cultivation of FLS with interferon gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) or IL-1 beta inhibited the expression of PPAR gamma as well as CCAAT/enhancer binding protein (C/EBP) nuclear activity, and thus suppressed adipocyte-like cell differentiation in vitro.

CONCLUSION

Our results indicate the importance of PPAR gamma and C/EBP in adipocyte-like cell differentiation of FLS and that the process is influenced by inflammatory cytokines, and suggest that the proinflammatory character of FLS in patients with RA is diminished during adipocyte-like cell differentiation.

Anti-apoptogenic function of TGFbeta1 for human synovial cells: TGFbeta1 protects cultured synovial cells from mitochondrial perturbation induced by several apoptogenic stimuli

OBJECTIVE

To investigate anti-apoptogenic mechanism of transforming growth factor beta1 (TGFbeta1) towards synovial cells.

METHODS

Isolated synovial cells, treated or not with TGFbeta1, were cultured in the presence or absence of anti-Fas IgM, proteasome inhibitor Z-Leu-Leu-Leu-aldehyde (LLL-CHO), etoposide, or C2-ceramide. After cultivation, apoptosis of synovial cells was examined by the presence of hypodiploid DNA(+) cells, the presence of terminal deoxy (d)-UTP nick end labelling(+) cells (TUNEL(+) cells), activation of caspases, and disruption of mitochondrial transmembrane potential (DeltaPsim).

RESULTS

Activation of caspase-9 and DeltaPsim was found in anti-Fas IgM treated synovial cells. The increment of both hypodiploid DNA(+) cells and TUNEL(+) cells accompanied by the activation of caspase-8 and caspase-3 was also determined in anti-Fas IgM treated synovial cells. These hallmarks for apoptosis induced by anti-Fas IgM were significantly suppressed in TGFbeta1 treated synovial cells. LLL-CHO, etoposide, and C2-ceramide also caused DeltaPsim, the increment of both hypodiploid DNA(+) cells and TUNEL(+) cells, and the activation of both Leu-Glu-His-Asp ase (LEHDase; caspase-9 like activity) and Asp-Glu-Val-Asp ase (DEVDase; caspase-3 like activity) in synovial cells. As determined in anti-Fas IgM treatment, TGFbeta1 significantly reduced apoptotic cell death of synovial cells induced by the above chemicals.

CONCLUSIONS

The protective effect of TGFbeta1 for mitochondrial homoeostasis may be important in the anti-apoptogenic function of TGFbeta1 for synovial cells.

Clinical outcome and survival of secondary (AA) amyloidosis

OBJECTIVE

In order to predict the clinical outcome of secondary (AA) amyloidosis patients with rheumatic diseases, we studied the clinical features at presentation of AA amyloidosis.

METHODS

We investigated the clinical characteristics and survival of 42 patients with biopsy-proven AA amyloidosis who were followed up in our department from 1983 to 2001.

RESULTS

A presenting factor which adversely influenced clinical outcome was a raised serum creatinine concentration at the time AA amyloidosis was diagnosed. Eight of 42 patients survived for 10 years or more after the presentation of AA amyloidosis, while 24 patients had died within 10 years. At the diagnosis of AA amyloidosis, cardiac involvement was detected in 11 of 24 non-survivors, whereas it was not detected in any of the 8 long-term survivors. Estimated survival at 5 years was 31.3% in those who had cardiac involvement, and was 63.3% in those who had no cardiac involvement at the presentation of AA amyloidosis.

CONCLUSION

Our results indicate that clinical outcome is related to renal function and cardiac involvement at the time AA amyloidosis is diagnosed. Amyloid-related cardiac involvement is one of the unfavorable predictive factors in AA amyloidosis patients.

Association of subacute cutaneous lupus erythematosus in a rheumatoid arthritis patient with Sjögren's syndrome

Abstract In this paper, we report a case of rheumatoid arthritis (RA) with Sjögren's syndrome (SS) in which the patient developed subacute cutaneous lupus erythematosus (SCLE). A 72-year-old woman, who had a 10-year history of RA and SS, developed annular erythematosus skin lesions involving her face, neck, and extremities. Serological tests showed that anti-SS-A/Ro antibodies and anti-DNA antibodies were elevated. Histological examination of the skin lesions demonstrated the liquefaction degeneration of the epidermal basal layer and perivascular mononuclear cell infiltration. The diagnosis of SCLE was made based on the clinical features and skin histological findings. The disease was well controlled with intralesional and systemic corticosteroids and became quiescent. This case report demonstrates the concurrence of sero-positive RA, SS, and SCLE, which seems to be quite rare.

Functional changes in rheumatoid fibroblast-like synovial cells through activation of peroxisome proliferator-activated receptor gamma-mediated signalling pathway

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand dependent transcriptional factor known to be a regulator of adipogenesis. Recent studies have also shown that stimulation of PPARgamma inhibits the transcriptional activities of other nuclear factors and down-regulates proinflammatory cytokine synthesis in T cells and monocytes. We examined, in the present study, the functional significance of PPARgamma expressed in fibroblast-like synovial cells (FLS) isolated from patients with rheumatoid arthritis (RA). Incubation of FLS with a synthetic PPARgamma ligand, troglitazone, inhibited endogenous production of TNF-alpha, IL-6 and IL-8, as well as matrix metalloprotease-3 (MMP-3), without inducing apoptosis of the cells. The gelatinase activity of FLS culture media was also inhibited by troglitazone. Electrophoretic mobility shift assay (EMSA) showed a significant reduction in the DNA binding activity of NF-kappaB in troglitazone-treated FLS in response to TNF-alpha or IL-1beta. Moreover, long-term cultivation of FLS with troglitazone resulted in morphological changes with marked lipid accumulation in these cells. Our results show a negative regulatory function for PPARgamma on cytokine and MMP production together with inhibition of cytokine-mediated inflammatory responses in rheumatoid synovial cells. Our results also suggest that FLS could differentiate into adipocyte-like cells in the presence of proper stimulatory signals including PPARgamma.

The role of peroxynitrite in cyclooxygenase-2 expression of rheumatoid synovium

OBJECTIVE

Reactive oxygen intermediates play an important role in the inflammatory processes of rheumatoid arthritis. Cyclooxygenase-2 is an inducible form of an enzyme involved in prostanoid biosynthesis. This study linked peroxynitrite (ONOO-) to the signaling pathways that induce COX-2.

RESULTS

Exposure of rheumatoid synovial cells to peroxynitrite resulted in COX-2 protein expression in a dose-dependent manner. RT-PCR analysis also demonstrated that COX-2 mRNA was induced in peroxynitrite-treated rheumatoid synovial cells. Dexamethasone markedly inhibited this peroxynitrite-mediated COX-2 expression at therapeutic concentrations.

CONCLUSION

This study demonstrates that oxidant stress is an important inducer of COX-2 in rheumatoid synovium. This induction may contribute to the amplification of prostanoids in the rheumatoid inflammatory process.

Successful plasmapheresis in alveolar hemorrhage associated with systemic lupus erythematosus

Abstract The case of an 18-year-old Japanese man with systemic lupus erythematosus (SLE) complicated by alveolar hemorrhage is described. The patient presented with fever, butterfly rash, and polyarthralgia, and was diagnosed with SLE. He suddenly developed alveolar hemorrhage during steroid pulse therapy. Treatment with plasmapheresis was initiated, with prompt clearing of the chest radiograph. This experience suggests that the prompt initiation of plasmapheresis should be considered for SLE patients with life-threating alveolar hemorrhage resistant to conventional immunosuppressive therapies.

Regulation of rheumatoid synoviocyte proliferation by endogenous p53 induction

The p53 tumour suppressor protein protects cells from tumorigenic alterations by inducing either cell growth arrest or apoptosis. In the present study, we investigated the role of endogenous p53 expressed in rheumatoid arthritis synovial fibroblasts which show transformed-appearing phenotypes. Type B synovial cells (fibroblast-like synovial cells) were exposed to a proteasome inhibitor, carbobenzoxyl-leucinyl-leucinyl-leucinal (MG-132). During this process, the expressions of p53 and p21 were examined by Western blot. Cell cycle analysis of the synovial cells was determined by DNA staining using propidium iodide (PI). Inhibition of proteasome resulted in the accumulation of p53 which was followed by an increase in the amount of a cyclin-dependent kinase (CDK)-inhibitor, p21. As a consequence, the retinoblastoma gene product, Rb, remained in the hypophosphorylated state, thus preventing PDGF-stimulated synovial cells from progressing into S-phase. This study shows that endogenous p53, which is inducible in rheumatoid synovial cells, is functionally active based on the findings that its expression blocks the G1/S transition by inhibiting the CDK-mediated phosphorylation of Rb via p21 induction. Thus the induction of p53 using proteasome inhibitor may provide a new approach in the treatment of RA.

Expression of membrane-type 1 matrix metalloproteinase in rheumatoid synovial cells

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is thought to be a putative regulator of pro-gelatinase A (MMP-2) in the rheumatoid synovium. In this study, we examined the effects of IL-1beta, one of the inflammatory cytokines, on the expression of MT1-MMP and the activation of pro-MMP-2 using rheumatoid synovial cells. We also studied the effects of KE-298 (2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid), a new disease-modifying anti-rheumatic drug (DMARD), on MT1-MMP expression of rheumatoid synovial cells. Type B synovial cells (fibroblast-like synovial cells) were cultured with KE-298 (25-100 microg/ml) in the presence of IL-1beta for 48 h. Activation of pro-MMP-2 secreted from synovial cells was analysed by gelatin zymography. Reverse transcription-polymerase chain reaction (RT-PCR) methods were used to detect MT1-MMP mRNA. MT1-MMP protein expression on synovial cells was examined by anti-MT1-MMP immunoblot. An active form of MMP-2 was demonstrated in the culture media conditioned by IL-1beta-stimulated synovial cells. In addition, MT1-MMP mRNA and protein expression of rheumatoid synovial cells were increased by IL-1beta treatment. KE-298 blocked this IL-1beta-induced pro-MMP-2 activation and MT1-MMP expression, but did not affect IL-1beta-induced tissue inhibitor of metalloproteinase-2 (TIMP-2) secretion from rheumatoid synovial cells. These findings indicate that activation of rheumatoid synovial cells by IL-1beta results in the induction of MT1-MMP expression. Given that MT1-MMP promotes matrix degradation by activating pro-MMP-2, these results suggest a novel mechanism whereby cytokine may contribute to articular destruction in rheumatoid arthritis (RA). KE-298 may prevent this process by down-regulating MT1-MMP expression.

Concomitant pituitary adenoma and Rathke's cleft cyst

We reviewed the clinical, radiological and surgical findings in patients with both pituitary adenoma and Rathke's cleft cyst. We retrospectively selected patients with both lesions from the 374 patients in whom a sellar/juxtasellar lesion was detected on MRI at 1.5 tesla. All patients received intravenous contrast medium. Concomitant pituitary adenoma and Rathke's cleft cyst were found in eight patients (2.1 %). The frequency of the combination was 3.5 % of pituitary adenomas and 11% of Rathke's cleft cysts. Symptoms were always due to the adenoma, secreting adrenocorticotrophin in two patients and growth hormone in six. The adenoma was larger in five patients, and the cyst in three. The cysts gave variable signal. The adenoma was adjacent to the cyst in seven patients, and enclosed it in the other patient. As a result of experience with MRI, concomitant pituitary adenoma and Rathke's cleft cyst are now known not to be as rare as thought previously. When a non-enhancing cyst-like structure is demonstrated in a patient with pituitary adenoma, the possibility of a coexisting Rathke's cleft cyst should be considered.

The first transmembrane domain of the P2X receptor subunit participates in the agonist-induced gating of the channel

Based on pharmacological properties, the P2X receptor family can be subdivided into those homo-oligomers that are sensitive to the ATP analog alphabeta-methylene ATP(alphabetameATP) (P2X(1) and P2X(3)) and those that are not (P2X(2), P2X(4), P2X(5), P2X(6), and P2X(7)). We exploited this dichotomy through the construction of chimeric receptors and site-directed mutagenesis in order to identify domains responsible for these differences in the abilities of extracellular agonists to gate P2X receptors. Replacement of the extracellular domain of the alphabetameATP-sensitive rat P2X(1) subunit with that of the alphabetameATP-insensitive rat P2X(2) subunit resulted in a receptor that was still alphabetameATP-sensitive, suggesting a non-extracellular domain was responsible for the differential gating of P2X receptors by various agonists. Replacement of the first transmembrane domain of the rat P2X(2) subunit with one from an alphabetameATP-sensitive subunit (either rat P2X(1) or P2X(3) subunit) converted the resulting chimera to alphabetameATP sensitivity. This conversion did not occur when the first transmembrane domain came from a non-alphabetameATP-sensitive subunit. Site-directed mutagenesis indicated that the C-terminal portion of the first transmembrane domain was important in determining the agonist selectivity of channel gating for these chimeras. These results suggest that the first transmembrane domain plays an important role in the agonist operation of the P2X receptor.

Polar residues of the second transmembrane domain influence cation permeability of the ATP-gated P2X(2) receptor

P2X receptors are simple polypeptide channels that mediate fast purinergic depolarizations in both nerve and muscle. Although the depolarization results mainly from the influx of Na(+), these channels also conduct a significant Ca(2+) current that is large enough to evoke transmitter release from presynaptic neurons. We sought to determine the molecular basis of this Ca(2+) conductance by a mutational analysis of recombinant P2X(2) receptors. Wild type and 31 mutant P2X(2) receptors were expressed in HEK-293 cells and studied under voltage-clamp. We found that the relative Ca(2+) permeability measured from the reversal potentials of ATP-gated currents was unaffected by neutralizing fixed charge (Asp(315), Asp(349)) near the mouths of the channel pore. By contrast, mutations that changed the character or side chain volume of three polar residues (Thr(336), Thr(339), Ser(340)) within the pore led to significant changes in P(Ca)/P(Cs). The largest changes occurred when Thr(339) and Ser(340) were replaced with tyrosine; these mutations almost completely abolished Ca(2+) permeability, reduced P(Li)/P(Cs) by about one-half, and shifted the relative permeability sequence of Cs(+), Rb(+), K(+), and Na(+) to their relative mobility in water. Our results suggest that the permeability sequence of the P2X(2) receptor arises in part from interactions of permeating cations with the polar side chains of three amino acids located in a short stretch of the second transmembrane domain.