ER Stress and Autophagy

Eukaryotic cells respond to various types of stresses caused by changes in the extracellular environment. Intracellular factors, such as the accumulation of misfolded proteins in the endoplasmic reticulum (ER), also cause stress and activate the unfolded protein response (UPR), which induces the expression of chaperones and proteins involved in the recovery process. However, if the stress is excessive or sustained, and ER function cannot be restored, the UPR triggers apoptosis, thereby removing the affected cell. It is now apparent that ER stress is also a potent trigger for autophagy, a self-degradative process that has an adaptive function. This review surveys the intersection of ER stress and autophagy and highlights the potential therapeutic implications thereof.

Postpartum-onset dermatomyositis: case report and literature review

Abstract Dermatomyositis (DM) is rare during the reproductive period, but when it does occur most reports have noted that it has an adverse effect on fetal outcome. Conversely, there is little information concerning the contribution of pregnancy to the development and course of DM. We describe here a patient with DM that developed after delivery of an infant and summarize previously documented cases of postpartum-onset DM. This case suggests that pregnancy could be a trigger for the development of DM.

CCR5 gene polymorphism is a genetic risk factor for radiographic severity of rheumatoid arthritis

The chemokine receptor [C-C chemokine receptor 5 (CCR5)] is expressed on diverse immune effecter cells and has been implicated in the pathogenesis of rheumatoid arthritis (RA). This study sought to determine whether single-nucleotide polymorphisms (SNPs) in the CCR5 gene and their haplotypes were associated with susceptibility to and severity of RA. Three hundred fifty-seven patients with RA and 383 healthy unrelated controls were recruited. Using a pyrosequencing assay, we examined four polymorphisms -1118 CTAT(ins) (/del) (rs10577983), 303 A>G (rs1799987), 927 C>T (rs1800024), and 4838 G>T (rs1800874) of the CCR5 gene, which were distributed over the promoter region as well as the 5' and 3' untranslated regions. No significant difference in the genotype, allele, and haplotype frequencies of the four selected SNPs was observed between RA patients and controls. CCR5 polymorphisms of -1118 CTAT(del) (P = 0.012; corrected P = 0.048) and 303 A>G (P = 0.012; corrected P = 0.048) showed a significant association with radiographic severity in a recessive model, and, as a result of multivariate logistic regression analysis, were found to be an independent predictor of radiographic severity. When we separated the erosion score from the total Sharp score, the statistical significance of CCR5 polymorphisms showed an increase; -1118 CTAT(ins) (/del) (P = 0.007; corrected P = 0.028) and 303 A>G (P = 0.007; corrected P = 0.028). Neither SNPs nor haplotypes of the CCR5 gene showed a significant association with joint space narrowing score. These results indicate that genetic polymorphisms of CCR5 are an independent risk factor for radiographic severity denoted by modified Sharp score, particularly joint erosion in RA.

Combination treatment with leflunomide and methotrexate for patients with active rheumatoid arthritis

OBJECTIVE

To determine the efficacy and safety of the combination of leflunomide and methotrexate for the treatment of patients with active rheumatoid arthritis (RA) in an open, non-comparative, multicentre trial.

METHODS

Seventy-four patients with active RA were enrolled to receive concomitantly leflunomide (no loading dose, 10 mg/day) and methotrexate (starting at 7.5 mg/week and titrating up to 15 mg/week) for 20 weeks. The primary end-point was a 20% improvement in the American College of Rheumatology (ACR) criteria at 20 weeks. Safety measures included evaluation of adverse events at each visit and laboratory data, including haematology and liver function tests. Intention-to-treat analyses were conducted.

RESULTS

Sixty-five patients completed 20 weeks of treatment, and 71.6% were responders based on the ACR20 criteria. After 20 weeks, the mean changes were -16.3 for tender joint count, -12.0 for swollen joint count, -44.0 for physician global assessment, -34.3 for patient global assessment, -22.7 for erythrocyte sedimentation rate, and -0.65 for the Health Assessment Questionnaire score. Adverse events occurred in 40.5% of the patients, and were considered serious in four patients who discontinued therapy. Abnormal liver function was noted for 16 patients (21.6%). Two of these patients were withdrawn from the study; after discontinuing the medication, their liver function recovered fully.

CONCLUSION

THE combination of leflunomide and methotrexate was effective and well tolerated in the treatment of active RA patients. This combination may be a useful option as an initial treatment for active RA before starting biological agents.

Cordycepin inhibits IL-1beta-induced MMP-1 and MMP-3 expression in rheumatoid arthritis synovial fibroblasts

OBJECTIVE

MMP is a key enzyme in the degradation of extracellular matrices, and its expression plays important roles in inflammatory diseases. Cordycepin (3'-deoxyadenosine), a bioactive compound of Cordyceps militaris, has been shown to exhibit many pharmacological activities, such as anti-cancer, anti-inflammatory and anti-infection activities. In this study, we aimed at the inhibitory effect of cordycepin on IL-1beta-induced MMP-1 and MMP-3 expression as well as the molecular basis using RA synovial fibroblasts (RASFs).

METHODS

RASFs were isolated from synovial tissue obtained from 12 patients with RA and cultured in monolayer. Expression of MMP-1 and MMP-3 was evaluated using western blotting and real-time PCR. Chemokines were analysed by ELISA. The phosphorylation of mitogen-activated protein kinase was measured by western blotting. Electrophoretic mobility shift assay was performed to evaluate binding activities of DNA to nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1).

RESULTS

Cordycepin inhibited IL-1beta-induced MMP-1 and MMP-3 expressions in RASFs in a dose-dependent manner. Among various chemokines [such as monocyte chemoattractant protein-1 (MCP-1), GRO-alpha, regulated upon activation, normal T-cell expressed and presumably secreted (RANTES) and epithelial neutrophil activating peptide 78 (ENA-78)], cordycepin specifically blocked IL-1beta-induced ENA-78 production in RASF. Moreover, cordycepin significantly inhibited IL-1beta-induced p38/JNK and AP-1 activation, but not extracellular signal-regulated kinase (ERK) and NF-kappaB activation.

CONCLUSIONS

Cordycepin is a potent inhibitor of IL-1beta-induced chemokine production and MMP expression and strongly blocks the p38/JNK/AP-1 signalling pathway in RASFs.

Massive gastrointestinal bleeding due to the rupture of arterial aneurysm in Behçet's disease: case report and literature review

Massive gastrointestinal bleeding is a very rare manifestation of gastrointestinal Behçet's disease, mainly from the gastrointestinal mucosal lesions. We report herein the case of a 50-year-old man with intestinal Behçet's disease who suffered massive hemorrhage from ruptured arterial aneurysm. Colonoscopy demonstrated large amount of fresh blood in the entire colon, but we were not able to localize bleeding focus anywhere in the colon. Angiography was performed and it revealed that a small aneurysm on the right ileocolic artery with apparent extravasation of contrast material. A guiding catheter was inserted to a right ileocolic artery and superselective arterial embolization using microcoils was successful. Following this procedure, the gastrointestinal bleeding gradually subsided and completely stopped within a few days. He is now treating with prednisolone and sulfasalazine without recurrent bleeding until now.

Chylothorax and chylopericardium as the initial clinical manifestation of Behcet’s disease

Behcet's disease (BD) is a chronic relapsing systemic vasculitic disorder affecting the arteries, veins, and vessels of any size. Large vein thrombosis in BD is not commonly developed and most commonly observed in the veins in the lower extremities and inferior or superior vena cava. In this report, a 18-year-old male patient with large vein thrombosis involving superior vena cava was presented. He was treated due to chylothorax and chylopericardium with SVC syndrome before diagnosis of BD. SVC thrombosis complicated by chylothorax and chyolpericardium can be a rare presenting initial symptom of BD.

Adult onset Still's disease flared with pericardial effusion

Adult onset Still's disease (AOSD) is characterized by spiking fevers, arthritis, rash, and involvement of multiple organs, and can be classified as self-limited, intermittent, and chronic disease groups. Cardiac manifestations include pericarditis and myocarditis. The case of this disease flared only with pericardial effusion is not reported. We describe a patient with adult onset Still's disease who was flared with pericardial effusion without other AOSD-associated symptoms, and propose that pericardial effusion should be included as a feature of flare in the intermittent disease group of adult onset Still's disease.

Reversible dementia in systemic lupus erythematosus without antiphospholipid antibodies or cerebral infarction

Dementia is a very rare neurological manifestation of systemic lupus erythematosus (SLE) and has a deep link with antiphospholipid antibodies (APL) and cerebral infarction in its development. However, nonvascular dementia irrelevant to APL or cerebral infarction has not been reported in patients with SLE until now. We describe a case of reversible dementia in an SLE patient without APL or cerebral infarction which was successfully treated with corticosteroid and cyclophosphamide. There are two significant points in this case. One is that humoral factors other than APL might be involved in the development of dementia. Secondly, reversible dementia without APL or cerebral infarction may respond more favorably to immunosuppressive therapy.

Recurrent transverse myelitis in primary antiphospholipid syndrome—case report and literature review

Transverse myelitis is an uncommon but well-known neurologic complication of systemic lupus erythematosus, and antiphospholipid antibodies have been implicated as having a pathogenic role of myelopathy in primary and secondary antiphospholipid syndrome. Transverse myelitis usually is monophasic, but recurrent transverse myelitis was reported in association with systemic lupus erythematosus, multiple sclerosis, and spinal arteriovenous malformations. It has been reported extremely rarely in patients with primary antiphospholipid syndrome. Herein we describe a patient with both conditions and propose that recurrent transverse myelitis should be included as a very rare feature of primary antiphospholipid syndrome.

Primary antiphospholipid syndrome presenting with abdominal angina and splenic infarction

The antiphospholipid syndrome is an autoimmune hypercoagulability syndrome in which a wide variety of thromboembolic diseases may occur. Gastrointestinal manifestations associated with vascular occlusion include Budd-Chiari syndrome, hepatic and splenic infarction, pancreatitis, omental and intestinal infarction, and esophageal variceal bleeding due to portal vein thrombosis, but chronic mesenteric ischemia associated with mesenteric arterial thrombosis is very rare in this syndrome. We experienced a female patient with primary antiphospholipid syndrome with abdominal angina and splenic infarction associated with celiac trunk and mesenteric arterial thromboses. This is the first report describing chronic mesenteric ischemia and splenic infarction in a patient with primary antiphospholipid syndrome.

Recurrent pseudotumor cerebri in systemic lupus erythematosus: a case report

Pseudotumor cerebri is an uncommon manifestation of neuropsychiatric systemic lupus erythematosus (SLE), and is characterized by an elevated intracranial pressure, papilledema with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents. Pseudotumor cerebri has been reported in a few sporadic cases in patients with systemic lupus erythematosus. However, the recurrent pseudotumor cerebri in patients with systemic lupus erythematosus which has been rarely reported, has not been reported in Korea. We experienced a 30-yr-old female patient with SLE who was presented with second attack of severe intractable headache. She was diagnosed pseudotumor cerebri twice and successfully treated with corticosteroid. Headache is the common symptom in patients with neuropsychiatric SLE and attributable to various causes. We suggest that it is important to define the cause of headache in patients with SLE and pseudotumor cerebri should be included in the spectrum of clinical manifestations during the course of SLE as a cause of headache.

Case report: diabetic muscle infarction presenting as knee arthralgia

Diabetic muscle infarction is a rare complication of diabetes and has characteristic clinical features including acute onset of pain with painful swelling, most commonly in the thigh or calf muscle, which gradually improves to complete resolution. Recently we experienced a case of diabetic muscular infarction presenting as knee joint pain due to involvement of the proximal portion of the leg muscle, which site has not been reported previously. This case shows that diabetic muscle infarction may involve sites other than the thigh and calf areas and should be considered in the differential diagnosis of knee arthralgia.

Mediastinal mass and brachial plexopathy caused by subclavian arterial aneurysm in Behçet's disease

Vascular involvement in Behçet's disease is divided into venous and arterial thrombosis and arterial aneurysmal formation. Subclavian arterial aneurysm rarely occurs in Behçet's disease; however, when it does occur, it causes serious aneurysmal rupture and local complications such as nerve compression and arterial ischemia. We describe the case of a 39-year-old male who presented with neurologic symptoms and signs of brachial plexopathy and mediastinal mass caused by Behçet's subclavian arterial aneurysm. This case shows that the occurrence of brachial plexopathy should be considered a manifestation of Behçet's disease, and that Behçet's aneurysm should be considered in the differential diagnosis of upper mediastinal mass.

IgG antibodies to type II collagen reflect inflammatory activity in patients with rheumatoid arthritis

OBJECTIVE

To determine the clinical significance of IgG antibodies to type II collagen (CII) and to define any correlation of antibodies to CII with the inflammatory response in patients with rheumatoid arthritis (RA).

METHODS

IgG antibodies to native human type II collagen (IgG anti-CII) were measured in sera and synovial fluid (SF) from patients with RA, patients with osteoarthritis (OA), and healthy controls by an improved ELISA. Demographic, clinical, and laboratory data including tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) levels were also obtained at the time of sampling in patients with RA.

RESULTS

The median level and positivity for circulating IgG anti-CII were higher in patients with RA (n = 297) than patients with OA (n = 34) and healthy controls (n = 50) (p < 0.001). The titers of IgG anti-CII in SF were also higher in RA (n = 45) than in OA (n = 16) (p < 0.001). In paired samples, the levels of IgG anti-CII were significantly higher in SF compared to the sera in patients with RA (n = 45) (p < 0.001), but levels were not different in patients with OA (n = 16). Circulating IgG anti-CII converted from positive to negative in 13 patients (10.7%) and from negative to positive in 18 patients (14.8%) among 122 patients with RA in whom IgG anti-CII were monitored sequentially at a mean interval of 12.2 months. IgG anti-CII positive patients (n = 98) had shorter disease duration (p = 0.04) and less frequent deformity (p = 0.013), and higher median erythrocyte sedimentation rate (ESR) (p = 0.001) and C-reactive protein (CRP) (p < 0.001) than IgG anti-CII negative patients (n = 120). The levels of IgG anti-CII correlated with CRP (r = 0.270) and ESR (r = 0.253). CRP decreased significantly in patients (n = 13) who converted from IgG anti-CII positive to negative (p = 0.013). IgG anti-CII positive patients (n = 40) had higher levels of TNF-alpha and IL-6 than negative patients (n = 40) (p < 0.001). Levels of IgG anti-CII correlated well with TNF-alpha (r = 0.617) and IL-6 (r = 0.347).

CONCLUSION

Increased IgG anti-CII in sera and SF in RA correlated directly with acute phase reactants and the proinflammatory cytokines TNF-alpha and IL-6. Our data suggest that IgG anti-CII could reflect inflammatory activity with a potential to destroy cartilage in the early stages of RA.

Divergent effect of cyclosporine on Th1/Th2 type cytokines in patients with severe, refractory rheumatoid arthritis

OBJECTIVE

To investigate the effect of cyclosporine on cytokine production, especially on T helper 1 (Th1) and T helper 2 (Th2) type cytokines, in patients with rheumatoid arthritis (RA).

METHODS

A 16 week randomized, double blind, placebo controlled study of cyclosporine (2.5 to 4 mg/kg/day) was conducted in 40 patients with severe, refractory RA who had residual inflammation and disability despite partial responses to prior maximal tolerated dose of methotrexate (MTX; < 15 mg/week) and low dose prednisone (< 10 mg/day). Clinical and laboratory variables, and circulating levels of interleukin 2 (IL-2), IL-4, IL-10, IL-12, tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) measured by ELISA were compared between patients (cyclosporine group) treated with cyclosporine plus MTX and those (placebo group) treated with placebo plus MTX at entry and at 16 weeks.

RESULTS

At 16 weeks, the cyclosporine group (n = 17), compared with the placebo group (n = 17), had greater decreases in tender joints, swollen joints, patient global assessment, patient self-assessed disability, and C-reactive protein, as well as having more patients with > 20% improvement. Comparison of circulating cytokines at entry and at 16 weeks showed significant decreases of IL-2 (median -61 vs 7 pg/ml; p = 0.004) ("+" denotes increase, "-" denotes decrease), IL-12 (median -313 vs -14 pg/ml; p = 0.002), TNF-alpha (median -55 vs 5 pg/ml; p < 0.001), and IFN-gamma (median -21 vs 5 pg/ml; p = 0.003), and a significant increase of IL-10 (median 55 vs -12 pg/ml; p < 0.001) in the cyclosporine group compared with the placebo group. The degree of IL-10 increases correlated strongly with the degree of IL-12 decreases in the cyclosporine group (r = 0.572, p = 0.016). However, there was no change in circulating IL-4 between the 2 groups. Within the cyclosporine group, the improved patients (n = 10) compared to the non-improved patients (n = 7) had a greater increase in circulating IL-10 (median 172.0 vs 85.2%; p = 0.01). The rate of increase of IL-10 strongly correlated with the rate of improvement of joint scores (r = 0.718, p = 0.001) after administration of cyclosporine.

CONCLUSION

Our results suggest that the therapeutic effect of cyclosporine is achieved by correcting a Th1/Th2 imbalance (a shift of Th1 type to Th2 type), which may be involved in the pathogenesis of RA; and that circulating IL-10 is useful to assess the clinical improvements in patients with RA after administration of cyclosporine.

Enhanced T cell proliferative response to type II collagen and synthetic peptide CII (255-274) in patients with rheumatoid arthritis

OBJECTIVE

To determine the presence of specific immune recognition of type II collagen (CII) and its immunodominant epitope CII (255-274) in patients with rheumatoid arthritis (RA).

METHODS

T cell proliferative responses to bovine CII and a synthetic peptide encompassing CII (255-274) in peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) from RA patients, and in PBMC from osteoarthritis (OA) patients and healthy controls were assayed by mixed lymphocyte culture.

RESULTS

The stimulation index (SI) and the number of positive (SI > or = 2) T cell responses to CII were higher in RA patients (n = 106) than in OA patients (n = 26) and healthy controls (n = 34). T cell responses to CII (255-274) were also enhanced in RA patients and correlated well with those to CII. In SFMC, positive responses to CII or CII (255-274) were detected in 61.9% of 42 RA patients. T cell responses to CII in SFMC were stronger and more prevalent than peripheral responses. The SI and positive responses to CII were higher in early RA than in late RA. Levels of IgG antibodies to CII in synovial fluid inversely correlated with T cell responses to CII.

CONCLUSION

T cell responses to CII or CII (255-274) were enhanced in RA, especially in early disease. Synthetic peptide CII (255-274), as well as native CII, could be recognized as immunogenic antigens by T cells, particularly in the synovial fluid. These observations suggest that CII-reactive T cells play an important role in the pathogenesis of RA. Peripheral tolerance induction using CII (255-274) might be useful in the treatment of RA.

Adult respiratory distress syndrome in systemic lupus erythematosus: causes and prognostic factors: a single center, retrospective study

OBJECTIVES

To determine the causes and prognostic factors of Adult Respiratory Distress Syndrome (ARDS) in patients with systemic lupus erythematosus (SLE).

METHODS

Among 544 Korean SLE patients, who were followed in the Lupus Clinic of the Catholic Medical Center from 1993 to 1997, patients diagnosed as ARDS were examined retrospectively. During the study period, non-SLE patients with ARDS were investigated and then compared to SLE patients with ARDS in terms of clinical variables.

RESULTS

Nineteen patients with SLE were revealed to have a history of ARDS (3.5%) and 13 (68.4%) of 19 patients died. Death related to ARDS was found in 34.2% of all deaths (n=38) from SLE during the study period. The frequency and causes of ARDS were as follows; 9 sepsis or bacteremia (47.4%), 2 miliary tuberculosis (10.5%), 2 invasive pulmonary aspergillosis (10. 5%), 2 acute pulmonary alveolar hemorrhage syndrome (10.5%), 1 acute lupus pneumonitis (5.3%), 1 massive hemorrhage due to placenta previa (5.3%), 1 aspiration pneumonitis (5.3%), 1 disseminated intravascular coagulation associated with systemic vasculitis (5.3%). The main organisms in sepsis were gram negative bacilli (61.5%) The median steroid dose administered 1 month before ARDS was significantly higher in patients (n=13) with infectious ARDS compared to those (n=6) with ARDS due to other causes (P=0.038). Comparison of the laboratory and clinical variables between the survivors (n=6) and the deceased (n=13) showed that the survivors had lower SLAM indices at presentation (P=0.004) and APACHE (Acute Physiology, Age, Chronic Health Evaluation) III scores within 24 h after diagnosis of ARDS (P=0.024) than the deceased. The APACHE III scores correlated well with the SLAM indices (r=0.615, P=0.007). Non-SLE patients with ARDS during the study period were selected for comparison to SLE patients with ARDS. Age at the onset of ARDS was younger in SLE (n=19) compared to non-SLE (n=190) (P<0.001). Duration from ARDS onset to death was shorter in SLE patients (P<0. 001). The mortality from ARDS tended to be higher in SLE patients (P=NS). The first-day APACHE III score was significantly higher in deceased SLE patients (n=13) compared to deceased non-SLE patients (n=105) (P=0.001).

CONCLUSIONS

ARDS was a common premortem event of SLE and showed a high fatality rate in SLE. The most common cause of ARDS in Korean patients with SLE was sepsis by gram negative bacilli. ARDS in SLE developed at a younger age, and progressed more rapidly compared to ARDS in general. The SLAM index and APACHE III score could be useful to predict the prognosis of ARDS in SLE.

A case of Sweet's syndrome in patient with dermatomyositis

Sweet's syndrome (SS) has been reported as an association with malignant neoplasms and autoimmune diseases, e.g., Behçet's disease, Sjogren's syndrome, and rheumatoid arthritis. But dermatomyositis (DM), one of the rare autoimmune diseases, was not reported as an associated disease of SS. We describe an interesting case of SS associated with DM. Diagnosis was made by skin biopsy, and subsequent clinical resolution occurred after institution of prednisolone.

A case of Behçet's disease with superior and inferior vena caval occlusion

Behçet's disease is a chronic multisystemic disorder involving many organs and characterized by recurrent oral and genital ulcers and relapsing iritis. A case of BD with large vein thrombosis involving superior and inferior vena cava is presented. Large vein thrombosis in BD is not commonly developed and most commonly observed in the inferior or superior vena cava. A review of the literature emphasizes the rarity of the combined superior and inferior vena caval occlusion. Existence of extensive large vein occlusion in BD is associated with limited therapy and poor prognosis.

Decreased tumour necrosis factor-beta production in TNFB*2 homozygote: an important predisposing factor of lupus nephritis in Koreans

Low TNF production and its association with TNF gene restriction fragment length polymorphism (RFLP) was demonstrated in (NZW/NZB) F1 mice. However, little is known about the significance of TNF production in association with TNF gene polymorphism in human SLE. This study was designed to evaluate the role of TNF production of peripheral blood mononuclear cells (PBMC) and its association with TNFB gene polymorphism in SLE, particularly lupus nephritis. TNFB gene polymorphism was defined by PCR-NcoI RFLP. TNF productions of phytohemagglutinin (PHA)-stimulated PBMC and T cells were examined by bioassay using L929 cell line and ELISA. The PBMC stimulated by PHA from patients with SLE (n = 60) tended to secrete less amounts of TNF by bioassay (1032 +/- 184 pg/ml vs 1524 +/- 224 pg/ml, P = 0.094), and TNF-beta by ELISA (P = 0.0082) than that from normal controls (n = 38). The low TNF-alpha producer was more frequent in nephritis than non-nephritis (34.4% vs 7.1% respectively, P < 0.01). TNF-beta also revealed similar results (53.1% vs 21.4%, P < 0.05). In SLE, mean production of TNF-beta was decreased in TNFB*2 homozygote (n = 18) than that in TNFB*1 homozygote (n = 9) (1126.3 +/- 145 pg/ml) vs 642 +/- 118.4 pg/ml, respectively, P = 0.021), whereas TNF-alpha production showed little difference between the two groups (710.1 +/- 56.4 vs 542.4 +/- 71.1 pg/ml, respectively, P = 0.149). Our results demonstrate that decreased TNF production of PBMC, which was significantly associated with TNFB*2 homozygosity, could be an important predisposing factor of lupus nephritis in Koreans.

Effects of nitric oxide (NO) synthesis inhibition on antitumor responses during interleukin-2 (IL-2) treatment of mice

OBJECTIVES

To evaluate if L-arginine: NO pathway is activated in tumor tissues during IL-2 therapy and to evaluate whether IL-2 induced NO synthesis represents an antitumor effector mechanism or an inhibitory factor against therapeutic effects of IL-2.

METHODS

Four groups [untreated control, NG-monomethyl-L-arginine (MLA) therapy only, IL-2 therapy only, IL-2/MLA therapy groups] of BALB/c mice were injected intraperitoneally with 2 x 10(8) Meth A tumor cells on day 0. MLA was administered subcutaneously with Alzet continuous infusion pumps on day 2. IL-2 therapy (180,000 IU s.c. every 12h for 5 days) was started on day 3. NO production within ascites tumors was assessed by measuring nitrite concentrations in cultures of ascites cells harvested on day 8. Survival and the rate of body weight increment of the mice were measured to evaluate therapeutic responses. Daily urinary nitrate excretion was monitored to demonstrate the effectiveness of MLA in inhibiting NO synthesis.

RESULTS

Nitrite production in supernatants of Meth A ascites cell cultures was 63 +/- 14 microM in IL-2 treated mice and 3.2 +/- 1.5 microM in untreated controls (p < 0.001). MLA prevented the IL-2 therapy induced increase in nitrite production. IL-2 therapy did not decrease the rate of body weight increment and marginally prolonged mean survival to 18.2 days, compared to 16.6 days in control mice (p = 0.255). MLA administration decreased the rate of body weight increment and prolonged mean survival of IL-2 treated mice (21.8 days, p = 0.001 versus IL-2 alone). Interestingly, the MLA treatment increased the rate of body weight increment and diminished the survival of control mice to 11.6 days (p = 0.003). MLA administration via Alzet continuous infusion pumps achieved approximately 60% suppression of urinary nitrate excretion by control mice. Subcutaneous IL-2 treatment strongly induced nitric oxide synthesis (up to 3.5 mumoles of urinary nitrate/ mouse/day). MLA also effectively suppressed IL-2 induced NO production.

CONCLUSION

L-arginine: NO pathway can be activated in malignant ascites by IL-2 therapy and NO synthesis functions as an inhibitory mechanism against IL-2 induced anti-tumor effects.