Improved induction of melanoma-reactive CTL with peptides from the melanoma antigen gp100 modified at HLA-A*0201-binding residues

Recognition of the melanoma Ag gp100 by tumor-infiltrating lymphocytes (TIL) in vitro has been correlated with tumor regression in patients with metastatic melanoma treated with the adoptive transfer of TIL plus IL-2. Three common gp100 epitopes have been identified that are recognized in the context of HLA-A2 by TIL from different patients: G9154 (KTWGQYWQV), G9209 (ITDQVPFSV), and G9280 (YLEPGPVTA). Upon stimulation with these peptides, melanoma-reactive CTL could be induced in vitro from PBL of some HLA-A2+ melanoma patients. However, numerous restimulations were required, and specific reactivity could not be generated in many patients. Therefore, to enhance the immunogenicity of gp100 peptides, amino acid substitutions were introduced into G9154, G9209, and G9280 at HLA-A*0201-binding anchor positions, but not at TCR contact residues, to increase peptide class I MHC-binding affinity. Several modified gp100 peptides bound with greater affinity to HLA-A*0201 than unmodified peptides and were recognized by TIL specific for the natural epitopes. These peptides were used to sensitize PBL from HLA-A2+ melanoma patients in vitro using peptide-pulsed autologous PBMC as stimulators. After five weekly restimulations with either the native G9209 or G9280 peptide, melanoma-reactive CTL could only be induced from two of seven patients. However, amino acid substitutions in these peptides enabled the induction of melanoma-reactive CTL from all seven patients. These results suggest that modified gp100 peptides may be more immunogenic than the native epitopes, and may be useful in immunotherapy protocols for patients with melanoma.

Improved induction of melanoma-reactive CTL with peptides from the melanoma antigen gp100 modified at HLA-A*0201-binding residues

Recognition of the melanoma Ag gp100 by tumor-infiltrating lymphocytes (TIL) in vitro has been correlated with tumor regression in patients with metastatic melanoma treated with the adoptive transfer of TIL plus IL-2. Three common gp100 epitopes have been identified that are recognized in the context of HLA-A2 by TIL from different patients: G9154 (KTWGQYWQV), G9209 (ITDQVPFSV), and G9280 (YLEPGPVTA). Upon stimulation with these peptides, melanoma-reactive CTL could be induced in vitro from PBL of some HLA-A2+ melanoma patients. However, numerous restimulations were required, and specific reactivity could not be generated in many patients. Therefore, to enhance the immunogenicity of gp100 peptides, amino acid substitutions were introduced into G9154, G9209, and G9280 at HLA-A*0201-binding anchor positions, but not at TCR contact residues, to increase peptide class I MHC-binding affinity. Several modified gp100 peptides bound with greater affinity to HLA-A*0201 than unmodified peptides and were recognized by TIL specific for the natural epitopes. These peptides were used to sensitize PBL from HLA-A2+ melanoma patients in vitro using peptide-pulsed autologous PBMC as stimulators. After five weekly restimulations with either the native G9209 or G9280 peptide, melanoma-reactive CTL could only be induced from two of seven patients. However, amino acid substitutions in these peptides enabled the induction of melanoma-reactive CTL from all seven patients. These results suggest that modified gp100 peptides may be more immunogenic than the native epitopes, and may be useful in immunotherapy protocols for patients with melanoma.

Thyroid involvement by malignant histiocytosis of Langerhans' cell type

Involvement of the thyroid gland by Langerhans' cell histiocytosis is quite rare. We describe the case of a 58-year-old man referred for treatment of a progressively enlarging goitre. The trachea was severely stenotic and adjacent structures such as the left carotid vein and the thyroid cartilage were also involved. Central diabetes insipidus and severe combined immunodeficiency were associated. Although fine needle aspiration biopsy of the thyroid was initially interpreted as papillary carcinoma, anaplastic thyroid cancer was suspected. Treatment with prednisolone, doxorubicin and irradiation controlled the tracheal compression. A diagnosis of thyroid Langerhans' cell histiocytosis was finally made on the basis of the presence of Birbeck granules and CD1a and CD4 antigen in the thyroid tumour cells. Furthermore, positive staining for CD68 and lysozyme suggested that the tumour cells may have had the character of phagocytic cells in addition to their dendritic cell nature. This is the first case of thyroid involvement by malignant histiocytosis of Langerhans' cell type with unusual phagocytic markers.

Long-term effects of eicosapentaenoic acid on diabetic peripheral neuropathy and serum lipids in patients with type II diabetes mellitus

The present study was undertaken to investigate the efficacy of a new, highly purified (purity greater than 91%), ethyl esterification product from natural eicosapentaenoic acid (EPA-E, C20:5 omega 3) in patients with type II diabetes mellitus (NIDDM). Hemodynamic changes were assessed at the level of the dorsalis pedis artery using an ultrasonic color Doppler duplex system before and after oral administration of EPA-E at a dose of 1800 mg/day for 48 weeks. The cross-sectional area of the dorsalis pedis artery increased significantly from 2.5 +/- 0.2 to 3.9 +/- 0.4 mm2 (48 weeks, mean +/- SE, p < 0.05). Moreover, EPA-E improved the clinical symptom (coldness, numbness) as well as the vibration perception threshold sense of the lower extremities [from 32.1 +/- 8.5 to 16.1 +/- 4.8 (48 weeks) microns]. A significant decrease of serum triglycerides was also noted by EPA-E administration. Furthermore, significant decrease of the excretion of albumin in urine [from 24.4 +/- 3.3 to 13.9 +/- 1.8 (48 weeks) mg/g.Cr, p < 0.05]. The results of this study suggest that EPA-E has significant beneficial effects on diabetic neuropathy and serum lipids as well as other diabetic complications such as nephropathy and macroangiopathy.

Tendinous movement of a human muscle during voluntary contractions determined by real-time ultrasonography

The degree of shortening or lengthening of muscles during joint actions has not been clarified in humans, although such information is essential in understanding human muscle functions. In this study, the tendinous movement of a muscle was determined by real-time ultrasonography during voluntary contractions. The tibialis anterior muscle (TA) was tested in five healthy men who performed dorsi- and plantar flexion movements (shortening and lengthening of TA) at two frequencies (0.1 and 1.5 Hz). The insertion point (eta) of fascicles onto the aponeurosis was clearly visualized on the ultrasonogram, and its position relative to a fixed marker moved proximally and distally according to dorsi- and plantar flexion of ankle joint. The movement of eta occurred in phase with the angular change of ankle joint, giving high correlations (r = 0.93 to 0.97) between the displacement of eta and the angle. The displacement of eta for one radian of joint angle change, 46.5 +/- 1.7 (SD) mm, was comparable to the reported moment arm of TA. The present method has many potential applications in the field of muscle physiology and biomechanics in humans.

Elastin-derived peptides and neutrophil elastase in bronchoalveolar lavage fluid

To evaluate effects of current smoking on the breakdown of lung elastin, we measured levels of elastin-derived peptides (EDP) in unconcentrated bronchoalveolar lavage (BAL) fluid from 42 community-based older asymptomatic volunteers (60 +/- 11 yr [mean +/- SD]) and examined the relationships of the concentrations of EDP with immunologically detected neutrophil elastase (NE) bound with alpha(1)-proteinase inhibitor and with esterolytic activity against the NE-sensitive synthetic substrate, methoxysuccinyl-alanyl-alanyl-prolyl-valyl paranitroanilide (MEOSAAPVNA). The measurement of EDP levels was carried out by an indirect, competitive ELISA, using a sheep IgG fraction generated against insoluble human lung elastin as a primary antibody. EDP concentrations were significantly elevated in current smokers (n = 24) compared with age-matched noncurrent smokers (n = 18) (29.9 +/- 3.5 [mean +/- SE] versus 17.0 +/- 1.8 ng/mg BAL fluid albumin, p < 0.01). We found weak but significant correlations of EDP levels with NE-alpha(1)-proteinase inhibitor complex (r = 0.38, p < 0.05) and with the esterolytic activity against the NE-sensitive synthetic substrate in BAL fluid (r = 0.65, p < 0.001). In addition, EDP levels in BAL fluid had a significant positive relationship with plasma cotinine concentrations (r = 0.53, p < 0.001), though not with pack-years of smoking (r = 0.1, NS). These data provide further evidence that the concentrations of EDP increase in BAL fluid from current smokers compared with noncurrent smokers and that enhanced breakdown of the lung elastin is associated with the increased load of NE in the lung.

[Isolated infranuclear oculomotor nerve palsy caused by traumatic midbrain hemorrhage: case report]

Traumatic brain stem hemorrhage is often associated with severe head injury and has a high mortality rate. When these patients survive, the midbrain syndromes are usually complicated. The authors report an unusual case with isolated oculomotor nerve palsy caused by acute traumatic midbrain hemorrhage. A 50-year-old woman was brought to Kobe City General Hospital because she had fallen off a bicycle and hit the face severely on the ground. On admission, she was drowsy. Neurological examination revealed normal muscle tone in all extremities without motor or sensory disturbance. Deep-tendon reflexes were symmetrical and there were no Babinski signs present. The left eye lid dropped and the left pupil was 5.5 mm in diameter without responses to light. The eye ball was slightly deviated to the left side on neutral position. There were no extraocular movements except for abduction to the left side. The right pupil measured 3 mm in diameter and was reactive to light promptly. Plane skull films failed to show fractures. Computed tomography (CT) scan 30 minutes after the accident suggested the existence of a hemorrhage in the anterior tegmentum of the left midbrain. Four hours later, a midbrain hemorrhage was diagnosed by consecutive CT scans. She was alert on the next day, although the third nerve palsy remained. The left blephaloptosis disappeared gradually during the next month. At 6 months after the accident, the left pupil was still dilated and did not react to light, either directly or indirectly. Medial gaze recovered almost fully, while both upward and downward movements were still limited. The mechanism of the isolated oculomotor nerve palsy in this case was discussed with a review of the related literature.

T-cell recognition of self peptides as tumor rejection antigens

Human melanoma antigens and their epitopes recognized by T cells have recently been identified. HLA-A2 binding epitopes of melanoma antigens MART-1 and gp 100 were characterized and suspected to be subdominant/cryptic self determinants. Together with other findings of tumor-specific mutated self peptides as tumor antigens recognized by T cells, the nature of the antitumor immune response to human melanoma has been revealed at a molecular level. These findings have implications not only for understanding of the immune response to self peptides in normal and pathologic conditions, but also for the development of immunotherapies for cancer and autoimmune diseases.

"Web-like obstruction"--a sign of regional complete remission after concurrent chemoradiotherapy in small cell lung cancer

Two patients with small cell lung cancer (SCLC) developed "web-like" mucosa that obstructed bronchi after concurrent chemoradiotherapy. It seemed that the orifice of the bronchi had disappeared. Since the patients were free of local recurrence and the histologic findings of "web-like" mucosa were negative for malignancy, we believe that "web-like obstruction" was additional sign of regional complete remission of SCLC after concurrent chemoradiotherapy.

The rationale for E2020 as a potent acetylcholinesterase inhibitor

The phase III drug-candidate, E2020, developed for treatment of Alzheimer's disease, and possibly other demenitas, and its analogues have been the focus of extensive molecular pharmacological and structural studies. The potency and selectivity of E2020 as an inhibitor of acetylcholinesterase, AChE, in the brain is established. A combination of molecular modeling and QSAR studies have been used throughout the evolution of the AChE inhibitor program leading to the benzylpiperidine series, and, ultimately, E2020. QSAR studies have identified requirements of optimize inhibition activity as a function of substituent choice on both the indanone and benzyl rings in the E2020 class of inhibitors. A combination of X-ray crystal structure studies of E2020 isomers and the molecular shape analysis, MSA, of E2020 and its analogues has led to a postulated active conformation, and molecular shape, for these AChE inhibitors. The active molecular shape corresponds to a high degree of shape similarity between the two E2020 isomers which, in turn, is consistent with the observed high inhibition potencies of both of these compounds. Intermolecular docking studies were carried out for E2020 and some analogues with the crystal structure of AChE when it became available. The docking simulations involving E2020 analogues suggest these inhibitors do not bind at the acetylcholine, ACh, active site, but rather at the most narrow location of the long channel leading to the active site. Intermolecular binding geometries are consistent with the postulated active conformations derived from structure-activity (receptor geometry independent) information.

[Behavioral changes induced by repeated administration of mazindol, an anorexiant, in rats]

Behavioral changes in locomotor activity and stereotyped behaviors induced by daily administration (for 7 days) of mazindol (5 and 10 mg/kg, po) were compared with those induced by methamphetamine (10 mg/kg) in rats. On day 1, mazindol increased locomotor activity, which was enhanced by daily administrations. Stereotyped behaviors were also induced by mazindol, which became more marked following daily administrations. Methamphetamine markedly increased stereotyped behavior rather than locomotor activity on day 1, and the effects were not enhanced by daily administrations. The increased locomotor activity and stereotyped behaviors caused by mazindol and methamphetamine were markedly reduced by the dopamine receptor antagonist pimozide (0.1-0.4 mg/kg, ip) in a dose-dependent manner. These results suggest that repeated mazindol administration enhances locomotor-stimulant and stereotypy-producing effects, which are mediated by the central dopaminergic system.

Deletion polymorphism in the angiotensin I converting enzyme (ACE) gene as a genetic risk factor for sarcoidosis

BACKGROUND

Genetic control of serum angiotensin I converting enzyme (SACE) levels has been suggested. A study was undertaken to elucidate the role of this polymorphism in sarcoidosis.

METHODS

Three hundred and forty one unrelated healthy controls and 103 consecutive patients with sarcoidosis participated in the study. SACE levels and an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene were studied in each subject and new reference intervals for SACE activity for each genotype were determined. The difference in genotype and allele frequencies between controls and patients was analysed and odds ratios were calculated to estimate the relative risk.

RESULTS

A significant association was seen between ACE gene polymorphism and SACE levels in both patients and controls. The new reference intervals for each genotype discriminated abnormal SACE levels in patients more accurately, especially those with genotype II. In women the frequencies of allele I were 0.68 (allele D 0.32) in controls and 0.58 (allele D 0.42) in patients, and the difference between the two female groups was significant (p < 0.05). Thus, an excess of genotype ID or DD was observed in female patients (odds ratio 2.18; 95% confidence interval 1.18 to 4.01; p = 0.01).

CONCLUSIONS

These findings suggest that ACE gene polymorphism is associated with SACE levels in both patients with sarcoidosis and controls. ACE gene polymorphism should be further evaluated as a candidate marker for an increased risk of sarcoidosis.

A novel fucosyltetrahexosylceramide in plerocercoids of the parasite Spirometra erinacei

This glycosphingolipid was tentatively designated as GalSEGLx, in which the carbohydrate structure is characterized by an additional galactose molecule attached to the reducing-end galactose of SEGLx [Gal beta-4 (Fuc alpha-3) Glc beta-3 Gal beta Cer], which was previously determined by us [Kawakami, Y., Nakamura, K., Kojima, H., Suzuki, M., Inagaki, F., Suzuki, A., Sonoki, S., Uchida, A., Murata, Y. & Tamai, Y. (1993) J. Biochem. 114, 677-683], through a beta 1-6 linkage. The ceramide contained sphinganine and 4D-hydroxysphinganine in an about equimolar ratio, and a non-hydroxy fatty acid with carbon atoms ranging from 16 to 28, 26:0, 28:0 and 28:1 being major components. Based on the finding that a novel carbohydrate structure. Gal beta-4 Glc beta-3 Gal, was commonly found in glycosphingolipids from the parasite, S. erinacei, we here propose the terms, spirometo series, for this core structure series, and spirometosides, for glycosphingolipids having this carbohydrate structure.

Total and segmental subcutaneous adipose tissue volume measured by ultrasound

Total and segmental subcutaneous adipose tissue volumes (SATV) were estimated and compared in 13 healthy young women with a mean age of 21.4 yr. Total and segmental (head and neck, forearm, upper arm, trunk, thigh, and lower leg) SATV were estimated from subcutaneous adipose tissue layer thickness and the body surface area; the former by B-mode ultrasound and the latter by direct measurement. Consecutive magnetic resonance images (MRI) were obtained from head to toe (10 mm thickness), from which adipose tissue areas as well as total and regional SATV were determined. SATV of the upper arm and thigh estimated by ultrasound was significantly lower compared to that of MRI-measured SATV; however, there were no significant differences found in the other four segments. As a result, total estimated SATV obtained was on average 5.5% lower with ultrasound than with MRI-measured total SATV; however, there were no statistically significant differences between the two values. Significant strong correlations were observed between MRI-measured total and segmental SATV, and SATV estimated by ultrasound (r = 0.79-0.95) for all segments except head and neck. These results show the effectiveness of the ultrasound method for estimating SATV; however, the quantitative analysis tissue volumes would require correction.

Human melanoma antigens recognized by T lymphocytes

Human melanoma antigens and their epitopes recognized by T cells have been identified using a variety of methods. These antigens are classified as 1) melanocyte specific melanosomal proteins (MART-1, gp100, tyrosinase and TRP-1), 2) proteins expressed in testis and a variety of cancers (MAGE-1, MAGE-3, BAGE and GAGE), 3) tumor specific mutated proteins (beta-catenin, MUM-1 and CDK4), and 4) others (p15). Some of the HLA-A2 binding non-mutated melanoma epitopes contained non-dominant anchor amino acids and have relatively low HLA-A2 binding affinity, suggesting that these epitopes were likely to be subdominant or cryptic self determinants. The significant correlation observed between vitiligo development and IL2 based immunotherapy suggested that autoreactive T cells specific for these self peptides were involved in melanoma regression in vivo. In addition, since adoptive transfer into patients of CTL recognizing these epitopes resulted in tumor regression, these epitopes may be tumor rejection antigens. Melanoma reactive CTL were efficiently induced from PBL of patients by in vitro stimulation with PBMC pulsed with these melanoma epitopes and may be useful in adoptive transfer protocols for the treatment of patients with metastatic melanoma. An immunization trial using the MART-1 and gp100 peptides in conjunction with incomplete Freund's adjuvant is in progress. These identified antigens may be useful for the development of new immunotherapies for the treatment of melanoma patients as well as for understanding the mechanisms of anti-tumor immune responses and autoimmune disorders against melanocytes.

[Use of the the ED046 kit to analyze serum KL-6 in patients with pneumonitis]

KL-6 is a mucinous glycoprotein expressed on Type 2 pneumonocytes, and serum levels of KL-6 are reported to be abnormally high in patients with interstitial pneumonia. A new assay kit for serum KL-6 (ED046) was used in the evaluation of patients with pneumonitis. To clarify whether KL-6 is a useful marker of pneumonitis activity, 649 subjects were studied, including 185 healthy controls, 187 patients with 3 types of interstitial lung diseases, and 277 patients with 4 types of non-interstitial lung diseases. The serum KL-6 level was significantly higher in the patients with pneumonitis (1285 +/- 1196 U/ml) than in the patients without pneumonitis (307 +/- 232 U/ml). The KL-6 level was also significantly higher in patients with clinically active pneumonitis (1708 +/- 1338 U/ml) than in those with inactive pneumonitis (820 +/- 796 U/ml) (p < 0.0001). Serum KL-6 levels correlated significantly with serum c-reactive protein, lactic dehydrogenase, and PaO2 values. These results suggest that the ED046 assay is useful for measuring KL-6 as a marker of pneumonitis activity.

Thallium-201 uptake, histopathological differentiation and Na-K ATPase in lung adenocarcinoma

To clarify differences in accumulation in 201 Tl scintigraphy, we examined the relationship between uptake of 201 Tl, histopathological differentiation and Na-K ATPase.

METHODS

Thallium-201 SPECT was performed twice: 15 min (early scan) and 120 min (delayed scan) after intravenous injection of 3 mCi 201 Tl-chloride. The uptake ratio of 201 Tl was calculated and compared with the grade of differentiation and the staining pattern of Na-K ATPase.

RESULTS

The sensitivity of 201 Tl SPECT for well-differentiated adenocarcinomas was lower than that for moderately and poorly differentiated ones. The uptake ratio on the delayed scan was significantly lower in the well-differentiated group than that in the moderately and poorly differentiated groups. This parameter was also significantly higher in the Na-K ATPase-positive group than the -negative group.

CONCLUSIONS

These results indicate that the uptake ratio of 201 Tl SPECT may be a noninvasive indicator of the grade of pathological differentiation of adenocarcinoma and provide insight into the relationship among 201 Tl SPECT, malignancy and Na-K ATPase.

[Bilateral chronic subdural hematomas presented with subarachnoid hemorrhage: report of two cases]

Computed tomography (CT) findings of chronic subdural hematomas are usually diagnostic, unless hematomas are isodense and bilateral. The authors report two cases of bilateral chronic subdural hematomas, in which CT scans on admission were both misdiagnosed as delayed subarachnoid hemorrhage (SAH). The first case was a 43-year-old woman who suffered from a sudden onset of headache and nausea. She had no past history of head injury. CT scans on admission did not clearly reveal the Sylvian fissures and the mesencephalic cistern, without any mass effects. A lumbar puncture demonstrated xanthochromic cerebrospinal fluid (CSF), which was considered to be responsible for her headache. Cerebral angiography performed on day 4 failed to demonstrate any cerebral vascular disorders. Follow-up CT scans on day 7 demonstrated a high density lesion in the left subdural space. Magnetic resonance images (MRIs) confirmed a diagnosis of bilateral chronic subdural hematomas. Removal of the hematomas cleared all signs and symptoms smoothly. The second case was a 44-year-old man who was referred from another hospital because of xanthochromic CSF found by lumbar puncture. He began to suffer headache and be subject to vomiting 6 weeks earlier and these symptoms were still present on the day of admission. CT scans did not clearly show the cerebral cisterns without mass effects. Because the second lumbar puncture showed xanthochromic CSF again, SAH from aneurysm was suspected. However, emergency cerebral angiography failed to demonstrate cerebral aneurysms. MRI performed two days later demonstrated bilateral chronic subdural hematomas. Following surgery, the patient improved immediately and was discharged from hospital without any complications. In both cases, a retrospective study of the angiograms revealed the evidence of bilateral avascular areas over the convexities in the venous phase. The reason why these subdural hematomas were missed at the time of angiography was due to too much attention being paid to the arterial phase in an effort aimed only at identifying cerebral aneurysms. There are no reports of chronic subdural hematoma which demonstrated sudden onset of headache associated with xanthochromic CSF.

Current status and research on chronic respiratory failure in Japan

Chronic respiratory failure is defined on the basis of gas exchange in the lung. Recent studies have suggested serious clinical problems in patients with disabling dyspnea not necessarily related to gas exchange. Home oxygen therapy not only prolongs life expectancy but also improves the quality of daily life. In Japan, pulmonary emphysema, sequelae of pulmonary tuberculosis, and interstitial pneumonia/pulmonary fibrosis are the 3 major diseases currently treated by home oxygen therapy. Respiratory failure caused by interstitial pneumonia/pulmonary fibrosis and lung cancer is on the increase and is also treated by home oxygen therapy. Clinical problems on mechanisms and treatment of chronic respiratory failure are reviewed from recent data.

Effects of exercise and CO2 inhalation on intersubject variability in ventilatory and heart rate responses to progressive hypoxia

Although the ventilatory and heart rate responses to hypoxia are known to vary widely among subjects, it is not known how exercise or hypercapnia influence the intersubject variability of these responses. If the intersubject variability increases under such conditions, the inherent response of individuals will have more impact on ventilation and heart rate under a variety of hypoxic conditions during exercise or with hypercapnia than at rest or with normocapnia. Seventeen healthy male volunteers underwent tests to measure ventilatory response to isocapnic progressive hypoxia three times respectively: at rest; during CO2 inhalation (end-tidal carbon dioxide tension (PET,CO2) raised by 5 torr from the baseline level); and during mild exercise with a cycle ergometer (12.5 W) in a supine position. The mean (SEM) value of hypoxic ventilatory response (HVR) (delta minute ventilation (V'E)/delta arterial oxygen saturation (Sa,O2) was significantly increased both in the exercise and hypercapnic runs compared with that in the control run (0.45 +/- 0.12, 0.34 +/- 0.08, respectively, vs 0.12 +/- 0.02 L.min-1/% fall), although the respiratory pattern was different under the two loaded conditions. The intersubject variation in HVR was also significantly increased during the two loaded conditions compared with the control, although a significant correlation remained between the control value and that obtained during either loaded condition (r = 0.66 and r = 0.60, respectively). The heart rate (HR) response evaluated by the slope factor (delta HR/delta Sa,O2) was not significantly different either in the mean value or in the intersubject variability among the three experimental conditions. In conclusion, exercise or CO2 inhalation not only increase the slope value of HVR but also amplify the intersubject variability of the response. In contrast, the HR response to hypoxia evaluated as a slope factor does not change with exercise or CO2 inhalation.

Progesterone induces vascular endothelial growth factor on retinal pigment epithelial cells in culture

Diabetic retinopathy is known to frequently deteriorate during pregnancy but the cause remains obscure. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is a potent vascular endothelial cell mitogen which is mainly up-regulated by hypoxia, and is closely associated with the development and progression of diabetic retinopathy. To examine the influence of the drastic hormonal alterations during pregnancy on the worsening of diabetic retinopathy, we examined the effects of estradiol (E2) and progesterone (P4) on the production of VEGF/VPF in bovine retinal pigment epithelial cells in culture. The VEGF/VPF production was significantly elevated (214.5 +/- 28.3 ng/g protein, P < 0.01) by 48 h of exposure to a high concentration of P4(10 microM), which is still within the physiological range during pregnancy, compared to that of the control group (147.7 +/- 17.9 ng/g protein). However, E2 significantly stimulated the production of VEGF/VPF only at concentrations (100 microM) much higher than normally encountered during pregnancy. These two hormones were not observed to have a synergistic effect, at least at physiological concentrations. As the increase in serum P4 levels during pregnancy is reported to be greater in pregnant diabetic patients with progressive retinopathy, our findings suggest that P4 may contribute to the worsening of diabetic retinopathy during pregnancy by up-regulating intraocular VEGF levels.