Expression of matrix metalloproteinases and inhibitor by human retinal pigment epithelium.

Extracellular matrix turnover is initiated, at least in part, by the regulated secretion of members of a family of matrix metalloproteinases. The authors show that interstitial collagenase, stromelysin, two gelatinases (the 72-kD and 92-kD type IV collagenases), and the tissue inhibitor of metalloproteinases (TIMP) are secreted into the culture medium of human retinal pigment epithelium (RPE). These enzymes and their inhibitor were identified by probing immunoblots of western transfers with specific polyclonal antibodies that were made against these proteins or against peptides containing unique sequences from these proteins. Stromelysin and the gelatinases are also active against substrates that are polymerized into polyacrylamide gel before electrophoresis and require metal ions (probably zinc and/or calcium) for activity. The phorbol mitogen, 12-tetradecanoylphorbol-13-acetate, differentially increases the levels of these metalloproteinases and TIMP found in retinal pigment epithelium culture medium with stromelysin and the 92-kD type IV collagenase responding most strongly and TIMP actually decreasing in certain cases. Additional changes in metalloproteinase profiles are observed after approximately 20 passage of several RPE lines in culture. Modulation of extracellular matrix turnover by changing RPE secretion of these matrix metalloproteinases and their TIMP, may play a central role in the normal function and in the pathology of the retina.

Serum gamma-glutamyl transpeptidase activity in patients receiving chronic phenytoin therapy.

To better define the incidence and range of elevated gamma-glutamyl transpeptidase (GGT) activity in patients taking a drug known to induce hepatic microsomal enzymes, GGT was measured in the sera of 58 patients before and after six months of phenytoin therapy. Enzyme activity at six months was greater than baseline in 52 of 58 patients (90%). GGT activity (normal, 0-50 units/liter) was 45.2 +/- 9.9 (mean +/- SEM) at baseline and 135.8 +/- 18.1 after six months of therapy, a mean threefold increase (P less than 0.001). Of the 45 patients with normal baseline GGT activity, some had marked elevation of serum GGT activity with values rising over 200 units/liter in eight patients and over 300 units/liter in four patients. Mean serum GGT activity remained significantly elevated at 12 and 24 months. This elevation in GGT activity was not influenced by age, sex, or additional anticonvulsant drug therapy. Both baseline and six-month GGT activity was lowest in patients who drank no alcohol, higher in patients who drank 0-1 pint/week, and greatest in patients who drank greater than 1 pint/week. All 13 patients with elevated baseline GGT activity were regular users of alcohol and/or taking other enzyme-inducing drugs. In conclusion, increase in serum GGT activity occurs in 90% of patients on long-term phenytoin therapy, most often to moderate but occasionally to high levels, and this rise in GGT activity is accentuated by regular consumption of alcohol.

Effects of phenytoin on man's immunity. Evaluation of changes in serum immunoglobulins, complement, and antinuclear antibody.

To determine the effects of phenytoin on serum immunoglobulins, complement, and antinuclear antibody conversion, a prospective, five-year longitudinal study was undertaken in 118 patients. Three major diagnostic groups were evaluated: 27 patients with idiopathic epilepsy, 50 with secondary epilepsy, and 41 with neuropathic syndromes without epilepsy. In addition, 83 normal volunteers were studied in a similar manner. Evaluations were performed prior to administration of phenytoin and at six-month intervals thereafter. Prior to treatment, patients with idiopathic epilepsy had a higher than expected incidence (13.5 percent, p less than 0.01) of low serum IgA (less than 61 mg/dl). Patients with secondary epilepsy and neuropathic disorders without epilepsy had a greater than expected incidence (9.2 percent, p less than 0.01; and 12 percent, p less than 0.01, respectively) of high serum IgA (greater than 417 mg/dl). Phenytoin treatment was associated with further decreases in serum IgA in patients with idiopathic epilepsy (p = 0.063) and secondary epilepsy (p = 0.008). Total serum IgE concentrations also decreased significantly in all patient categories during treatment with phenytoin. Minor decreases in serum IgG and IgM were noted, but serum IgD and complement remained unaffected. Antinuclear antibodies were observed with essentially the same frequency (10 percent) before and after phenytoin therapy.

Phenytoin influence on human lymphocyte mitogen response: a prospective study of epileptic and nonepileptic patients.

The results of this prospective study fail to confirm previously reported phenytoin suppression of lymphocyte responsiveness to mitogens. Our data show a significantly greater than expected percentage (p less than 0.0001) of patients requiring phenytoin treatment have low lymphocyte responsiveness to mitogens prior to phenytoin therapy. Analysis of changes in each individual's response during phenytoin treatment as compared with their pre-phenytoin responses shows a consistent trend to increased responsiveness to concanavalin A, pokeweed mitogen, and to a suboptimal concentration of phytohemagglutinin. This trend was most pronounced for patients whose serum IgA concentration was decreased while taking phenytoin, whereas there was no such trend for individuals whose serum IgA levels were not decreased. This phenomenon was not related to neurological disease classification. Phenytoin added directly to lymphocyte cultures depressed lymphocyte responses to all mitogens in a small (less than 20%) but significant degree, confirming similar in vitro studies by other investigators. Because of limited serum proteins for phenytoin binding in culture medium, these in vitro studies have little application to possible phenytoin effects on lymphocytes of patients taking it to prevent seizures. Thus, the suggestion that phenytoin causes depressed lymphocyte responses to mitogens in epileptic patients appears unwarranted.

Glucocorticoid therapy in the preleukemic syndrome (hemopoietic dysplasia): identification of responsive patients using in-vitro techniques.

Bone marrow cells from 54 patients with the preleukemic syndrome were cultured in agar (granulocyte colony forming units) in the presence and absence of cortisol. Twenty-four patients were given trials of prednisone therapy after the initial culture was performed. Cortisol (in vitro) failed to enhance colony growth in 29 of these 34 cases, and none of the 29 patients responded to prednisone therapy. Cortisol enhanced colony growth in five patients and three of these responded favorably to prednisone therapy. The correlation of in-vivo with in-vitro events is significant (P less than 0.005). Glucocorticoid therapy is of value in the management of a small number of patients with the preleukemic syndrome but is hazardous in those who fail to respond. These preliminary observations suggest that bone marrow cell culture techniques may aid in the identification of those patients who will and those who will not respond favorably to such therapy.

Neutropenia in three patients with rheumatic disorders. Suppression of granulopoiesis by control-sensitive thymus-dependent lymphocytes.

A man with polymyalgia rheumatica (patient 1) and two patients (2 and 3) with Felty's syndrome had neutropenia at the time of diagnosis. Bone marrow samples in each patient were cellular but showed an "arrest" of granulocyte maturation at the myelocyte stage. Agar colony growth of marrow cells from each patient was subnormal but increased after removal of sheep erythrocytes rosette-forming cells (thymus-dependent [T] cells) from marrow cell suspensions before culture. Preincubation of marrow cells with cortisol also enhanced colony growth. Maximum enhancement with cortisol occurred at 1 mM (patient 1), 1 microM (patient 2), and 10 nM (patient 3). Cortisol failed to enhance colony growth after removal of T cells from marrow cell suspensions. Peripheral blood lymphocytes (PBL) and PBL-conditioned medium from all three patients inhibited colony growth of normal human marrow cells. Cortisol treatment of PBL or T depletion from PBL abrogated the inhibition in coculture and with conditioned medium. Prednisone therapy resulted in the disappearance of suppressor T-cell function concomitant with hematologic improvement in patients 2 and 3, but suppressor T cells persisted in patient 1, who did not respond to prednisone. We conclude that cortisol-sensitive T lymphocytes inhibited granulopoiesis in vitro probably by elaboration of a soluble factor or factors. Our results suggest (a) that neutropenia in these patients resulted, at least in part, from T-cell suppression of granulopoiesis, (b) that the effectiveness of prednisone therapy was a result of its inhibition of suppressor T cells, and (c) that responses to glucocorticoid therapy may be predicted in such patients with the agar culture technique and cortisol dose response in vitro.

Effect of sodium salicylate on human and mouse granulopoiesis in vitro.

Sodium salicylate inhibited generation of granulocyte and macrophage colonies when added to soft agar cultures of mouse or human bone marrow cells (CFUc) containing colony-stimulating factor (CSF). This effect was dose-dependent with over 90% inhibition at 48 mg%. The salicylate effect was not decreased with increasing concentrations of CSF, but inhibition was reversed when salicylate-treated CFUc were washed with drug-free medium before plating. CSF production was not inhibited by salicylate.