Neurofilament results for the phase II neuroprotection study of phenytoin in optic neuritis.

BACKGROUND: A randomized trial of phenytoin in acute optic neuritis (ON) demonstrated a 30% reduction in retinal nerve fiber layer (RNFL) loss with phenytoin versus placebo. Here we present the corresponding serum neurofilament analyses. METHODS: Eighty-six acute ON cases were randomized to receive phenytoin (4-6 mg/kg/day) or placebo for 3 months, and followed up for 6 months. Serum was collected at baseline, 3 and 6 months for analysis of neurofilament heavy chain (NfH) and neurofilament light chain (NfL). RESULTS: Sixty-four patients had blood sampling. Of these, 58 and 56 were available at 3 months, and 55 and 54 were available at 6 months for NfH and NfL, respectively. There was no significant correlation between serum NfH and NfL at the time points tested. For NfH, the difference in mean placebo - phenytoin was -44 pg/ml at 3 months (P = 0.019) and -27 pg/ml at 6 months (P = 0.234). For NfL, the difference was 1.4 pg/ml at 3 months (P = 0.726) and -1.6 pg/ml at 6 months (P = 0.766). CONCLUSIONS: At 3 months, there was a reduction in NfH, but not NFL, in the phenytoin versus placebo group, while differences at 6 months were not statistically significant. This suggests a potential neuroprotective role for phenytoin in acute ON, with the lower NfH at 3 months, when levels secondary to degeneration of the anterior visual pathway are still elevated, but not at 6 months, when levels have normalized.

'Progressive MS - macro views': The need for novel clinical trial paradigms to enable drug development for progressive MS.

This article outlines the principal challenges to establish a standard phase-2 approach for progressive multiple sclerosis (PMS) and presents referring strategies to accelerate the registration process via a guidance approved by regulatory agencies. Accordingly, the contribution of 'big datasets' for a better understanding of the natural history of primary-progressive multiple sclerosis (PPMS) and secondary-progressive multiple sclerosis (SPMS) and of their prognostic factors and the value of novel biomarkers are discussed. The establishment of new industry-academic initiatives, such as independent consortia under the umbrella of Progressive MS Alliance (PMSA), with the endorsement of MS organizations and Scientific Societies (e.g. European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS)) may be crucial to overcome some of the current challenges. Within this frame, the continuous interaction with regulatory agencies is instrumental for the formal validation of the many developments suitable to improve clinical trialling in PMS.

Composite end points to assess delay of disability progression by MS treatments.

BACKGROUND: The Expanded Disability Status Scale (EDSS) has low sensitivity and reliability for detecting sustained disability progression (SDP) in multiple sclerosis (MS) trials. OBJECTIVE: This study evaluated composite disability end points as alternatives to EDSS alone. METHODS: SDP rates were determined using 96-week data from the Olympus trial (rituximab in patients with primary progressive MS). SDP was analyzed using composite disability end points: SDP in EDSS, timed 25-foot walk test (T25FWT), or 9-hole peg test (9HPT) (composite A); SDP in T25FWT or 9HPT (composite B); SDP in EDSS and (T25FWT or 9HPT) (composite C); and SDP in any two (EDSS, T25FWT, and 9HPT) (composite D). RESULTS: Overall agreements between EDSS and other disability measures in defining SDP were 66%-73%. Composite A showed similar treatment effect estimate versus EDSS alone with much higher SDP rates. Composite B, C, and D all showed larger treatment effect estimate with different or similar SDP rates versus EDSS alone. Using composite A (24-week confirmation only), B, C, or D could reduce sample sizes needed for MS trials. CONCLUSION: Composite end points including multiple accepted disability measures could be superior to EDSS alone in analyzing disability progression and should be considered in future MS trials.

Production of B cell stimulatory factor-2 and interferon gamma in the central nervous system during viral meningitis and encephalitis. Evaluation in a murine model infection and in patients.

Synthesis of B cell-stimulating factor-2 (BSF-2) and IFN-gamma was shown in cerebrospinal fluids (CSF) collected from mice with experimental viral meningitis. In the CSF, the level of BSF-2 started to increase 24 h after intracerebral infection with lymphocytic choriomeningitis virus (LCMV) with rapid increase after day 4. IFN-gamma was not detected in the CSF before day 5 or 6 after infection, but increased sharply thereafter. In athymic nude mice, LCMV infection did not result in meningitis, and both BSF-2 and IFN-gamma levels were only slightly and transiently elevated. These findings suggest that activated mature T cells are required for development of disease and production of both BSF-2 and IFN-gamma. As observed in mice, BSF-2 was also detected in 16 out of 19 CSF samples collected from patients with acute viral infections of the central nervous system (CNS). Intrathecal production of BSF-2 and IFN-gamma may be instrumental in local production of antiviral antibodies by B lymphocytes/plasma cells invading the CNS during viral CNS disease.

Genotype-Phenotype correlations in multiple sclerosis: HLA genes influence disease severity inferred by 1HMR spectroscopy and MRI measures.

Genetic susceptibility to multiple sclerosis (MS) is associated with the human leukocyte antigen (HLA) DRB1*1501 allele. Here we show a clear association between DRB1*1501 carrier status and four domains of disease severity in an investigation of genotype-phenotype associations in 505 robust, clinically well characterized MS patients evaluated cross-sectionally: (i) a reduction in the N-acetyl-aspartate (NAA) concentration within normal appearing white matter (NAWM) via (1)HMR spectroscopy (P = 0.025), (ii) an increase in the volume of white matter (WM) lesions utilizing conventional anatomical MRI techniques (1,127 mm(3); P = 0.031), (iii) a reduction in normalized brain parenchymal volume (nBPV) (P = 0.023), and (iv) impairments in cognitive function as measured by the Paced Auditory Serial Addition Test (PASAT-3) performance (Mean Z Score: DRB1*1501+: 0.110 versus DRB1*1501-: 0.048; P = 0.004). In addition, DRB1*1501+ patients had significantly more women (74% versus 63%; P = 0.009) and a younger mean age at disease onset (32.4 years versus 34.3 years; P = 0.025). Our findings suggest that DRB1*1501 increases disease severity in MS by facilitating the development of more T2-foci, thereby increasing the potential for irreversible axonal compromise and subsequent neuronal degeneration, as suggested by the reduction of NAA concentrations in NAWM, ultimately leading to a decline in brain volume. These structural aberrations may explain the significant differences in cognitive performance observed between DRB1*1501 groups. The overall goal of a deep phenotypic approach to MS is to develop an array of meaningful biomarkers to monitor the course of the disease, predict future disease behaviour, determine when treatment is necessary, and perhaps to more effectively recommend an available therapeutic intervention.

PIB is a non-specific imaging marker of amyloid-beta (Abeta) peptide-related cerebral amyloidosis.

The in vivo imaging probe [11C]-PIB (Pittsburgh Compound B, N-methyl[11C]2-(4'-methylaminophenyl-6-hydroxybenzathiazole) is under evaluation as a key imaging tool in Alzheimer's disease (AD) and to date has been assumed to bind with high affinity and specificity to the amyloid structures associated with classical plaques (CPs), one of the pathological hallmarks of the disease. However, no studies have systematically investigated PIB binding to human neuropathological brain specimens at the tracer concentrations achieved during in vivo imaging scans. Using a combination of autoradiography and histochemical techniques, we demonstrate that PIB, in addition to binding CPs clearly delineates diffuse plaques and cerebrovascular amyloid angiopathy (CAA). The interaction of PIB with CAA was not fully displaceable and this may be linked to the apolipoprotein E-epsilon4 allele. PIB was also found to label neurofibrillary tangles, although the overall intensity of this binding was markedly lower than that associated with the amyloid-beta (Abeta) pathology. The data provide a molecular explanation for PIB's limited specificity in diagnosing and monitoring disease progression in AD and instead indicate that the ligand is primarily a non-specific marker of Abeta-peptide related cerebral amyloidosis.

Antiadhesive properties of biological surfaces are protective against stimulated granulocytes.

Despite the fact that a series of endogenous and exogenous inflammatory mediators are potent activators of circulating granulocytes, damage of vascular endothelium, a primary target tissue, is a rather unusual event in systemic inflammatory states. Since mediator-induced neutrophil hyperadhesiveness on plastic tissue culture dishes is invariably accompanied by intense release of lysosomal granule constituents and respiratory burst activation, thus representing a powerful model to investigate neutrophil cytotoxic states, comparative studies with neutrophils suspended in autologous plasma in the presence or absence of N-formyl-Met-Leu-Phe (2.5 microM), the most potent adhesion inducer, were performed on different biologic surfaces. On optimally adherent closed monolayers of cultured endothelial cells or fibroblasts we observed poor stimulation of adhesion as well as minimal granule release and hexose monophosphate pathway activation. Functional behavior of neutrophils on single molecular components of basal laminas such as fibronectin and collagen (type IV) coats was intermediate, with positive adhesion promotion but markedly reduced metabolic activation. When tested on endothelial cell-derived extracellular matrices, neutrophils again showed functional nonresponsiveness to N-formyl-Met-Leu-Phe. Scanning electron microscopy revealed an impressive congruency between the degree of cellular spreading and metabolic activation in the presence of N-formyl-Met-Leu-Phe, with maximally flattened neutrophils on plastic vs. nonspread, polarized cells on monolayers. Identical results were obtained by using other adhesion inducers such as complement-activated plasma or endotoxin. Lack of cell injury by N-formyl-Met-Leu-Phe-exposed neutrophils was corroborated by the absence of tracer release from [111In]tropolonate-labeled endothelium. These results indicate that biologic surfaces possess antiadhesive properties that protect them from cytotoxic damage by stimulated angry phagocytes.

Matrix metalloproteinase upregulation in chronic inflammatory demyelinating polyneuropathy and nonsystemic vasculitic neuropathy.

OBJECTIVE: To determine the expression pattern and cellular source of matrix metalloproteinases (MMPs) in chronic inflammatory demyelinating polyneuropathy (CIDP) and nonsystemic vasculitic neuropathy (NSVN). BACKGROUND: MMPs are endopeptidases involved in tissue destruction and infiltration by immune cells in multiple sclerosis and Guillain-Barré syndrome. Enzyme inhibitors of MMPs attenuate clinical symptoms in corresponding animal models of these diseases. MMP inhibition may therefore be a novel approach for the treatment of CIDP and NSVN. However, the spectrum of MMPs expressed in chronic inflammatory neuropathies has not been established. METHODS: The expression of MMP-2, MMP-3, MMP-7, and MMP-9 in T cells, macrophages, and stromal cells in CIDP, NSVN, and noninflammatory neuropathies (NIN) was quantitated by immunohistochemistry. Results were correlated with clinical and electrophysiologic findings. RESULTS: The production of MMP-2 and MMP-9 is increased in nerve tissue in CIDP and NSVN compared with NIN. T cells are the predominant source of MMP-2 and MMP-9 in CIDP and NSVN, whereas macrophages contribute only to a minor extent. Stromal cells of the perineurium/epineurium are an additional source of MMP-2 in NSVN, but not in CIDP. Expression of MMP-3 and MMP-7 was not detectable in CIDP or NSVN. Expression of MMP-2 and MMP-9 did not correlate with clinical disease activity and electrophysiologic measurements. CONCLUSIONS: The upregulation of MMP-2 and MMP-9 is a specific feature of CIDP and NSVN, and selective inhibitors of these enzymes could be used to prevent inflammatory tissue damage. The similar increase of MMP-2 and MMP-9 in both demyelinating (CIDP) and nondemyelinating (NSVN) neuropathies raises doubts about whether MMPs play a primary role in demyelination.

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in viral meningitis: upregulation of MMP-9 and TIMP-1 in cerebrospinal fluid.

A hallmark of viral meningitis is the invasion of monocytes, lymphocytes and, in the initial phase of the disease, neutrophils into the subarachnoidal space. By their degradation of different macromolecular components in the extracellular connective tissue, matrix metalloproteinases (MMPs) may be essential for the breakdown of the vessel wall in the meninges and the choroid plexus. In this study, the occurrence of MMP-1, MMP-2, MMP-3 and MMP-9 and the two tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2, was monitored in the cerebrospinal fluid (CSF) from patients with viral meningitis. Of the proteinases, MMP-9 was found in 13 of 39 (33%) patients, but not in controls; the levels being correlated with the neutrophil cell number in CSF. The CSF concentration of TIMP-1 was increased three-fold compared to the control group (median 233 ng/ml; range 9.4-1252.5 ng/ml) and was correlated to the levels of total protein in CSF. Of the other MMPs and TIMPs assayed, MMP-2 and TIMP-2 were constitutively expressed and not upregulated in viral meningitis. High levels of MMP-9 and MMP-2, as measured by ELISA, was associated with high proteolytic activity detected in CSF by zymography. In conclusion, invasion of the leukocytes into the CSF compartment in viral meningitis may involve MMP-9, its proteolytic effect likely being controlled by expression of TIMP-1.

Brain tumors: detection of B-cell stimulatory factor-2/interleukin-6 in the absence of oligoclonal bands of immunoglobulins.

24 patients with neoplasia of the central nervous system (CNS-N) were investigated for the presence of B-cell stimulatory factor-2/interleukin-6 (IL-6) in the cerebrospinal fluid (CSF). Whereas IL-6 was detected in 21 (88%) of these CSF samples, only 6% of CSF from non-inflammatory brain diseases and 12% of the samples from multiple sclerosis patients were positive. IL-6 was found in both primary and secondary CNS-N. The presence of IL-6, a cytokine which activates B-lymphocytes to produce high-rate immunoglobulin (Ig) synthesis, is in contrast to the ineffective intrathecal B-cell activation as suggested by the failure to detect oligoclonal bands of Igs in CNS-N.

In pneumococcal meningitis a novel water-soluble inhibitor of matrix metalloproteinases and TNF-alpha converting enzyme attenuates seizures and injury of the cerebral cortex.

Matrix metalloproteinases (MMPs) and TNF-alpha converting enzyme (TACE) contribute to the pathophysiology of bacterial meningitis. To date, MMP-inhibitors studied in models of meningitis were compromised by their hydrophobic nature. We investigated the pharmacokinetics and the effect of TNF484, a water-soluble hydroxamate-based inhibitor of MMP and TACE, on disease parameters and brain damage in a neonatal rat model of pneumococcal meningitis. At 1 mg/kg q6h TNF484 reduced soluble TNF-alpha and the collagen degradation product hydroxyproline in the cerebrospinal fluid. Clinically, TNF484 attenuated the incidence of seizures and was neuroprotective in the cortex. Water-soluble MMP-inhibitors may hold promise in the therapy of bacterial meningitis.

Neurofilament heavy chain in CSF correlates with relapses and disability in multiple sclerosis.

OBJECTIVE: Neurodegeneration is now accepted as a pathologic hallmark of multiple sclerosis (MS). We sought to discover whether CSF levels of neurofilament heavy chain protein (NfH(SMI35)) correlate with disability, disease activity, or specific stages of MS. METHODS: An electrochemiluminescence immunoassay was used to retrospectively measure NfH(SMI35) in CSF of patients with clinically isolated syndrome (CIS) (n = 63), relapsing-remitting multiple sclerosis (RRMS) (n = 39), secondary progressive multiple sclerosis (SPMS) (n = 25), primary progressive multiple sclerosis (PPMS) (n = 23), or controls (n = 73). Cell count and CSF levels of immunoglobulin and albumin were also measured. RESULTS: CSF levels of NfH(SMI35) increased with age in controls (r(s) = 0.50, p < 0.0001) and CIS (r(s) = 0.50, p < 0.0001); this effect was less pronounced in RRMS (r(s) = 0.35, p = 0.027) and absent in SPMS/PPMS. After age correction, NfH(SMI35) levels were found to be higher in all disease stages compared to control. Relapses were associated with higher CSF NfH(SMI35) values compared with stable disease. NfH(SMI35) levels correlated with EDSS scores in patients with CIS and RRMS (r(s) = 0.33, p = 0.001), and during relapse (r(s) = 0.35, p = 0.01); the correlation was most prominent in RRMS during relapse (r(s) = 0.54, p = 0.01). This was not the case for any of the other CSF markers examined. CONCLUSIONS: Neuronal loss is a feature of aging, and the age-dependent increase of CSF NfH(SMI35) suggests that this loss accelerates over time. For MS, increased NfH(SMI35) levels reflect the superimposed presence of further neurodegenerative processes. Evaluation of NfH(SMI35) levels is likely to provide a useful surrogate for measuring the rate of neurodegeneration in MS. Furthermore, the dissociation of NfH(SMI35) levels with biomarkers of inflammation suggests that the mechanisms responsible for their production are at least partly independent.

Gelatinase B [matrix metalloproteinase (MMP)-9] and collagenases (MMP-8/-13) are upregulated in cerebrospinal fluid during aseptic and bacterial meningitis in children.

We investigated the protein expression of gelatinases [matrix metalloproteinase (MMP)-2 and -9] and collagenases (MMP-8 and -13) in cerebrospinal fluid (CSF) from patients with bacterial (BM, n = 17) and aseptic (AM, n = 14) meningitis. In both, MMP-8 and -9 were increased in 100% of patients, whereas MMP-13 was detectable in 53% and 82% respectively. Three patients with clinical signs of meningitis, without CSF pleocytosis, scored positive for all three MMPs. MMP-8 appeared in two isoforms, granulocyte-type [polymorphonuclear cell (PMN)] and fibroblast/macrophage (F/M) MMP-8. Analysis of kinetic changes from serial lumbar punctures showed that these MMPs are independently regulated, and correlate only partly with CSF cytosis or levels of the endogenous inhibitor, tissue inhibitor of matrix metalloproteinase-1. In vitro, T cells, peripheral blood mononuclear cells (PBMCs) and granulocytes (PMN) release MMP-8 and -9, whereas MMP-13 could be found only in the former two cell types. Using models of exogenous (n-formyl-Met-Leu-Phe, T cell receptor cross-linking) and host-derived stimuli (interleukin-2), the kinetics and the release of the MMP-8, -9 and -13 showed strong variation between these immune cells and suggest release from preformed stocks. In addition, MMP-9 is also synthesized de novo in PBMCs and T cells. In conclusion, invading immune cells contribute only partially to MMPs in CSF during meningitis, and parenchymal cells are an equally relevant source. In this context, in patients with clinical signs of meningitis, but without CSF pleocytosis, MMPs seem to be a highly sensitive marker for intrathecal inflammation. The present data support the concept that broad-spectrum enzyme inhibition targeting gelatinases and collagenases is a potential strategy for adjunctive therapy in infectious meningitis.

Differential regulation of metzincins in experimental chronic renal allograft rejection: potential markers and novel therapeutic targets.

Chronic renal allograft rejection is characterized by alterations in the extracellular matrix compartment and in the proliferation of various cell types. These features are controlled, in part by the metzincin superfamily of metallo-endopeptidases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase (ADAM) and meprin. Therefore, we investigated the regulation of metzincins in the established Fisher to Lewis rat kidney transplant model. Studies were performed using frozen homogenates and paraffin sections of rat kidneys at day 0 (healthy controls) and during periods of chronic rejection at day +60 and day +100 following transplantation. The messenger RNA (mRNA) expression was examined by Affymetrix Rat Expression Array 230A GeneChip and by real-time Taqman polymerase chain reaction analyses. Protein expression was studied by zymography, Western blot analyses, and immunohistology. mRNA levels of MMPs (MMP-2/-11/-12/-14), of their inhibitors (tissue inhibitors of metalloproteinase (TIMP)-1/-2), ADAM-17 and transforming growth factor (TGF)-beta1 significantly increased during chronic renal allograft rejection. MMP-2 activity and immunohistological staining were augmented accordingly. The most important mRNA elevation was observed in the case of MMP-12. As expected, Western blot analyses also demonstrated increased production of MMP-12, MMP-14, and TIMP-2 (in the latter two cases as individual proteins and as complexes). In contrast, mRNA levels of MMP-9/-24 and meprin alpha/beta had decreased. Accordingly, MMP-9 protein levels and meprin alpha/beta synthesis and activity were downregulated significantly. Members of metzincin families (MMP, ADAM, and meprin) and of TIMPs are differentially regulated in chronic renal allograft rejection. Thus, an altered pattern of metzincins may represent novel diagnostic markers and possibly may provide novel targets for future therapeutic interventions.

Neurotoxicity of antituberculous drugs in a patient without active tuberculosis.

A 56-year old patient presented 3 months after initiation of an antituberculous regimen with Isoniacid (INH, 5 mg/kg daily), Ethambutol (20 mg/kg daily) and Rifampicin (675 mg daily) a mild sensory polyneuropathy and a bilateral retrobulbar neuritis which progressed to a severe optic atrophy. Multiple hyperintense foci were detected with NMR-imaging in the cerebral white matter suggestive of demyelination. INH and Ethambutol are known for their neurotoxic effects but suggestion was made that neurologic signs may not be due to drug neurotoxicity but could be induced by immunological processes initiated by the tubercle bacillus. In the reported patient the suspected tuberculosis of the urogenital tract was never proved histologically. Most likely his neurological symptoms were therefore cause by the administration of INH and Ethambutol. Patients with a low serum zinc level and a slow acetylation of INH are reported to be at special risk; both factors were present in our patient.

[Pregnancy, contraception and epilepsy]. / Schwangerschaft, Antikonzeption und Epilepsie.

Epilepsy is the most common neurological disease of females in reproductive age. Problems concerning contraception, reproduction, teratogenicity and antiepileptic therapy preceding and during pregnancy are discussed and recommendations made. We underline the advantages of a planned pregnancy with optimal adjustment of antiepileptic drug therapy and recommend prophylactic treatment with folic acid before and during, and with vitamin K towards the end of pregnancy.

PIP: Epilepsy is the most common neurological disease of women of reproductive age. Until the mid 20-th century, its diagnosis meant no possibility of marriage and children. The advances of therapy, however, have assured that most patients can live a normal life. The major points are underscored including the interaction between epilepsy and pregnancy involving the mechanisms of congenital anomalies. The frequency of attacks during pregnancy. Pregnancy complications under epilepsy. Epilepsy and fetal malformations. Pharmacological mechanisms of teratogenicity: epoxides, free radicals, folic acid deficiency, teratogenicity of new antiepileptics and preparation with indications. Pharmacotherapy before and during pregnancy, including contraception in attack-prone patients: oral contraceptives and hormonal abortion (RU-486). Special pharmacokinetics of antiepileptics during pregnancy; dose selection and adjustment, bleeding risk and vitamin K substitution. The planning of pregnancy in epilepsy and prenatal diagnosis. Regarding indications based on existing data, it can be stated that there is a genetically higher risk of congenital malformations with primary epilepsy of parents. The risk of defect depends on the dose and quantity of medications given irrespective of the type of antiepileptics. In stabilized epilepsy, the probability of giving birth to a normal child is over 90%. The risk of congenital defects in the offspring of seizure-prone parents on genetic, and, in the case of antiepileptic therapy on medicament-toxicological grounds, is on the average 2-3 times higher. There is an elevated danger posed for the fetus by the tonic-clonic seizures of the mother through asphyxia and direct injuries by falling. The risk from an uncontrolled epilepsy is higher than the risk of malformation through antiepileptics. It is possible but statistically not proven that valproate results in an increased rate of spina bifida (1% selective risk). Prenatal diagnosis allows detection of early defects to decide on abortion or preterm birth to reduce the neurological deficit.

Matrix metalloproteinases in immunity.

Matrix metalloproteinases (MMPs) are a family of zinc-containing endo-proteinases that share structural domains but differ in substrate specificity, cellular sources, and inducibility. Macrophage production and secretion of large quantities of many MMPs, after contact with matrix proteins, is enhanced by surface determinants on activated T cells and suppressed by cytokines from Th1 and Th2 cells. T cells secrete predominantly the gelatinases MMP-2 and -9, after beta 1, integrin- or vascular cell adhesion molecule (VCAM)-1-dependent stimulation by cytokines and inflammatory mediators. MMPs of both T cells and macrophages facilitate secretion of TNF-alpha, by cleavage of the membrane-bound form. T cell MMPs prepare connective tissue matrices for T cell chemotaxis across basement membranes and through tissues. The greater amounts of diverse MMPs from macrophages are capable of degrading connective tissues, which may release stored growth factors. In limited studies of animal models of autoimmunity, specific MMP inhibitors have significantly decreased edema and inflammatory tissue damage, suggesting possible therapeutic benefits.

Interleukin 15 stimulates production of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 by human peripheral blood mononuclear cells.

In peripheral blood mononuclear cells (PBMC), matrix metalloproteinase (MMP)-9 mediates the extravasation of immune cells and may be involved in tissue destruction during inflammation. We investigated the effect of the pro-inflammatory cytokines interleukin (IL-)12 and 15 on the secretion of MMP-9 in PBMC. IL-15, but not IL-12, induces MMP-9 in PBMC and in T cells. Moreover, the combination of IL-15 and IL-2 had an additive effect. In contrast, both IL-12 and IL-15 induced the release of tissue inhibitor of metalloproteinases (TIMP)-1. IL-15 led to a dose-dependent increase of the MMP-9/TIMP-1 ratio as a measure for increased proteolytic capacity. We conclude that IL-15 mediates its effects in inflammation in part through MMP-9.