The effect of physical activity on cytokine levels in adults living with type 1 diabetes-a preliminary study.

The aim of this study is to investigate whether physical activity and the level of body fat are factors reducing the level of pro-inflammatory cytokines in people with T1DM. Twenty-five men (27.8 ± 9.4 years old; 178.9 ± 6.9 cm; 80.6 ± 12 kg) and 18 women (28.1 ± 12.5 years old; 162.4 ± 5.5; 63.1 ± 9.9 kg) were divided into four groups based on body fat percentage and level of physical activity (AN-active people with normal body fat; IAN-inactive people with normal body fat; AO-active people with excessive body fat, IAO-inactive people with excessive body fat). The level of cytokines in the blood serum was assessed. The level of IL-8 was higher (measurable) in inactive men, regardless of adiposity degree and in women, only in the inactive group with normal body fat. IL-6 was found only in active men with excessive adiposity. In conclusion, the findings from this study allow to indicate that moderate level of physical activity may contribute to a reduction in the development of systemic low-grade inflammation in patients with T1DM, and thus, may reduce the risk of CVD.

Multiscale characterization of electrospun non-wovens for corneal regeneration: Impact of microstructure on mechanical, optical and biological properties.

The multiscale approach in designing substrates for regenerative medicine endows them with beneficial properties determining their performance in the body. Substrates for corneal regeneration should reveal the proper transparency, mechanical properties and microstructure to maintain the functionality of the regenerated tissue. In our study, series of non-wovens with different fibres orientation (random (R), aligned (A)), topography (shish-kebab (KK), core-shell (CS)) and thickness were fabricated via electrospinning. The samples were assessed for mechanical (static tensile test) and optical properties (spectroscopy UV-Vis). The research evaluated the impact of different microstructures on the viability and morphology of three cell lines (Hs 680, HaCaT and RAW 264.7). The results showed how the fibres arrangement influenced mechanical behaviour of the non-wovens. The randomly oriented fibres were more elongated (up to 50 mm) and had a lower maximum tensile force (up to 0.46 N). In turn, the aligned fibres were characterized by lower elongation (up to 19 mm) and higher force (up to 1.45 N). The conducted transparency tests showed the relation between thickness (of the non-woven and fibres) and morphology of the substrate and light transmission. To simulate the in vivo conditions, prior to the light transmission studies, samples were immersed in water. All the samples exhibited high transparency after immersion in water (>80%). The impact of various morphologies was observed in the in vitro studies. All the samples proved high cells viability. Moreover, the substrate morphology had a significant impact on the orientation and arrangement of the fibroblast cytoskeleton. The aligned fibres were oriented in exactly the same direction. The conducted research proved that, by altering the non-wovens microstructure, the properties can be adjusted so as to induce the desirable cellular reaction. This indicates the high potential of electrospun fibres in terms of modulating the corneal cell behaviour in response to the implanted substrate.

Correlation between porosity and physicochemical and biological properties of electrospinning PLA/PVA membranes for skin regeneration.

Electrospinning is an increasingly popular technique for obtaining scaffolds for skin regeneration. However, electrospun scaffolds may also have some disadvantages, as the densely packed fibers in the scaffold structure can limit the penetration of skin cells into the inner part of the material. Such a dense arrangement of fibers can cause the cells to treat the 3D material as 2D one, and thus cause them to accumulate only on the upper surface. In this study, bi-polymer scaffolds made of polylactide (PLA) and polyvinyl alcohol (PVA) electrospun in a sequential or a concurrent system were investigated in a different PLA:PVA ratio (2:1 and 1:1). The properties of six types of model materials were investigated and compared i.e.; the initial materials electrospun by the sequential (PLA/PVA, 2PLA/PVA) and the concurrent system (PLA||PVA) and the same materials with removed PVA fibers (PLA/rPVA, 2PLA/rPVA, PLA||rPVA). The fiber models were intended to increase the porosity and coherent structure parameters of the scaffolds. The applied treatment involving the removal of PVA nanofibers increased the size of interfibrous pores formed between the PLA fibers. Ultimately, the porosity of the PLA/PVA scaffolds increased from 78 % to 99 %, and the time of water absorption decreased from 516 to 2 s. The change in wettability was induced by a synergistic effect of decrease in roughness after washing out and the presence of residual PVA fibers. The chemical analysis carried out confirmed the presence of PVA residues on the PLA fibers (FTIR-ATR study). In vitro studies were performed on human keratinocytes (HaKaT) and macrophages (RAW264.7), for which penetration into the inner part of the PLAIIPVA scaffold was observed. The new proposed approach, which allows the removal of PVA fibers from the bicomponent material, allows to obtain a scaffold with increased porosity, and thus better permeability for cells and nutrients.

Effect of Ionic and Non-Ionic Surfactant on Bovine Serum Albumin Encapsulation and Biological Properties of Emulsion-Electrospun Fibers.

Emulsion electrospinning is a method of modifying a fibers' surface and functional properties by encapsulation of the bioactive molecules. In our studies, bovine serum albumin (BSA) played the role of the modifier, and to protect the protein during the electrospinning process, the W/O (water-in-oil) emulsions were prepared, consisting of polymer and micelles formed from BSA and anionic (sodium dodecyl sulfate-S) or nonionic (Tween 80-T) surfactant. It was found that the micelle size distribution was strongly dependent on the nature and the amount of the surfactant, indicating that a higher concentration of the surfactant results in a higher tendency to form smaller micelles (4-9 µm for S and 8-13 µm for T). The appearance of anionic surfactant micelles reduced the diameter of the fiber (100-700 nm) and the wettability of the nonwoven surface (up to 77°) compared to un-modified PCL polymer fibers (100-900 nm and 130°). The use of a non-ionic surfactant resulted in better loading efficiency of micelles with albumin (about 90%), lower wettability of the nonwoven fabric (about 25°) and the formation of larger fibers (100-1100 nm). X-ray photoelectron spectroscopy (XPS) was used to detect the presence of the protein, and UV-Vis spectrophotometry was used to determine the loading efficiency and the nature of the release. The results showed that the location of the micelles influenced the release profiles of the protein, and the materials modified with micelles with the nonionic surfactant showed no burst release. The release kinetics was characteristic of the zero-order release model compared to anionic surfactants. The selected surfactant concentrations did not adversely affect the biological properties of fibrous substrates, such as high viability and low cytotoxicity of RAW macrophages 264.7.

The influence of myofascial release on pain and selected indicators of flat foot in adults: a controlled randomized trial.

Flat foot pain is a common complaint that requires therapeutic intervention. Currently, myofascial release techniques are often used in the therapy of musculoskeletal disorders. A group of 60 people suffering from flat feet with associated pain. Patients were assigned to four groups (15 people each): MF-myofascial release, E-the exercise program, MFE-myofascial release and the exercise program, C-no intervention. The rehabilitation program lasted 4 weeks. The NRS scale was used to examine pain intensity and FreeMed ground reaction force platform was used to examine selected static and dynamic foot indicators. Statistically significant pain reduction was obtained in all research. A static test of foot load distribution produced statistically significant changes only for selected indicators. In the dynamic test, statistically significant changes were observed for selected indicators, only in the groups subjected to therapeutic intervention. Most such changes were observed in the MF group. In the dynamic test which assessed the support phase of the foot, statistically significant changes were observed only for selected subphases. Most such changes were observed in the MFE group. Both exercise and exercise combined with myofascial release techniques, and especially myofascial release techniques alone, significantly reduce pain in a flat foot. This study shows a limited influence of both exercises and myofascial release techniques on selected static and dynamic indicators of a flat foot.

Effect of Three Months Pilates Training on Balance and Fall Risk in Older Women.

This study assessed the effect of Pilates exercises on balance and fall risk in older women. Participants comprised 50 older women aged over 60 years, divided randomly into two groups: the experimental group (n = 30), which took part in Pilates sessions two times per week for three months, and the control group (n = 20). The control group did not participate in such sessions but also did not participate in any other rehabilitation programs or additional physical activity except everyday activities. Before and after the training cycle, all women underwent an assessment using Timed Up and Go (TUG), the One Leg Stance Test (OLST), a test performed on a Freestep baropodometric platform, and the tests performed on a Biosway platform. After the training, significantly decreased values of the surface of the ellipse (p = 0.0037) and mean values of velocity (p = 0.0262) for the right foot in the experimental group were observed. The Limits of Stability (LoS) test (p = 0.005) and the Modified Clinical Test of Sensory Interaction on Balance (m-CTSIB) performed on an unstable surface with eyes closed (p = 0.0409) indicated statistically significant changes in the experimental group. None of the above changes were statistically significant in relation to the control group. Pilates training affected the participants' balance by improving LOS and reducing fall risk.

The Influence of the Physiotherapeutic Program on Selected Static and Dynamic Foot Indicators and the Balance of Elderly Women Depending on the Ground Stability.

Seniors are a constantly growing group of people in many societies. It is necessary to develop physiotherapeutic programs to improve their mobility. The aim of this study was to assess the impact of the physiotherapeutic program conducted unstable ground on selected indicators of motor functions of elderly women. Sixty women (60-80 years) participated in the research. Group A (N = 20) underwent a 12-week physiotherapeutic program on stable ground, group B (N = 20) followed an exercise program on unstable ground, and group C (N = 20) (control group) had no therapeutic intervention. The effects of the therapy were assessed by using a FreeMed platform (foot load analysis) and a Biosway balance system. The results were compared using ANOVA (the one-way analysis), the Kruskal-Wallis test and also the post hoc tests (Tukey's test and the multiple comparison test). In group A, a statistically significant change was observed in the static test and balance assessment, in group B this was observed in the static and dynamic foot tests and balance assessment, in group C, no statistical significance was achieved. The authors' physiotherapeutic program had a statistically significant effect on changes in the balance and selected indicators of the motor functions of the examined people. Comparing the results before and after the therapy more improvement changes were noted in women training on an unstable ground compared to women training on a stable ground.

Effects of Process Parameters on Structure and Properties of Melt-Blown Poly(Lactic Acid) Nonwovens for Skin Regeneration.

Skin regeneration requires a three-dimensional (3D) scaffold for cell adhesion, growth and proliferation. A type of the scaffold offering a 3D structure is a nonwoven material produced via a melt-blown technique. Process parameters of this technique can be adapted to improve the cellular response. Polylactic acid (PLA) was used to produce a nonwoven scaffold by a melt-blown technique. The key process parameters, i.e., the head and air temperature, were changed in the range from 180-270 °C to obtain eight different materials (MB1-MB8). The relationships between the process parameters, morphology, porosity, thermal properties and the cellular response were explored in this study. The mean fiber diameters ranged from 3 to 120 µm. The average material roughness values were between 47 and 160 µm, whereas the pore diameters ranged from 5 to 400 µm. The calorimetry thermograms revealed a correlation between the temperature parameters and crystallization. The response of keratinocytes and macrophages exhibited a higher cell viability on thicker fibers. The cell-scaffold interaction was observed via SEM after 7 days. This result proved that the features of melt-blown nonwoven scaffolds depended on the processing parameters, such as head temperature and air temperature. Thanks to examinations, the most suitable scaffolds for skin tissue regeneration were selected.

The influence of the Kinesio Taping on selected ultrasonography measurements, and quality of life in patients with rotator cuff lesions.

The assessment of the six-week influence of Kinesio Taping combined with a rehabilitation on selected ultrasonography measurements, the level of disability, and the quality of life in patients with rotator cuff lesions. 60 participants were randomly assigned into a taping group (KT combined with a six-week rehabilitating protocol) and a control group (only rehabilitation protocol). In all patients the following assessments were performed twice: USG, UEFI and NHP questionnaires. In the examination of the subacromial space and the subacromial bursa in the taping group, no statistical significance was observed. A statistically significant change in the thickness of the muscles was obtained only for the thickness of the infraspinatus in the taping group. A statistically significant change was obtained in the assessment of tendinopathy only for the supraspinatus muscle in both groups. Within both groups a statistically significant difference was observed in the average UEFI and NHP scores; however, the differences in the scores obtained between the groups were not statistically significant. The use of KT with a rehabilitation program did not yield statistically significantly better results in the improvement of selected shoulder region indicators, the function of the upper limb and the quality of life.

Porous poly(lactic acid) based fibres as drug carriers in active dressings.

PURPOSE: The polymeric porous surface of fibres (PLA) may influence the kinetics of release of biologically active compounds (gentamicin, G and ethacridine lactate, R) affecting development of a bacterial biofilm. METHODS: The porous fibres with different morphology were manufactured by the electrospinning method from ternary systems composed of PLA and selected solvents. Fibres morphology was examined using a scanning electron microscopy (SEM), their structure was analyzed by FT-IR ATR spectroscopy and differential scanning calorimetry (DSC). Changes in the drug release profile were measured using ICP/UV-Vis methods and the resulting bactericidal or bacteriostatic properties were tested by two-layer disk diffusion test in relation to various drug incorporation methods. RESULTS: The porous fibres can be applied to produce drug-bearing membranes. The spectroscopic studies confirmed incorporation of gentamicin into the fibres and the presence of ethacridine lactate on their surface. Bimodal fibres distribution (P3) promoted faster release of gentamicin and ethacridine lactate from P3G and P3R materials. The electrospinning process coupled with the vapor induced phase separation influenced the glass transition temperature of the porous polymer fibres. The pre/post-electrospinning modification influenced the glass transition, maximum temperature of cold crystallization and melting point of the porous membrane, compared to the neat polymer. The polylactide fibres with gentamicin showed strong bactericidal effect on Gram-positive bacteria, while fibres with ethacridine lactate were bacteriostatic. CONCLUSIONS: The obtained fibres with complex surface morphology can be used as a membrane in active dressings as they make it possible to control the release profile of the active compounds.

Conjugates of Copper Alginate with Arginine-Glycine-Aspartic Acid (RGD) for Potential Use in Regenerative Medicine.

Current restrictions on the use of antibiotics, associated with increases in bacterial resistance, require new solutions, including materials with antibacterial properties. In this study, copper alginate fibers obtained using the classic wet method were used to make nonwovens which were modified with arginine-glycine-aspartic acid (RGD) derivatives. Stable polysaccharide-peptide conjugates formed by coupling with 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate (DMT/NMM/TosO-), and materials with physically embedded RGD derivatives, were obtained. The materials were found to be characterized by very high antibacterial activity against S. aureus and K. pneumoniae. Cytotoxicity studies confirmed that the materials are not cytotoxic. Copper alginate conjugates with RGD peptides have strong potential for use in regenerative medicine, due to their biocompatibility and innate antibacterial activity.

Challenges in 3D culturing of neutrophils: Assessment of cell viability.

Standard cell culturing on plastic plates (two dimensional (2D) cultures) does not represent the actual microenvironment where cells reside in tissues. The three dimensional (3D) systems, composed of extracellular matrix and/or pure amino acids which form a scaffold for cells, are more accurate in this respect. 3D cultures were primarily developed for cancer cells but there is also a need for their application in studies on inflammatory leukocytes. Herein we describe our approach to study neutrophil-like cells in the 3D system. We describe measures taken to establish a neutrophil-like cell line (nHL-60) and selection of 3D scaffolds (PuraMatrix alone or enriched with collagen type I) for their culturing. We focus on challenges in measurement of neutrophil viability in 3D cultures and based on our data we suggest application of resazurin, rather than tetrazolium-based dyes or trypan blue exclusion, for evaluation of neutrophil viability.

The membrane with polylactide and hyaluronic fibers for skin substitute.

PURPOSE: Skin substitutes are heterogeneous group of scaffolds (natural or synthetic) and cells. We hypothesize that nanofibers with layer composition made of polylactide (PLA) and sodium hyaluronate (HA) obtained using electrospinning method are a good matrix for cell adhesion and proliferation. METHODS: Optimal conditions of electrospinning of PLA and HA nanofibers to create layered compositions (PLA membrane covered with HA nonwovens) were determined by modifying parameters such as the appropriate amount of solvents, polymer concentration, mixing temperature and electrospinning process conditions. By changing the parameters, it was possible to control the diameter and properties of both polymer fibers. The spinning solution were characterized by surface tension and rheology. A scanning electron microscope (SEM) was used to determine the morphology and fiber diameters: PLA and HA. Structure of the PLA/HA nonwoven was analyzed using spectroscopy (FTIR/ATR). Biocompatibility of the nonwoven with fibroblasts (ECM producers) was assessed in the in vitro conditions. RESULTS: The results showed that stable conditions for the formation of submicron PLA fibers were obtained using a 13% wt. solution of the polymer, dissolved in a 3:1 mixture of DCM:DMF at 45 °C. The hyaluronic fibers were prepared from a 12% wt. solution of the polymer dissolved in a 2:1 mixture of ammonia water and ethyl alcohol. All materials were biocompatible but to a different degree. CONCLUSIONS: The proposed laminate scaffold was characterized by a hydrophobic-hydrophilic domain surface with a maintained fiber size of both layers. The material positively underwent biocompatibility testing in contact with fibroblasts.

Comparison of Selected Morphological, Rheological and Biochemical Parameters of Winter Swimmers' Blood at the End of One Winter Swimming Season and at the Beginning of Another.

The aim of the study was to examine potential differences in the morphological, rheological and biochemical blood parameters of winter swimmers who remained physically active during the period between the end of one winter swimming season and the beginning of another. The study included a group of healthy winter swimmers (n = 17, all between 30 and 60 years of age). Six months following the end of winter season, the levels of mean corpuscular hemoglobin concentration and mean corpuscular hemoglobin turned out to be significantly higher, while erythrocyte count and hematocrit level significantly lower than at the baseline. Moreover, the break in winter swimming was reflected by a significant increase in median erythrocyte elongation index at all shear stress levels ≥ 1.13 Pa. The only significant changes in biochemical parameters of the blood pertained to an increase in the concentration of transferrin and to a decrease in the total protein, albumin and beta-1 globulin concentrations. Seasonal effort of winter swimmers between the end of one winter swimming season and the beginning of another has a positive influence on morphological, rheological and biochemical blood parameters.

Oxygen plasma surface modification augments poly(L-lactide-co-glycolide) cytocompatibility toward osteoblasts and minimizes immune activation of macrophages.

Here, we report on modification of one of the model biomedical polymers, poly L-lactide-co-glycolide (PLGA; 85:15), by reactive ion etching (RIE) oxygen plasma treatment. PLGA's major disadvantage is high hydrophobicity which restrains binding of cell-adhesive proteins and host cells. In the current approach, we aimed to answer two questions: (1) will only short (10 s) and moderate (20-200 mTorr, 45-90 W) RIE oxygen plasma treatment, leading to decrease of water contact angle by only up to 10°, sufficiently improve PLGA adherence to cells, and (2) how will this affect osteoblasts and activation of the immune system? All obtained modified PLGAs had improved hydrophilicity but unaltered roughness (as revealed by water contact angle measurements, X-ray photoelectron spectroscopy, and atomic force microscopy) resulting in significantly improved adhesion of osteoblasts (MG-63) and their low activation. Importantly, macrophages (RAW 264.7), one of the key cells initiating inflammation and bone resorption, responded significantly less vigorously to the modified polymers, expressing/releasing lower amounts of nitric oxide, matrix metalloproteinases (MMP-9), and pro-inflammatory cytokines (TNF-α, IL-6, IL-12p70, IFN-γ, IL-10). We conclude that already slight RIE oxygen plasma modification of PLGA is sufficient to improve its surface properties, and enhance cytocompatibility. Most importantly, this type of modification prevents excessive immune response.

Impact of poly(L-lactide) versus poly(L-lactide-co-trimethylene carbonate) on biological characteristics of fibroblasts and osteoblasts.

Bone tissue loss due to injury or disease often requires application ofautologous tissue grafts or artificial biomaterials to fill the fracture. Synthetic biomaterials provide temporary structural support for bone tissue and can be subsequently colonized by host tissue-specific cells. One of the most investigated groups of biomaterials are degradable polymers that naturally decompose in tissues with time. In particular aliphatic polyesters such as polylactides were reported to fulfill biocompatibility requirements as they induce a minor or lack an immune response and integrate with the surrounding tissue. Here we report on the biological effects of two polymers: poly(L-lactide) (PLLA) and a copolymer of L-lactide and trimethylene carbonate (PLTMC) on osteoblasts (MG-63) and fibroblasts (L-929). Osteoblasts are bone forming cells that are in the closest contact with the potential implant while fibroblasts produce the stroma forming the extracellular matrix (ECM) and along with macrophages initiate inflammation. We detected that both types of cells adhered better to PLLA than to PLTMC which might be related to the more rough surface of the former. However, both polymers, but especially PLTMC, increased apoptotic death of both cell types. Moreover, in contrast to PLLA, PLTMC modulated the production of some immune-related mediators by fibroblasts: it increased nitric oxide production and synthesis of numerous pro-inflammatory factors, cytokines (TNF-a and IL-6) activating leukocytes, and ECM-degrading MMP-9 which facilitates leukocyte migration. Thus, overall, our data suggest that PLTMC is less cytocompatible than PLLA.

Fibrous polymeric composites based on alginate fibres and fibres made of poly-ε-caprolactone and dibutyryl chitin for use in regenerative medicine.

This work concerns the production of fibrous composite materials based on biodegradable polymers such as alginate, dibutyryl chitin (DBC) and poly-ε-caprolactone (PCL). For the production of fibres from these polymers, various spinning methods were used in order to obtain composite materials of different composition and structure. In the case of alginate fibres containing the nanoadditive tricalcium phosphate (TCP), the traditional method of forming fibres wet from solution was used. However in the case of the other two polymers the electrospinning method was used. Two model systems were tested for biocompatibility. The physicochemical and basic biological tests carried out show that the submicron fibres produced using PCL and DBC have good biocompatibility. The proposed hybrid systems composed of micrometric fibres (zinc and calcium alginates containing TCP) and submicron fibres (DBC and PCL) meet the requirements of regenerative medicine. The biomimetic fibre system, the presence of TCP nanoadditive, and the use of polymers with different resorption times provide a framework with specific properties on which bone cells are able to settle and proliferate.

Surface characterization, collagen adsorption and cell behaviour on poly(L-lactide-co-glycolide).

Poly(L-lactide-co-glycolide) (PLG) was modified through the adsorption of collagen to improve the behaviour of fibroblasts and osteoblasts. As reference materials cell-resistant polystyrene (PS) and cell-conductive tissue-culture polystyrene (TCPS) were also evaluated. The physicochemical surface properties of the materials were studied by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle measurements. The morphology of cells was examined using optical microscopy, while their growth was evaluated by both crystal violet and MTT tests. Nitric oxide level and protein concentration were tested in cell supernatants. The results showed that the adsorbed amount and the organization of the adsorbed collagen were influenced by surface hydrophobicity. Cell culture experiments on native substrates revealed that cell attachment, spreading and growth enhanced, depending on the substrate, in the following order: PS

Enhanced early vascular permeability in gelatinase B (MMP-9)-deficient mice: putative contribution of COX-1-derived PGE2 of macrophage origin.

Increased vascular permeability leading to vascular leakage is a central feature of all inflammatory reactions and is critical for the formation of an inflammatory exudate. The leakage occurs because of gap formation between endothelial cells and breakdown of the basement membrane barriers. The present study aimed to investigate the role of gelatinase B [matrix metalloproteinase 9 (MMP-9)], known to be involved in neutrophil exudation, in changes of vascular permeability at the early stages of acute zymosan peritonitis. We show that although MMP-9 is being released already within the first minutes of peritonitis, its lack, induced pharmacologically or genetically, does not decrease but rather increases vasopermeability. In mice treated with an inhibitor of gelatinases (A and B), a tendency to increased vasopermeability existed, and in MMP-9-/- mice [knockout (KO)], the difference was statistically significant in comparison with their controls. Moreover, in intact KO mice, significantly augmented production of prostaglandin E(2) (PGE(2)) of cyclooxygenase 1 (COX-1) origin was detected, and depletion of peritoneal macrophages, but not mast cells, decreased vasopermeability in KO mice. Thus, the increase of vasopermeability observed on KO mice is a result of the increased production of COX-1-derived PGE(2) by peritoneal macrophages. We conclude that genetic deficiency in gelatinase B might lead to the development of a compensatory mechanism involving the COX pathway.

Gelatinase B/matrix metalloproteinase-9 contributes to cellular infiltration in a murine model of zymosan peritonitis.

Murine zymosan-induced peritonitis represents a well-defined model of acute inflammation. However, the molecular mechanisms by which leukocytes degrade basement membranes during extravasation into the peritoneum are not clear. Gelatinase B (MMP-9) is thought to participate in cellular migration, yet its role in leukocyte transmigration through endothelia during inflammation remains controversial. The aim of the present study was to evaluate the role of MMP-9 in the cell influx during zymosan-induced experimental peritonitis. In zymosan-treated Balb/c mice MMP-9 and its natural inhibitor (tissue inhibitor of metalloproteinase 1 - TIMP-1) were present in the peritoneal fluid and plasma at the time of peritoneal neutrophil (polymorphonuclear leukocyte - PMN) infiltration and persisted there until the time of monocytes/macrophages influx. To probe the function of gelatinases, gelatinase B-deficient mice (MMP-9(-/-)) were used as well as Balb/c mice treated with cyclic CTTHWGFTLC (INH), a specific peptide inhibitor of gelatinases. The studies revealed that in either group of mice deprived of MMP-9 activity, PMN infiltration was impaired at the time of their maximal extravasation (6h) while tumor necrosis factor alpha (TNF-alpha), cytokine-induced neutrophil chemoattractant (KC) and interleukin 10 (IL-10) levels were not changed. At later stages (24 h post-zymosan) a significant increase in PMNs was observed in MMP-9(-/-) mice, but not in the inhibitor-treated mice, in comparison to their respective controls. Moreover, intraperitoneal (i.p.) injection of recombinant mouse pro-MMP-9 induced leukocyte accumulation in peritoneum. Collectively, the findings indicate that gelatinase B participates in leukocyte transmigration; however, its function can be compensated by other mechanisms.