Luís Cristóvão Porto

Mechanical forces induce scar remodeling. Study in non-pressure-treated versus pressure-treated hypertrophic scars.

Reparative process of second and third degree burns usually results in hypertrophic scar formation that can be treated by pressure. Although this method is efficient, its mechanisms of action are not known. In this work, we have studied the histological organization of hypertrophic scars submitted to pressure. Skin biopsies were performed 2 to 7 months after the onset of treatment in two adjacent regions of the scar, non-pressure- or pressure-treated and analyzed by immunohistochemistry and transmission electron microscopy for extracellular matrix organization and cellular morphology. In non-pressure-treated regions, fibrillin deposits did not present the classical candelabra-like pattern under epidermis and were reduced in dermis; in pressure-treated regions the amount was increased compared to non-pressure-treated regions but the organization was still disturbed. In non-pressure-treated regions, elastin was present in patch deposits; in pressure-treated regions elastin formed fibers, smaller than in normal dermis. Tenascin was present in the whole dermis in non-pressure-treated regions, whereas in pressure-treated regions it was observed only under epidermis and around vessels, as in normal skin. alpha-Smooth muscle actin-expressing myofibroblasts were absent in normal skin, present in large amounts in non-pressure-treated regions, and almost absent in pressure-treated regions. The disturbed ultrastructural organization of dermal-epidermal junction observed in non-pressure-treated regions disappeared after pressure therapy; typical features of apoptosis in fibroblastic cells and morphological aspects of collagen degradation were observed in pressure-treated regions. Our results show that, in hypertrophic scars, pressure therapy restores in part the extracellular matrix organization observed in normal scar and induces the disappearance of alpha-smooth muscle actin-expressing myofibroblasts, probably by apoptosis. We suggest that the pressure acts by accelerating the remission phase of the postburn reparative process.

Emphysema and metalloelastase expression in mouse lung induced by cigarette smoke.

Cigarette smoke (CS) causes pulmonary emphysema in humans and elastin degradation plays a key role in its pathogenesis. Previous studies on CS-exposed animals have been equivocal and have not clearly demonstrated the progression of the disease. In this study, morphometry was used to assess lung modifications to alveolar septa, airspaces, elastic and collagen fibers, and alveolar macrophages. Male (n = 40) C57/BL6 mice were exposed 3 times/day, whole body, to CS from three cigarettes for 10, 20, 30, or 60 days. Control groups (n = 10) were sham-smoked or received no exposure (day 0, n = 10). Morphometry included measurements of volume fraction of alveolar septa and airspaces, elastic and collagen fibers, and surface fraction of elastic fibers and alveolar septa. Morphometrical differences in mice after 60 days of exposure were greater than those after 10, 20, or 30 days, suggesting a progression of the disease. Inflammatory lesions in the lungs of mice contained significantly more metalloelastase (MMP-12) in macrophages at 10, 20, and 30 days than in controls of mice exposed for 60 days. These results suggest that elastin degradation took place during development of pulmonary changes in mice exposed to CS, and activation of MMPs specific for elastin may be a determining factor for susceptibility to emphysema.

Age-related changes in natural killer cell receptors from childhood through old age

Most studies on natural killer (NK) cells and aging have focused on overall cell numbers and global cytotoxic activity. NK cell functions are controlled by surface receptors belonging to three major families: killer cell immunoglobulin-like receptors (KIRs), natural cytotoxicity receptors (NCRs), and C-type lectins. The expression of these receptors was investigated from childhood through old age in T, NKT- and NK cells and also in the CD56(dim) (cytotoxic) and CD56(bright) (responsible for cytokine production) NK cell subsets. A decrease in the expression of activating receptors (NKp30 and NKp46) was observed in NK cells in elderly individuals. KIR expression was increased only in the CD56(bright) subset. Children presented similar results regarding expression of NKp30 and KIR, but not NKp46. NKG2D expression was decreased in T cells of elderly subjects. Analysis of KIR genotype revealed that KIR2DL5 and KIR2DS3 were significantly associated with old age. Cytotoxic activity was preserved from childhood through old age, suggesting that the increase of the absolute number of CD56(dim), observed in elderly, may represent a compensatory mechanism for the receptor expression alterations. This initial study provides the framework for more focused studies of this subject, which are necessary to determine whether the changing balance of NK receptor expression may influence susceptibility to infectious, inflammatory, and neoplastic diseases.

Fibrillin-1 and elastin are differentially expressed in hypertrophic scars and keloids

Hypertrophic scars and keloids are two forms of excessive cutaneous scarring. Considering the importance of extracellular matrix elements in tissue repair, a morphological and quantitative analysis of the elastic system components (fibrillin‐1 and elastin) was performed in normal skin, normal scars, hypertrophic scars, and keloids. In superficial and deep dermis, fibrillin‐1 volume density was significantly higher in normal skin compared with normal scars, hypertrophic scars, and keloids. The fibrillin‐1 volume density did not show differences between hypertrophic scars and keloids in superficial or deep dermis. In superficial dermis, elastin volume density was higher in normal skin compared with normal scars, hypertrophic scars, and keloids. In deep dermis, the elastin volume density was higher in keloids compared with normal skins, normal scars, and hypertrophic scars. We showed that the distribution of fibrillin‐1 and elastin is disrupted in all kinds of scars analyzed, but there are two patterns: one for normal scars and another for excessive scars.

Oxidative stress in mouse plasma and lungs induced by cigarette smoke and lipopolysaccharide

Short-term exposure to cigarette smoke (CS) or lipopolysaccharide (LPS) leads to acute lung inflammation through oxidant-antioxidant imbalance. We studied the response in mice exposed to smoke or LPS during five consecutive days, as measured by superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, as well as lipid peroxidation and nitric oxide levels in bronchoalveolar lavage fluid (BALF), lung homogenates, and plasma. Control mice were exposed to ambient air. Exposure to CS or LPS led to a similar influx of alveolar macrophages and neutrophils into the BALF; however, hydroxyproline levels were increased only in the CS group (p<0.001); SOD activity was increased in the BALF (p<0.001) and lung homogenates (p<0.05) of the CS group but was decreased in the BALF (p<0.05), lung homogenates (p<0.05) and plasma (p<0.01) of the LPS group. CAT activity was increased in the BALF (p<0.01), lung homogenates (p<0.001) and plasma (p<0.05) of the CS group but decreased in the BALF (p<0.001) and plasma (p<0.05) of the LPS group. GPx activity was reduced in the BALF (p<0.01) and plasma (p<0.01) of both the CS and LPS groups. Lipid peroxidation was increased in the BALF (p<0.001) and lung homogenates (p<0.001) of the CS group. Finally, the levels of nitrite were reduced in the CS (p<0.01) and LPS (p<0.001) groups. Our data show that the activity profiles of enzymes contributing to oxidant-antioxidant imbalance in the lungs differ depending on the inflammatory stimulus, and that SOD, CAT and GPx may be useful markers of oxidative stress in acute lung inflammation induced by exposure to CS.

Evaluation of trehalose and sucrose as cryoprotectants for hematopoietic stem cells of umbilical cord blood.

Bone marrow transplantation (BMT) is a therapeutic procedure that involves transplantation of hematopoietic stem cells (HSC). To date, there are three sources of HSC for clinical use: bone marrow; mobilized peripheral blood; and umbilical cord blood (UCB). Depending on the stem cell source or type of transplantation, these cells are cryopreserved. The most widely used cryoprotectant is dimethylsulfoxide (Me(2)SO) 10% (v/v), but infusion of Me(2)SO-cryopreserved cells is frequently associated with serious side effects in patients. In this study, we assessed the use of trehalose and sucrose for cryopreservation of UCB cells in combination with reduced amounts of Me(2)SO. The post-thawed cells were counted and tested for viability with Trypan blue, the proportion of HSC was determined by flow cytometry, and the proportion of hematopoeitic progenitor cells was measured by a colony-forming unit (CFU) assay. A solution of 30mmol/L trehalose with 2.5% Me(2)SO (v/v) or 60mmol/L sucrose with 5% Me(2)SO (v/v) produced results similar to those for 10% (v/v) Me(2)SO in terms of the clonogenic potential of progenitor cells, cell viability, and numbers of CD45(+)/34(+) cells in post-thawed cord blood cryopreserved for a minimum of 2 weeks. Thus, cord blood, as other HSC, can be cryopreserved with 1/4 the standard Me(2)SO concentration with the addition of disaccharides. The use of Me(2)SO at low concentrations in the cryopreservation solution may improve the safety of hematopoietic cell transplantation by reducing the side effects on the patient.

Vascularization pattern in hypertrophic scars and keloids: a stereological analysis.

Wound healing is a complex process that does not always occur harmoniously and may lead to pathological scar development, such as hypertrophic scars and keloids. Considering that vascularization can play a role in the development of these scars, and that the literature is controversial, we performed a stereological analysis of dermal for vessels of normal skin, normal scars, hypertrophic scars, and keloids. The parameters studied concerned vessels: surface density, length density; for vessels and myofibroblasts: volume density, in papillary and reticular dermis. The pattern of dermal vascularization in normal skin and normal scar showed no differences. In papillary demis, the number of vessels was higher in hypertrophic scars and keloids than in normal skin (p < 0.05). Vessels of hypertrophic scars were more dilated than those of normal skin (p < 0.01). In reticular dermis, vessels were present in higher amount in hypertrophic scars and keloids than in normal skin (p < 0.025; p < 0.001, respectively). The pattern of vascularization did not show any differences between hypertrophic scars and keloids. Our results show that hypertrophic scars and keloids have a distinct pattern of vascularization compared to normal skin and normal scars. This indicates that abnormal vascularization can be involved in the development of hypertrophic scars and keloids.

Mate tea reduced acute lung inflammation in mice exposed to cigarette smoke

OBJECTIVE Short-term cigarette smoke exposure has been associated with acute lung inflammation (ALI) and oxidative damage. We studied mate tea (Ilex paraguariensis infusion) as a possible nutritional resource for ALI. METHODS C57BL/6 mice (n = 30) were administered with mate tea orally (150 mg/kg, CSMO), mate tea intraperitonially (150 mg/kg, CSMIP), or the vehicle (CS) and then exposed to cigarette smoke for 5 d (six cigarettes per day). The control group was sham-smoked (n = 30). One day after the final exposure, mice were sacrificed. Bronchoalveolar lavages were performed and lungs removed for biochemical (lung homogenates) and histologic analyses. RESULTS Mate tea reduced the increase of alveolar macrophages and neutrophils in bronchoalveolar lavages (cells x 10(3)/mL) of the CSMO (214.3 +/- 21.4 and 12.2 +/- 4.9) and CSMIP (248.3 +/- 11.1 and 12.1 +/- 2.3) groups compared with the CS group (425.9 +/- 28.1 and 140.5 +/- 20.1). Mate tea reduced lipid peroxidation (the control group was considered 100%) and tumor necrosis factor-alpha (picograms per milliliter) in the CSMO group (61.3 +/- 11.3 and 185.3 +/- 21.8) compared with the CS group (150.0 +/- 18.1 and 242.3 +/- 13.2). Matrix metalloprotease-9 activity was higher in the CS group and lower in the CSMO group. Oxidative and inflammatory markers in the CSMO group were not different from those in the control group. CONCLUSION These data imply a potential antioxidant role for mate tea on ALI. Further studies are needed to determine such mechanisms and to explore its potential as an anti-inflammatory and nutritional resource in lung damaged by cigarette smoke exposure.

Effects of Euterpe oleracea Mart. (AÇAÍ) extract in acute lung inflammation induced by cigarette smoke in the mouse

Short term inhalation of cigarette smoke (CS) induces significant lung inflammation due to an imbalance of oxidant/antioxidant mechanisms. Açai fruit (Euterpe oleracea) has significant antioxidant and anti-inflammatory actions. The present study aimed to determine whether oral administration of an açai stone extract (ASE) could reduce lung inflammation induced by CS. Thirty C57BL/6 mice were assigned to three groups (n=10 each): the Control+A group was exposed to ambient air and treated orally with ASE 300 mg/kg/day; the CS group was exposed to smoke from 6 cigarettes per day for 5 days; and the CS+A group was exposed to smoke from 6 cigarettes per day for 5 days and treated orally with ASE (300 mg/kg/day). On day 6, all mice were sacrificed. After bronchoalveolar lavage, the lungs were removed for histological and biochemical analyses. The CS group exhibited increases in alveolar macrophage (AMs) and neutrophil numbers (PMNs), myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase activities (GPx), TNF-α expression, and nitrites levels in lung tissue when compared with the control ones (p<0.001 for all parameters). The AMs, PMNs, MPO, SOD, CAT, GPx and nitrite were significantly reduced by oral administration of ASE when compared with CS group (p<0.001 for all parameters, with exception of AMs p<0.01). The present results suggested that systemic administration of an ASE extract could reduce the inflammatory and oxidant actions of CS. Thus, the results of this study in mice should stimulate future studies on ASE as a potential agent to protect against CS-induced inflammation in humans.

Report from the killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop: worldwide variation in the KIR loci and further evidence for the co-evolution of KIR and HLA

The killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop (IHIWS) sought to explore worldwide population variation in the KIR loci, and to examine the relationship between KIR genes and their human leukocyte antigen (HLA) ligands. Fifteen laboratories submitted KIR genotype and HLA ligand data in 27 populations from six broad ethnic groups. Data were analyzed for correlations between the frequencies of KIR and their known HLA ligands. In addition, allelic typing was performed for KIR2DL2 and 3DL1 in a subset of populations. Strong and significant correlations were observed between KIR2DL2, 2DL3 genotype frequencies and the frequency of their ligand, HLA-C1. In contrast, only weak associations were seen for 3DL1, 3DS1 and the HLA-Bw4 ligand. Although some aspects of the correlations observed here differ from those reported in other populations, these data provide additional evidence of linked evolutionary histories for some KIR and HLA loci. Investigation of allele-level variation for the B haplotype locus KIR 2DL2 showed that two alleles, *001 and *003, predominate in all populations in this study. Much more allelic variation was observed for the A haplotype locus 3DL1, with several alleles observed at moderate frequencies and extensive variation observed between populations.