Galectin-3: A Friend but Not a Foe during Trypanosoma cruzi Experimental Infection.

Trypanosoma cruzi interacts with host cells, including cardiomyocytes, and induces the production of cytokines, chemokines, metalloproteinases, and glycan-binding proteins. Among the glycan-binding proteins is Galectin-3 (Gal-3), which is upregulated after T. cruzi infection. Gal-3 is a member of the lectin family with affinity for ß-galactose containing molecules; it can be found in both the nucleus and the cytoplasm and can be either membrane-associated or secreted. This lectin is involved in several immunoregulatory and parasite infection process. Here, we explored the consequences of Gal-3 deficiency during acute and chronic T. cruzi experimental infection. Our results demonstrated that lack of Gal-3 enhanced in vitro replication of intracellular parasites, increased in vivo systemic parasitaemia, and reduced leukocyte recruitment. Moreover, we observed decreased secretion of pro-inflammatory cytokines in spleen and heart of infected Gal-3 knockout mice. Lack of Gal-3 also led to elevated mast cell recruitment and fibrosis of heart tissue. In conclusion, galectin-3 expression plays a pivotal role in controlling T. cruzi infection, preventing heart damage and fibrosis.

More resistant tendons obtained from the association of Heteropterys aphrodisiaca and endurance training.

BACKGROUND: Popular Brazilian medicine uses Heteropterys aphrodisiaca infusion as a tonic or stimulant, for the treatment of nervous debility and breakdown and for muscle and bone weakness. This study investigated the effects of Heteropterys aphrodisiaca infusion on the tendon properties and extracellular matrix of rats under endurance training. METHODS: Wistar rats were grouped as follows: CS- control sedentary, HS- H. aphrodisiaca sedentary, CT-control trained, HT- H. aphrodisiaca trained. The training protocol consisted in running on a motorized treadmill, five times a week, with weekly increase in treadmill speed and duration. Control groups received water while the HS and HT groups received H. aphrodisiaca infusion, daily, by gavage for the 8 weeks of training. Achilles tendons were frozen for biochemical and biomechanical analysis or preserved in Karnovsky's fixative, then processed for histomorphological analysis with light microscopy. RESULTS: Biomechanical analysis showed significant increase in maximum load, maximum stress, modulus of elasticity and stiffness of the HT animals' tendons. The metalloproteinase-2 activity was reduced in the HT group. The compression region of HT animals' tendons had a stronger and more intense metachromasy, which suggests an increase in glycosaminoglycan concentration in this region of the tendon. The most intense birefringence was observed in both compression and tension regions of HT animals' tendons, which may indicate a higher organizational level of collagen bundles. The hydroxyproline content increased in the HT group. CONCLUSIONS: The association of endurance training with H. aphrodisiaca resulted in more organized collagen bundles and more resistant tendons to support higher loads from intense muscle contraction. Despite the clear anabolic effects of Heteropterys aphrodisiaca and the endurance exercise association, no side effects were observed, such as those found for synthetic anabolic androgenic steroids.

Structural and biochemical analysis of the effect of immobilization followed by stretching on the calcaneal tendon of rats.

Little is known about the stretching effects on the biochemical and morphological features of tendons submitted to a long period of immobilization. Our purpose was to evaluate the response of rat tendons to stretching procedures after immobilization. The animals were separated into five experimental groups: GI--control of immobilized and euthanized animals; GII--immobilized and euthanized animals; GIII--control of immobilized animals and afterward stretched or allowed free cage activity; GIV--immobilized and stretched animals; and GV--immobilized and allowed free cage activity. Analysis in SDS-PAGE showed no remarkable differences among the groups, but a prominent collagen band was observed in GV, as compared to GIV and the control group, both in the compression and tension regions. Hydroxyproline content was highest in the compression region of GII. No differences among the groups were observed in the tension region. In regard to the concentration of noncollagenous proteins, differences were detected only in the tension region, where larger concentrations were found in the GII. When GII and GIV were compared, highest values were found in the GII. A more abundant presence of sulfated glycosaminoglycans, especially chondroitin sulfate, was detected in GIV, at the compression region of tendons. The presence of dermatan sulfate was outstanding in the compression and tension regions of the GII and GV groups. In the Ponceau SS stained sections, analyzed under polarization microscopy, GII exhibited the highest disorganization of the collagen bundles, partially recovered after stretching or with only remobilization. Our results indicate that a revision in the stretching procedures, in terms of duration and periodicity of the sessions, could benefit the efficiency of the stretching in cases of previous immobilization of tendons.