Luiz Antonio Rodrigues de Freitas

Clinical Utility of Polymerase Chain Reaction—Based Detection of Leishmania in the Diagnosis of American Cutaneous Leishmaniasis

We evaluated the use of polymerase chain reaction (PCR) for diagnosis of American cutaneous leishmaniasis (ACL) in an area in Bahia, Brazil, where Leishmania braziliensis is endemic. Leishmania DNA was detected in 50 cases, yielding a positivity rate of 100%, which was higher than the rates for all of the other diagnostic methods studied--namely, the Montenegro skin test, anti-Leishmania serological testing, and microscopic examination of lesion biopsy specimens. These findings have led us to propose guidelines for the diagnosis of ACL that use PCR as the principal means of parasitological confirmation of cases.

Differential properties of CBA/J mononuclear phagocytes recovered from an inflammatory site and probed with two different species of Leishmania

While CBA/J mice fail to be permissive to Leishmania amazonensis-driven pathogenic processes, they heal easily following Leishmania major infection. The early-phase events are crucial to the outcome of Leishmania infection and it is known that macrophages (Mphi) are important in infection control. In the present study we investigated the role of Mphi in driving CBA/J susceptibility to L. amazonensis. We performed kinetic studies and compared the capacity of L. amazonensis and L. major to infect Mphi. There was no difference in percentages of infection or parasite burden for 6 h between the two groups. In contrast, after 12 h we observed that infection was about twice as high in L. amazonensis- than in L. major-infected Mphi. In addition, rIFN-gamma added to the cultures induced nitric oxide (NO) production, and did not modify L. amazonensis infection, although the percentage of L. major infection was significantly reduced. This reduction in L. major infection is a TNF-alpha dependent mechanism as L. major-infected Mphi expressed twice as much TNF-alpha mRNA as L. amazonensis-infected cells, and anti-TNF-alpha reversed the IFN-gamma effect. Moreover, rTNF-alpha plus IFN-gamma were able to significantly reduce the percentage of L. amazonensis-infected cells but not to the same extent as in L. major infection. Despite having higher NO production than IFN-gamma-treated cells, AMG addition to IFN-gamma-plus TNF-alpha-treated cells only partially reversed the inhibition in L. major, but not in L. amazonensis infection. Thus, in this study, we demonstrated that L. amazonensis both inactivated and resisted innate and IFN-gamma-induced Mphi killing mechanisms, indicating that the nature of the parasite and its interaction with Mphi could determine immune response polarization.

In vivo lymphocyte activation and apoptosis by lectins of the Diocleinae subtribe

This paper reports the overall effects of three lectins, extracted from Canavalia brasiliensis, Dioclea violacea, and D. grandiflora, on BALB/c mice popliteal draining lymph nodes. These lectins have presented high stimulatory capacity on lymph node T cells. Additionally, they were able to induce apoptosis and inflammation (frequently associated with high endothelial venule necrosis). The data presented here suggest that the Diocleinae lectins studied can stimulate in vivo T cell activation and apoptosis, as well as present important side effects.

Effects of light-to-moderate alcohol consumption on steatosis and steatohepatitis in severely obese patients.

Objectives The effect of light-to-moderate alcohol consumption (LMAC) in nonalcoholic fatty liver disease (NAFLD) remains a controversial subject. The aim of this study was to evaluate the relationship between LMAC and the severity of NAFLD in morbidly obese patients. Methods We studied 132 patients undergoing liver biopsy during bariatric surgery. The patients were divided into three groups: G1: alcohol intake greater than 20 g/day and less than 40 g/day; G2: alcohol intake less than 20 g/day; G3: no alcohol intake. Insulin resistance was defined by the Homeostasis Model Assessment (>3). NAFLD was classified according to the Matteoni types: type I: steatosis alone; type II: steatosis with inflammation; types III–IV: steatosis with ballooning and/or fibrosis. Results The mean age was 37.3±11 years. Sixty-three percent were females and body mass index was 43.9±5.6 kg/m2. G1, G2, and G3 included 19, 56, and 57 patients, respectively. Histological diagnoses classified by levels of alcohol were: G1: 10.5% normal liver, 89.5% type III or IV; G2: 10.7% normal liver, 1.8% type I or II, and 87.5% grade III or IV; G3: 10.5% normal liver, 3.5% type I or II, and 86% type III or IV (one had cirrhosis). The presence of IR was similar in moderate and no alcohol consumption (81.3 and 78.7%) but significantly less in the light consumption group (54%, P<0.05). Conclusion The results suggest that LMAC may have a protection effect against IR in severely obese patients. However, it had no impact on the severity of activity and stage of liver disease.

Intramitochondrial crystalline inclusions in nonalcoholic steatohepatitis

Mitochondrial dysfunction is an important element in the pathogenesis of nonalcoholic steatohepatitis (NASH). Intramitochondrial crystals (IMCs) are a well‐documented morphological abnormality seen on transmission electron microscopy in this disease. It has been suggested that IMCs consist of phospholipids, but their exact composition remain uncertain many years after their discovery. Micellar phase transitions of phospholipid bilayers is a well‐known but little‐studied phenomenon in living systems. Its presence in the mitochondria of NASH would offer significant insight into the disease with possible therapeutic implications. We postulated that intramitochondrial disturbances in NASH are sufficient to produce such transitions and that their detection in fresh biopsies would therefore be a dynamic process. To test this, we performed a blinded, prospective analysis of fresh liver biopsy samples immediately fixed under different conditions. Quantitative transmission electron microscopy morphometry, performed by systematically counting total mitochondria and IMCs within areas of uniform dimension, showed a stepwise decline in IMCs with cooler fixation temperature in each subject studied. Randomization testing (Monte Carlo resampling) confirmed that the detection of IMCs was strongly dependent on fixation temperature (P < 0.0001). Conclusion: These results indicate that the intramitochondrial crystals characteristic of NASH are highly dynamic and unstable structures. The findings offer the strongest support yet for their origin in micellar phase transitions. We speculate that such transitions result from microenvironmental changes within the mitochondria and carry therapeutic implications, especially in regard to dietary manipulations of mitochondrial lipid composition. (HEPATOLOGY 2009.)

Non-alcoholic fatty liver disease and insulin resistance: importance of risk factors and histological spectrum.

Background Non-alcoholic fatty liver disease (NAFLD) has been associated with several metabolic conditions (MC) and secondary causes, but the relationship between insulin resistance (IR) and the underlying aetiology of NAFLD has not been extensively explored. Objective To determine the frequency of IR among NAFLD patients and to describe IR according to risk factors and histological findings of the disease. Methodology A case-series study of 64 patients with clinical and histological diagnosis of NAFLD. IR was calculated by homeostasis model assessment (HOMA) and IR was considered when HOMA ⩾3. Histological grades of NAFLD were: stage 1, steatosis isolated; stage 2, steatosis and inflammation; stage 3, steatosis and ballooning degeneration; stage 4, steatosis and fibrosis and/or Mallory bodies. Fibrosis was graded 0–4 (cirrhosis). Results IR was found in 21 (33%) patients. Among those with IR, 16 patients (76%) had associated MC and five patients (24%) had exposure to petrochemicals. The mean value of HOMA varied from 3.5 in NAFLD associated with MC to 1.6 in patients with exposure to petrochemicals (P<0.03). Waist circumference was the metabolic factor most strongly associated with IR (P<0.005). Steatohepatitis (NASH) was observed in 54 (84.3%) cases. The HOMA mean value was significantly higher in patients with advanced fibrosis. Conclusions IR occurred in 33% of the NAFLD patients, being more frequent among those with MC than among those with exposure to petrochemicals. The presence of IR in cases with advanced fibrosis suggests that it may influence the prognosis of NAFLD.

American Cutaneous Leishmaniasis unresponsive to antimonial drugs: successful treatment using combination of N‐Methilglucamine Antimoniate plus Pentoxifylline

Background American cutaneous leishmaniasis is characterized by single or multiple ulcerations. Cytokines, among other factors, have been shown to influence lesion development and tumoral necrosis factor‐alpha is a major cytokine implicated in pathogenesis of ulcers.

Zika virus infection induces mitosis abnormalities and apoptotic cell death of human neural progenitor cells

Zika virus (ZIKV) infection has been associated with severe complications both in the developing and adult nervous system. To investigate the deleterious effects of ZIKV infection, we used human neural progenitor cells (NPC), derived from induced pluripotent stem cells (iPSC). We found that NPC are highly susceptible to ZIKV and the infection results in cell death. ZIKV infection led to a marked reduction in cell proliferation, ultrastructural alterations and induction of autophagy. Induction of apoptosis of Sox2+ cells was demonstrated by activation of caspases 3/7, 8 and 9, and by ultrastructural and flow cytometry analyses. ZIKV-induced death of Sox2+ cells was prevented by incubation with the pan-caspase inhibitor, Z-VAD-FMK. By confocal microscopy analysis we found an increased number of cells with supernumerary centrosomes. Live imaging showed a significant increase in mitosis abnormalities, including multipolar spindle, chromosome laggards, micronuclei and death of progeny after cell division. FISH analysis for chromosomes 12 and 17 showed increased frequency of aneuploidy, such as monosomy, trisomy and polyploidy. Our study reinforces the link between ZIKV and abnormalities in the developing human brain, including microcephaly.

1,8‐Cineole protects against liver failure in an in‐vivo murine model of endotoxemic shock

The effects of 1,8‐cineole on d‐galactosamine/lipopolysaccharide (GalN/LPS)‐induced shock model of liver injury was investigated in mice. The co‐administration of GalN (700 mg kg−1, i.p.) and LPS (5 μg kg−1, i.p.) greatly elevated serum concentrations of tumour necrosis factor‐α (TNF‐α), alanine aminotransferase and aspartate aminotransferase, and induced massive hepatic necrosis and lethality in 100% of control mice. Pretreatment with 1,8‐cineole (400 mg kg−1, p.o.) and dexamethasone (1 mg kg−1, s.c.),60 min before GalN/LPS, offered complete protection (100%) against the lethal shock and acute elevation in serum TNF‐α and serum transaminases. Hepatic necrosis induced by GalN/LPS was also greatly reduced by both 1,8‐cineole and dexamethasone treatment. The results indicate that 1,8‐cineole protects mice against GalN/LPS‐induced liver injury through the inhibition of TNF‐α production, and suggest that 1,8‐cineole may be a promising agent to combat septic‐shock‐associated pathologies.

Current Status of Stem Cell Therapy for Liver Diseases

Liver failure is one of the main causes of death worldwide and is a growing health problem. Since the discovery of stem cell populations capable of differentiating into specialized cell types, including hepatocytes, the possibility of their utilization in the regeneration of the damaged liver has been a focus of intense investigation. A variety of cell types were tested both in vitro and in vivo, but the definition of a more suitable cell preparation for therapeutic use in each type of liver lesions is yet to be determined. Here we review the protocols described for differentiation of stem cells into hepatocytes, the results of cell therapy in animal models of liver diseases, as well as the available data of the clinical trials in patients with advanced chronic liver disease.