Mechanisms of programmed cell death associated to severe dengue in human renal lesions.

Dengue virus (DENV) is a global health problem. Severe dengue can manifest with hemorrhage and signs of organ dysfunction, including the kidneys. The innate immune system is an important barrier against arbovirus infection and, specifically in dengue, the cytokines IL1ß and IL18 and caspase-1 activation make up a set of host immune strategies. Cell death mechanisms include pyroptosis, necroptosis and autophagy, each with peculiar markers: gasdermin, RIPK3/MLKL, LC3, respectively. In DENV infection, necrosis and apoptosis are involved and, when infecting monocytes and macrophages in vitro, DENV is capable of inducing pyroptosis. Our objective was to explore the presence of markers of necroptosis, pyroptosis and autophagy in renal lesions caused by DENV. MATERIAL AND METHODS: twenty specimens of lesions from patients who died due to DENV infection, from the pathology department of Hospital Guilherme Álvaro, Santos, SP, were subjected to histological and immunohistochemical studies. Histological sections were stained with hematoxylin-eosin to evaluate tissue changes or collected for research with antibodies: anti-DENV (Instituto Evandro Chagas-PA), RIPK3 (NBP2-45592), MLKL (ab184718), gasdermin D (#36425), LC3 (14600-AP), caspase 1 (#98033), IL1ß (AF201-NA) and IL18 (SC6178). Semi-quantitative analysis was performed on 20 glomeruli and evaluation on tubules and mononuclear cells. This study was approved by the ethics committee of the USP Faculty of Medicine. RESULTS: histological analysis demonstrated glomerular congestion, glomerulitis (medium to severe), acute kidney injury and hyalinization of the glomeruli. Viral antigens were visualized on mononuclear cells. LC3 (autophagy) expression ranged from moderate to intense (++/+++) in glomeruli, tubules and mononuclear cells. The expression of gasdermin (pyroptosis) was mild (+) in most cases in the glomeruli and moderate (++) in the tubules. RIPK3 and MLKL (necroptosis) mild in tubules and mononuclear cells (+). The expression of the cytokines IL1ß and IL18 and caspase 1 was moderate (++). Statistical analysis showed greater expression of LC3 over the others. CONCLUSIONS: Our results contribute to the understanding of the pathogenesis of renal involvement in severe dengue, considering the likely anti-viral mechanism of autophagy. To a lesser extent, pyroptosis is also present, corroborating previous data.

Characterization of the Th17 profile immune response in cases of human rabies transmitted by dogs and its interference in the disease pathogenesis.

The Th17 profile immune response is influenced by the presence of cytokines such as IL-1, IL-6, TGF-ß, IL-17, and IL-23. We sought to characterize the Th17 profile in CNS samples from human rabies cases transmitted by dogs and examine its possible influence on disease pathogenesis. We observed a high expression of TGF-ß, followed by IL-23, IL-17 and IL-6, and a low expression of IL-1ß and IFN-γ. Those results suggest the participation of Th17 in rabies virus neuroinfection transmitted by dogs. IL-23 probably plays a role in maintaining the Th17 profile, but it can also interfere with the establishment of the Th1 profile and viral clearance.

Paradoxical effects of vitamin C in Chagas disease.

Trypanosoma cruzi infection stimulates inflammatory mediators which cause oxidative stress, and the use of antioxidants can minimize the sequelae of Chagas disease. In order to evaluate the efficacy of vitamin C in minimizing oxidative damage in Chagas disease, we orally administered ascorbic acid to Swiss mice infected with 5.0 × 104 trypomastigote forms of T. cruzi QM2 strain. These animals were treated for 60 days to investigate the acute phase and 180 days for the chronic phase. During the acute phase, the animals in the infected and treated groups demonstrated lower parasitemia and inflammatory processes were seen in more mice in these groups, probably due to the higher concentration of nitric oxide, which led to the formation of peroxynitrite. The decrease in reduced glutathione concentration in this group showed a circulating oxidant state, and this antioxidant was used to regenerate vitamin C. During the chronic phase, the animals in the infected and treated group showed a decrease in ferric reducing ability of plasma and uric acid concentrations as well as mobilization of bilirubin (which had higher plasma concentration), demonstrating cooperation between endogenous non-enzymatic antioxidants to combat increased oxidative stress. However, lower ferrous oxidation in xylenol orange concentrations was found in the infected and treated group, suggesting that vitamin C provided biological protection by clearing the peroxynitrite, attenuating the chronic inflammatory process in the tissues and favoring greater survival in these animals. Complex interactions were observed between the antioxidant systems of the host and parasite, with paradoxical actions of vitamin C.

Detection of Toxoplasma gondii in two southern Wooly spider monkeys (Brachyteles arachnoides-Geoffroy, 1806) from the Rio de Janeiro primate center, Brazil.

BACKGROUND: Toxoplasmosis led to the death of two Brachyteles arachnoides, an endangered atelid. METHODS: The diagnosis was established by necropsy, histopathological, immunohistochemical and ultrastructural changes. RESULTS: The analysis confirms the presence of Toxoplasma gondii. CONCLUSIONS: This report contributes to the development of protocols for health surveillance on maintenance and conservation of southern muriquis.

Malakoplakia after renal transplantation in the current era of immunosuppressive therapy: case report and literature review.

Malakoplakia is a rare chronic granulomatous disease of unknown cause. It is thought to be caused by an acquired bactericidal defect of macrophages. Malakoplakia is associated with chronic infections and immunosuppression. Although it occurs mainly in the urinary tract, it has already been reported in almost every organ system. The isolation of bacteria, especially Escherichia coli, is common in malakoplakia patients. Here, we present a case of primary cutaneous malakoplakia in a kidney transplant recipient who had been taking prednisone, tacrolimus, and mycophenolate. Culture of a lesion grew Burkholderia cepacia complex. Treatment with high doses of trimethoprim-sulfamethoxazole was successful. We also present a systematic review of the literature, identifying 4 previously reported cases of malakoplakia after renal transplantation under similar immunosuppressive therapy, most occurring in the urinary tract or perineum and following benign courses to cure. Data in the literature suggest that malakoplakia has become even rarer since changes were made in the immunosuppressive therapy employed after kidney transplantation.

Respiratory syncytial virus (RSV) pneumonia in a southern muriqui (Brachyteles arachnoides).

BACKGROUND: An adult male Brachyteles arachanoides, kept in captivity since 1990, was found dead without apparent clinical evidence. METHODS: Necropsy report, histopathology, immunohistochemistry, and ultrastructural examination were conducted. RESULTS: Pulmonary syncytial cells were positive for respiratory syncytial virus (RSV), and ultrastructural examination revealed viral particles inside macrophages compatible with the Paramyxoviridae family. CONCLUSIONS: Muriquis are susceptible to RSV pneumonia followed by respiratory distress syndrome and death.

Are the severe injuries of cutaneous leishmaniasis caused by an exacerbated Th1 response?

American tegumentary leishmaniasis (ATL) is a disease whose clinical features are strongly related to the type of immune response it induces. Herein we report an atypical presentation of cutaneous leishmaniasis in a woman with a severe and extensive sore located in her leg, and we describe the differences between the usual local immune response in ATL and the local immune response in this patient. We observed an intense inflammatory response characterized by Th1 cells and cytokines with conspicuous expression of Toll-like receptor 3 (TLR-3). Few parasites were present, but there was an extensive tissue damage. We also discuss the immunological factors that could be related to the atypical presentation.

The expression of TLR9 in human cutaneous leishmaniasis is associated with granuloma.

The Toll-like receptor (TLR) signalling pathway is the first system that defends against Leishmania. After recognising Leishmania as nonself, TLRs trigger NF-κB expression.NF-κB proceeds to the nucleus and promotes the transcription of pro-inflammatory cytokines. TLR9 is thus an important factor in the induction of an effective immune response against Leishmania. We examined the pattern of TLR9 expression in 12 patients with cutaneous leishmaniasis caused by Leishmania braziliensis detected by polymerase chain reaction. Normal skin was analysed as a negative control. TLR9 expression was examined in the dermis and epidermis by immunohistochemical analysis of paraffin-embedded biopsy tissue. TLR9 expression was primarily observed in the granuloma. The protein was detected in a few cells in the dermis. A lower expression level was detected in the epidermis of patients with leishmaniasis when compared with normal skin. The presence of TLR9 in the skin of patients with cutaneous leishmaniasis is associated with granuloma and expressed by macrophages.

Tissue and serum immune response in chronic hepatitis C with mild histological lesions.

The immunopathogenesis of chronic hepatitis C virus (HCV) infection is a matter of great controversy and has been suggested to involve a complex balance between cytokines with pro and anti-inflammatory activity. We investigated the expression of inflammatory cells and cytokines in the liver and serum of 51 chronically HCV infected patients and compared them to data from two sets of normal controls: 51 healthy blood donors and 33 liver biopsies of healthy liver donors. We also assessed the relationship between selected cytokines and cell populations in hepatic compartments and the disease stage. Compared with controls, hepatitis C patients had a greater expression of portal TNF-alpha, TGF-beta and CD4(+) and acinar IFN-gamma, TNF-alpha, IL-1beta and IL-4, as well as a higher serum concentration of IL-2, IL-10 and TGF-beta. Significant positive correlations were found between portal CD4+ and TNF-alpha, portal CD8(+) and TGF-beta, portal CD45(+)RO and TNF-alpha, acinar CD45(+)RO and IFN-gamma and acinar CD57(+) and TGF-beta. In conclusion, we have shown that (i) in this sample of predominantly mild disease, the immune response was associated with a pro-inflammatory response pattern, (ii) CD4(+) T-lymphocytes played a major role in orchestrating the immune response and (iii) these events primarily took place in the portal space.

Leptospirosis pulmonary haemorrhage syndrome is associated with linear deposition of immunoglobulin and complement on the alveolar surface.

Leptospirosis is a zoonotic infection associated with severe diseases such as leptospirosis pulmonary haemorrhage syndrome (LPHS). The cause of pulmonary haemorrhage is unclear. Understanding which mechanisms and processes are involved in LPHS will be important in treatment regimens under development for this life-threatening syndrome. In the present study, we evaluated 30 lung specimens from LPHS patients and seven controls using histology and immunohistochemistry (detection of IgM, IgG, IgA and C3) in order to describe the pathological features associated with this syndrome. Immunoglobulin deposits were detected on the alveolar surface in 18/30 LPHS patients. Three staining patterns were observed for the immunoglobulins and C3 in the lung tissues of LPHS patients: AS, delicate linear staining adjacent to the alveolar surface, which was indicative of a membrane covering the luminal surface of type I and II pneumocyte cells; S, heterogeneous staining which was sporadically distributed along the alveolar septum; and IA, weak, focal intra-alveolar granular staining. Human LPHS is associated with individual and unique histological patterns that differ from those of other causes of pulmonary haemorrhage. In the present study, it was found that the linear deposition of immunoglobulins (IgA, IgG and IgM) and complement on the alveolar surface may play a role in the pathogenesis of pulmonary haemorrhage in human leptospirosis.