Long-term lung inflammation is reduced by estradiol treatment in brain dead female rats

OBJECTIVES: Lung transplantation is limited by the systemic repercussions of brain death (BD). Studies have shown the potential protective role of 17β-estradiol on the lungs. Here, we aimed to investigate the effect of estradiol on the long-lasting lung inflammatory state to understand a possible therapeutic application in lung donors with BD. METHODS: Female Wistar rats were separated into 3 groups: BD, subjected to brain death (6h); E2-T0, treated with 17β-estradiol (50 μg/mL, 2 mL/h) immediately after brain death; and E2-T3, treated with 17β-estradiol (50 μg/ml, 2 ml/h) after 3h of BD. Complement system activity and macrophage presence were analyzed. TNF-α, IL-1β, IL-10, and IL-6 gene expression (RT-PCR) and levels in 24h lung culture medium were quantified. Finally, analysis of caspase-3 gene and protein expression in the lung was performed. RESULTS: Estradiol reduced complement C3 protein and gene expression. The presence of lung macrophages was not modified by estradiol, but the release of inflammatory mediators was reduced and TNF-α and IL-1β gene expression were reduced in the E2-T3 group. In addition, caspase-3 protein expression was reduced by estradiol in the same group. CONCLUSIONS: Brain death-induced lung inflammation in females is modulated by estradiol treatment. Study data suggest that estradiol can control the inflammatory response by modulating the release of mediators after brain death in the long term. These results strengthen the idea of estradiol as a therapy for donor lungs and improving transplant outcomes.

17ß-Estradiol, a potential ally to alleviate SARS-CoV-2 infection

Considering that female sexual hormones may modulate the inflammatory response and also exhibit direct effects on the cells of the immune system, herein, we intend to discuss the sex differences and the role of estradiol in modulating the lung and systemic inflammatory response, focusing on its possible application as a treatment modality for SARS-CoV-2 patients. COVID-19 patients develop severe hypoxemia early in the course of the disease, which is silent most of the time. Small fibrinous thrombi in pulmonary arterioles and a tumefaction of endothelial were observed in the autopsies of fatal COVID-19 cases. Studies showed that the viral infection induces a vascular process in the lung, which included vasodilation and endothelial dysfunction. Further, the proportions of CD4+ T and CD8+ T lymphocytes were strongly reduced in patients with severe SARS-CoV-2 infection. Estradiol is connected with CD4+ T cell numbers and increases T-reg cell populations, affecting immune responses to infection. It is known that estradiol exerts a protective effect on endothelial function, activating the generation of nitric oxide (NO) via endothelial nitric oxide synthase. Estrogen attenuates the vasoconstrictor response to various stimuli and induces vasodilation in the pulmonary vasculature during stress situations like hypoxia. It exerts a variety of rapid actions, which are initiated after its coupling with membrane receptors, which in turn, may positively modulate vascular responses in pulmonary disease and help to maintain microvascular flow. Direct and indirect mechanisms underlying the effects of estradiol were investigated, and the results point to a possible protective effect of estradiol against COVID-19, indicating that it may be considered as an adjuvant therapeutic element for the treatment of patients affected by the novel coronavirus.

Influence of brain death and associated trauma on solid organ histological characteristics / Influência da morte encefálica e do trauma associado nas características histológicas de órgãos sólidos

PURPOSE: To evaluate histopathological alterations triggered by brain death and associated trauma on different solid organs in rats. METHODS: Male Wistar rats (n=37) were anesthetized with isoflurane, intubated and mechanically ventilated. A trepanation was performed and a balloon catheter inserted into intracraninal cavity and rapidly inflated with saline to induce brain death. After induction, rats were monitored for 30, 180, and 360 min for hemodynamic parameters and exsanguinated from abdominal aorta. Heart, lung, liver, and kidney were removed and fixed in paraffin to evaluation of histological alterations (H&E). Sham-operated rats were trepanned only and used as control group. RESULTS: Brain dead rats showed a hemodynamic instability with hypertensive episode in the first minute after the induction followed by hypotension for approximately 1 h. Histological analyses showed that brain death induces vascular congestion in heart (p<0.05), and lung (p<0.05); lung alveolar edema (p=0.001), kidney tubular edema (p<0.05); and leukocyte infiltration in liver (p<0.05). CONCLUSIONS: Brain death induces hemodynamic instability associated with vascular changes in solid organs and compromises most severely the lungs. However, brain death associated trauma triggers important pathophysiological alterations in these organs.

OBJETIVO: Avaliar as alterações histopatológicas desencadeadas pela morte encefálica e pelo trauma associado em diferentes órgãos sólidos em ratos. MÉTODOS: Ratos Wistar machos (n=37) foram anestesiados com isoflurano, entubados e mecanicamente ventilados. Foi realizada trepanação e um cateter foi inserido na cavidade intracraniana e insuflado rapidamente para induzir morte encefálica. Após a indução, os ratos foram monitorados por 30, 180 e 360 min para parâmetros hemodinâmicos e exsanguinados pela aorta abdominal. Coração, pulmão, fígado e rim foram removidos e fixados em parafina para avaliação de alterações histológicas (H&E). Ratos falso-operados foram apenas trepanados e usados como grupo controle. RESULTADOS: Ratos com morte encefálica apresentaram instabilidade hemodinâmica com episódio hipertensivo no primeiro minuto após a indução seguido de hipotensão por aproximadamente 1 hora. Análises histológicas demonstraram que a morte encefálica induz congestão vascular no coração (p<0,05) e pulmão (p<0,05); edema alveolar (p=0,001); edema tubular (p<0,05); e infiltrado leucocitário no fígado (p<0,05). CONCLUSÕES: A morte encefálica induz instabilidade hemodinâmica associada com mudanças vasculares em órgãos sólidos e compromete mais severamente os pulmões. Contudo, o trauma associado à morte encefálica desencadeia importantes alterações fisiopatológicas naqueles órgãos.

Paradoxical effects of brain death and associated trauma on rat mesenteric microcirculation: an intravital microscopic study

OBJECTIVE: Experimental findings support clinical evidence that brain death impairs the viability of organs for transplantation, triggering hemodynamic, hormonal, and inflammatory responses. However, several of these events could be consequences of brain death-associated trauma. This study investigated microcirculatory alterations and systemic inflammatory markers in brain-dead rats and the influence of the associated trauma. METHOD: Brain death was induced using intracranial balloon inflation; sham-operated rats were trepanned only. After 30 or 180 min, the mesenteric microcirculation was observed using intravital microscopy. The expression of Pselectin and ICAM-1 on the endothelium was evaluated using immunohistochemistry. The serum cytokine, chemokine, and corticosterone levels were quantified using enzyme-linked immunosorbent assays. White blood cell counts were also determined. RESULTS: Brain death resulted in a decrease in the mesenteric perfusion to 30 percent, a 2.6-fold increase in the expression of ICAM-1 and leukocyte migration at the mesentery, a 70 percent reduction in the serum corticosterone level and pronounced leukopenia. Similar increases in the cytokine and chemokine levels were seen in the both the experimental and control animals. CONCLUSION: The data presented in this study suggest that brain death itself induces hypoperfusion in the mesenteric microcirculation that is associated with a pronounced reduction in the endogenous corticosterone level, thereby leading to increased local inflammation and organ dysfunction. These events are paradoxically associated with induced leukopenia after brain damage.

Efeitos hemodinâmicos e metabólicos iniciais da perfusão hipotérmica intestinal in situ. Avaliação de um novo modelo canino de autotransplante intestinal / Initial hemodynamic and metabolic effects of intestinal hypothermic perfusion in situ. An alternative model of canine intestinal autotransplantation

O transplante intestinal tem sido utilizado como uma alternativa promissora no tratamento da síndrome do intestino curto em pacientes adultos e pediátricos. Vários modelos experimentais foram desenvolvidos com a finalidade de testar diferentes soluções de preservação. No entanto são modelos complexos que levam, muitas vezes, um tempo prolongado para a sua realização. OBJETIVO: Neste estudo, desenvolvemos um modelo alternativo de autotransplante intestinal in situ analisando os efeitos hemodinâmicos e metabólicos iniciais da perfusão hipotérmica com solução de Ringer lactato. MÉTODOS: Foram utilizados seis cães machos sem raça definida (22,8±1,4 Kg); as variáveis hemodinâmicas sistêmicas foram obtidas por meio de cateter arterial e pelo Swan-Ganz. A perfusão do trato gastrintestinal foi avaliada pela medida do fluxo sangüíneo da veia mesentérica superior (FSVMS, fluxômetro ultra-sônico), e através da medida do pCO2 intestinal (pCO2-int e pCO2-gap, tonometria a gás). Inicialmente realizamos a secção do jejuno proximal e íleo distal e isolamento dos vasos mesentéricos com fitas cardíacas, todo o tecido nervoso e linfático em torno do eixo vascular intestinal foi seccionado. O território mesentérico foi perfundido através da artéria mesentérica superior por 30 minutos com 1000 ml de Ringer lactato a 4ºC, e o efluente drenado através de uma pequena incisão na veia mesentérica superior. Os animais foram observados por 120 min após o inicio do período de reperfusão. Amostras de sangue foram obtidas da aorta abdominal, para análise gasométrica. RESULTADOS: A perfusão intestinal hipotérmica induziu uma redução do FSMVS apenas nos primeiros 30 min de reperfusão (587±70,9 para 398±102,8 ml/min) e um aumento do pCO2-gap (2±2,7 para 29,8±6 mmHg). Não foram observadas alterações significativas em relação a parâmetros hemodinâmicos e metabólicos sistêmicos (PAM, DC, pH, excesso de bases, hemoglobina) assim como na temperatura central. CONCLUSAO: O modelo de autotransplante intestinal é extremamente útil e de fácil execução, para a avaliação inicial de soluções de preservação e/ou drogas antioxidantes, comumente utilizadas no transplante de intestino.