Brucella abortus Promotes a Fibrotic Phenotype in Hepatic Stellate Cells, with Concomitant Activation of the Autophagy Pathway

Expression of cytokine and Apoptosis-Associated genes in mice bone Marrow-Derived Macrophages stimulated with Brucella recombinant type IV secretion effectors

BACKGROUND

Brucellosis is an economically important infectious caused by most commonly by Brucella. Detection of infected animals at the early stage is important for controlling the disease. The diagnostic antigens, usually protein antigens, have attracted much interest. However, the accurate mechanism of immune response is still unknown. The secretory effectors (BPE005, BPE275, and BPE123) of the type IV secretion system (T4SS) were involved in the intracellular circulation process of Brucella and the immune responses of the host.

METHODS

Genes encoding three B. abortus effector proteins (BPE005, BPE275, and BPE123) of T4SS were cloned and the recombinant proteins were expressed and purified. The purified recombinant proteins were named rBPE005, rBPE275 and rBPE123. Then, the expressions of Th1- and Th2-related cytokine genes were analyzed in mice bone marrow-derived macrophages (BMDMs) after stimulation with rBPE005, rBPE275, and rBPE123. Furthermore, four apoptosis-associated genes (Caspase-3, Caspase-8, Bax, and Bcl-2) were also detected to explore the damage of the proteins to the cells.

RESULTS

Expressions of all Th1- and Th2-related cytokine genes were induced with three proteins, and different cytokine expression patterns induced by each protein depend on the stimulation time and dose of protein. However, expressions of apoptosis-related genes did not change.

CONCLUSION

These results showed that the secreted antigens of Brucella induced an immune reaction via the production of Th1- and Th2-type cytokines in BMDMs without exerting any damage on the cells.

Autophagy in erectile dysfunction: focusing on apoptosis and fibrosis

In most types of erectile dysfunction, particularly in advanced stages, typical pathological features observed are reduced parenchymal cells coupled with increased tissue fibrosis. However, the current treatment methods have shown limited success in reversing these pathologic changes. Recent research has revealed that changes in autophagy levels, along with alterations in apoptosis and fibrosis-related proteins, are linked to the progression of erectile dysfunction, suggesting a significant association. Autophagy, known to significantly affect cell fate and tissue fibrosis, is currently being explored as a potential treatment modality for erectile dysfunction. However, these present studies are still in their nascent stage, and there are limited experimental data available. This review analyzes erectile dysfunction from a pathological perspective. It provides an in-depth overview of how autophagy is involved in the apoptotic processes of smooth muscle and endothelial cells and its role in the fibrotic processes occurring in the cavernosum. This study aimed to develop a theoretical framework for the potential effectiveness of autophagy in preventing and treating erectile dysfunction, thus encouraging further investigation among researchers in this area.

Effector Proteins of Type IV Secretion System: Weapons of Brucella Used to Fight Against Host Immunity

Brucella is an intracellular bacterial pathogen capable of long-term persistence in the host, resulting in chronic infections in livestock and wildlife. The type IV secretion system (T4SS) is an important virulence factor of Brucella and is composed of 12 protein complexes encoded by the VirB operon. T4SS exerts its function through its secreted 15 effector proteins. The effector proteins act on important signaling pathways in host cells, inducing host immune responses and promoting the survival and replication of Brucella in host cells to promote persistent infection. In this article, we describe the intracellular circulation of Brucella-infected cells and survey the role of Brucella VirB T4SS in regulating inflammatory responses and suppressing host immune responses during infection. In addition, the important mechanisms of these 15 effector proteins in resisting the host immune response during Brucella infection are elucidated. For example, VceC and VceA assist in achieving sustained survival of Brucella in host cells by affecting autophagy and apoptosis. BtpB, together with BtpA, controls the activation of dendritic cells during infection, induces inflammatory responses, and controls host immunity. This article reviews the effector proteins secreted by Brucella T4SS and their involvement in immune responses, which can provide a reliable theoretical basis for the subsequent mechanism of hijacking the host cell signaling pathway by bacteria and contribute to the development of better vaccines to effectively treat Brucella bacterial infection.

Analysis of Clinical Characteristics and Blood Cell in Adult Patients with Brucella Bloodstream Infection of Different Blood Groups

The clinical manifestations and blood cell varied among patients with Brucella bloodstream infection. This study aimed to explore the clinical characteristics and blood cells of adult Brucella bloodstream infection patients with different ABO blood groups. This study retrospectively analyzed 77 adult Brucella bloodstream infection patients. Demographic characteristics, clinical manifestations, laboratory data, and blood cell differences of adult Brucella bloodstream infection patients were analyzed. For Brucella bloodstream infection patients, the blood group was distributed as: B > O > A > AB. The main symptoms of the patients were fever (94.81%), and 56 patients (72.70%) were complicated with liver injury. The highest proportion of liver injury was 93.33% in patients with blood group A and 52.38% in blood group O (P < 0.05). There were 19 cases (24.68%) with spondylitis, 30 cases (38.96%) with anemia, 28 (36.36%) with leukopenia, 16 (20.78%) with thrombocytopenia, without notable differences between different blood groups (P > 0.05). The proportion of lymphocytes in patients with the AB blood group was the highest (39.46 ± 11.21), and in patients with the B blood group was the lowest (28.00 ± 12.10), with significant difference between different blood groups (P < 0.05). Patients with Brucella bloodstream infection with blood group A were more prone to liver injury than those with blood group O. More attention should be paid to liver injury when receiving patients with blood group A. The proportion of lymphocytes in patients with blood group B and AB was different, suggesting that they may have different immune states.

Cell and Tissue Tropism of Brucella spp

Brucella spp. are facultatively intracellular bacteria that can infect, survive, and multiply in various host cell types in vivo and/or in vitro. The genus Brucella has markedly expanded in recent years with the identification of novel species and hosts, which has revealed additional information about the cell and tissue tropism of these pathogens. Classically, Brucella spp. are considered to have tropism for organs that contain large populations of phagocytes such as lymph nodes, spleen, and liver, as well as for organs of the genital system, including the uterus, epididymis, testis, and placenta. However, experimental infections of several different cultured cell types indicate that Brucella may actually have a broader cell tropism than previously thought. Indeed, recent studies indicate that certain Brucella species in particular hosts may display a pantropic distribution in vivo. This review discusses the available knowledge on cell and tissue tropism of Brucella spp. in natural infections of various host species, as well as in experimental animal models and cultured cells.

Abnormal liver findings as the first manifestation in a patient with brucellosis : Case report

In January 2019, a 30-year-old woman admitted to our inpatient department presented with undulating fever, pain in several joints, and significantly elevated liver enzymes and lactate dehydrogenase. After extended examination, infection with Brucella melitensis with liver, musculoskeletal, and pulmonary involvement was diagnosed and treated. Diagnosis was based on clinical examination, laboratory findings including seroconversion as a proof of immune response, magnetic resonance imaging, three-phase bone scintigraphy, and F‑18 FDG-PET (F-18 Flourdeoxyglucose positron emission tomography) illustrating the bone involvement and its normalization upon treatment. After treatment the patient showed a remarkable improvement of clinical symptoms within a short period. The patient remained symptom free and polymerase chain reaction (PCR) testing for brucellosis was negative, even at the follow-up examination 12 months after the end of the antibiotic therapy. The family members were also examined due to the similar travel history, and by this, brucellosis was also diagnosed in her husband but not in her children.

Understanding the implication of autophagy in the activation of hepatic stellate cells in liver fibrosis: are we there yet?

Liver fibrosis (LF) occurs as a result of persistent liver injury and can be defined as a pathologic, chronic, wound-healing process in which functional parenchyma is progressively replaced by fibrotic tissue. As a phenomenon involved in the majority of chronic liver diseases, and therefore prevalent, it exerts a significant impact on public health. This impact becomes even more patent given the lack of a specific pharmacological therapy, with LF only being ameliorated or prevented through the use of agents that alleviate the underlying causes. Hepatic stellate cells (HSCs) are fundamental mediators of LF, which, activated in response to pro-fibrotic stimuli, transdifferentiate from a quiescent phenotype into myofibroblasts that deposit large amounts of fibrotic tissue and mediate pro-inflammatory effects. In recent years, much effort has been devoted to understanding the mechanisms through which HSCs are activated or inactivated. Using cell culture and/or different animal models, numerous studies have shown that autophagy is enhanced during the fibrogenic process and have provided specific evidence to pinpoint the fundamental role of autophagy in HSC activation. This effect involves - though may not be limited to - the autophagic degradation of lipid droplets. Several hepatoprotective agents have been shown to reverse the autophagic alteration present in LF, but clinical confirmation of these effects is pending. On the other hand, there is evidence that implicates autophagy in several anti-fibrotic mechanisms in HSCs that stimulate HSC cell cycle arrest and cell death or prevent the generation of pro-fibrotic mediators, including excess collagen accumulation. The objective of this review is to offer a comprehensive analysis of published evidence of the role of autophagy in HSC activation and to provide hints for possible therapeutic targets for the treatment and/or prevention of LF related to autophagy. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Uncovering the Hidden Credentials of Brucella Virulence

Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.

Self-eating: friend or foe? The emerging role of autophagy in fibrotic diseases

Fibrosis occurs in most human organs including the liver, lung, heart and kidney, and is crucial for the progression of most chronic diseases. As an indispensable catabolic process for intracellular quality control and homeostasis, autophagy occurs in most mammalian cells and is implicated in many biological processes including fibrogenesis. Although advances have been made in understanding autophagy process, the potential role of autophagy in fibrotic diseases remains controversial and has recently attracted a great deal of attention. In the current review, we summarize the commonalities of autophagy affecting different types of fibrosis in different organs, including the liver, lung, heart, and kidney as well as in cystic fibrosis, systematically outline the contradictory results and highlight the distinct role of autophagy during the various stages of fibrosis. In summary, the exact role autophagy plays in fibrogenesis depends on specific cell types and different stimuli, and identifying and evaluating the pathogenic contribution of autophagy in fibrogenesis will promote the discovery of novel therapeutic strategies for the clinical management of these fibrotic diseases.

Long non-coding RNA HAGLROS regulates lipid metabolism reprogramming in intrahepatic cholangiocarcinoma via the mTOR signaling pathway

Alternation of long non-coding RNA (lncRNA) is implicated in intrahepatic cholangiocarcinoma (ICC) development. HAGLROS is a lncRNA with a length of 699 bp, which is involved in the progression of various cancers. But the mechanism of HAGLROS in ICC remains unknown. In this study, the sh-HAGLROS-1 or sh-HAGLROS-2 was transfected into QBC939 cells, and overexpressing HAGLROS vector was transfected into KMCH cells. HAGLROS expression in ICC tissues and cell lines was detected, and its association with ICC prognosis was further analyzed. Lipid accumulation and lipid-related indicators (TG, LDL-C, TC and HDLC) in QBC939 and KMCH cells were measured. ICC cell viability, invasion and migration were measured. Western blot analysis was used to detect levels of the mTOR axis-related proteins and autophagy-related proteins (LC3I, LC3II, Beclin and P62). The levels of serum lipids and SREBP1 positive expression in transplanted tumors of nude mice were detected. HAGLROS was highly expressed in ICC and negatively correlated with prognosis. QBC939 cells with knocking down HAGLROS exhibited reduced lipid-related protein levels, blocked ICC cellular processes, inactivated mTOR axis, and increased autophagy. QBC939 cells with overexpressing HAGLROS showed opposite trends. The lipid-related protein levels in serum of nude mice and SREBP1 positive expression in transplanted tumors were diminished. Taken together, sh-HAGLROS inactivated the mTOR axis and promoted autophagy, thereby improving lipid metabolism reprogramming in ICC. This study may offer novel ICC treatments.

miR-146b-5p Plays a Critical Role in the Regulation of Autophagy in ∆per Brucella melitensis-Infected RAW264.7 Cells

Brucella-caused brucellosis is one of the most widespread worldwide zoonoses. Lipopolysaccharide (LPS) of Brucella, which functions as pathogen-associated molecular patterns (PAMPs), is an important virulence factor that elicits protective antibodies. Per of B. melitensis is involved in the biosynthesis of the O-side chain of LPS. Autophagy is a crucial element of the innate immune response against intracellular pathogens including Brucella. In this study, we observed that autophagy was inhibited in RAW264.7 cells infected with Brucella melitensis ∆per. And, a high-throughput array-based screen and qRT-PCR validation were performed to identify the differentially expressed miRNAs in RAW264.7 cells infected with B. melitensis M5-90 ∆per. The results suggested that mmu-miR-146a-5p, mmu-miR-155-5p, mmu-miR-146b-5p, and mmu-miR-3473a were upregulated and mmu-miR-30c-5p was downregulated. During B. melitensis M5-90 ∆per infection, the increased expression of miR-146b-5p inhibited the autophagy activation in RAW264.7 cells. Using a bioinformatics approach, Tbc1d14 was predicted to be a potential target of miR-146b-5p. The results of a luciferase reporter assay indicated that miR-146b-5p directly targeted the 3'-UTR of Tbc1d14, and the interaction between miR-146b-5p and the 3'-UTR of Tbc1d14 was sequence-specific. High-throughput RNA-Seq-based screening was performed to identify differentially expressed genes in Tbc1d14-expressing RAW264.7 cells, and these were validated by qRT-PCR. Among the differentially expressed genes, four autophagy associated genes, IFNγ-inducible p47 GTPase 1 (IIGP1), nuclear receptor binding protein 2 (Nrbp2), transformation related protein 53 inducible nuclear protein 1 (Trp53inp1), and immunity-related GTPase family M member 1 (Irgm1), were obtained. Our findings provide important insights into the functional mechanism of LPS of B. melitensis.

Immunopathogenesis of Hepatic Brucellosis

The hepatic immune system can induce rapid and controlled responses to pathogenic microorganisms and tumor cells. Accordingly, most of the microorganisms that reach the liver through the blood are eliminated. However, some of them, including Brucella spp., take advantage of the immunotolerant capacity of the liver to persist in the host. Brucella has a predilection for surviving in the reticuloendothelial system, with the liver being the largest organ of this system in the human body. Therefore, its involvement in brucellosis is practically invariable. In patients with active brucellosis, the liver is commonly affected, and the most frequent clinical manifestation is hepatosplenomegaly. The molecular mechanisms implicated in liver damage have been recently elucidated. It has been demonstrated how Brucella interacts with hepatocytes inducing its death by apoptosis. The inflammatory microenvironment and the direct effect of Brucella on hepatic stellate cells (HSC) induce their activation and turn these cells from its quiescent form to their fibrogenic phenotype. This HSC activation induced by Brucella infection relies on the presence of a functional type IV secretion system and the effector protein BPE005 through a mechanism involved in the activation of the autophagic pathway. Finally, the molecular mechanisms of liver brucellosis observed so far are shedding light on how the interaction of Brucella with liver cells may play an important role in the discovery of new targets to control the infection. In this review, we report the current understanding of the interaction between liver structural cells and immune system cells during Brucella infection.

Bacteria Exploit Autophagy For Their Own Benefit

Autophagy is a lysosomal degradation pathway to clear long-lived proteins, protein aggregates, and damaged organelles. Certain microorganisms can be eliminated by an autophagic degradation process termed xenophagy. However, many pathogens deploy highly evolved mechanisms to evade autophagic degradation. What is more, series of pathogens have developed different strategies to exploit autophagy to ensure their survival. These bacteria could induce autophagy and/or prevent autophagosomes fusion with lysosomes through secreted effector proteins or utilizing host components, thereby maintaining the localization of the bacteria within the autophagosomes where they replicate. Here, we review the current knowledge of the mechanisms developed by the bacteria to benefit from autophagy for their survival.