Liver immunobiology

Tissue adaptation of CD4 T lymphocytes in homeostasis and cancer

The immune system is traditionally classified as a defense system that can discriminate between self and non-self or dangerous and non-dangerous situations, unleashing a tolerogenic reaction or immune response. These activities are mainly coordinated by the interaction between innate and adaptive cells that act together to eliminate harmful stimuli and keep tissue healthy. However, healthy tissue is not always the end point of an immune response. Much evidence has been accumulated over the years, showing that the immune system has complex, diversified, and integrated functions that converge to maintaining tissue homeostasis, even in the absence of aggression, interacting with the tissue cells and allowing the functional maintenance of that tissue. One of the main cells known for their function in helping the immune response through the production of cytokines is CD4+ T lymphocytes. The cytokines produced by the different subtypes act not only on immune cells but also on tissue cells. Considering that tissues have specific mediators in their architecture, it is plausible that the presence and frequency of CD4+ T lymphocytes of specific subtypes (Th1, Th2, Th17, and others) maintain tissue homeostasis. In situations where homeostasis is disrupted, such as infections, allergies, inflammatory processes, and cancer, local CD4+ T lymphocytes respond to this disruption and, as in the healthy tissue, towards the equilibrium of tissue dynamics. CD4+ T lymphocytes can be manipulated by tumor cells to promote tumor development and metastasis, making them a prognostic factor in various types of cancer. Therefore, understanding the function of tissue-specific CD4+ T lymphocytes is essential in developing new strategies for treating tissue-specific diseases, as occurs in cancer. In this context, this article reviews the evidence for this hypothesis regarding the phenotypes and functions of CD4+ T lymphocytes and compares their contribution to maintaining tissue homeostasis in different organs in a steady state and during tumor progression.

Updates on the Immune Cell Basis of Hepatic Ischemia-Reperfusion Injury

Liver ischemia-reperfusion injury (IRI) is the main cause of organ dysfunction and failure after liver surgeries including organ transplantation. The mechanism of liver IRI is complex and numerous signals are involved but cellular metabolic disturbances, oxidative stress, and inflammation are considered the major contributors to liver IRI. In addition, the activation of inflammatory signals exacerbates liver IRI by recruiting macrophages, dendritic cells, and neutrophils, and activating NK cells, NKT cells, and cytotoxic T cells. Technological advances enable us to understand the role of specific immune cells during liver IRI. Accordingly, therapeutic strategies to prevent or treat liver IRI have been proposed but no definitive and effective therapies exist yet. This review summarizes the current update on the immune cell functions and discusses therapeutic potentials in liver IRI. A better understanding of this complex and highly dynamic process may allow for the development of innovative therapeutic approaches and optimize patient outcomes.

Physicochemical Properties and Route of Systemic Delivery Control the In Vivo Dynamics and Breakdown of Radiolabeled Gold Nanostars

The in vivo dynamics of nanoparticles requires a mechanistic understanding of multiple factors. Here, for the first time, the surprising breakdown of functionalized gold nanostars (F-AuNSs) conjugated with antibodies and 64 Cu radiolabels in vivo and in artificial lysosomal fluid ex vivo, is shown. The short-term biodistribution of F-AuNSs is driven by the route of systemic delivery (intravenous vs intraperitoneal) and long-term fate is controlled by the tissue type in vivo. In vitro studies including endocytosis pathways, intracellular trafficking, and opsonization, are combined with in vivo studies integrating a milieu of spectroscopy and microcopy techniques that show F-AuNSs dynamics is driven by their physicochemical properties and route of delivery. F-AuNSs break down into sub-20 nm broken nanoparticles as early as 7 days postinjection. Martini coarse-grained simulations are performed to support the in vivo findings. Simulations suggest that shape, size, and charge of the broken nanoparticles, and composition of the lipid membrane depicting various tissues govern the interaction of the nanoparticles with the membrane, and the rate of translocation across the membrane to ultimately enable tissue clearance. The fundamental study addresses critical gaps in the knowledge regarding the fate of nanoparticles in vivo that remain a bottleneck in their clinical translation.

Maternal hepatic immunology during pregnancy

The liver plays pivotal roles in immunologic responses, and correct hepatic adaptations in maternal immunology are required during pregnancy. In this review, we focus on anatomical and immunological maternal hepatic adaptations during pregnancy, including our recent reports in this area. Moreover, we summarize maternal pregnancy-associated liver diseases, including hyperemesis gravidarum; intrahepatic cholestasis of pregnancy; preeclampsia, specifically hemolysis, elevated liver enzymes, and low platelet count syndrome; and acute fatty liver of pregnancy. In addition, the latest information about the factors that regulate hepatic immunology during pregnancy are reviewed for the first time, including human chorionic gonadotropin, estrogen, progesterone, growth hormone, insulin like growth factor 1, oxytocin, adrenocorticotropic hormone, adrenal hormone, prolactin, melatonin and prostaglandins. In summary, the latest progress on maternal hepatic anatomy and immunological adaptations, maternal pregnancy-associated diseases and the factors that regulate hepatic immunology during pregnancy are discussed, which may be used to prevent embryo loss and abortion, as well as pregnancy-associated liver diseases.

Enhanced bacterial clearance in early secondary sepsis in a porcine intensive care model

Early secondary sepsis (ESS), occurring after recent inflammatory activation is associated with a reduced inflammatory response. If this attenuation also is associated with decreased bacterial killing, the need for antibiotic efficacy might be greater than in primary sepsis (PS). This prospective, randomised interventional study compares bacterial killing in ESS and PS in a large animal intensive care sepsis model. 38 pigs were intravenously administered live Escherichia coli for 3 h. Before baseline ESS was pre-exposed to endotoxin 24 h, whereas PS was not. Bacterial growth was measured in organs immediately post-mortem, repeatedly during 6 h in blood in vivo and for blood intrinsic bactericidal capacity ex vivo. Splenic growth was lower in ESS animals, than in PS animals (3.31 ± 0.12, vs. 3.84 ± 0.14 log10 CFU/mL, mean ± SEM) (p < 0.01) with a similar trend in hepatic growth (p = NS). Blood bacterial count at 2 h correlated with splenic bacterial count in ESS (ESS: r = 0.71, p < 0.001) and to blood killing capacity in PS (PS: r = 0.69, p < 0.001). Attenuated inflammation in ESS is associated with enhanced antibacterial capacities in the spleen. In ESS blood bacterial count is related to splenic killing and in PS to blood bactericidal capacity. The results suggest no increased need for synergistic antibiotic combinations in ESS.

Liver pathology in COVID-19 related death and leading role of autopsy in the pandemic

BACKGROUND

Information on liver involvement in patients with coronavirus disease 2019 is currently fragmented.

AIM

To highlight the pathological changes found during the autopsy of severe acute respiratory syndrome coronavirus 2 positive patients.

METHODS

A systematic literature search on PubMed was carried out until June 21, 2022.

RESULTS

A literature review reveals that pre-existing liver disease and elevation of liver enzyme in these patients are not common; liver enzyme elevations tend to be seen in those in critical conditions. Despite the poor expression of viral receptors in the liver, it seems that the virus is able to infect this organ and therefore cause liver damage. Unfortunately, to date, the search for the virus inside the liver is not frequent (16% of the cases) and only a small number show the presence of the virus. In most of the autopsy cases, macroscopic assessment is lacking, while microscopic evaluation of livers has revealed the frequent presence of congestion (42.7%) and steatosis (41.6%). Less frequent is the finding of hepatic inflammation or necrosis (19%) and portal inflammation (18%). The presence of microthrombi, frequently found in the lungs, is infrequent in the liver, with only 12% of cases presenting thrombotic formations within the vascular tree.

CONCLUSION

To date, the greatest problem in interpreting these modifications remains the association of the damage with the direct action of the virus, rather than with the inflammation or alterations induced by hypoxia and hypovolemia in patients undergoing oxygen therapy and decompensated patients.

Abnormally primed CD8 T cells: The Achilles' heel of CHB

Chronic hepatitis B virus (HBV) infection continues to be a significant public health challenge, and more than 250 million people around world are infected with HBV. The clearance of HBV with virus-specific CD8 T cells is critical for a functional cure. However, naïve HBV-specific CD8 T cells are heavily hindered during the priming process, and this phenomenon is closely related to abnormal cell and signal interactions in the complex immune microenvironment. Here, we briefly summarize the recent progress in understanding the abnormal priming of HBV-specific CD8 T cells and some corresponding immunotherapies to facilitate their functional recovery, which provides a novel perspective for the design and development of immunotherapy for chronic HBV infection (CHB). Finally, we also highlight the balance between viral clearance and pathological liver injury induced by CD8 T-cell activation that should be carefully considered during drug development.

Eph/Ephrin Promotes the Adhesion of Liver Tissue-Resident Macrophages to a Mimicked Surface of Liver Sinusoidal Endothelial Cells

Kupffer cells are maintained via self-renewal in specific microenvironmental niches, primarily the liver sinusoidal endothelial cells (LSECs). In this study, we propagated tissue-resident macrophages (Mø) from mouse liver using mixed culture with hepatic fibroblastic cells. Propagated liver Mø express Id3, Lxra and Spic transcription factors, which are required for Kupffer cell characterization. Thus, Kupffer cell properties are likely to be maintained in liver Mø propagated using mixed culture with fibroblastic cells. We revealed (i) gene expression of certain Eph receptors and ephrin ligands including EphA2, ephrin-A1, EphB4, and ephrin-B1 in propagated liver Mø and primary LSECs, (ii) immunohistochemical localization of these Eph/ephrin member molecules indicating common expression in Kupffer cells and LSECs, and (iii) surface expression of several integrin α and β subunits, including α4β1, αLβ2, αMβ2, and αXβ2 integrin in propagated liver Mø and that of the corresponding ligands ICAM-1 and VCAM-1 in primary LSECs. Moreover, EphA/ephrin-A and EphB/ephrin-B interactions promoted liver Mø adhesion to the ICAM-1-adsorbed surface, which mimicked that of LSECs and may be implicated in the residence of Kupffer cells in the liver sinusoid. Further studies on regulating the residence and regeneration of Kupffer cells in related hepatic disorders are required to validate our findings.

Characterization of S100A12 from nile tilapia (Oreochromis niloticus) and its roles on inflammatory responses

S100A12 is a member of S100 proteins family that induces pro-inflammatory response via ligating with the receptor for advanced glycation end products (RAGE) and subsequent activation of intracellular signal transduction pathways. But information about fish S100A12 remain largely unclear. In this study, the S100A12 homolog (On-S100A12) was identified from Nile tilapia (Oreochromis niloticus). On-S100A12 was mainly expressed in liver and intestine. After Streptococcus agalactiae infection in vivo, S100A12 significantly increased in brain, intestine, liver and head kidney, suggesting S100A12 might played roles in immune response. The further in vitro experiments found that recombinant protein of S100A12 (rOn-S100A12) upregulated the expression of IL1-β, TLR2, TNF-α and inhibited the expression of IL-10, indicating On-S100A12 promoted inflammatory response and activation of M1 macrophages. The present data lay a foundation to further explore the roles of fish S100 during immune defense and will also be beneficial for better understanding of fish immune-regulatory network.

Risk Association of Liver Cancer and Hepatitis B with Tree Ensemble and Lifestyle Features

The second-largest cause of death by cancer in Korea is liver cancer, which leads to acute morbidity and mortality. Hepatitis B is the most common cause of liver cancer. About 70% of liver cancer patients suffer from hepatitis B. Early risk association of liver cancer and hepatitis B can help prevent fatal conditions. We propose a risk association method for liver cancer and hepatitis B with only lifestyle features. The diagnostic features were excluded to reduce the cost of gathering medical data. The data source is the Korea National Health and Nutrition Examination Survey (KNHANES) from 2007 to 2019. We use 3872 and 4640 subjects for liver cancer and hepatitis B model, respectively. Random forest is employed to determine functional relationships between liver diseases and lifestyle features. The performance of our proposed method was compared with six machine learning methods. The results showed the proposed method outperformed the other methods in the area under the receiver operator characteristic curve of 0.8367. The promising results confirm the superior performance of the proposed method and show that the proposed method with only lifestyle features provides significant advantages, potentially reducing the cost of detecting patients who require liver health care in advance.

Increased expression of miR-224-5p in circulating extracellular vesicles of patients with reduced coronary flow reserve

Background

Endothelial and microvascular dysfunction are pivotal causes of major adverse cardiac events predicted by coronary flow reserve (CFR). Extracellular Vesicles (EVs) have been studied extensively in the pathophysiology of coronary artery disease. However, little is known on the impact of the non-coding RNA content of EVs with respect to CFR.

Methods

We carried out a study among 120 patients divided by high-CFR and low-CFR to profile the miRNA content of circulating EVs.

Results

A multiplex array profiling on circulating EVs revealed mir-224-5p (p-value ≤ 0.000001) as the most differentially expressed miRNA in the Low-CFR group and showed a significantly independent relationship to CFR. Literature survey indicated the origin of the miR from liver cells and not of platelet, leukocyte, smooth muscle or endothelial (EC) origin. A q-PCR panel of the conventional cell type-EVs along with hepatic EVs showed that EVs from liver cells showed higher expression of the miR-224-5p. FACS analysis demonstrated the presence of liver-specific (ASGPR-1+/CD14−) EVs in the plasma of our cohort with the presence of Vanin-1 required to enter the EC barrier. Hepatic EVs with and without the miR-224-5p were introduced to ECs in-vitro, but with no difference in effect on ICAM-1 or eNOS expression. However, hepatic EVs elevated endothelial ICAM-1 levels per se independent of the miR-224-5p.

Conclusion

This indicated a role of hepatic EVs identified by the miR-224-5p in endothelial dysfunction in patients with Low CFR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02756-w.

Enrichment Methods for Murine Liver Non-Parenchymal Cells Differentially Affect Their Immunophenotype and Responsiveness towards Stimulation

Hepatocytes comprise the majority of the liver and largely exert metabolic functions, whereas non-parenchymal cells (NPCs)—comprising Kupffer cells, dendritic cells and liver sinusoidal endothelial cells—control the immunological state within this organ. Here, we compared the suitability of two isolation methods for murine liver NPCs. Liver perfusion (LP) with collagenase/DNase I applied via the portal vein leads to efficient liver digestion, whereas the modified liver dissociation (LD) method combines mechanical dissociation of the retrieved organ with enzymatic degradation of the extracellular matrix. In cases of both LP and LD, NPCs were enriched by subsequent gradient density centrifugation. Our results indicate that LP and LD are largely comparable with regards to the yield, purity, and composition of liver NPCs. However, LD-enriched liver NPCs displayed a higher degree of activation after overnight cultivation, and accordingly were less responsive towards stimulation with toll-like receptor ligands that are frequently used as adjuvants, e.g., in nano-vaccines. We conclude that LP is more suitable for obtaining liver NPCs for subsequent in vitro studies, whereas LD as the less laborious method, is more convenient for parallel isolation of larger numbers of samples for ex vivo analysis.

The role of the immune system in the pathogenesis of NAFLD and potential therapeutic impacts of mesenchymal stem cell-derived extracellular vesicles

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by intra-hepatocyte triglyceride accumulation and concomitant involvement of the immune system with subsequent histological changes, tissue damage, and clinical findings. There are various molecular pathways involved in the progression of NAFLD including lipotoxicity, endoplasmic reticulum stress, and the immune response. Both innate and adaptive immune systems are involved in the NAFLD pathogenesis, and crosstalk between the immune cells and liver cells participates in its initiation and progression. Among the various treatments for this disease, new cell based therapies have been proposed. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC) (MSC-EVs) are new cell-free vehicles with low immunogenicity, which can suppress detrimental immune responses in inflamed tissues. This review aimed to express the immune system's molecular pathways associated with the initiation and progression of NAFLD. Then, the possible role of MSC-EVs in the treatment of this entity through immune response modulation was discussed. Finally, engineered EVs enhanced by specific therapeutic miRNA were suggested for alleviating the pathological cellular events in liver disease.

Transcriptome signature changes in the liver of a migratory passerine

The liver plays a principal role in avian migration. Here, we characterised the liver transcriptome of a long-distance migrant, the Northern Wheatear (Oenanthe oenanthe), sampled at different migratory stages, looking for molecular processes linked with adaptations to migration. The analysis of the differentially expressed genes suggested changes in the periods of the circadian rhythm, variation in the proportion of cells in G1/S cell-cycle stages and the putative polyploidization of this cell population. This may explain the dramatic increment in the liver's metabolic capacities towards migration. Additionally, genes involved in anti-oxidative stress, detoxification and innate immune responses, lipid metabolism, inflammation and angiogenesis were regulated. Lipophagy and lipid catabolism were active at all migratory stages and increased towards the fattening and fat periods, explaining the relevance of lipolysis in controlling steatosis and maintaining liver health. Our study clears the way for future functional studies regarding long-distance avian migration.

The dual role of immune response in acetaminophen hepatotoxicity: Implication for immune pharmacological targets

Acetaminophen (APAP), one of the most widely used antipyretic and analgesic drugs, principally contributes to drug-induced liver injury when taken at a high dose. APAP-induced liver injury (AILI) results in extensive necrosis of hepatocytes along with the occurrence of multiple intracellular events such as metabolic activation, cell injury, and signaling pathway activation. However, the specific role of the immune response in AILI remains controversial for its complicated regulatory mechanisms. A variety of inflammasomes, immune cells, inflammatory mediators, and signaling transduction pathways are activated in AILI. These immune components play antagonistic roles in aggravating the liver injury or promoting regeneration. Recent experimental studies indicated that natural products showed remarkable therapeutic effects against APAP hepatotoxicity due to their favorable efficacy. Therefore, this study aimed to review the present understanding of the immune response in AILI and attempted to establish ties among a series of inflammatory cascade reactions. Also, the immune molecular mechanisms of natural products in the treatment of AILI were extensively reviewed, thus providing a fundamental basis for exploring the potential pharmacological targets associated with immune interventions.

A copper-zinc-superoxide dismutase (CuZnSOD) from redlip mullet, Liza haematocheila: Insights to its structural characteristics, immune responses, antioxidant activity, and potent antibacterial properties

Copper-zinc superoxide dismutase (CuZnSOD) is a nuclear-encoded metalloenzyme responsible for scavenging harmful reactive oxygen species (ROS). In this study, the CuZnSOD homolog from redlip mullet (Liza haematochelia) (MuCuZnSOD) was structurally and functionally characterized to evaluate its antioxidant capacity, antibacterial properties, and protective level in various pathogenic stress conditions. Structural characteristics of MuCuZnSOD were evaluated using different bioinformatics tools. Pairwise sequence comparison and evolutionary tree structure revealed that the MuCuZnSOD sequence was closely related to the CuZnSOD sequence of Oplegnathus fasciatus with a 94.2% sequence identity. Sequence alignment analysis indicated that the CuZnSOD domain was well conserved. The highest transcriptional expression of MuCuZnSOD was identified in the blood. Immune challenge with lipopolysaccharide (LPS), Lactococcus garvieae, and polyinosinic-polycytidylic acid (poly I:C) exhibited an increased MuCuZnSOD mRNA expression in the blood and liver. Transfected green fluorescent protein-fused MuCuZnSOD was localized in the cytoplasm. Recombinant MuCuZnSOD (rMuCuZnSOD) was overexpressed in a bacterial system. The rMuCuZnSOD possessed significant antioxidant properties as determined by conventional xanthine oxidase assay. The optimum pH and temperature of rMuCuZnSOD were found to be pH 9 and 25 °C, respectively. rMuCuZnSOD enzyme activity increased in a concentration-dependent manner. Treatment with potassium cyanide highly inhibited the rMuCuZnSOD activity. rMuCuZnSOD possessed a significant peroxidation activity in the presence of HCO₃- ions as demonstrated by the increased viability in cells treated with the enzyme in the presence of hydrogen peroxide. Antibacterial assays showed that rMuCuZnSOD had significant growth-inhibitory effects on both gram-positive and gram-negative bacteria. Collectively, our findings demonstrate that MuCuZnSOD is an essential antioxidant protein, which regulates the host defense mechanisms and innate immunity under oxidative stress.

Beyond Metabolism: Role of the Immune System in Hepatic Toxicity

The liver is primarily thought of as a metabolic organ; however, the liver is also an important mediator of immunological functions. Key perspectives on this emerging topic were presented in a symposium at the 2018 annual meeting of the American College of Toxicology entitled "Beyond metabolism: Role of the immune system in hepatic toxicity." Viral hepatitis is an important disease of the liver for which insufficient preventive vaccines exist. Host immune responses inadequately clear these viruses and often potentiate immunological inflammation that damages the liver. In addition, the liver is a key innate immune organ against bacterial infection. Hepatocytes and immune cells cooperatively control systemic and local bacterial infections. Conversely, bacterial infection can activate multiple types of immune cells and pathways to cause hepatocyte damage and liver injury. Finally, the immune system and specifically cytokines and drugs can interact in idiosyncratic drug-induced liver injury. This rare disease can result in a disease spectrum that ranges from mild to acute liver failure. The immune system plays a role in this disease spectrum.

Bovine hepatic miRNAome profiling and differential miRNA expression analyses between beef steers with divergent feed efficiency phenotypes

MicroRNAs (miRNAs) are small RNA molecules involved in regulation of multiple biological processes through modulating expression of their target genes. Here we employed RNAseq to profile liver tissue miRNAome of 60 steers from Angus, Charolais, and Kinsella Composite (KC) populations. Of these animals, 36 animals (n = 12 for each breed) were utilized to identify differentially expressed (DE) miRNAs between animals with high (n = 6) or low (n = 6) phenotypic values of residual feed intake (RFI), a common measurement of feed efficiency. At a threshold of fold-change > 1.5 and P-value < 0.05, we detected 12 (7 up- and 5 downregulated in low-RFI animals), 18 (12 up- and 6 downregulated), and 13 (8 up- and 5 downregulated) DE miRNAs for Angus, Charolais, and KC steers, respectively. Most of the DE miRNAs were breed specific, with bta-miR-449a and bta-miR-AB-2 being differentially expressed in all three breeds. The predicted target genes of the identified DE miRNA are mainly involved in cell cycle, cell death and survival, cell signaling, cellular growth and proliferation, protein trafficking, cell morphology, cell-to-cell signaling and interaction, cellular development, molecular transport, post-translational modification, as well as nutrient metabolism (lipids, carbohydrates, protein and amino acid). Our results provide insights into the bovine hepatic miRNAome and their potential roles in molecular regulation of RFI in beef cattle.

Expression analyses of C-type lectins (CTLs) in Manila clam under cold stress provide insights for its potential function in cold resistance of Ruditapes philippinarum

Manila clam Ruditapes philippinarum is an economically and scientifically important marine bivalve species. C-type lectin acts as a pattern-recognition receptor (PPR), plays a crucial role in the innate immunity of invertebrates, and involves in pathogen recognition, and cell-cell interaction. In this study, six different types of C-type lectin genes, CTL-1, CTL-2, CTL-3, CTL-4, CTL-5, and CTL-6, were identified from the R. philippinarum. CTL amino acid sequence was highly conserved compare to other invertebrate CTL sequences. Also, the temporal expressions of CTLs mRNA were detected in R. philippinarum with higher expression level in hepatopancreas and gill, and with lower expression levels in other tissues. The expression pattern of CTL genes in hepatopancreas were investigated under low-temperature stress using real-time quantitative fluorescence PCR (RT-qPCR) and the results showed that the transcription of CTL mRNAs were induced after low-temperature challenge. Overall, the sequence analysis and the expression patterns of CTLs provide clues for understanding the response of the Manila clam to low-temperature stress.

Helicobacter hepaticus infection induces chronic hepatitis and fibrosis in male BALB/c mice via the activation of NF-κB, Stat3, and MAPK signaling pathways

BACKGROUND

It has been documented that Helicobacter hepaticus (H hepaticus) infection is linked to chronic hepatitis and liver cancer. However, our understanding of the molecular mechanisms underlying progression of the H hepaticus-induced hepatic inflammation to cellular hepatocarcinoma is still limited.

MATERIALS AND METHODS

In our study, male BALB/c mice were infected by H hepaticus for 8, 12, 16, 20, and 24 weeks. Histopathology, H hepaticus colonization dynamics, select signaling pathways, and expression of key inflammatory cytokines in the liver were examined.

RESULTS

We found that H hepaticus was detectible in feces of mice at 7 days postinfection (DPI) by PCR, but it was not detected in the livers by PCR until 8 weeks postinfection (WPI). In addition, abundance of colonic and hepatic H hepaticus was progressively increased over the infection duration. H hepaticus-induced hepatic inflammation and fibrosis were aggravated over the infection duration, and necrosis or cirrhosis developed in the infected liver at 24 WPI H hepaticus infection increased levels of alanine aminotransferase and aspartate aminotransferase. Moreover, mRNA levels of Il-6 and Tnf-α were significantly elevated in the livers of H hepaticus-infected mice compared to uninfected control from 8 WPI to 24 WPI. Furthermore, Stat3, nuclear factor-κB (p65), and MAPK (Erk1/2 and p38) were activated by H hepaticus infection.

CONCLUSIONS

These data demonstrated that male BALB/c mice can be used as a new mouse model of H hepaticus-induced liver diseases and that the H hepaticus-induced liver injury is triggered by NF-κB, Jak-Stat, and MAPK signaling pathways.

Differential Thermoregulatory and Inflammatory Patterns in the Circadian Response to LPS-Induced Septic Shock

Sepsis is caused by a dysregulated host response to infection, and characterized by uncontrolled inflammation together with immunosuppression, impaired innate immune functions of phagocytes and complement activation. Septic patients develop fever or hypothermia, being the last one characteristic of severe cases. Both lipopolysaccharide (LPS) and Tumor Necrosis Factor (TNF)-α- induced septic shock in mice is dependent on the time of administration. In this study, we aimed to further characterize the circadian response to high doses of LPS. First, we found that mice injected with LPS at ZT11 developed a higher hypothermia than those inoculated at ZT19. This response was accompanied by higher neuronal activation of the preoptic, suprachiasmatic, and paraventricular nuclei of the hypothalamus. However, LPS-induced Tnf-α and Tnf-α type 1 receptor (TNFR1) expression in the preoptic area was time-independent. We also analyzed peritoneal and spleen macrophages, and observed an exacerbated response after ZT11 stimulation. The serum of mice inoculated with LPS at ZT11 induced deeper hypothermia in naïve animals than the one coming from ZT19-inoculated mice, related to higher TNF-α serum levels during the day. We also analyzed the response in TNFR1-deficient mice, and found that both the daily difference in the mortality rate, the hypothermic response and neuronal activation were lost. Moreover, mice subjected to circadian desynchronization showed no differences in the mortality rate throughout the day, and developed lower minimum temperatures than mice under light-dark conditions. Also, those injected at ZT11 showed increased levels of TNF-α in serum compared to standard light conditions. These results suggest a circadian dependency of the central thermoregulatory and peripheral inflammatory response to septic-shock, with TNF-α playing a central role in this circadian response.

Macrophage Phenotype and Function in Liver Disorder

Hepatic macrophages are a remarkably heterogeneous population consisting of self-renewing tissue-resident phagocytes, termed Kupffer cells (KCs), and recruited macrophages derived from peritoneal cavity as well as the bone marrow. KCs are located in the liver sinusoid where they scavenge the microbe from the portal vein to maintain liver homeostasis. Liver injury may trigger hepatic recruitment of peritoneal macrophages and monocyte-derived macrophages. Studies describing macrophage accumulation have shown that hepatic macrophages are involved in the initiation and progression of various liver diseases. They act as tolerogenic antigen-presenting cells to inhibit T-cell activation by producing distinct sets of cytokines, chemokines, and mediators to maintain or resolve inflammation. Furthermore, by releasing regenerative growth factors, matrix metalloproteinase arginase, they promote tissue repair. Recent experiments found that KCs and recruited macrophages may play different roles in the development of liver disease. Given that hepatic macrophages are considerably plastic populations, their phenotypes and functions are likely switching along disease progression. In this review, we summarize current knowledge about the role of tissue-resident macrophages and recruited macrophages in pathogenesis of alcoholic liver disease (ALD), non-alcoholic steatohepatitis (NASH), viral hepatitis, and hepatocellular carcinoma (HCC).

Liver transcriptome profiling of beef steers with divergent growth rate, feed intake, or metabolic body weight phenotypes1

Average daily gain (ADG) and daily dry matter intake (DMI) are key determinants of beef industry profitability. These traits together with metabolic body weight (MWT) are combined as component traits to calculate residual feed intake (RFI), a common measure of feed efficiency in beef cattle. Recently, there have been significant efforts towards molecular genetic characterization of RFI through transcriptomic studies in different breeds and tissues. However, molecular mechanisms of RFI component traits still remain predominately unexplored. Therefore, in the current study, we investigated the hepatic transcriptomic profiles and their associations with ADG, DMI, and MWT in Angus, Charolais, and Kinsella Composite (KC) populations through global RNAseq analyses. In each population and for each trait, 12 steers with extreme phenotypes (n = 6 low and n = 6 high) were analyzed for differential gene expression. These animals were from 20 beef steers of each Angus, Charolais, and KC breed population that were initially selected for a transcriptome study of RFI. At a false discovery rate <0.05 and fold change >1.5, we identified 123, 102, and 78 differentially expressed (DE) genes between high- and low-ADG animals of Angus, Charolais, and KC populations, respectively. For DMI, 108, 180, and 156 DE genes were identified between high- and low-DMI from Angus, Charolais, and KC populations, respectively, while for MWT, 80, 82, and 84 genes were differentially expressed between high- and low-MWT animals in Angus, Charolais, and KC populations, respectively. The identified DE genes were largely breed specific (81.7% for ADG, 82.7% for DMI, and 83% for MWT), but were largely involved in the same biological functions across the breeds. Among the most enriched biological functions included metabolism of major nutrients (lipids, carbohydrates, amino acids, vitamins, and minerals), small molecule biochemistry, cellular movement, cell morphology, and cell-to-cell signaling and interaction. Notably, we identified multiple DE genes that are involved in cholesterol biosynthesis, and immune response pathways for the 3 studied traits. Thus, our findings present potential molecular genetic mechanisms and candidate genes that influence feed intake, growth, and MWT of beef cattle.

Digital gene expression analysis in the liver of ScpB-vaccinated and Streptococcus agalactiae-challenged Nile tilapia

In recent years, streptococcal diseases have severely threatened the development of tilapia aquaculture, but effective prevention and control methods have not yet been established. To understand the immune responses of vaccinated Nile tilapia (Oreochromis niloticus), digital gene expression (DGE) technology was applied in this study to detect the gene expression profile of the Nile tilapia (O. niloticus) liver in response to ScpB (Streptococcal C5a peptidase from group B Streptococcus, ScpB) vaccination and a Streptococcus agalactiae-challenge. The control and the ScpB-vaccinated Nile tilapia yielded a total of 25,788,734 and 27,088,598 clean reads, respectively. A total of 1234 significant differentially expressed unigenes were detected (P < 0.05), of which 236 were significantly up-regulated, and 269 were significantly down-regulated (P < 0.05, |fold|>2, FDR<0.05). Of the differentially expressed gene, the identified genes which were enriched using databases of GO and KEGG could be categorized into a total of 67 functional groups and were mapped to 153 signaling pathways including 15 immune-related pathways. The differentially expressed genes (TLR1, TLR2, TLR3, TLR5, TLR9, MyD88, C3, IL-1β, IL-10) were detected in the expression profiles, and this was subsequently verified via quantitative real-time PCR (qPCR). The results of this study can serve as a basis for future research not only on the molecular mechanism of S. agalactiae invasion, but also on the anti-S. agalactiae mechanism in targeted tissues of Nile tilapia.

Differential expression of T helper cytokines in the liver during early pregnancy in sheep

Liver plays important roles in the innate and adaptive immunity, and contributes to the maternal immune adjustments during pregnancy in mice and rats. T helper 1 (Th1) and Th2 cytokines are related to immune response. However, expression of Th1 and Th2 cytokines in maternal livers is unclear during early pregnancy in sheep. In this study, livers were collected on day 16 of the estrous cycle and on days 13, 16 and 25 of pregnancy (n = 6 for each group) in ewes, and qRT-PCR, western blot and immunohistochemistry were used to analyze the expression of Th1 and Th2 cytokines in the livers. Our results showed that interferon-gamma (IFN-γ), interleukin (IL)-2, IL-4, IL-6 and IL-10 were downregulated, and IL-5 was upregulated in the livers during early pregnancy. Furthermore, there was no effect for early pregnancy on expression of TNF-β in the livers, and the IFN-γ protein was limited to the endothelial cells of the proper hepatic arteries and portal veins. In conclusion, early pregnancy exerted its effect on the liver to regulate the Th cytokines expression, but there was no evident shift from Th1 to Th2 cytokines, which may be necessary for the maternal hepatic immune adjustments during early pregnancy in sheep.

A severe mouse model of spinal muscular atrophy develops early systemic inflammation

Spinal muscular atrophy (SMA) is a fatal genetic disease, mainly affecting children. A number of recent studies show, aside from lower motor neuron degeneration and atrophy of skeletal muscles, widespread defects present in the central nervous system (CNS) and peripheral non-neuronal cell types of SMA patients and mouse models, particularly of severe forms. However, molecular mechanisms underlying the multi-organ manifestations of SMA were hardly understood. Here, using histology, flow cytometry and gene expression analysis in both messenger RNA and protein levels in various tissues, we found that a severe SMA mouse model develops systemic inflammation in early symptomatic stages. SMA mice had an enhanced intestinal permeability, resulting in microbial invasion into the circulatory system. Expression of proinflammatory cytokines was increased in all tissues and the acute phase response in the liver was activated. Systemic inflammation further mobilized glucocorticoid signaling and in turn led to dysregulation of a large set of genes, including robust upregulation of FAM107A in the spinal cord, increased expression of which has been implicated in neurodegeneration. Moreover, we show that lipopolysaccharide challenge markedly suppressed survival of motor neuron 2 exon 7 splicing in all examined peripheral and CNS tissues, resulting in global survival of motor neuron level reduction. Therefore, we identified a novel pathological mechanism in a severe SMA mouse model, which affects phenotypic severity through multiple paths and should contribute to progression of broad neuronal and non-neuronal defects.

Ameliorative effects of Moringa oleifera leaf extract on levofloxacin-induced hepatic toxicity in rats

Fluoroquinolones are some of the most common antibiotics used by clinicians all over the world. Levofloxacin, a fluoroquinolone, is used therapeutically in numerous countries; however, it can cause an increase in liver function tests and liver dysfunction. The current study was designed to determine the effect of Levofloxacin (40 mg/kg body weight (b.wt.) daily for 2 weeks) on rat liver function and oxidative stress markers as well as to evaluate the potential hepatoprotective effects of Moringa oleifera leaf extract as a known antioxidant herb. M. oleifera leaf extract was found to improve the hepatic dysfunction induced by Levofloxacin by recovering liver enzymatic activities (alanine aminotransferase [ALT], aspartate aminotransferase [AST] and gamma-glutamyl transferase [GGT]) to normal levels. The extract also reversed the antioxidant imbalance as measured by catalase and superoxide dismutase activities as well as by reduced glutathione and malondialdehyde levels. Moreover, M. oleifera leaf extract induced anti-inflammation by improving the production of interleukin (IL)-10. Additionally, its presence attenuated the downregulation of IL-1 induced by Levofloxacin alone from hepatic tissue. It can be concluded that M. oleifera extract can help reduce the side effects caused by Levofloxacin administration.

Cord-derived mesenchymal stem cells therapy for liver cirrhosis in children with refractory Henoch-Schonlein purpura: A case report

RATIONALE

To explore the curative effect of human umbilical cord-derived mesenchymal stem cell (ucMSC) therapy for patients with liver cirrhosis complicated with immune thrombocytopenia and refractory Henoch-Schonlein purpura (HSP).

PATIENT CONCERNS

A 12-year-old boy presented to our hospital with an 11-month history of purpura on the skin of both lower limbs accompanied by thrombocytopenia. The patient had a history of repeated swelling and painful dorsum pedis, followed by skin redness.

DIAGNOSIS

Bone marrow slides showed megakaryocyte maturation disorder. Based on the pathology and drug abuse history, he was diagnosed with nodular cirrhosis, secondary allergic purpura, and thrombocytopenia, etiologies related to his drugs and an immune dysfunction.

INTERVENTIONS

ucMSC transplantation was performed, the liver damaging drugs were discontinued, and the appropriate liver immunosuppressive drugs were administered. ucMSCs were injected 8 times/wk in 2 months, with a median cell count of 5.65 × 10/L, ranging from 5.48 to 5.98 × 10/L.

OUTCOMES

As the patient's skin rash resolved, his platelets gradually increased to >150 × 10/L and liver transaminase levels gradually decreased to a normal level. Ultrasonography of the abdomen indicated that the round nodules in the liver decreased in size and that the spleen thickness also decreased.

LESSONS

This is a unique case of significant HSP with associated thrombocytopenia in a patient with liver cirrhosis. Long-term oral administration of excessive herbal medicine may cause liver damage. We believe that ucMSCs provide a novel approach for the treatment of liver cirrhosis.

Primary hepatocytes and their cultures for the testing of drug-induced liver injury

Drug-induced liver injury is a major reason for discontinuation of drug development and withdrawal of drugs from the market. Intensive efforts in the last decades have focused on the establishment and finetuning of liver-based in vitro models for reliable prediction of hepatotoxicity triggered by drug candidates. Of those, primary hepatocytes and their cultures still are considered the gold standard, as they provide an acceptable reflection of the hepatic in vivo situation. Nevertheless, these in vitro systems cope with gradual deterioration of the differentiated morphological and functional phenotype. The present paper gives an overview of traditional and more recently introduced strategies to counteract this dedifferentiation process in an attempt to set up culture models that can be used for long-term testing purposes. The relevance and applicability of such optimized cultures of primary hepatocytes for the testing of drug-induced cholestatic liver injury is demonstrated.

Immune Responses in the Liver

The liver is a key, frontline immune tissue. Ideally positioned to detect pathogens entering the body via the gut, the liver appears designed to detect, capture, and clear bacteria, viruses, and macromolecules. Containing the largest collection of phagocytic cells in the body, this organ is an important barrier between us and the outside world. Importantly, as portal blood also transports a large number of foreign but harmless molecules (e.g., food antigens), the liver's default immune status is anti-inflammatory or immunotolerant; however, under appropriate conditions, the liver is able to mount a rapid and robust immune response. This balance between immunity and tolerance is essential to liver function. Excessive inflammation in the absence of infection leads to sterile liver injury, tissue damage, and remodeling; insufficient immunity allows for chronic infection and cancer. Dynamic interactions between the numerous populations of immune cells in the liver are key to maintaining this balance and overall tissue health.

Molecular characterization and expression analysis of a novel r-spondin member (rspo2l) in Chinese tongue sole (Cynoglossus semilaevis)

Numerous studies suggest R-spondins (Rspos) plays a role in mammalian sex development and differentiation by activating WNT signaling pathways. However, Rspos are frequently less reported in teleosts. In this study, a molecular characterization and expression analysis was conducted with a new rspondin member in the Chinese tongue sole, rspondin2-like (rspo2l). The length of rspo2l cDNA is 1251 bp with 732 bp of coding sequence. A qRT-PCR analysis revealed that the transcription of rspo2l was distributed in various tissues, with high transcription levels in the liver, skin, and gills which might indicate a possible role in immunity. We next examined a time-course of transcription levels in four immune tissues (gill, liver, spleen, and kidney) after Vibrio harveyi challenge. It was found that rspo2l was up-regulated in the gills, spleen, and kidney and down-regulated in the liver, and the greatest responses occurred at 24 and 48 h after bacterial challenge. An assessment of β-catenin, the key regulator of the canonical WNT signaling pathway, at different time points in four immune organs revealed that its transcription profile was similar to that of rspo2l after bacterial challenge. The results suggest that tongue sole rspo2l might play a role in immune responses after bacterial challenge, while the potential link with the WNT signaling pathway still requires further investigation. This is the first report about the involvement of rspondins in fish immune responses.

Captivity influences immune responses, stress endocrinology, and organ size in house sparrows (Passer domesticus)

Studies using wild animals in laboratory-based research require bringing wild-captured organisms into a novel setting, which can have long-lasting impacts on physiology and behavior. In several species, captivity stimulates stress hormone production and can alter immune function. Despite this, there is little consensus on how captivity influences stress hormone regulation, or if captivity-induced changes in stress hormone production and regulation mediate changes in immune function. In this study, we investigate the influence of captivity on the physiology of a wild bird commonly-used in laboratory-based research, the house sparrow (Passer domesticus). We tested how captivity influences stress endocrinology, immune responses, and organ mass, and also investigated if the production or regulation of corticosterone, the main stress hormone in birds, correlated with changes in immunity. We found that baseline corticosterone concentrations and maximum capacity of the adrenals to secrete corticosterone increase following captivity and remain elevated after 9weeks of captivity. A measure of innate immune function, the bactericidal ability of plasma, also increased with time spent in captivity. Wound healing was also influenced by time spent in captivity, with birds taking almost 2days longer to heal if they were wounded after 3weeks in captivity when compared with birds that were wounded immediately upon capture. Additionally, captivity caused notable reductions in spleen and liver mass. Together, these results imply that captivity can have long-lasting effects on house sparrow corticosterone release and immune function, and suggest that even after 9weeks house sparrows do not acclimate physiologically to life in captivity.

Clonorchis sinensis antigens alter hepatic macrophage polarization in vitro and in vivo

Clonorchis sinensis infection elicits hepatic inflammation, which can lead to cholangitis, periductal hepatic fibrosis, liver cirrhosis, and even cholangiocarcinoma. Hepatic macrophages are an intrinsic element of both innate and acquired immunity. This study was conducted to demonstrate the dynamics of hepatic macrophage polarization during C. sinensis infection in mice and to identify factors regulating this polarization. Treatment of hepatic macrophages isolated from normal mice with C. sinensis excretory/secretory products (ESPs) resulted in the preferential generation of classically activated hepatic macrophages (M1 macrophages) and the production of pro-inflammatory cytokines. Additionally, cells stimulated with C. sinensis ESPs exhibited changes in cellular morphology. During the early stages of C. sinensis infection, hepatic macrophages preferentially differentiated into M1 macrophages; however, during the C. sinensis mature worm stage, when eggs are released, there were significant increases in the abundance of both M1 macrophages and alternatively activated hepatic macrophages (M2 macrophages). Moreover, there was a further increase in the M2 macrophage count during the fibrotic and cirrhotic stage of infection. Notably, this fibrotic and cirrhotic stage promoted a strong increase in the proportion of Arg-1-producing macrophages (M2 phenotype), which were associated with fibrosis and tissue repair in the liver. Our results suggest that the dynamic polarization of hepatic macrophages as C. sinensis infection progresses is related to the histological lesions present in liver tissue. Hepatic macrophages thus play an important role in local immunity during C. sinensis infection.

Infection with Clonorchis sinensis is a major public health problem in Asia, resulting in loss of liver function and chronic liver diseases, including cancers. However, to the best of our knowledge, the immune response to fluke infection in the liver has not been systematically investigated. Here, we demonstrated that C. sinensis infection triggered a shift in the characteristics of macrophages, the primary cells associated with host immunity, throughout the course of the worm’s life cycle. Eventually, the increased number of M2 macrophages may result in fibrosis and the remodeling of bile ducts within the liver. Our findings suggest that, while the infection initially led to changes in the immune response that facilitated C. sinensis survival, ongoing infection may also reduce the severity of disruption of liver function. Hepatic macrophages activated during C. sinensis infection may not only be operating in histological lesions around the bile duct, but may also play a role in local immunity.

Paraoxonase-1 activity is related to Trichinella spiralis-induced hepatitis in rats

BACKGROUND

Little is known about the potential adverse effects of a chronic zoonotic nematode Trichinella spiralis infection on hepatic inflammation and its relationship to paraoxonase (PON)-1 and butyrylcholinesterase (BuChE) activities. Therefore, we aimed to examine the effects of T. spiralis infection on hepatic synthesis of PON1.

METHODS

Wistar rats were infected with 2500 first-stage larvae (L1) of T. spiralis, and serum PON1 and BuChE activities were evaluated. Hepatic expression levels of PON1, BuChE and various cytokines and chemokines [interleukin (IL)-1, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, and transforming growth factor (TGF)-β1] were evaluated for up to 9 weeks post-infection (p.i.). The effect of these changes on the degree of hepatic apoptosis was also investigated.

RESULTS

Trichinella spiralis infection in rats induced significant decreases in serum PON1 activities from day 2 until week 7 p.i. and BuChE activity starting from day 4 until 2 weeks p.i. Moreover, T. spiralis infection increased serum pro-inflammatory cytokines IL-1, IL-6 and TNF-α as well as chemokines MCP-1, MIP-1α and TGF-β1 during the enteral phase of the parasite life cycle. The anti-inflammatory cytokines IL-4 and IL-10 showed significant increases during the enteral phase for the former and the muscle phase for the latter. These were associated with hepatic inflammation and apoptosis. These events typically decreased hepatic PON1 and BuChE mRNA expression.

CONCLUSIONS

Immune responses mounted against T. spiralis infection in rats were associated with hepatic inflammation and a subsequent decrease in serum PON1 and BuChE activities.

Inflammation-induced CD69+ Kupffer cell feedback inhibits T cell proliferation via membrane-bound TGF-β1

Kupffer cells, tissue-resident macrophage lineage cell, are enriched in vertebrate liver. The mouse F4/80⁺ Kupffer cells have been subclassified into two subpopulations according to their phenotype and function: CD68⁺ subpopulation with potent reactive oxygen species (ROS) production and phagocytic capacities, and CD11b⁺ subpopulation with a potent capacity to produce T helper 1 cytokines. In addition, CD11b⁺ Kupffer cells/macrophages may be migrated from the bone marrow or spleen, especially in inflammatory conditions of the liver. For analyzing diverse Kupffer cell subsets, we infected mice with Listeria monocytogenes and analyzed the phenotype variations of hepatic Kupffer cells. During L. monocytogenes infection, hepatic CD69⁺ Kupffer cells were significantly induced and expanded, and CD69⁺ Kupffer cells expressed higher level of CD11b, and particularly high level of membrane-bound TGF-β1 (mTGF-β1) but lower level of F4/80. We also found that clodronate liposome administration did not eliminate hepatic CD69⁺ Kupffer cell subset. We consider the hepatic CD69⁺ Kupffer cell population corresponds to CD11b⁺ Kupffer cells, the bone marrow-derived population. Hepatic CD69⁺ Kupffer cells suppressed Ag-nonspecific and OVA-specific CD4 T cell proliferation through mTGF-β1 both in vitro and in vivo, meanwhile, they did not interfere with activation of CD4 T cells. Thus, we have identified a new subset of inflammation-induced CD69⁺ Kupffer cells which can feedback inhibit CD4 T cell response via cell surface TGF-β1 at the late stage of immune response against infection. CD69⁺ Kupffer cells may contribute to protect host from pathological injure by preventing overactivation of immune response.

Identification of a C-type lectin from tilapia (Oreochromis niloticus) and its functional characterization under low-temperature stress

C-type lectin, which plays an important role in fish innate immunity, was cloned from tilapia and its functional characterization under low-temperature stress is reported. Its ORF is 453 bp, encoding 150 amino acids, and has a 5'UTR of 83 bp, a 3'UTR of 559 bp, and a poly (A) tail. The tilapia C-type lectin genomic DNA was acquired with a length of 5714 bp, containing six exons and five introns. Its promoter sequence was cloned and has a length of 2251 bp. The highest promoter activity occurs in the regulatory region (-900 bp to -450 bp). A hemagglutination assay of recombinant tilapia C-type lectin protein showed positive hemagglutination of rabbit and tilapia erythrocytes. RT-qPCR and western blot assays showed that its expression in the liver, spleen, and intestine were clearly affected by low-temperature stress. Thus, tilapia C-type lectin appear to be affected by abiotic stress, as well as by biological stress.

Transcriptome analysis of the livers of ducklings hatched normally and with assistance

Objective

“Hatchability” is an important economic trait in domestic poultry. Studies on poultry hatchability focus mainly on the genetic background, egg quality, and incubation conditions, whereas the molecular mechanisms behind the phenomenon that some ducklings failed to break their eggshells are poorly understood.

Methods

In this study, the transcriptional differences between the livers of normally hatched and assisted ducklings were systematically analyzed.

Results

The results showed that the clean reads were de novo assembled into 161,804 and 159,083 unigenes (≥200-bp long) by using Trinity, with an average length of 1,206 bp and 882 bp, respectively. The defined criteria of the absolute value of log2 fold-change ≥1 and false discovery rate≤0.05 were differentially expressed and were significant. As a result, 1,629 unigenes were identified, the assisted ducklings showed 510 significantly upregulated and 1,119 significantly down-regulated unigenes. In general, the metabolic rate in the livers of the assisted ducklings was lower than that in the normal ducklings; however, compared to normal ducklings, glucose-6-phosphatase and ATP synthase subunit alpha 1 associated with energy metabolism were significantly upregulated in the assisted group. The genes involved in immune defense such as major histocompatibility complex (MHC) class I antigen alpha chain and MHC class II beta chain 1 were downregulated in the assisted ducklings.

Conclusion

These data provide abundant sequence resources for studying the functional genome of the livers in ducks and other poultry. In addition, our study provided insight into the molecular mechanism by which the phenomenon of weak embryos is regulated.

Leishmania infantum antigens modulate memory cell subsets of liver resident T lymphocyte

In the recent years, the liver has been recognized as an important immune organ with major regulatory functions and immune memory, adding to the well-described vital metabolic functions. There are evidences from experimental infections performed with visceral Leishmania species that immune responses to parasite infection can be organ-specific. The liver is the compartment of acute resolving infection, with minimal tissue damage and resistance to reinfection, whereas the spleen is the compartment of parasite persistence. Control of hepatic infection in mice requires a coordinated immune response that involves the development of inflammatory granulomas. It is also described that the liver harbors populations of resident lymphocytes, which may exhibit memory characteristics. Therefore, the present study aims to address the role of the liver as an immune memory organ in the context of Leishmania infantum infection, by characterizing phenotypically resident liver T lymphocytes. The dynamics of memory T cells in L. infantum infected BALB/c mice and the effect of anti-leishmanial treatment in the differentiation of memory cell subsets were analyzed. The potential of recognition, differentiation and selection of memory lymphocytes by three L. infantum recombinant proteins were also explored. L. infantum infection generates effector and central memory T cells, but the cells did not expand when recalled, demonstrating a possible parasite silencing effect. The treatment with a leishmanicidal drug (antimoniate meglumine) increases the levels of memory and effector T cells, eliciting a more robust hepatic immune response. L. infantum parasites with a decreased sensitivity to the leishmanicidal drug favor the expansion of memory CD8⁺ T cell subset, but inhibit the proliferation of CD8⁺ T effector cells, possibly assuring their own survival. The recombinant proteins LirCyp1 and LirSOD are strongly recognized by memory cells of treated mice, indicating that these proteins might be used in a prophylactic or therapeutic vaccine formulation. Thus, L. infantum released antigens induce the development of immune memory subsets in the liver resident T cell population that specifically recognized parasite antigens, including recombinant proteins.

Roles of acetylation-dependent regulation in pathogenesis of chronic hepatitis B virus infection: Potential application as targets for antiviral treatment

In recent years, many studies have confirmed that epigenetics and acetylation-dependent regulation play important roles in the pathogenesis of chronic hepatitis and primary hepatocellular carcinoma. This paper systematically introduces the roles and possible mechanisms of acetylation and its related signal pathways in the pathogenesis of chronic hepatitis B virus (HBV) infection, which may provide a potential novel strategy for the therapy of chronic HBV infection.

Burkholderia pseudomallei rpoS mediates iNOS suppression in human hepatocyte (HC04) cells

Burkholderia pseudomallei is an intracellular Gram-negative bacterial pathogen and the causative agent of melioidosis, a widespread disease in Southeast Asia. Reactive nitrogen, in an intermediate form of nitric oxide (NO), is one of the first lines of defense used by host cells to eliminate intracellular pathogens, through the stimulation of inducible nitric oxide synthase (iNOS). Studies in phagocytotic cells have shown that the iNOS response is muted in B. pseudomallei infection, and implicated the rpoS sigma factor as a key regulatory factor mediating suppression. The liver is a main visceral organ affected by B. pseudomallei, and there is little knowledge about the interaction of liver cells and B. pseudomallei. This study investigated the induction of iNOS, as well as autophagic flux and light-chain 3 (LC3) localization in human liver (HC04) cells in response to infection with B. pseudomallei and its rpoS deficient mutant. Results showed that the rpoS mutant was unable to suppress iNOS induction and that the mutant showed less induction of autophagy and lower co-localization with LC3, and this was coupled with a lower intracellular growth rate. Combining these results suggest that B. pseudomallei rpoS is an important factor in establishing infection in liver cells.

This study investigated the induction of nitric oxide synthase (iNOS) in human hepatocyte cells (HC-04) infected with wild-type Burkholderia pseudomallei or an rpoS mutant. RpoS was implicated in the ability to suppress iNOS induction and with the induction of autophagy, indicating that it plays an important role in B. pseudomallei interactions with liver cells.

Inflammatory responses to neutral fat and fatty acids in multiple organs in a rat model of fat embolism syndrome

Fat embolism syndrome (FES) is a common complication of long bone fractures. FES is rare but with significant morbidity and occasional fatalities. Studies of animal models of FES are numerous; however, few studies compare inflammatory reactions in multiple organs. The present study investigated the effect of neutral fat and fatty acids, which cause changes in multiple organs and induce FES. Using rats we evaluated the ratio of lung-to-body weight and conducted histological analyses and quantitative analysis of inflammatory cytokine mRNAs in the lungs following intravenous administration of neutral fat or fatty acids. Neutral fat increased the ratio of lung-to-body weight, and neutral fat formed emboli in lung capillaries. The levels of interleukin-1 beta (IL-1β), IL-6 and tumor necrosis factor-alpha (TNF-α) in the lungs increased after injection of neutral fat and oleic acid. Analysis of the histologic changes revealed that the highest numbers of fat droplets, occluding the capillaries of the lungs, kidney, heart, and brain formed 12h after the injection of neutral fat and fat droplets gradually diminished 48h later. Fat droplets were not detected in any organs after the injection of oleic acid. IL-1β and TNF-α levels in the lungs were elevated 9-24h after the injection of neutral fat, although IL-6 levels peaked at 6h. After injection of oleic acid, peak levels of IL-1β, IL-6, and TNF-α were detected at 6h, and IL-6 again increased in all organs and plasma at 15h. Neutral fat, but not fatty acids, formed emboli in the capillaries of multiple organs. These findings suggest that neutral fat increased inflammatory cytokine levels by forming emboli in organ capillaries, particularly in the lungs, while oleic acid augmented inflammatory cytokine levels by stimulating endothelial cells of multiple organs.

Role of Kupffer cells in hepatitis B/C viral hepatitis

Kupffer cells (KCs) are the largest group of tissue macrophages. KCs in the hepatic sinusoid contact with pathogens from circulation earliest. The quantity of KCs increases significantly in patients with viral hepatitis, suggesting that KCs play an important role in viral hepatitis related immunity. KCs can not only engulf virus particles, but also present antigens, secrete cytokines, and participate in a variety of inflammatory responses, immune tolerance and liver injury. In hepatitis B virus (HBV)/hepatitis C virus (HCV) infections, the diversity of KCs-related cytokines, the complexity of interactions of receptor signaling pathways as well as the duality of cytotoxic effect, indicate that KCs play a dual role in the immune response; the activation of KCs regulates the balance of inflammatory and anti-inflammatory mechanisms in viral hepatitis.

Histologic Features of Postnatal Development of Immune System Organs in the Sprague-Dawley Rat

The immune system of the rat undergoes substantial functional and morphological development during the postnatal period. Some aspects of this development are genetically predetermined, while other aspects depend on environmental influences. Detailed information on postnatal development is important in the interpretation of histopathologic findings in juvenile toxicology and pubertal assay studies, as well as other studies conducted in juvenile rats. Studies were conducted to provide detailed characterization of histologic features of the major functional compartments of immune system organs in male and female Sprague-Dawley rats at weekly intervals from the day of birth through postnatal day (PND) 42. Maturation of the individual immune system organs occurred across a range of ages, with histologic maturation of T-cell-related compartments typically occurring prior to maturation of B-cell-related compartments. The sequence of histologic maturation was bone marrow and thymus on PND 14, mesenteric lymph node on PND 21, Peyer's patches and bronchus-associated lymphoid tissue on PND 28, mandibular lymph node, nasopharynx-associated lymphoid tissue, and diffuse mucosal mononuclear cell population of small intestine on PND 35, and spleen on PND 42. An estimation of functional maturation can be made based on the morphological indications of maturity of each compartment of immune system organs, but histologic indications of maturity do not confirm functional immunocompetence.

Characterization of distinct subpopulations of hepatic macrophages in HFD/obese mice

The current dogma is that obesity-associated hepatic inflammation is due to increased Kupffer cell (KC) activation. However, recruited hepatic macrophages (RHMs) were recently shown to represent a sizable liver macrophage population in the context of obesity. Therefore, we assessed whether KCs and RHMs, or both, represent the major liver inflammatory cell type in obesity. We used a combination of in vivo macrophage tracking methodologies and adoptive transfer techniques in which KCs and RHMs are differentially labeled with fluorescent markers. With these approaches, the inflammatory phenotype of these distinct macrophage populations was determined under lean and obese conditions. In vivo macrophage tracking revealed an approximately sixfold higher number of RHMs in obese mice than in lean mice, whereas the number of KCs was comparable. In addition, RHMs comprised smaller size and immature, monocyte-derived cells compared with KCs. Furthermore, RHMs from obese mice were more inflamed and expressed higher levels of tumor necrosis factor-α and interleukin-6 than RHMs from lean mice. A comparison of the MCP-1/C-C chemokine receptor type 2 (CCR2) chemokine system between the two cell types showed that the ligand (MCP-1) is more highly expressed in KCs than in RHMs, whereas CCR2 expression is approximately fivefold greater in RHMs. We conclude that KCs can participate in obesity-induced inflammation by causing the recruitment of RHMs, which are distinct from KCs and are not precursors to KCs. These RHMs then enhance the severity of obesity-induced inflammation and hepatic insulin resistance.

The teleostean liver as an immunological organ: Intrahepatic immune cells (IHICs) in healthy and benzo[a]pyrene challenged rainbow trout (Oncorhynchus mykiss)

The existence of a resident population of intrahepatic immune cells (IHICs) is well documented for mammalian vertebrates, however, it is uncertain whether IHICs are present in the liver of teleostean fish. In the present study we investigated whether trout liver contains an IHIC population, and if so, what the relative cellular composition of this population is. The results provide clear evidence for the existence of an IHIC population in trout liver, which constitutes 15-29% of the non-hepatocytes in the liver, and with a cellular composition different to that of the blood leukocyte population. We also analyzed the response of IHICs to a non-infectious liver challenge with the hepatotoxic and immunotoxic chemical, benzo[a]pyrene (BaP). Juvenile trout were treated with BaP (25 or 100mg/kgbw) at levels sufficient to induce the molecular pathway of BaP metabolism while not causing pathological and inflammatory liver changes. The IHIC population responded to the BaP treatments in a way that differed from the responses of the leukocyte populations in trout blood and spleen, suggesting that IHICs are an independently regulated immune cell population.