Recapitulation of SARS-CoV-2 infection and cholangiocyte damage with human liver ductal organoids

Establishment of a human organoid-based evaluation system for assessing interspecies infection risk of animal-borne coronaviruses

The COVID-19 pandemic presents a major threat to global public health. Several lines of evidence have shown that the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), along with two other highly pathogenic coronaviruses, SARS-CoV and Middle East Respiratory Syndrome (MERS-CoV) originated from bats. To prevent and control future coronavirus outbreaks, it is necessary to investigate the interspecies infection and pathogenicity risks of animal-related coronaviruses. Currently used infection models, including in vitro cell lines and in vivo animal models, fail to fully mimic the primary infection in human tissues. Here, we employed organoid technology as a promising new model for studying emerging pathogens and their pathogenic mechanisms. We investigated the key host-virus interaction patterns of five human coronaviruses (SARS-CoV-2 original strain, Omicron BA.1, MERS-CoV, HCoV-229E, and HCoV-OC43) in different human respiratory organoids. Five indicators, including cell tropism, invasion preference, replication activity, host response and virus-induced cell death, were developed to establish a comprehensive evaluation system to predict coronavirus interspecies infection and pathogenicity risks. Using this system, we further examined the pathogenicity and interspecies infection risks of three SARS-related coronaviruses (SARSr-CoV), including WIV1 and rRsSHC014S from bats, and MpCoV-GX from pangolins. Moreover, we found that cannabidiol, a non-psychoactive plant extract, exhibits significant inhibitory effects on various coronaviruses in human lung organoid. Cannabidiol significantly enhanced interferon-stimulated gene expression but reduced levels of inflammatory cytokines. In summary, our study established a reliable comprehensive evaluation system to analyse infection and pathogenicity patterns of zoonotic coronaviruses, which could aid in prevention and control of potentially emerging coronavirus diseases.

A prospects tool in virus research: Analyzing the applications of organoids in virus studies

Organoids have emerged as a powerful tool for understanding the biology of the respiratory, digestive, nervous as well as urinary system, investigating infections, and developing new therapies. This article reviews recent progress in the development of organoid and advancements in virus research. The potential applications of these models in studying virul infections, pathogenesis, and antiviral drug discovery are discussed.

COVID-19 drug discovery and treatment options

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused substantial morbidity and mortality, and serious social and economic disruptions worldwide. Unvaccinated or incompletely vaccinated older individuals with underlying diseases are especially prone to severe disease. In patients with non-fatal disease, long COVID affecting multiple body systems may persist for months. Unlike SARS-CoV and Middle East respiratory syndrome coronavirus, which have either been mitigated or remained geographically restricted, SARS-CoV-2 has disseminated globally and is likely to continue circulating in humans with possible emergence of new variants that may render vaccines less effective. Thus, safe, effective and readily available COVID-19 therapeutics are urgently needed. In this Review, we summarize the major drug discovery approaches, preclinical antiviral evaluation models, representative virus-targeting and host-targeting therapeutic options, and key therapeutics currently in clinical use for COVID-19. Preparedness against future coronavirus pandemics relies not only on effective vaccines but also on broad-spectrum antivirals targeting conserved viral components or universal host targets, and new therapeutics that can precisely modulate the immune response during infection.

COVID-19-associated secondary sclerosing cholangitis with liver transplantation

We report on two cases of orthotopic liver transplantation (OLTX) due to SARS-Cov2-associated secondary sclerosing cholangitis (SSC) following long-term artificial respiration and extra-corporal membrane oxygenation in intensive care. Under these conditions, SSC is a rapidly progredient biliary disease featuring degenerative cholangiopathy, loss of bile ducts, ductular and parenchymal cholestasis, biliary fibrosis, and finally cirrhosis. Reduced perfusion and oxygenation of the peribiliary plexus, severe concurrent infections, and secondary medico-toxic effects appear to play a crucial role in the pathogenesis of the disease. A direct cytopathic effect of SARS-Cov2 on endothelial cells followed by thrombosis and fibrosing obliteration in all parts of the vascular bed of the liver may enhance the virus-associated liver disease and particularly SSC.

Who Is the Intermediate Host of RNA Viruses? A Study Focusing on SARS-CoV-2 and Poliovirus

The COVID-19 pandemic has sparked a surge in research on microbiology and virology, shedding light on overlooked aspects such as the infection of bacteria by RNA virions in the animal microbiome. Studies reveal a decrease in beneficial gut bacteria during COVID-19, indicating a significant interaction between SARS-CoV-2 and the human microbiome. However, determining the origins of the virus remains complex, with observed phenomena such as species jumps adding layers to the narrative. Prokaryotic cells play a crucial role in the disease's pathogenesis and transmission. Analyzing previous studies highlights intricate interactions from clinical manifestations to the use of the nitrogen isotope test. Drawing parallels with the history of the Poliovirus underscores the need to prioritize investigations into prokaryotic cells hosting RNA viruses.

Liver organoids and their application in liver cancer research

Liver cancer, a common and intractable liver-related disease, is a malignant tumor with a high morbidity, which needs a high treatment cost but still lacks perfect clinical treatment methods. Looking for an effective platform for liver cancer study and drug screening is urgent and important. Traditional analytical methods for liver disease studies mainly rely on the 2D cell culture and animal experiments, which both cannot fully recapitulate physiological and pathological processes of human liver. For example, cell culture can only show basic functions of cells in vitro, while animal models always hold the problem of species divergence. The organoids, a 3D invitro culture system emerged in recent years, is a cell-bound body with different cell types and has partial tissue functions. The organoid technology can reveal the growth state, structure, function and characteristics of the tissue or organ, and plays an important role in reconstructing invitro experimental models that can truly simulate the human liver. In this paper, we will give a brief introduction of liver organoids and review their applications in liver cancer research, especially in liver cancer pathogenesis, drug screening, precision medicine, regenerative medicine, and other fields. We have also discussed advantages and disadvantages of organoids, as well as future directions and perspectives towards liver organoids.

Using Liver Organoids as Models to Study the Pathobiology of Rare Liver Diseases

Liver organoids take advantage of several important features of pluripotent stem cells that self-assemble in a three-dimensional culture matrix and reproduce many aspects of the complex organization found within their native tissue or organ counterparts. Compared to other 2D or 3D in vitro models, organoids are widely believed to be genetically stable or docile structures that can be programmed to virtually recapitulate certain biological, physiological, or pathophysiological features of original tissues or organs in vitro. Therefore, organoids can be exploited as effective substitutes or miniaturized models for the study of the developmental mechanisms of rare liver diseases, drug discovery, the accurate evaluation of personalized drug responses, and regenerative medicine applications. However, the bioengineering of organoids currently faces many groundbreaking challenges, including a need for a reasonable tissue size, structured organization, vascularization, functional maturity, and reproducibility. In this review, we outlined basic methodologies and supplements to establish organoids and summarized recent technological advances for experimental liver biology. Finally, we discussed the therapeutic applications and current limitations.

Deep-Orga: An improved deep learning-based lightweight model for intestinal organoid detection

PROBLEM

Organoids are 3D cultures that are commonly used for biological and medical research in vitro due to their functional and structural similarity to source organs. The development of organoids can be assessed by morphological tests. However, manual analysis of organoid morphology requires intensive labor from professionals and is prone to observer discrepancies.

AIM

Computer-assisted methods alleviate the pressure of manual labor, especially with the development of deep learning, the performance of morphological detection has been further improved. The aim of this paper is to automate the assessment of organoid morphology using deep learning techniques to reduce the labor pressure of professionals.

METHODS

Based on the lightweight model YOLOX, a lightweight intestinal organoid detection model named Deep-Orga is proposed. First, the performance of the Deep-Orga model is compared with other classical models on the intestinal organoids dataset. Then, ablation experiments are used to validate the improvement of the model detection performance by the improved module. Finally, Deep-Orga is compared with other methods.

RESULTS

Deep-Orga achieves optimal organoid detection with a partial increase in computational effort. Using Deep-Orga to replace the manual analysis process provides a new automated method for organoid morphology evaluation.

CONCLUSION

Deep-Orga proposed in this paper is able to accurately assess organoid development, effectively relieving the labor pressure of professionals and avoiding the subjectivity of assessment. This paper demonstrates the potential application of deep learning in the field of organoid morphology analysis.

Molecular mechanisms underlying SARS-CoV-2 hepatotropism and liver damage

In coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) primarily targets the respiratory system, but evidence suggests extrapulmonary organ involvement, notably in the liver. Viral RNA has been detected in hepatic tissues, and in situ hybridization revealed virions in blood vessels and endothelial cells. Electron microscopy confirmed viral particles in hepatocytes, emphasizing the need for understanding hepatotropism and direct cytopathic effects in COVID-19-related liver injury. Various factors contribute to liver injury, including direct cytotoxicity, vascular changes, inflammatory responses, immune reactions from COVID-19 and vaccinations, and drug-induced liver injury. Although a typical hepatitis presentation is not widely documented, elevated liver biochemical markers are common in hospitalized COVID-19 patients, primarily showing a hepatocellular pattern of elevation. Long-term studies suggest progressive cholestasis may affect 20% of patients with chronic liver disease post-SARS-CoV-2 infection. The molecular mechanisms underlying SARS-CoV-2 infection in the liver and the resulting liver damage are complex. This "Editorial" highlights the expression of the Angiotensin-converting enzyme-2 receptor in liver cells, the role of inflammatory responses, the impact of hypoxia, the involvement of the liver's vascular system, the infection of bile duct epithelial cells, the activation of hepatic stellate cells, and the contribution of monocyte-derived macrophages. It also mentions that pre-existing liver conditions can worsen the outcomes of COVID-19. Understanding the interaction of SARS-CoV-2 with the liver is still evolving, and further research is required.

Development trends of human organoid-based COVID-19 research based on bibliometric analysis

Coronavirus disease 2019 (COVID-19), a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a catastrophic threat to human health worldwide. Human stem cell-derived organoids serve as a promising platform for exploring SARS-CoV-2 infection. Several review articles have summarized the application of human organoids in COVID-19, but the research status and development trend of this field have seldom been systematically and comprehensively studied. In this review, we use bibliometric analysis method to identify the characteristics of organoid-based COVID-19 research. First, an annual trend of publications and citations, the most contributing countries or regions and organizations, co-citation analysis of references and sources and research hotspots are determined. Next, systematical summaries of organoid applications in investigating the pathology of SARS-CoV-2 infection, vaccine development and drug discovery, are provided. Lastly, the current challenges and future considerations of this field are discussed. The present study will provide an objective angle to identify the current trend and give novel insights for directing the future development of human organoid applications in SARS-CoV-2 infection.

COVID-19-associated liver injury: Adding fuel to the flame

COVID-19 is mainly characterized by respiratory disorders and progresses to multiple organ involvement in severe cases. With expansion of COVID-19 and SARS-CoV-2 research, correlative liver injury has been revealed. It is speculated that COVID-19 patients exhibited abnormal liver function, as previously observed in the SARS and MERS pandemics. Furthermore, patients with underlying diseases such as chronic liver disease are more susceptible to SARS-CoV-2 and indicate a poor prognosis accompanied by respiratory symptoms, systemic inflammation, or metabolic diseases. Therefore, COVID-19 has the potential to impair liver function, while individuals with preexisting liver disease suffer from much worse infected conditions. COVID-19 related liver injury may be owing to direct cytopathic effect, immune dysfunction, gut-liver axis interaction, and inappropriate medication use. However, discussions on these issues are infancy. Expanding research have revealed that angiotensin converting enzyme 2 (ACE2) expression mediated the combination of virus and target cells, iron metabolism participated in the virus life cycle and the fate of target cells, and amino acid metabolism regulated immune response in the host cells, which are all closely related to liver health. Further exploration holds great significance in elucidating the pathogenesis, facilitating drug development, and advancing clinical treatment of COVID-19-related liver injury. This article provides a review of the clinical and laboratory hepatic characteristics in COVID-19 patients, describes the etiology and impact of liver injury, and discusses potential pathophysiological mechanisms.

Modeling Liver Development and Disease in a Dish

Historically, biological research has relied primarily on animal models. While this led to the understanding of numerous human biological processes, inherent species-specific differences make it difficult to answer certain liver-related developmental and disease-specific questions. The advent of 3D organoid models that are either derived from pluripotent stem cells or generated from healthy or diseased tissue-derived stem cells have made it possible to recapitulate the biological aspects of human organs. Organoid technology has been instrumental in understanding the disease mechanism and complements animal models. This review underscores the advances in organoid technology and specifically how liver organoids are used to better understand human-specific biological processes in development and disease. We also discuss advances made in the application of organoid models in drug screening and personalized medicine.

SARS-CoV-2 viral liver aggregates and scarce parenchymal infection implicate systemic disease as a driver of abnormal liver function

BACKGROUND

Liver function tests (LFTs) are elevated in >50% of hospitalized individuals infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), with increased enzyme levels correlating with a more severe COVID-19 course. Despite these observations, evaluations of viral presence within liver parenchyma and viral impact on liver function remain controversial.

METHODS AND RESULTS

Our work is a comprehensive immunopathological evaluation of liver tissue from 33 patients with severe, and ultimately fatal, cases of SARS-CoV-2 infection. Coupled with clinical data, we reveal the absence of SARS-CoV-2 infection in cholangiocytes and hepatocytes despite dramatic systemic viral presence. Critically, we identify significant focal viral sinusoidal aggregates in 2/33 patients and single viral RNA molecules circulating in the hepatic sinusoids of 15/33 patients. Utilizing co-immunofluorescence, focal viral liver aggregates in patients with COVID-19 were colocalized to platelet and fibrin clots, indicating the presence of virus-containing sinusoidal microthrombi. Furthermore, this patient cohort, from the initial months of the COVID-19 pandemic, demonstrates a general downtrend of LFTs over the course of the study timeline and serves as a remarkable historical time point of unattenuated viral replication within patients.

CONCLUSIONS

Together, our findings indicate that elevated LFTs found in our patient cohort are not due to direct viral parenchymal infection with SARS-CoV-2 but rather likely a consequence of systemic complications of COVID-19. This work aids in the clinical treatment considerations of patients with SARS-CoV-2 as therapies for these patients may be considered in terms of their direct drug hepatotoxity rather than worsening hepatic function due to direct infection.

Outcomes in Patients with Liver Dysfunction Post SARS-CoV-2 Infection: What Should We Measure?

Aim

Since 2019, the COVID-19 pandemic wreaked havoc all over the world. Early in the course of the pandemic, multiple hepatic manifestations of COVID-19 were noted. We aim to categorize hepatic dysfunction and its outcome in COVID-19 infection.

Methods

This is a review article based on a literature search in PubMed and Medline databases for articles detailing short-term and long-term outcomes of COVID-19 related liver dysfunction.

Results

The most common hepatic manifestation of COVID-19 was aspartate amino transferase (AST) predominant transaminase elevation. Transaminases improve once the COVID-19 infection resolves. In addition, COVID-19 cholangiopathy, autoimmune hepatitis associated COVID-19, and splanchnic venous thrombosis triggered by COVID-19 are other manifestations. Patients with preexisting liver disease, especially those with cirrhosis, have poor prognosis with COVID-19 infections compared to the general population. Elevations in liver tests were associated with severe COVID-19 infections. Patients with chronic liver disease have a higher risk of morbidity and mortality from COVID-19 infection. Among patients with chronic liver disease, decompensated liver cirrhosis, hepatocellular carcinoma and alcohol-associated liver disease were associated with an increased risk of severity and mortality from COVID-19 infection. Interactions between antiviral therapy for COVID-19 and hepatitis B/hepatitis C medications must be considered in patients with chronic viral hepatitis and COVID-19 infection. COVID-19 vaccination-related hepatic dysfunction has been reported.

Conclusion

COVID-19 is here to stay. Hepatic dysfunction in COVID-19 signals severe COVID-19 infections. Patients with chronic liver disease have higher mortality from COVID-19 than general population. It is important to remember the lessons learned throughout the covid pandemic to take care of patients with COVID-19 now and in the future. Further studies are needed to document long-term outcomes in patients with COVID-19 who developed hepatic dysfunction.

Organoids to Remodel SARS-CoV-2 Research: Updates, Limitations and Perspectives

The novel COVID-19 pneumonia caused by the SARS-CoV-2 virus poses a significant threat to human health. Scientists have made significant efforts to control this virus, consequently leading to the development of novel research methods. Traditional animal and 2D cell line models might not be suitable for large-scale applications in SARS-CoV-2 research owing to their limitations. As an emerging modelling method, organoids have been applied in the study of various diseases. Their advantages include their ability to closely mirror human physiology, ease of cultivation, low cost, and high reliability; thus, they are considered to be a suitable choice to further the research on SARS-CoV-2. During the course of various studies, SARS-CoV-2 was shown to infect a variety of organoid models, exhibiting changes similar to those observed in humans. This review summarises the various organoid models used in SARS-CoV-2 research, revealing the molecular mechanisms of viral infection and exploring the drug screening tests and vaccine research that have relied on organoid models, hence illustrating the role of organoids in remodelling SARS-CoV-2 research.

Panic at the Bile Duct: How Intrahepatic Cholangiocytes Respond to Stress and Injury

In the liver, biliary epithelial cells (BECs) line intrahepatic bile ducts (IHBDs) and are primarily responsible for modifying and transporting hepatocyte-produced bile to the digestive tract. BECs comprise only 3% to 5% of the liver by cell number but are critical for maintaining choleresis through homeostasis and disease. To this end, BECs drive an extensive morphologic remodeling of the IHBD network termed ductular reaction (DR) in response to direct injury or injury to the hepatic parenchyma. BECs are also the target of a broad and heterogenous class of diseases termed cholangiopathies, which can present with phenotypes ranging from defective IHBD development in pediatric patients to progressive periductal fibrosis and cancer. DR is observed in many cholangiopathies, highlighting overlapping similarities between cell- and tissue-level responses by BECs across a spectrum of injury and disease. The following core set of cell biological BEC responses to stress and injury may moderate, initiate, or exacerbate liver pathophysiology in a context-dependent manner: cell death, proliferation, transdifferentiation, senescence, and acquisition of neuroendocrine phenotype. By reviewing how IHBDs respond to stress, this review seeks to highlight fundamental processes with potentially adaptive or maladaptive consequences. A deeper understanding of how these common responses contribute to DR and cholangiopathies may identify novel therapeutic targets in liver disease.

The Lasting Effects of COVID-19 on the Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

It is estimated that around 30% of the population living in Western countries has metabolic dysfunction-associated steatotic liver disease (MASLD), a spectrum of pathology (not attributed to alcohol/substance intake) initiated by steatosis and progression toward inflammation and irreversible fibrosis metabolic dysfunction-associated steatohepatitis (MASH). With inflammation being a key component of the transition to MASH, it raises the question of whether the ongoing COVID-19 pandemic, which has notoriously induced hyperinflammatory states, may influence the progression of MASLD. Specifically, it remains unclear if the potential chronic sequelae of COVID-19 in patients who recovered from it may increase the predisposition for MASH. Since MASH maintains a high risk for hepatocellular carcinoma, liver failure, and the need for a liver transplant, the potential additive effects of COVID-19 could prove critical to study. Thus, the objective of this study was to conduct a literature review to examine if COVID-19 could have chronic sequelae that affect the progression of MASLD pathogenesis. It was hypothesized that severe cases of COVID-19 could induce systemic inflammation, metabolic changes, and lasting gut microbiome alterations that lead to inflammatory and fibrotic changes in the liver, similar to those seen in MASH. A scoping review of the literature was conducted utilizing the PubMed database. Studies that examined hepatobiliary pathology, gut microbiome, systemic inflammation, metabolic changes, drug-induced liver injury (DILI), and hypoxia seen in COVID-19 were included. Human studies of adult cohorts, animal models, and in vitro experiments were included. Genetic components of MASLD were not examined. Exclusion criteria also encompassed any studies not referencing the hepatobiliary, gastrointestinal tract, portal system, or systemic circulation. Findings indicated a frequent trend of elevated liver enzymes, mild steatosis, Kupffer cell hyperplasia, and hepatobiliary congestion. It was found that direct cytopathic effects on hepatocytes were unlikely, but the direct viral insult of cholangiocytes was a potential complication. High serum levels of IL-1, TNF-a, and MCP-1, in COVID-19 were found as potential risk factors for MASH development. Hypoxia, altered lipid metabolism, and iatrogenic DILI were also proposed as potential precipitators of MASH development. Notably, lasting changes in gut microbiome were also frequently observed and correlated closely with those seen in MASH.

Engineering Materials and Devices for the Prevention, Diagnosis, and Treatment of COVID-19 and Infectious Diseases

Following the global spread of COVID-19, scientists and engineers have adapted technologies and developed new tools to aid in the fight against COVID-19. This review discusses various approaches to engineering biomaterials, devices, and therapeutics, especially at micro and nano levels, for the prevention, diagnosis, and treatment of infectious diseases, such as COVID-19, serving as a resource for scientists to identify specific tools that can be applicable for infectious-disease-related research, technology development, and treatment. From the design and production of equipment critical to first responders and patients using three-dimensional (3D) printing technology to point-of-care devices for rapid diagnosis, these technologies and tools have been essential to address current global needs for the prevention and detection of diseases. Moreover, advancements in organ-on-a-chip platforms provide a valuable platform to not only study infections and disease development in humans but also allow for the screening of more effective therapeutics. In addition, vaccines, the repurposing of approved drugs, biomaterials, drug delivery, and cell therapy are promising approaches for the prevention and treatment of infectious diseases. Following a comprehensive review of all these topics, we discuss unsolved problems and future directions.

Acute abdomen in patients with covid-19: an integrative review

INTRODUCTION

upon infection with SARS-CoV-2, patients presented with non-classical symptoms, such as gastrointestinal phenomena including loss of appetite, nausea, vomiting, diarrhea, and abdominal pain abdominal pain. These occurrences, typically, were found in severely affected patients with COVID-19. With this, the aim of this paper is to analyze the available knowledge on the development of acute abdomen in SARS-CoV-2 infected patients.

METHODOLOGY

this is an Integrative Review in PubMed, Web of Science and VHL databases. The following descriptors were used: "Acute abdomen", "COVID-19", "Abdominal pain" and "SARS-CoV-2" with the Boolean operator "AND", and articles relevant to the theme were selected. Initially, 331 articles were selected, all published between 2020 and 2023, in Portuguese and/or English. After analysis, 11 articles matched the proposed objective.

RESULTS

the relationship between tenderness in the right upper region or the presence of Murphy's sign contributed in the association between abdominal pain and the more severe forms of COVID-19 in infected patients. The number of diagnoses for acute conditions such as cholecystitis, appendicitis, diverticulitis and pancreatitis decreased with the pandemic, but at the same time there was an increase in the duration of surgical procedures and in the length of hospital stays. These acute abdominal conditions were the result of delayed demand for hospital care, which also contributed to an increase in the conversion rate to open surgery and in the number of perforative conditions.

CONCLUSION

the development of acute abdomen in SARS-CoV-2 infected patients was predictive of an unfavorable prognosis.

Differences in clinical characteristics and liver injury between patients diagnosed with the Omicron subvariant BA.5.2 and the prototype of SARS-CoV-2: a single center retrospective study

BACKGROUND

The purpose of this study was to investigate the differences between the clinical characteristics and the factors influencing liver injury in patients with the Omicron subvariant BA.5.2 (Omicron BA.5.2) and the prototype of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

Between December 30, 2019 and November 30, 2022, 157 patients infected with the SARS-CoV-2 prototype and 199 patients infected with the Omicron BA.5.2 were included in this case-control, single-center, retrospective study. Differences in clinical characteristics and liver injury between the Omicron BA.5.2 patients and the prototype patients were subsequently analyzed.

RESULTS

None of the Omicron BA.5.2 patients reached the critical state, and showed relatively milder symptoms including fever, cough, headache, muscle soreness, nausea or vomiting, diarrhea, anorexia and hypoxia. The Omicron BA.5.2 had a lower effect on body temperature (T), white blood cell (WBC) count, hematocrit (HCT), C-reactive protein (CRP) level, D-dimer, finger pulse oxygen saturation (SpO2) and lung lesions. The differences in liver injury between the two groups were related to the severity of the disease, T, blood oxygen levels, albumin (ALB), CRP, and medication usage. Gender, body mass index, and CRP levels influenced liver damage in the Omicron BA.5.2 patients. In particular, CRP was an independent risk factor for liver injury. Because the severity of liver function damage was considerably low, only a small number of Omicron BA.5.2 patients required liver-protective treatment.

CONCLUSION

Liver injury is expected in the COVID-19 patients. The Omicron BA.5.2 patients showed milder symptoms of liver injury than the prototype patients. However, dynamic monitoring of liver function is warranted, especially for individuals presenting with elevated levels of CRP.

Secondary Sclerosing Cholangitis After SARS-CoV2: ICU Ketamine Use or Virus-Specific Biliary Tropism and Injury in the Context of Biliary Ischemia in Critically Ill Patients?

Purpose

From the beginning of the Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV2) pandemic, different cases of a cholangiopathy with features of secondary sclerosing cholangitis in critically ill patients (SSC-CIP) have been reported. Patients developing it are generally recovering from severe Coronavirus disease 19 (COVID-19) and required intensive care unit (ICU) admission and mechanical ventilation. Many of them have been administered with ketamine during their ICU stay. The pathogenesis of this novel disease is still debated, and, since prognosis is poor, efforts are needed in order to better understand it.

Patients and Methods

In this review, we focused our attention on COVID-19 SSC clinical, imaging, and histology findings in order to clarify the different pathogenetic options, particularly in regard of the ischemic-direct viral damage and ketamine-related theories, beginning with a recapitulation of SSC-CIP and ketamine-induced cholangiopathy in abusers. The research has been conducted using PubMed and Google Scholar databases. Key-words were "Secondary Sclerosing Cholangiopathy", "SSC-CIP", "Secondary Sclerosing Cholangiopathy in critically ill patients", "Ketamine and cholangiopathy", "Ketamine abusers and liver disease", "Ketamine-related cholangiopathy", "SARS-CoV2 infection and liver disease", "post Covid-19 secondary sclerosing cholangitis", "Covid-19 cholangiopathy".

Results

Many authors, based on the clinical, histological, imaging, and prognostic features of the disease, have pointed out the similarities between post COVID-19 SSC and SSC-CIP; however, peculiar features in the former were not previously observed. Therefore, a direct viral cytopathic action and SARS-CoV2-related coagulopathy are considered the most likely causes. On the other hand, ketamine, with the available data, cannot be surely linked as the main determinant cause of cholangiopathy. Moreover, ketamine-induced cholangitis (KIC) presentation is different from post COVID-19 SSC. Its role as a cofactor precipitating the disease cannot be ruled out.

Conclusion

Post COVID-19 SSC is a rare clinical entity following severe COVID-19 disease. The most accepted theory is that a sum of different insults determines the disease: biliary ischemia, direct viral damage, toxic bile, possibly worsened by ketamine and hyperinflammation due to the cytokine storm. Given the severe prognosis of the disease, with persistent cholangiopathy, organ failure, and orthotopic liver transplantation (OLT), further study on this novel clinical entity is needed.

Strategic use of organoids and organs-on-chip as biomimetic tools

Organoid development and organ-on-a-chip are technologies based on differentiating stem cells, forming 3D multicellular structures resembling organs and tissues in vivo. Hence, both can be strategically used for disease modeling, drug screening, and host-pathogen studies. In this context, this review highlights the significant advancements in the area, providing technical approaches to organoids and organ-on-a-chip that best imitate in vivo physiology.

Mouse Models for Human Herpesviruses

More than one hundred herpesviruses have been isolated from different species so far, with nine infecting humans. Infections with herpesviruses are characterized by life-long latency and represent a significant challenge for human health. To investigate the consequences of infections and identify novel treatment options, in vivo models are of particular relevance. The mouse has emerged as an economical small animal model to investigate herpesvirus infections. However, except for herpes simplex viruses (HSV-1, HSV-2), human herpesviruses cannot infect mice. Three natural herpesviruses have been identified in mice: mouse-derived cytomegalovirus (MCMV), mouse herpesvirus 68 (MHV-68), and mouse roseolovirus (MRV). These orthologues are broadly used to investigate herpesvirus infections within the natural host. In the last few decades, immunocompromised mouse models have been developed, allowing the functional engraftment of various human cells and tissues. These xenograft mice represent valuable model systems to investigate human-restricted viruses, making them particularly relevant for herpesvirus research. In this review, we describe the various mouse models used to study human herpesviruses, thereby highlighting their potential and limitations. Emphasis is laid on xenograft mouse models, covering the development and refinement of immune-compromised mice and their application in herpesvirus research.

Sequencing the SARS-CoV-2 Genome from Stool Samples of Post-acute Cases Implicates a Novel Mutation Associated with Reduced Antibody Neutralization

Whole-genome SARS-CoV-2 sequencing tools are crucial for tracking the COVID-19 pandemic. However, current techniques require sampling of actively infectious patients following COVID-19 testing to recover enough SARS-CoV-2 RNA from the nasopharyngeal passage, which rapidly clears during the first few weeks of infection. A prospective assessment of the viral genome sourced from recovered non-infectious patients would greatly facilitate epidemiological tracking. Thus, we developed a protocol to isolate and sequence the genome of SARS-CoV-2 from stool samples of post-acute SARS-CoV-2 patients, at timepoints ranging from 10-120 days after onset of symptoms. Stool samples were collected from patients at varying timepoints post-convalescence, and viral DNA was isolated and sequenced using the QIAamp Viral RNA Mini Kit (Qiagen Inc.) and Ion Ampliseq^™ Library Kit Plus (Life Technologies Corporation). Capacity of neutralizing antibodies in patient plasma was tested using a Luminex panel (Coronavirus Ig Total Human 11-Plex ProcartaPlex^™ Panel, ThermoFisher). Of 64 samples obtained from post-acute patients, 21 (32.8%) yielded sufficient material for whole-genome sequencing. This allowed us to identify widely divergent phylogenetic relativity of the SARS-CoV-2 genome from post-acute patients living in the same households and infected around the same time. Additionally, we observed that individuals who recovered from infection expressed varying degrees of antibodies against SARS-CoV-2 structural proteins that corresponded to distinct variants. Interestingly, we identified a novel point mutation in the viral genome where infected patients expressed antibodies with a significantly reduced capacity to neutralize the virus in vitro relative to that of those infected with the wild-type strain. Altogether, we demonstrate a protocol to successfully sequence the SARS-CoV-2 genome from stool samples from patients up to 4 months post-infection, which can be applied to studies that assess the relationship between variants and immune response post-hoc and safe monitoring of the SARS-CoV-2 genome during the pandemic.

Post-COVID-19 cholangiopathy: A systematic review

BACKGROUND

The recent and still ongoing pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entailed various long-term complications, including post-infectious cholangiopathy.

AIM

To identify the available studies concerning post-coronavirus disease 2019 (COVID-19) cholangiopathy.

METHODS

An extensive bibliographical search was carried out in PubMed and in Cochrane Library to identify the articles (retrospective and prospective studies, cohort studies, case series and case reports) published between January 1, 2020 and August 22, 2022, using both MeSH terms and free-language keywords: cholangiopathy; COVID-19; post-COVID-19 cholangiopathy; SARS-CoV-2.

RESULTS

Thirteen studies fulfilled the inclusion criteria, which included 64 patients suffering from this condition. The patients were male in 82.8% of cases. Liver transplant was executed in 6 patients and scheduled in 7 patients, while 2 patients refused the surgical approach. Therefore in 23.4% of the cases, performing this procedure appeared to be necessary.

CONCLUSION

This review has revealed that generally the involvement of the liver in the course of SARS-CoV-2 infection is mild and transient, inducing cholestasis of cholangiocytes but can also be severe enough to cause organ failure in some cases.

In vitro high-content tissue models to address precision medicine challenges

The field of precision medicine allows for tailor-made treatments specific to a patient and thereby improve the efficiency and accuracy of disease prevention, diagnosis, and treatment and at the same time would reduce the cost, redundant treatment, and side effects of current treatments. Here, the combination of organ-on-a-chip and bioprinting into engineering high-content in vitro tissue models is envisioned to address some precision medicine challenges. This strategy could be employed to tackle the current coronavirus disease 2019 (COVID-19), which has made a significant impact and paradigm shift in our society. Nevertheless, despite that vaccines against COVID-19 have been successfully developed and vaccination programs are already being deployed worldwide, it will likely require some time before it is available to everyone. Furthermore, there are still some uncertainties and lack of a full understanding of the virus as demonstrated in the high number new mutations arising worldwide and reinfections of already vaccinated individuals. To this end, efficient diagnostic tools and treatments are still urgently needed. In this context, the convergence of bioprinting and organ-on-a-chip technologies, either used alone or in combination, could possibly function as a prominent tool in addressing the current pandemic. This could enable facile advances of important tools, diagnostics, and better physiologically representative in vitro models specific to individuals allowing for faster and more accurate screening of therapeutics evaluating their efficacy and toxicity. This review will cover such technological advances and highlight what is needed for the field to mature for tackling the various needs for current and future pandemics as well as their relevancy towards precision medicine.

Unraveling the Molecular and Cellular Pathogenesis of COVID-19-Associated Liver Injury

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) continues to cause substantial morbidity and mortality. Most infections are mild; however, some patients experience severe and potentially fatal systemic inflammation, tissue damage, cytokine storm, and acute respiratory distress syndrome. Patients with chronic liver disease have been frequently affected, experiencing high morbidity and mortality. In addition, elevated liver enzymes may be a risk factor for disease progression, even in the absence of underlying liver disease. While the respiratory tract is a primary target of SARS-CoV-2, it has become evident that COVID-19 is a multisystemic infectious disease. The hepatobiliary system might be influenced during COVID-19 infection, ranging from a mild elevation of aminotransferases to the development of autoimmune hepatitis and secondary sclerosing cholangitis. Furthermore, the virus can promote existing chronic liver diseases to liver failure and activate the autoimmune liver disease. Whether the direct cytopathic effects of the virus, host reaction, hypoxia, drugs, vaccination, or all these risk factors cause liver injury has not been clarified to a large extent in COVID-19. This review article discussed the molecular and cellular mechanisms involved in the pathogenesis of SARS-CoV-2 virus-associated liver injury and highlighted the emerging role of liver sinusoidal epithelial cells (LSECs) in virus-related liver damage.

Post-COVID-19 cholangiopathy: Current understanding and management options

Post-coronavirus disease 2019 (COVID-19) cholangiopathy (PCC) is a rare but life-threatening complication of COVID-19 infection. PCC typically presents when patients recovering from the contagion and manifests as cholestasis in patients with no history of pre-existing liver disease. The pathogenesis of PCC is little understood. Hepatic injury in PCC could be mediated by the predilection of severe acute respiratory syndrome coronavirus 2 for cholangiocytes. Though PCC shows some resemblance to secondary sclerosing cholangitis in critically ill patients, it is considered as a separate and unique entity in the literature. Various treatment options like ursodeoxycholic acid, steroids, plasmapheresis, and endoscopic retrograde cholangiopancreatography guided interventions have been tried but with limited success. We have noticed significant improvement in liver function with antiplatelet therapy in a couple of patients. PCC can progress to end-stage liver disease necessitating liver transplantation. In this article, we discuss the current knowledge of PCC focusing on its pathophysiology, clinical manifestations, and management strategies.

Merits and challenges of iPSC-derived organoids for clinical applications

Induced pluripotent stem cells (iPSCs) have entered an unprecedented state of development since they were first generated. They have played a critical role in disease modeling, drug discovery, and cell replacement therapy, and have contributed to the evolution of disciplines such as cell biology, pathophysiology of diseases, and regenerative medicine. Organoids, the stem cell-derived 3D culture systems that mimic the structure and function of organs in vitro, have been widely used in developmental research, disease modeling, and drug screening. Recent advances in combining iPSCs with 3D organoids are facilitating further applications of iPSCs in disease research. Organoids derived from embryonic stem cells, iPSCs, and multi-tissue stem/progenitor cells can replicate the processes of developmental differentiation, homeostatic self-renewal, and regeneration due to tissue damage, offering the potential to unravel the regulatory mechanisms of development and regeneration, and elucidate the pathophysiological processes involved in disease mechanisms. Herein, we have summarized the latest research on the production scheme of organ-specific iPSC-derived organoids, the contribution of these organoids in the treatment of various organ-related diseases, in particular their contribution to COVID-19 treatment, and have discussed the unresolved challenges and shortcomings of these models.

Mechanisms of severe acute respiratory syndrome coronavirus-2 induced liver damage and alteration of some liver biomarkers: A review

The most serious problem for people suffering from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is liver damage. The liver is a frequently affected organ due to the metabolizing and detoxifying functions of several endogenous and exogenous molecules. In COVID-19-affected individuals, even moderate loss of hepatic function could dramatically affect the therapeutic efficacy of antiviral drugs metabolized in the liver. The clear mechanism of hepatocellular damage from SARS-CoV-2 infection is not fully understood. The main objective of this review is to identify potential mechanisms of SARS-2 induced liver damage, treatment outcomes in SARS-CoV-2-infected patients, and future direction. Electronic databases including Web of Science, Google Scholar, MEDLINE, Scopus, and Cochrane library were used to systematically search without limitation of publication date and status. Observational, retrospective cohort, prospective case-control, cohort studies, cross-sectional studies, or clinical trials were included. Liver damage in coronavirus patients is characterized by histopathological changes and abnormal elevation of some liver function tests. These abnormalities include elevation of Alanine aminotransferase, Aspartate aminotransferase, Gamma-glutamyl transferase, Alkaline phosphatase, and Serum bilirubin levels. Histopathological changes of the liver might consist of complete or partial thrombosis of the portal and sinusoidal vessels, portal tract fibrosis, and focally markedly enlarged and fibrotic hepatocytes. Understanding the fundamental molecular and immunological processes of COVID-19-related liver injury is essential for the selection of appropriate drugs and the logical development of successful treatment.

The interplay of cells, polymers, and vascularization in three-dimensional lung models and their applications in COVID-19 research and therapy

Millions of people have been affected ever since the emergence of the corona virus disease of 2019 (COVID-19) outbreak, leading to an urgent need for antiviral drug and vaccine development. Current experimentation on traditional two-dimensional culture (2D) fails to accurately mimic the in vivo microenvironment for the disease, while in vivo animal model testing does not faithfully replicate human COVID-19 infection. Human-based three-dimensional (3D) cell culture models such as spheroids, organoids, and organ-on-a-chip present a promising solution to these challenges. In this report, we review the recent 3D in vitro lung models used in COVID-19 infection and drug screening studies and highlight the most common types of natural and synthetic polymers used to generate 3D lung models.

SARS-CoV-2 induced liver injury: Incidence, risk factors, impact on COVID-19 severity and prognosis in different population groups

Liver is unlikely the key organ driving mortality in coronavirus disease 2019 (COVID-19) however, liver function tests (LFTs) abnormalities are widely observed mostly in moderate and severe cases. According to this review, the overall prevalence of abnormal LFTs in COVID-19 patients ranges from 2.5% to 96.8% worldwide. The geographical variability in the prevalence of underlying diseases is the determinant for the observed discrepancies between East and West. Multifactorial mechanisms are implicated in COVID-19-induced liver injury. Among them, hypercytokinemia with "bystander hepatitis", cytokine storm syndrome with subsequent oxidative stress and endotheliopathy, hypercoagulable state and immuno-thromboinflammation are the most determinant mechanisms leading to tissue injury. Liver hypoxia may also contribute under specific conditions, while direct hepatocyte injury is an emerging mechanism. Except for initially observed severe acute respiratory distress syndrome corona virus-2 (SARS-CoV-2) tropism for cholangiocytes, more recent cumulative data show SARS-CoV-2 virions within hepatocytes and sinusoidal endothelial cells using electron microscopy (EM). The best evidence for hepatocellular invasion by the virus is the identification of replicating SARS-CoV-2 RNA, S protein RNA and viral nucleocapsid protein within hepatocytes using in-situ hybridization and immunostaining with observed intrahepatic presence of SARS-CoV-2 by EM and by in-situ hybridization. New data mostly derived from imaging findings indicate possible long-term sequelae for the liver months after recovery, suggesting a post-COVID-19 persistent live injury.

The Intersection of COVID-19 and Metabolic-Associated Fatty Liver Disease: An Overview of the Current Evidence

The global population is currently experiencing the impact of the SARS-CoV-2 coronavirus, which has caused the Coronavirus Disease 2019 (COVID-19) pandemic. With our profound comprehension of COVID-19, encompassing the involvement sequence of the respiratory tract, gastrointestinal system, and cardiovascular apparatus, the multiorgan symptoms of this infectious disease have been discerned. Metabolic-associated fatty liver disease (MAFLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is a pervasive public health concern intricately linked with metabolic dysregulation and estimated to afflict one-fourth of the global adult population. The burgeoning focus on the association between COVID-19 and MAFLD is justified by the potential role of the latter as a risk factor for both SARS-CoV-2 infection and the subsequent emergence of severe COVID-19 symptoms. Investigations have suggested that changes in both innate and adaptive immune responses among MAFLD patients may play a role in determining the severity of COVID-19. The remarkable similarities observed in the cytokine pathways implicated in both diseases imply the existence of shared mechanisms governing the chronic inflammatory responses characterizing these conditions. The effect of MAFLD on the severity of COVID-19 illness remains uncertain, as indicated by conflicting results in cohort investigations.

Orthotopic Liver Transplantation of a SARS-CoV-2 Negative Recipient from a Positive Donor: The Border between Uncertainty and Necessity in a Pandemic Era- Case Report and Overview of the Literature

(1) Introduction: Liver transplantation represents the gold-standard therapy in eligible patients with acute liver failure or end-stage liver disease. The COVID-19 pandemic dramatically affected the transplantation landscape by reducing patients' addressability to specialized healthcare facilities. Since evidence-based acceptance guidelines for non-lung solid organ transplantation from SARS-CoV-2 positive donors are lacking, and the risk of bloodstream-related transmission of the disease is debatable, liver transplantation from SARS-CoV-2 positive donors could be lifesaving, even if long-term interactions are unpredictable. The aim of this case report is to highlight the relevance of performing liver transplantation from SARS-CoV-2 positive donors to negative recipients by emphasizing the perioperative care and short-term outcome. (2) Case presentation: A 20-year-old female patient underwent orthotropic liver transplantation for Child-Pugh C liver cirrhosis secondary to overlap syndrome, from a SARS-CoV-2 positive brain death donor. The patient was not infected nor vaccinated against SARS-CoV-2, and the titer of neutralizing antibodies against the spike protein was negative. The liver transplantation was performed with no significant complications. As immunosuppression therapy, the patient received 20 mg basiliximab (Novartis Farmacéutica S.A., Barcelona, Spain) and 500 mg methylprednisolone (Pfizer Manufacturing Belgium N.V, Puurs, Belgium) intraoperatively. Considering the risk of non-aerogene-related SARS-CoV-2 reactivation syndrome, the patient received remdesivir 200 mg (Gilead Sciences Ireland UC, Carrigtohill County Cork, Ireland) in the neo-hepatic stage, which was continued with 100 mg/day for 5 days. The postoperative immunosuppression therapy consisted of tacrolimus (Astellas Ireland Co., Ltd., Killorglin, County Kerry, Ireland) and mycophenolate mofetil (Roche România S.R.L, Bucharest, Romania) according to the local protocol. Despite the persistent negative PCR results for SARS-CoV-2 in the upper airway tract, the blood titer of neutralizing antibodies turned out positive on postoperative day 7. The patient had a favorable outcome, and she was discharged from the ICU facility seven days later. (3) Conclusions: We illustrated a case of liver transplantation of a SARS-CoV-2 negative recipient, whose donor was SARS-CoV-2 positive, performed in a tertiary, university-affiliated national center of liver surgery, with a good outcome, in order to raise the medical community awareness on the acceptance limits in the case of COVID-19 incompatibility for non-lung solid organs transplantation procedures.

COVID-19 Induced Liver Injury from a New Perspective: Mitochondria

Liver damage is a common sequela of COVID-19 (coronavirus disease 2019), worsening the clinical outcomes. However, the underlying mechanism of COVID-induced liver injury (CiLI) is still not determined. Given the crucial role of mitochondria in hepatocyte metabolism and the emerging evidence denoting SARS-CoV-2 can damage human cell mitochondria, in this mini-review, we hypothesized that CiLI happens following hepatocytes' mitochondrial dysfunction. To this end, we evaluated the histologic, pathophysiologic, transcriptomic, and clinical features of CiLI from the mitochondria' eye view. Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the causative agent of COVID-19, can damage hepatocytes through direct cytopathic effects or indirectly after the profound inflammatory response. Upon entering the hepatocytes, the RNA and RNA transcripts of SARS-CoV-2 engages the mitochondria. This interaction can disrupt the mitochondrial electron transport chain. In other words, SARS-CoV-2 hijacks the hepatocytes' mitochondria to support its replication. In addition, this process can lead to an improper immune response against SARS-CoV-2. Besides, this review outlines how mitochondrial dysfunction can serve as a prelude to the COVID-associated cytokine storm. Thereafter, we indicate how the nexus between COVID-19 and mitochondria can fill the gap linking CiLI and its risk factors, including old age, male sex, and comorbidities. In conclusion, this concept stresses the importance of mitochondrial metabolism in hepatocyte damage in the context of COVID-19. It notes that boosting mitochondria biogenesis can possibly serve as a prophylactic and therapeutic approach for CiLI. Further studies can reveal this notion.

Liver Damage and COVID-19: At Least a “Two-Hit” Story in Systematic Review

COVID-19 pandemic waves have hit on our lives with pulmonary and, also, gastrointestinal symptoms. The latter also includes acute liver damage linked to direct SARS-CoV-2 action and/or drug-induced (DILI) in the frame of pre-existing chronic liver disease. We aimed to review literature data regarding liver damage during COVID-19. We conducted a systematic search on the main medical databases for original articles, reviews, meta-analyses, randomized clinical trials and case series using the following keywords and acronyms and their associations: liver disease, COVID-19, acute liver damage, drug-induced liver injury, antivirals. Acute liver damage due to SARS-CoV-2 infection is common among COVID-19 patients and is generally self-limiting. However, chronic hepatic diseases, such as metabolic-associated fatty liver disease (MAFLD), are associated with a less favorable prognosis, especially when alkaline phosphatases show a significant rise. Pathophysiology of COVID-19 liver damage is multifaceted and helps understand differences in liver derangement among patients. Thus, early recognition, monitoring and treatment of liver damage are crucial in these patients. In the frame of a not-ending pandemic sustained by SARS-CoV-2, it is crucial to recognize acute hepatic decompensation due to the virus and/or drugs used for COVID-19 treatment.

Human liver organoid: modeling liver steatosis and beyond

Steatosis, as the early stage of nonalcoholic fatty acid disease (NAFLD), would progress into nonalcoholic steatohepatitis (NASH) and liver failure without intervention. Despite the development of animal models, there is still a lack of the human-relevant platform for steatosis modeling and drug & target discovery. Hendriks et al., reporting in Nature Biotechnology, leveraged human fetal liver organoids to recapitulate steatosis by introducing nutritional and genetic triggers. Using these engineered liver organoid-derived steatosis models, they screened drugs that alleviate steatosis, and mined common mechanism of effective compounds. Further, inspired by the results of drug screening, the arrayed CRISPR-LOF screening targeting 35 lipid metabolism genes was performed, and FADS2 was identified as a critical regulator of steatosis.

Liver organoids: established tools for disease modeling and drug development

In the past decade, liver organoids have evolved rapidly as valuable research tools, providing novel insights into almost all types of liver diseases, including monogenic liver diseases, alcohol-associated liver disease, metabolic-associated fatty liver disease, various types of (viral) hepatitis, and liver cancers. Liver organoids in part mimic the microphysiology of the human liver and fill a gap in high-fidelity liver disease models to a certain extent. They hold great promise to elucidate the pathogenic mechanism of a diversity of liver diseases and play a crucial role in drug development. Moreover, it is challenging but opportunistic to apply liver organoids for tailored therapies of various liver diseases. The establishment, applications, and challenges of different types of liver organoids, for example, derived from embryonic, adult, or induced pluripotent stem cells, to model different liver diseases, are presented in this review.

Features of Liver Injury in COVID-19 Pathophysiological, Biological and Clinical Particularities

The outbreak of the coronavirus pandemic in March 2020 has caused unprecedented pressure on public health and healthcare. The spectrum of COVID-19 onset is large, from mild cases with minor symptoms to severe forms with multi-organ dysfunction and death. In COVID-19, multiple organ damage has been described, including lung damage, acute kidney injury, liver damage, stroke, cardiovascular and digestive tract disorders. The aspects of liver injury are different, sometimes presenting with only a slight increase in liver enzymes, but sometimes with severe liver injury, leading to acute liver failure requiring liver transplantation. In patients with chronic liver disease, especially liver cirrhosis, immune dysfunction can increase the risk of infection. Immune dysfunction has a multifactorial physiopathological mechanism, implying a complement system and macrophage activation, lymphocyte and neutrophil activity dysfunction, and intestinal dysbiosis. This review aims to evaluate the most relevant studies published in the last years related to the etiopathogenetic, biochemical, and histological aspects of liver injury in patients diagnosed with COVID-19. Liver damage is more evident in patients with underlying chronic liver disease, with a significantly higher risk of developing severe outcomes of COVID-19 and death. Systemic inflammation, coagulation disorders, endothelial damage, and immune dysfunction explain the pathogenic mechanisms involved in impaired liver function. Although various mechanisms of action of SARS-CoV-2 on the liver cell have been studied, the impact of the direct viral effect on hepatocytes is not yet established.

TNFα aggravates detrimental effects of SARS-CoV-2 infection in the liver

Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus does not only lead to pulmonary infection but can also infect other organs such as the gut, the kidney, or the liver. Recent studies confirmed that severe cases of COVID-19 are often associated with liver damage and liver failure, as well as the systemic upregulation of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNFα). However, the impact these immune mediators in the liver have on patient survival during SARS-CoV-2 infection is currently unknown. Here, by performing a post-mortem analysis of 45 patients that died from a SARS-CoV-2 infection, we find that an increased expression of TNFA in the liver is associated with elevated mortality. Using publicly available single-cell sequencing datasets, we determined that Kupffer cells and monocytes are the main sources of this TNFα production. Further analysis revealed that TNFα signaling led to the upregulation of pro-inflammatory genes that are associated with an unfavorable outcome. Moreover, high levels of TNFA in the liver were associated with lower levels of interferon alpha and interferon beta. Thus, TNFα signaling in the infected SARS-CoV-2 liver correlates with reduced interferon levels and overall survival time.

COVID-19 related liver injuries in pregnancy

While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) quickly spread across the globe, our understanding of its pathogenic mechanisms evolved. Importantly, coronavirus disease 2019 (COVID-19) is now considered a syndromic multisystem inflammatory disease involving not only the respiratory system but also the cardiovascular, excretory, nervous, musculoskeletal, and gastrointestinal systems. Moreover, a membrane-bound form of angiotensin-converting enzyme 2, the entry receptor for SARS-CoV-2, is expressed on the surface of cholangiocytes and hepatocytes, suggesting the potential of COVID-19 to involve the liver. With the widespread distribution of SARS-CoV-2 throughout the population, infection during pregnancy is no longer a rare occurrence; however, little is known about the course of hepatic injuries and related outcomes in pregnant SARS-CoV-2-positive women. Thus, the understudied topic of COVID-related liver disease during pregnancy poses a great challenge for the consulting gynecologist and hepatologist. In this review, we aim to describe and summarize potential liver injuries in pregnant women with COVID-19.

Bidirectional Relationship between Glycemic Control and COVID-19 and Perspectives of Islet Organoid Models of SARS-CoV-2 Infection

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leads to morbidity and mortality, with several clinical manifestations, and has caused a widespread pandemic. It has been found that type 2 diabetes is a risk factor for severe coronavirus disease 2019 (COVID-19) illness. Moreover, accumulating evidence has shown that SARS-CoV-2 infection can increase the risk of hyperglycemia and diabetes, though the underlying mechanism remains unclear because of a lack of authentic disease models to recapitulate the abnormalities involved in the development, regeneration, and function of human pancreatic islets under SARS-CoV-2 infection. Stem-cell-derived islet organoids have been valued as a model to study islets’ development and function, and thus provide a promising model for unraveling the mechanisms underlying the onset of diabetes under SARS-CoV-2 infection. This review summarized the latest results from clinical and basic research on SARS-CoV-2-induced pancreatic islet damage and impaired glycemic control. Furthermore, we discuss the potential and perspectives of using human ES/iPS cell-derived islet organoids to unravel the bidirectional relationship between glycemic control and SARS-CoV-2 infection.

Secondary Sclerosing Cholangitis due to Severe COVID-19: An Emerging Disease Entity?

INTRODUCTION

Coronavirus disease 2019 (COVID-19) can lead to many extrapulmonary manifestations. In this case series, we report on 7 patients developing secondary sclerosing cholangitis (SSC) after severe COVID-19 with intensive care treatment.

METHODS

Between March 2020 and November 2021, 544 patient cases with cholangitis treated at a German tertiary care centre were screened for SSC. Patients found to be suffering from SSC were assigned to COVID-19 group if SSC presented after a severe course of COVID-19 and to non-COVID-19 group if not. Peak liver parameters as well as intensive care treatment factors and data generated from liver elastography were compared between both groups.

RESULTS

We identified 7 patients who developed SSC after a severe course of COVID-19. In the same period, 4 patients developed SSC due to other causes. Mean values of gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP) were higher in the COVID-19 group than in the non-COVID-19 group (GGT: 2,689 U/L vs. 1,812 U/L and ALP: 1,445 U/L vs. 1,027 U/L), whereas intensive care treatment factors were comparable in both groups. Only the mean duration of mechanical ventilation was shorter in the COVID-19 group than in the non-COVID-19 group (22.1 days vs. 36.7 days). Liver elastography indicated a fast progression to liver cirrhosis with a mean liver stiffness of 17.3 kilopascals (kPa) in less than 12 weeks in the COVID-19 group.

CONCLUSIONS

Our data suggest a more severe course of SSC when caused by SARS-CoV-2. Reasons for this are probably multifactorial, including a direct cytopathogenic effect of the virus.

Gastrointestinal and Hepatobiliary Symptoms and Disorders with Long (Chronic) COVID Infection

Long COVID is a novel syndrome characterizing new or persistent symptoms weeks after COVID-19 infection and involving multiple organ systems. This review summarizes the gastrointestinal and hepatobiliary sequelae of long COVID syndrome. It describes potential biomolecular mechanisms, prevalence, preventative measures, potential therapies, and health care and economic impact of long COVID syndrome, particularly of its gastrointestinal (GI) and hepatobiliary manifestations.

COVID-19 and non-alcoholic fatty liver disease: Biological insights from multi-omics data

We explored the shared pathophysiological mechanisms between COVID-19 and non-alcoholic fatty liver disease (NAFLD) by integrating multi-omics data. We studied common genetic risk factors and underlying biological processes using functional enrichment analysis. To understand the sex-specific pathways involved in the clinical course of SARS-CoV-2 infection, we processed sex-stratified data from COVID-19 genome-wide association datasets. We further explored the transcriptional signature of the liver cells in healthy and COVID-19 tissue specimens. We also integrated genetic and metabolomic information. We found that COVID-19 and NAFLD share biological disease mechanisms, including pathways that regulate the inflammatory and lipopolysaccharide response. Single-cell transcriptomics revealed enrichment of complement-related pathways in Kupffer cells, syndecan-mediated signalling in plasma cells, and epithelial-to-mesenchymal transition in hepatic stellate cells. The strategy of pathway-level analysis of genomic and metabolomic data uncovered l-lactic acid, Krebs cycle intermediate compounds, arachidonic acid and cortisol among the most prominent shared metabolites.

Organoids of the male reproductive system: Challenges, opportunities, and their potential use in fertility research

Organoids are units of function of a given organ able to reproduce, in culture, a biological structure similar in architecture and function to its counterpart in vivo. Today, it is possible to develop an organoid from a fragment of tissue, a stem cell located in an adult organ, an embryonic stem cell, or an induced pluripotent stem cell. In the past decade, many organoids have been developed which mimic stomach, pancreas, liver and brain tissues, optic cups, among many others. Additionally, different male reproductive system organs have already been developed as organoids, including the prostate and testis. These 3D cultures may be of great importance for urological cancer research and have the potential to be used in fertility research for the study of spermatozoa production and maturation, germ cells-somatic cells interactions, and mechanisms of disease. They also provide an accurate preclinical pipeline for drug testing and discovery, as well as for the study of drug resistance. In this work, we revise the current knowledge on organoid technology and its use in healthcare and research, describe the male reproductive system organoids and other biomaterials already developed, and discuss their current application. Finally, we highlight the research gaps, challenges, and opportunities in the field and propose strategies to improve the use of organoids for the study of male infertility situations. This article is categorized under: Reproductive System Diseases > Stem Cells and Development Reproductive System Diseases > Biomedical Engineering.

Insights into organoid-based modeling of COVID-19 pathology

Since December 2019, various types of strategies have been applied due to the emergent need to investigate the biology and pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to discover a functional treatment. Different disease modeling systems, such as mini-organ technology, have been used to improve our understanding of SARS-CoV-2 physiology and pathology. During the past 2 years, regenerative medicine research has shown the supportive role of organoid modeling in controlling coronavirus disease 2019 (COVID-19) through optimal drug and therapeutic approach improvement. Here, we overview some efforts that have been made to study SARS-CoV-2 by mimicking COVID-19 using stem cells. In addition, we summarize a perspective of drug development in COVID-19 treatment via organoid-based studies.

Analysis of Bacteriophage Behavior of a Human RNA Virus, SARS-CoV-2, through the Integrated Approach of Immunofluorescence Microscopy, Proteomics and D-Amino Acid Quantification

SARS-CoV-2, one of the human RNA viruses, is widely studied around the world. Significant efforts have been made to understand its molecular mechanisms of action and how it interacts with epithelial cells and the human microbiome since it has also been observed in gut microbiome bacteria. Many studies emphasize the importance of surface immunity and also that the mucosal system is critical in the interaction of the pathogen with the cells of the oral, nasal, pharyngeal, and intestinal epithelium. Recent studies have shown how bacteria in the human gut microbiome produce toxins capable of altering the classical mechanisms of interaction of viruses with surface cells. This paper presents a simple approach to highlight the initial behavior of a novel pathogen, SARS-CoV-2, on the human microbiome. The immunofluorescence microscopy technique can be combined with spectral counting performed at mass spectrometry of viral peptides in bacterial cultures, along with identification of the presence of D-amino acids within viral peptides in bacterial cultures and in patients' blood. This approach makes it possible to establish the possible expression or increase of viral RNA viruses in general and SARS-CoV-2, as discussed in this study, and to determine whether or not the microbiome is involved in the pathogenetic mechanisms of the viruses. This novel combined approach can provide information more rapidly, avoiding the biases of virological diagnosis and identifying whether a virus can interact with, bind to, and infect bacteria and epithelial cells. Understanding whether some viruses have bacteriophagic behavior allows vaccine therapies to be focused either toward certain toxins produced by bacteria in the microbiome or toward finding inert or symbiotic viral mutations with the human microbiome. This new knowledge opens a scenario on a possible future vaccine: the probiotics vaccine, engineered with the right resistance to viruses that attach to both the epithelium human surface and gut microbiome bacteria.

Induced Pluripotent Stem Cell-Derived Organoids: Their Implication in COVID-19 Modeling

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a significant global health issue. This novel virus's high morbidity and mortality rates have prompted the scientific community to quickly find the best COVID-19 model to investigate all pathological processes underlining its activity and, more importantly, search for optimal drug therapy with minimal toxicity risk. The gold standard in disease modeling involves animal and monolayer culture models; however, these models do not fully reflect the response to human tissues affected by the virus. However, more physiological 3D in vitro culture models, such as spheroids and organoids derived from induced pluripotent stem cells (iPSCs), could serve as promising alternatives. Different iPSC-derived organoids, such as lung, cardiac, brain, intestinal, kidney, liver, nasal, retinal, skin, and pancreatic organoids, have already shown immense potential in COVID-19 modeling. In the present comprehensive review article, we summarize the current knowledge on COVID-19 modeling and drug screening using selected iPSC-derived 3D culture models, including lung, brain, intestinal, cardiac, blood vessels, liver, kidney, and inner ear organoids. Undoubtedly, according to reviewed studies, organoids are the state-of-the-art approach to COVID-19 modeling.

COVID-19: gastrointestinal and hepatobiliary manifestations

SARS-CoV-2 is the viral agent of COVID-19, a pandemic that surfaced in 2019. Although predominantly a respiratory ailment, patients with COVID-19 can have gastrointestinal (GI) and hepatobiliary manifestations. These manifestations are often mild and transient, but they can be severe and consequential. In the GI tract, ischemic enterocolitis is the most common and significant consequence of COVID-19. In the liver, the reported pathologic findings may often be related to consequences of severe systemic viral infection, but reports of hepatitis presumed to be due to SARS-CoV-2 suggest that direct viral infection of the liver may be a rare complication of COVID-19. In both the GI tract and liver, lingering symptoms of GI or hepatic injury after resolution of pulmonary infection may be part of the evolving spectrum of long COVID.