Camostat mesilate attenuates pancreatic fibrosis via inhibition of monocytes and pancreatic stellate cells activity

A combination of nirmatrelvir and ombitasvir boosts inhibition of SARS-CoV-2 replication

Antiviral therapeutics are highly effective countermeasures for the treatment of coronavirus disease 2019 (COVID-19). However, development of resistance to antivirals undermines their effectiveness. Combining multiple antivirals during patient treatment has the potential to overcome the evolutionary selective pressure towards antiviral resistance, as well as provide a more robust and efficacious treatment option. The current evidence for effective antiviral combinations to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication is limited. Here, we demonstrate a combination of nirmatrelvir with ombitasvir, to jointly bring about potent inhibition of SARS-CoV-2 replication. We developed an in vitro 384- well plate cytopathic effect assay for the evaluation of antiviral combinations against Calu-3 cells infected with SARS-CoV-2 and found, that a combination of ombitasvir and nirmatrelvir was synergistic; thereby decreasing the nirmatrelvir IC50 by approx. 16-fold. The increased potency of the nirmatrelvir-ombitasvir combination, over nirmatrelvir alone afforded a greater than 3 log10 reduction in viral titre, which is sufficient to fully prevent the detection of progeny SARS-CoV-2 viral particles at 48 h post infection. The mechanism of this potentiated effect was shown to be, in-part, due to joint inhibition of the 3-chymotrypsin-like protease via a positive allosteric modulation mechanism.

A comprehensive review on the global efforts on vaccines and repurposed drugs for combating COVID-19

The recently discovered coronavirus, known as SARS-CoV-2, is a highly contagious and potentially lethal viral infection that was declared a pandemic by the World Health Organization on March 11, 2020. Since the beginning of the pandemic, an unprecedented number of COVID-19 vaccine candidates have been investigated for their potential to manage the pandemic. Herein, we reviewed vaccine development and the associated research effort, both traditional and forward-looking, to demonstrate the advantages and disadvantages of their technology, in addition to their efficacy limitations against mutant SARS-CoV-2. Moreover, we report repurposed drug discovery, which mainly focuses on virus-based and host-based targets, as well as their inhibitors. SARS-CoV-2 targets include the main protease (Mpro), and RNA-dependent RNA-polymerase (RdRp), which are the most well-studied and conserved across coronaviruses, enabling the development of broad-spectrum inhibitors of these enzymes.

Drug repositioning in the COVID-19 pandemic: fundamentals, synthetic routes, and overview of clinical studies

INTRODUCTION

Drug repositioning is a strategy to identify a new therapeutic indication for molecules that have been approved for other conditions, aiming to speed up the traditional drug development process and reduce its costs. The high prevalence and incidence of coronavirus disease 2019 (COVID-19) underline the importance of searching for a safe and effective treatment for the disease, and drug repositioning is the most rational strategy to achieve this goal in a short period of time. Another advantage of repositioning is the fact that these compounds already have established synthetic routes, which facilitates their production at the industrial level. However, the hope for treatment cannot allow the indiscriminate use of medicines without a scientific basis.

RESULTS

The main small molecules in clinical trials being studied to be potentially repositioned to treat COVID-19 are chloroquine, hydroxychloroquine, ivermectin, favipiravir, colchicine, remdesivir, dexamethasone, nitazoxanide, azithromycin, camostat, methylprednisolone, and baricitinib. In the context of clinical tests, in general, they were carried out under the supervision of large consortiums with a methodology based on and recognized in the scientific community, factors that ensure the reliability of the data collected. From the synthetic perspective, compounds with less structural complexity have more simplified synthetic routes. Stereochemical complexity still represents the major challenge in the preparation of dexamethasone, ivermectin, and azithromycin, for instance.

CONCLUSION

Remdesivir and baricitinib were approved for the treatment of hospitalized patients with severe COVID-19. Dexamethasone and methylprednisolone should be used with caution. Hydroxychloroquine, chloroquine, ivermectin, and azithromycin are ineffective for the treatment of the disease, and the other compounds presented uncertain results. Preclinical and clinical studies should not be analyzed alone, and their methodology's accuracy should also be considered. Regulatory agencies are responsible for analyzing the efficacy and safety of a treatment and must be respected as the competent authorities for this decision, avoiding the indiscriminate use of medicines.

Potential treatments of COVID-19: Drug repurposing and therapeutic interventions

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection is caused when Spike-protein (S-protein) present on the surface of SARS-CoV-2 interacts with human cell surface receptor, Angiotensin-converting enzyme 2 (ACE2). This binding facilitates SARS-CoV-2 genome entry into the human cells, which in turn causes infection. Since the beginning of the pandemic, many different therapies have been developed to combat COVID-19, including treatment and prevention. This review is focused on the currently adapted and certain other potential therapies for COVID-19 treatment, which include drug repurposing, vaccines and drug-free therapies. The efficacy of various treatment options is constantly being tested through clinical trials and in vivo studies before they are made medically available to the public.

Antitarget, Anti-SARS-CoV-2 Leads, Drugs, and the Drug Discovery-Genetics Alliance Perspective

The most advanced antiviral molecules addressing major SARS-CoV-2 targets (Main protease, Spike protein, and RNA polymerase), compared with proteins of other human pathogenic coronaviruses, may have a short-lasting clinical efficacy. Accumulating knowledge on the mechanisms underlying the target structural basis, its mutational progression, and the related biological significance to virus replication allows envisaging the development of better-targeted therapies in the context of COVID-19 epidemic and future coronavirus outbreaks. The identification of evolutionary patterns based solely on sequence information analysis for those targets can provide meaningful insights into the molecular basis of host-pathogen interactions and adaptation, leading to drug resistance phenomena. Herein, we will explore how the study of observed and predicted mutations may offer valuable suggestions for the application of the so-called "synthetic lethal" strategy to SARS-CoV-2 Main protease and Spike protein. The synergy between genetics evidence and drug discovery may prioritize the development of novel long-lasting antiviral agents.

A Double-Blind, Randomized, Placebo-Controlled, Phase II Clinical Study To Evaluate the Efficacy and Safety of Camostat Mesylate (DWJ1248) in Adult Patients with Mild to Moderate COVID-19

Although several antiviral agents have become available for coronavirus disease 2019 (COVID-19) treatment, oral drugs are still limited. Camostat mesylate, an orally bioavailable serine protease inhibitor, has been used to treat chronic pancreatitis in South Korea, and it has an in vitro inhibitory potential against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study was a double-blind, randomized, placebo-controlled, multicenter, phase 2 clinical trial in mild to moderate COVID-19 patients. We randomly assigned patients to receive either camostat mesylate (DWJ1248) or placebo orally for 14 days. The primary endpoint was time to clinical improvement of subject symptoms within 14 days, measured using a subjective 4-point Likert scale. Three hundred forty-two patients were randomized. The primary endpoint was nonsignificant, where the median times to clinical improvement were 7 and 8 days in the camostat mesylate group and the placebo group, respectively (hazard ratio [HR] = 1.09; 95% confidence interval [CI], 0.84 to 1.43; P = 0.50). A post hoc analysis showed that the difference was greatest at day 7, without reaching significance. In the high-risk group, the proportions of patients with clinical improvement up to 7 days were 45.8% (50/109) in the camostat group and 38.4% (40/104) in the placebo group (odds ratio [OR] = 1.33; 95% CI, 0.77 to 2.31; P = 0.31); the ordinal scale score at day 7 improved in 20.0% (18/90) of the camostat group and 13.3% (12/90) of the placebo group (OR = 1.68; 95% CI, 0.75 to 3.78; P = 0.21). Adverse events were similar in the two groups. Camostat mesylate was safe in the treatment of COVID-19. Although this study did not show clinical benefit in patients with mild to moderate COVID-19, further clinical studies for high-risk patients are needed. (This trial was registered with ClinicalTrials.gov under registration no. NCT04521296).

Between early and established chronic pancreatitis: A proposal of "acinar-ductal hybrid mechanism"

BACKGROUND/OBJECTIVES

The recently proposed "new mechanistic definition of chronic pancreatitis (CP)" categorized early CP as a reversible condition. However, there is no clear explanation regarding the pathological condition of early CP, the reason for the development of the disease in only a small portion of the patients with risk factors, and the mechanism for transition from a reversible pathological condition to an irreversible one.

METHODS

Based on the available information, a mechanism that could provide answers to the queries associated with CP was proposed.

RESULTS

Acinar-ductal coordination is very important for the physiological secretion of pancreatic juice. Inflammation originating from acinar cells undermines the function of proximal ducts and leads to a vicious cycle of sustained inflammation by increasing the viscosity and decreasing the alkalinity of pancreatic juice. Persistent elevation of ductal pressure due to stagnation of pancreatic juice caused by protein plugs, stones, or fibrous scar of ducts converts the reversible pathological condition of early CP to an irreversible one. Diagnostic criteria for early CP proposed by Japanese researchers have enabled to the recognition of patients showing a progression from early to established CP. However, most patients diagnosed with early CP do not experience progression of the disease, suggesting the inadequate specificity of the criteria.

CONCLUSION

The "acinar-ductal hybrid mechanism" may explain the pathological condition and progression of early CP. To diagnose early CP more accurately, it is essential to discover specific biomarkers that can discriminate "early CP" from "acute pancreatitis (AP)/recurrent acute pancreatitis (RAP)" and "established CP." Therapeutic intervention in clinical practices through various new approaches is expected to improve the prognosis of patients with CP.

Drug repurposing for the treatment of COVID-19

Coronavirus disease 2019 (COVID-19) remains prevalent worldwide since its onset was confirmed in Wuhan, China in 2019. Vaccines against the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have shown a preventive effect against the onset and severity of COVID-19, and social and economic activities are gradually recovering. However, the presence of vaccine-resistant variants has been reported, and the development of therapeutic agents for patients with severe COVID-19 and related sequelae remains urgent. Drug repurposing, also called drug repositioning or eco-pharma, is the strategy of using previously approved and safe drugs for a therapeutic indication that is different from their original indication. The risk of severe COVID-19 and mortality increases with advancing age, cardiovascular disease, hypertension, diabetes, and cancer. We have reported three protein-protein interactions that are related to heart failure, and recently identified that one mechanism increases the risk of SARS-CoV-2 infection in mammalian cells. This review outlines the global efforts and outcomes of drug repurposing research for the treatment of severe COVID-19. It also discusses our recent finding of a new protein-protein interaction that is common to COVID-19 aggravation and heart failure.

Tailored phenyl esters inhibit ClpXP and attenuate Staphylococcus aureus α-hemolysin secretion

Novel strategies against multidrug‐resistant bacteria are urgently needed in order to overcome the current silent pandemic. Manipulation of toxin production in pathogenic species serves as a promising approach to attenuate virulence and prevent infections. In many bacteria such as Staphylococcus aureus or Listeria monocyotgenes, serine protease ClpXP is a key contributor to virulence and thus represents a prime target for antimicrobial drug discovery. The limited stability of previous electrophilic warheads has prevented a sustained effect of virulence attenuation in bacterial culture. Here, we systematically tailor the stability and inhibitory potency of phenyl ester ClpXP inhibitors by steric shielding of the ester bond and fine‐tuning the phenol leaving group. Out of 17 derivatives, two (MAS‐19 and MAS‐30) inhibited S. aureus ClpP peptidase and ClpXP protease activities by >60 % at 1 μM. Furthermore, the novel inhibitors did not exhibit pronounced cytotoxicity against human and bacterial cells. Unlike the first generation phenylester AV170, these molecules attenuated S. aureus virulence markedly and displayed increased stability in aqueous buffer compared to the previous benchmark AV170.

The discovery and development of transmembrane serine protease 2 (TMPRSS2) inhibitors as candidate drugs for the treatment of COVID-19

INTRODUCTION

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused the devastating pandemic named coronavirus disease 2019 (COVID-19). Unfortunately, the discovery of antiviral agents to combat COVID-19 is still an unmet need. Transmembrane serine protease 2 (TMPRSS2) is an important mediator in viral infection and thus, TMPRRS2 inhibitors may be attractive agents for COVID-19 treatment.

AREAS COVERED

This review article discusses the role of TMPRSS2 in SARS-CoV-2 cell entry and summarizes the inhibitors of TMPRSS2 and their potential anti-SARS activity. Two known TMPRSS2 inhibitors, namely camostat and nafamostat, approved drugs for the treatment of pancreatitis, are under clinical trials as potential drugs against COVID-19.

EXPERT OPINION

Due to the lack of the crystal structure of TMPRSS2, homology models have been developed to study the interactions of known inhibitors, including repurposed drugs, with the enzyme. However, novel TMPRSS2 inhibitors have been identified through high-throughput screening, and appropriate assays studying their in vitro activity have been set up. The discovery of TMPRSS2's crystal structure will facilitate the rational design of novel inhibitors and in vivo studies and clinical trials will give a clear answer if TMPRSS2 inhibitors could be a new weapon against COVID-19.

Camostat mesilate inhibits pro-inflammatory cytokine secretion and improves cell viability by regulating MFGE8 and HMGN1 in lipopolysaccharide-stimulated DF-1 chicken embryo fibroblasts

Camostat mesilate (CM) possesses potential anti-viral and anti-inflammatory activities. However, it remains unknown whether CM is involved in lipopolysaccharide (LPS)-mediated inflammatory responses and cell injury. In this project, differentially expressed proteins (DEPs, fold change ≥ 1.2 or ≤ 0.83 and Q value ≤ 0.05) in response to LPS stimulation alone or in combination with CM were identified through tandem mass tags (TMT)/mass spectrometry (MS)-based proteomics analysis in DF-1 chicken embryo fibroblasts. The mRNA expression levels of filtered genes were determined by RT-qPCR assay. The results showed that CM alleviated the detrimental effect of LPS on cell viability and inhibited LPS-induced TNF-α and IL-6 secretions in DF-1 chicken embryo fibroblasts. A total of 141 DEPs that might be involved in mediating functions of both LPS and CM were identified by proteomics analysis in DF-1 chicken embryo fibroblasts. LPS inhibited milk fat globule EGF and factor V/VIII domain containing (MFGE8) expression and induced high mobility group nucleosome binding domain 1 (HMGN1) expression, while these effects were abrogated by CM in DF-1 chicken embryo fibroblasts. MFGE8 knockdown facilitated TNF-α and IL-6 secretions , reduced cell viability, stimulated cell apoptosis in DF-1 chicken embryo fibroblasts co-treated with LPS and CM. HMGN1 loss did not influence TNF-α and IL-6 secretions, cell viability, and cell apoptosis in DF-1 chicken embryo fibroblasts co-treated with LPS and CM. In conclusion, CM exerted anti-inflammatory and pro-survival activities by regulating MFGE8 in LPS-stimulated DF-1 chicken embryo fibroblasts, deepening our understanding of the roles and molecular basis of CM in protecting against Gram-negative bacteria.

A Comparative Study of Endoscopic Ultrasonography and Histopathology Images for the Diagnosis of Early Chronic Pancreatitis

OBJECTIVE

The concept of early chronic pancreatitis (ECP) and its diagnostic criteria were first proposed by Japan, using endoscopic ultrasonography (EUS) findings for diagnosis. However, these findings have not been supported by pathological findings. We aimed to examine the association between the EUS and pathological findings of the same area of the pancreas.

METHODS

In 12 patients who underwent pancreaticoduodenectomy for distal bile duct cancer without accompanying pancreatitis, a comparative analysis between preoperative EUS and pathological findings was performed. The part of the pancreas adjoining the portal vein was evaluated.

RESULTS

In 7 cases, abnormal EUS findings included in the diagnostic criteria for ECP were seen; the correlation of the accuracy of lobularity seen on EUS compared with the pathological findings of the pancreatic parenchyma (inflammatory cell infiltration, atrophy of acinar cells, and fibrosis) was high (83.3%-91.7%). Pancreatic duct findings revealed that the accuracy of the hyperechoic margin of the pancreatic duct on EUS compared with pathological findings (wall thickness of pancreatic duct) was high (83.3%).

CONCLUSIONS

Endoscopic ultrasonography findings for ECP, according to Japan's 2019 revised criteria, lobularity, and the hyperechoic margin of the pancreatic duct may highly correspond to the pathological findings of chronic inflammation.

Coronavirus disease and the cardiovascular system: a narrative review of the mechanisms of injury and management implications

Coronavirus disease (COVID-19), first identified in Wuhan, China, in December 2019, is now a pandemic, having already spread to 188 countries, with more than 28,280,000 infections worldwide. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the responsible infectious agent, and similar to other human coronaviruses, uses membrane-bound angiotensin-converting enzyme 2 (membrane-bound ACE2) for entry into the host cells. COVID-19 has important cardiovascular implications, especially for patients with pre-existing cardiovascular co-morbidities, potentially mediated through several mechanisms, including direct myocardial injury, worsening of those pre-existing cardiovascular co-morbidities, and adverse cardiovascular effects of potential therapies for COVID-19. The disease is causing a significant burden on health systems worldwide. Elective surgeries and procedures were postponed for a considerable period of time, and many patients with known cardiovascular disease (CVD) risk factors presented late to hospitals, for fear of contracting COVID-19, with serious adverse consequences. Significant negative impact on a population level is highlighted by prolonged isolation, decreased exercise and physical activity, and higher levels of depression and anxiety, all predisposing to elevated cardiovascular risk. This article provides a timely overview of COVID-19 and its impact on the cardiovascular system, focusing on the pathogenesis, potential adverse cardiovascular events, the potential treatment options, protection for health care providers and patients, and what the cardiovascular community could do to mitigate the impact of COVID-19.

The situation of small molecules targeting key proteins to combat SARS-CoV-2: Synthesis, metabolic pathway, mechanism of action, and potential therapeutic applications

Due to the global epidemic and high mortality of 2019 coronavirus disease (COVID-19), there is an immediate need to discover drugs that can help before a vaccine becomes available. Given that the process of producing new drugs is so long, the strategy of repurposing existing drugs is one of the promising options for the urgent treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19 disease. Although FDA has approved Remdesivir for the use in hospitalized adults and pediatric patients suffering from COVID-19, no fully effective and reliable drug has been yet identified worldwide to treat COVID-19 specifically. Thus, scientists are still trying to find antivirals specific to COVID-19. This work reviews the chemical structure, metabolic pathway, mechanism of action of existing drugs with potential therapeutic applications for COVID-19. Further, we summarized the molecular docking stimulation of the medications related to key protein targets. These already drugs could be developed for further clinical trials to supply suitable therapeutic options for patients suffering from COVID-19.

COVID-19: Potential Repurposing Drugs

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the most infectious diseases and caused coronavirus disease in 2019 (COVID-19). It has been widely spread worldwide and infected more than 28 million peoples in 215 countries, and more than 920,000 have now died from COVID-19. To date, no effective antiviral drugs or specific vaccines have been discovered yet. In this bewilderment, the potential therapeutic antiviral drug targets for the COVID-19 are repurposing to speed up the discovery of effective treatment. The most potential drug targets are continuously published, especially Favipiravir, Chloroquine, Hydroxychloroquine, and Remdesivir. Moreover, the antiviral target proteins and anti-host target proteins were reported continuously. This review summarized the current research studies of potential therapeutic drug targets being tested against the SARS-CoV-2. It will provide information relative to potential repurposing drugs to overcome the COVID-19.

Targeting host cell proteases as a potential treatment strategy to limit the spread of SARS-CoV-2 in the respiratory tract

As the death toll of Coronavirus disease 19 (COVID-19) continues to rise worldwide, it is imperative to explore novel molecular mechanisms for targeting SARS-CoV-2. Rather than looking for drugs that directly interact with key viral proteins inhibiting its replication, an alternative and possibly add-on approach is to dismantle the host cell machinery that enables the virus to infect the host cell and spread from one cell to another. Excellent examples of such machinery are host cell proteases whose role in viral pathogenesis has been demonstrated in numerous coronaviruses. In this review, we propose two therapeutic modalities to tackle SARS-CoV-2 infections; the first is to transcriptionally modulate the expression of cellular proteases and their endogenous inhibitors and the second is to directly inhibit their enzymatic activity. We present a nonexhaustive collection of clinically investigated drugs that act by one of these mechanisms and thus represent promising candidates for preclinical in vitro testing and hopefully clinical testing in COVID-19 patients.

Current Trends and Future Approaches in Small-Molecule Therapeutics for COVID-19

The novel coronavirus (SARS-CoV-2) pandemic has created a global public health emergency. The pandemic is causing substantial morbidity, mortality and significant economic loss. Currently, no approved treatments for COVID-19 are available, and it is likely to takes at least 12-18 months to develop a new vaccine. Therefore, there is an urgent need to find new therapeutics that can be progressed to clinical development as soon as possible. Repurposing regulatory agency-approved drugs and experimental drugs with known safety profiles can provide important repositories of compounds that can be fast-tracked to clinical development. Globally, over 500 clinical trials involving repurposed drugs have been registered, and over 150 have been initiated, including some backed by the World Health Organisation (WHO). This review is intended as a guide to research into small-molecule therapies to treat COVID-19; it discusses the SARS-CoV-2 infection cycle and identifies promising viral therapeutic targets, reports on a number of promising pre-approved small-molecule drugs with reference to over 150 clinical trials worldwide, and offers a perspective on the future of the field.

Overview of Targets and Potential Drugs of SARS-CoV-2 According to the Viral Replication

Since the novel coronavirus pandemic, people around the world have been touched in varying degrees, and this pandemic has raised a major global health concern. As there is no effective drug or vaccine, it is urgent to find therapeutic drugs that can serve to deal with the current epidemic situation in all countries and regions. We searched drugs and response measures for SARS-CoV-2 in the PubMed database, and then updated the potential targets and therapeutic drugs from the perspective of the viral replication cycle. The drug research studies of the viral replication cycle are predominantly focused on the process of the virus entering cells, proteases, and RdRp. The inhibitors of the virus entry to cells and RdRp, such as Arbidol, remdesivir, favipiravir, EIDD-2081, and ribavirin, are in clinical trials, while most of the protease inhibitors are mainly calculated by molecular docking technology, which needs in vivo and in vitro experiments to prove the effect for SARS-CoV-2. This review summarizes the drugs targeting the viral replication process and provides a basis and directions for future drug development and reuse on the protein level of COVID-19.

Immune response and possible therapeutics in COVID-19

COVID-19 has emerged as a pandemic affecting about 213 countries in all the continents of the globe, resulting in more than 37.8 million individuals getting infected and over 1.08 million deaths worldwide, jeopardizing global human health and the economy. This presents an urgent need to develop therapies that target the SARS-CoV2 virus specifically. This review aims at presenting the available information on the coronavirus disease 2019 along with various drugs that are having widespread use until a vaccine candidate is available to aid in the development of therapeutic strategies against COVID-19.

Targeting TMPRSS2 and Cathepsin B/L together may be synergistic against SARS-CoV-2 infection

The entry of SARS-CoV-2 into target cells requires the activation of its surface spike protein, S, by host proteases. The host serine protease TMPRSS2 and cysteine proteases Cathepsin B/L can activate S, making two independent entry pathways accessible to SARS-CoV-2. Blocking the proteases prevents SARS-CoV-2 entry in vitro. This blockade may be achieved in vivo through 'repurposing' drugs, a potential treatment option for COVID-19 that is now in clinical trials. Here, we found, surprisingly, that drugs targeting the two pathways, although independent, could display strong synergy in blocking virus entry. We predicted this synergy first using a mathematical model of SARS-CoV-2 entry and dynamics in vitro. The model considered the two pathways explicitly, let the entry efficiency through a pathway depend on the corresponding protease expression level, which varied across cells, and let inhibitors compromise the efficiency in a dose-dependent manner. The synergy predicted was novel and arose from effects of the drugs at both the single cell and the cell population levels. Validating our predictions, available in vitro data on SARS-CoV-2 and SARS-CoV entry displayed this synergy. Further, analysing the data using our model, we estimated the relative usage of the two pathways and found it to vary widely across cell lines, suggesting that targeting both pathways in vivo may be important and synergistic given the broad tissue tropism of SARS-CoV-2. Our findings provide insights into SARS-CoV-2 entry into target cells and may help improve the deployability of drug combinations targeting host proteases required for the entry.

Kallikrein 13 serves as a priming protease during infection by the human coronavirus HKU1

Unlike SARS-CoV-2, the human coronavirus HKU1 normally causes relatively mild respiratory tract infections; however, it shares with SARS-CoV-2 the mechanism of using its surface spike (S) protein to enter target cells. Because the host receptor for HCoV-HKU1 is unknown, efforts to study the virus in cell culture systems have proved difficult. Milewska et al. found that knockout of the protease kallikrein 13 (KLK13) in human airway epithelial cells blocked their infection by HCoV-HKU1, that overexpression of KLK13 in nonpermissive cells enabled their infection by the virus, and that KLK13 cleaved the viral S protein. Together, these findings suggest that KLK13 is a priming enzyme for viral entry and may help to establish cell lines that can facilitate further investigation of the mechanism of viral pathogenesis.

Human coronavirus HKU1 (HCoV-HKU1) is associated with respiratory disease and is prevalent worldwide, but an in vitro model for viral replication is lacking. An interaction between the coronaviral spike (S) protein and its receptor is the primary determinant of tissue and host specificity; however, viral entry is a complex process requiring the concerted action of multiple cellular elements. Here, we found that the protease kallikrein 13 (KLK13) was required for the infection of human respiratory epithelial cells and was sufficient to mediate the entry of HCoV-HKU1 into nonpermissive RD cells. We also demonstrated the cleavage of the HCoV-HKU1 S protein by KLK13 in the S1/S2 region, suggesting that KLK13 is the priming enzyme for this virus. Together, these data suggest that protease distribution and specificity determine the tissue and cell specificity of the virus and may also regulate interspecies transmission.

Camostat Mesylate May Reduce Severity of Coronavirus Disease 2019 Sepsis: A First Observation

Severe acute respiratory syndrome coronavirus 2 cell entry depends on angiotensin-converting enzyme 2 and transmembrane serine protease 2 and is blocked in cell culture by camostat mesylate, a clinically proven protease inhibitor. Whether camostat mesylate is able to lower disease burden in coronavirus disease 2019 sepsis is currently unknown.

Design

Retrospective observational case series.

Setting

Patient treated in ICU of University hospital Göttingen, Germany.

Patients

Eleven critical ill coronavirus disease 2019 patients with organ failure were treated in ICU.

Interventions

Compassionate use of camostat mesylate (six patients, camostat group) or hydroxychloroquine (five patients, hydroxychloroquine group).

Measurements and Main Results

Clinical courses were assessed by Sepsis-related Organ Failure Assessment score at days 1, 3, and 8. Further, viral load, oxygenation, and inflammatory markers were determined. Sepsis-related Organ Failure Assessment score was comparable between camostat and hydroxychloroquine groups upon ICU admission. During observation, the Sepsis-related Organ Failure Assessment score decreased in the camostat group but remained elevated in the hydroxychloroquine group. The decline in disease severity in camostat mesylate treated patients was paralleled by a decline in inflammatory markers and improvement of oxygenation.

Conclusions

The severity of coronavirus disease 2019 decreased upon camostat mesylate treatment within a period of 8 days and a similar effect was not observed in patients receiving hydroxychloroquine. Camostat mesylate thus warrants further evaluation within randomized clinical trials.

Targeting Crucial Host Factors of SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide since its first incidence in Wuhan, China, in December 2019. Although the case fatality rate of COVID-19 appears to be lower than that of SARS and Middle East respiratory syndrome (MERS), the higher transmissibility of SARS-CoV-2 has caused the total fatality to surpass other viral diseases, reaching more than 1 million globally as of October 6, 2020. The rate at which the disease is spreading calls for a therapy that is useful for treating a large population. Multiple intersecting viral and host factor targets involved in the life cycle of the virus are being explored. Because of the frequent mutations, many coronaviruses gain zoonotic potential, which is dependent on the presence of cell receptors and proteases, and therefore the targeting of the viral proteins has some drawbacks, as strain-specific drug resistance can occur. Moreover, the limited number of proteins in a virus makes the number of available targets small. Although SARS-CoV and SARS-CoV-2 share common mechanisms of entry and replication, there are substantial differences in viral proteins such as the spike (S) protein. In contrast, targeting cellular factors may result in a broader range of therapies, reducing the chances of developing drug resistance. In this Review, we discuss the role of primary host factors such as the cell receptor angiotensin-converting enzyme 2 (ACE2), cellular proteases of S protein priming, post-translational modifiers, kinases, inflammatory cells, and their pharmacological intervention in the infection of SARS-CoV-2 and related viruses.

Old Drugs for a New Virus: Repurposed Approaches for Combating COVID-19

There is a large global unmet need for effective countermeasures to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19). The development of novel antiviral drugs is expensive and too slow to meet the immediate need. The repurposing of drugs that are approved or are under advanced clinical investigation provides a cost- and time-effective therapeutic solution. This review summarizes the major repurposed approaches that have been proposed or are already being studied in clinical trials for COVID-19. Among these approaches are drugs that aim to reduce SARS-CoV-2 replication by targeting either viral enzymatic functions or cellular factors required for the viral life cycle. Drugs that modulate the host immune response to SARS-CoV-2 infection by boosting it to enhance viral clearance or by suppressing it to prevent excessive inflammation and tissue injury represent another category. Lastly, we discuss means to discover repurposed drugs and the ongoing challenges associated with the off-label use of existing drugs in the context of the COVID-19 outbreak.

Targeting TMPRSS2 in SARS-CoV-2 Infection

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has rapidly caused a global pandemic associated with a novel respiratory infection: coronavirus disease-19 (COVID-19). Angiotensin-converting enzyme-2 (ACE2) is necessary to facilitate SARS-CoV-2 infection, but-owing to its essential metabolic roles-it may be difficult to target it in therapies. Transmembrane protease serine 2 (TMPRSS2), which interacts with ACE2, may be a better candidate for targeted therapies. Using publicly available expression data, we show that both ACE2 and TMPRSS2 are expressed in many host tissues, including lung. The highest expression of ACE2 is found in the testes, whereas the prostate displays the highest expression of TMPRSS2. Given the increased severity of disease among older men with SARS-CoV-2 infection, we address the potential roles of ACE2 and TMPRSS2 in their contribution to the sex differences in severity of disease. We show that expression levels of ACE2 and TMPRSS2 are overall comparable between men and women in multiple tissues, suggesting that differences in the expression levels of TMPRSS2 and ACE2 in the lung and other non-sex-specific tissues may not explain the gender disparities in severity of SARS CoV-2. However, given their instrumental roles for SARS-CoV-2 infection and their pleiotropic expression, targeting the activity and expression levels of TMPRSS2 is a rational approach to treat COVID-19.

Structural Basis of SARS-CoV-2- and SARS-CoV-Receptor Binding and Small-Molecule Blockers as Potential Therapeutics

Over the past two decades, deadly coronaviruses, with the most recent being the severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) 2019 pandemic, have majorly challenged public health. The path for virus invasion into humans and other hosts is mediated by host-pathogen interactions, specifically virus-receptor binding. An in-depth understanding of the virus-receptor binding mechanism is a prerequisite for the discovery of vaccines, antibodies, and small-molecule inhibitors that can interrupt this interaction and prevent or cure infection. In this review, we discuss the viral entry mechanism, the known structural aspects of virus-receptor interactions (SARS-CoV-2 S/humanACE2, SARS-CoV S/humanACE2, and MERS-CoV S/humanDPP4), the key protein domains and amino acid residues involved in binding, and the small-molecule inhibitors and other drugs that have (as of June 2020) exhibited therapeutic potential. Specifically, we review the potential clinical utility of two transmembrane serine protease 2 (TMPRSS2)-targeting protease inhibitors, nafamostat mesylate and camostat mesylate, as well as two novel potent fusion inhibitors and the repurposed Ebola drug, remdesivir, which is specific to RNA-dependent RNA polymerase, against human coronaviruses, including SARS-CoV-2.

Novel airway smooth muscle-mast cell interactions and a role for the TRPV4-ATP axis in non-atopic asthma

Mast cell–airway smooth muscle (ASM) interactions play a major role in the immunoglobulin (Ig)E- dependent bronchoconstriction seen in asthma but less is known about IgE-independent mechanisms of mast cell activation. Transient receptor potential cation channel, subfamily V, member 4 (TRPV4) activation causes contraction of human ASM via the release of cysteinyl leukotrienes (cysLTs) but the mechanism is unknown. The objective of the present study was to investigate a role for IgE-independent, mast cell–ASM interaction in TRPV4-induced bronchospasm.

A technique not previously applied to respiratory research now uncovers important IgE-independent mechanisms involved in human mast cell–airway smooth muscle interactions that may be responsible for the bronchospasm associated with non-atopic asthmahttp://bit.ly/2U1n5nT

Potential therapeutic targets and promising drugs for combating SARS-CoV-2

As of April 9, 2020, a novel coronavirus (SARS-CoV-2) had caused 89,931 deaths and 1,503,900 confirmed cases worldwide, which indicates an increasingly severe and uncontrollable situation. Initially, little was known about the virus. As research continues, we now know the genome structure, epidemiological and clinical characteristics, and pathogenic mechanisms of SARS-CoV-2. Based on this knowledge, potential targets involved in the processes of virus pathogenesis need to be identified, and the discovery or development of drugs based on these potential targets is the most pressing need. Here, we have summarized the potential therapeutic targets involved in virus pathogenesis and discuss the advances, possibilities, and significance of drugs based on these targets for treating SARS-CoV-2. This review will facilitate the identification of potential targets and provide clues for drug development that can be translated into clinical applications for combating SARS-CoV-2.

Evaluation and Management of Suspected Early Chronic Pancreatitis (ECP)

PURPOSE OF REVIEW

Chronic pancreatitis in the advanced stages leads to significant health care utilization because of the associated complications. Early-stage diagnosis could prevent the development of these complications by appropriate management. In this article, we reviewed the recent evidence pertaining to the diagnosis and management of early chronic pancreatitis (ECP).

RECENT FINDINGS

The working group for the International Consensus Guidelines for Chronic Pancreatitis has published consensus-based statements to streamline the diagnosis of ECP. There is no international consensus on the definition and diagnosis of ECP. The Revised Japanese Diagnostic Criteria for ECP based on clinical features and endoscopic ultrasound findings have been proposed. Large prospective cohort studies are needed to develop and validate internationally acceptable diagnostic criteria. ECP is recognized as a distinct stage in the development and progression of CP. Consensus-based definitions and diagnostic criteria need to be developed.

Combating the Coronavirus Pandemic: Early Detection, Medical Treatment, and a Concerted Effort by the Global Community

The World Health Organization (WHO) has declared the outbreak of 2019 novel coronavirus, known as 2019-nCoV, a pandemic, as the coronavirus has now infected over 2.6 million people globally and caused more than 185,000 fatalities as of April 23, 2020. Coronavirus disease 2019 (COVID-19) causes a respiratory illness with symptoms such as dry cough, fever, sudden loss of smell, and, in more severe cases, difficulty breathing. To date, there is no specific vaccine or treatment proven effective against this viral disease. Early and accurate diagnosis of COVID-19 is thus critical to curbing its spread and improving health outcomes. Reverse transcription-polymerase chain reaction (RT-PCR) is commonly used to detect the presence of COVID-19. Other techniques, such as recombinase polymerase amplification (RPA), loop-mediated isothermal amplification (LAMP), clustered regularly interspaced short palindromic repeats (CRISPR), and microfluidics, have allowed better disease diagnosis. Here, as part of the effort to expand screening capacity, we review advances and challenges in the rapid detection of COVID-19 by targeting nucleic acids, antigens, or antibodies. We also summarize potential treatments and vaccines against COVID-19 and discuss ongoing clinical trials of interventions to reduce viral progression.

Pancreatic Stellate Cells: The Key Orchestrator of The Pancreatic Tumor Microenvironment

Pancreatic cancer is one of the most challenging adenocarcinomas due to its hostile molecular behavior and complex tumor microenvironment. It has been recently postulated that pancreatic stellate cells (PSCs), the resident lipid-storing cells of the pancreas, are important components of the tumor microenvironment as they can transdifferentiate into highly proliferative myofibroblasts in the context of tissue injury. Targeting tumor-stromal crosstalk in the tumor microenvironment has emerged as a promising therapeutic strategy against pancreatic cancer progression and metastasis. This chapter brings a broad view on the biological and pathological role of PSCs in the pancreas, activated stellate cells in the onset of tissue fibrosis, and tumor progression with particular emphasis on the bidirectional interactions between tumor cells and PSCs. Further, potential therapeutic regimens targeting activated PSCs in the pre-clinical and clinical trials are discussed.

International consensus statements on early chronic Pancreatitis. Recommendations from the working group for the international consensus guidelines for chronic pancreatitis in collaboration with The International Association of Pancreatology, American Pancreatic Association, Japan Pancreas Society, PancreasFest Working Group and European Pancreatic Club

BACKGROUND

Chronic pancreatitis (CP) is a progressive inflammatory disorder currently diagnosed by morphologic features. In contrast, an accurate diagnosis of Early CP is not possible using imaging criteria alone. If this were possible and early treatment instituted, the later, irreversible features and complications of CP could possibly be prevented.

METHOD

An international working group supported by four major pancreas societies (IAP, APA, JPS, and EPC) and a PancreasFest working group sought to develop a consensus definition and diagnostic criteria for Early CP. Ten statements (S1-10) concerning Early CP were used to gauge consensus on the Early CP concept using anonymous voting with a 9 point Likert scale. Consensus required an alpha ≥0.80.

RESULTS

No consensus statement could be developed for a definition of Early-CP or diagnostic criteria. There was consensus on 5 statements: (S2) The word "Early" in early chronic pancreatitis is used to describe disease state, not disease duration. (S4) Early CP defines a stage of CP with preserved pancreatic function and potentially reversible features. (S8) Genetic variants are important risk factors for Early CP and can add specificity to the likely etiology, but they are neither necessary nor sufficient to make a diagnosis. (S9) Environmental risk factors can provide evidence to support the diagnosis of Early CP, but are neither necessary nor sufficient to make a diagnosis. (S10) The differential diagnosis for Early CP includes other disorders with morphological and functional features that overlap with CP.

CONCLUSIONS

Morphology based diagnosis of Early CP is not possible without additional information. New approaches to the accurate diagnosis of Early CP will require a mechanistic definition that considers risk factors, biomarkers, clinical context and new models of disease. Such a definition will require prospective validation.

Novel and Experimental Therapies in Chronic Pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disease of the pancreas. The currently available treatment of CP is aimed at controlling symptoms and managing complications. Unfortunately, no specific treatment is available to halt the progression of the disease process because the pathophysiological perturbations in CP are not well understood. In this review, we discuss various therapeutic targets and investigational agents acting on these targets. Among these, therapies modulating immune cells and those acting on pancreatic stellate cells appear promising and may translate into clinical benefit in near future. However, these experimental therapies are mostly in animal models and they do not recapitulate all aspects of human disease. Still they may be beneficial in developing effective therapeutic modalities to curb inflammation in chronic pancreatitis.

Mathematical model of chronic pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disease of the pancreas, leading to its fibrotic destruction. There are currently no drugs that can stop or slow the progression of the disease. The etiology of the disease is multifactorial, whereas recurrent attacks of acute pancreatitis are thought to precede the development of CP. A better understanding of the pathology of CP is needed to facilitate improved diagnosis and treatment strategies for this disease. The present paper develops a mathematical model of CP based on a dynamic network that includes macrophages, pancreatic stellate cells, and prominent cytokines that are present at high levels in the CP microenvironment. The model is represented by a system of partial differential equations. The model is used to explore in silico potential drugs that could slow the progression of the disease, for example infliximab (anti-TNF-[Formula: see text]) and tocilizumab or siltuximab (anti-IL-6/IL-6R).

Pancreatic stellate cell: Pandora's box for pancreatic disease biology

Pancreatic stellate cells (PSCs) were identified in the early 1980s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Several pathways (e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and miRNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

Membrane-anchored Serine Protease Matriptase Is a Trigger of Pulmonary Fibrogenesis

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a devastating disease that remains refractory to current therapies.

OBJECTIVES

To characterize the expression and activity of the membrane-anchored serine protease matriptase in IPF in humans and unravel its potential role in human and experimental pulmonary fibrogenesis.

METHODS

Matriptase expression was assessed in tissue specimens from patients with IPF versus control subjects using quantitative reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blotting, while matriptase activity was monitored by fluorogenic substrate cleavage. Matriptase-induced fibroproliferative responses and the receptor involved were characterized in human primary pulmonary fibroblasts by Western blot, viability, and migration assays. In the murine model of bleomycin-induced pulmonary fibrosis, the consequences of matriptase depletion, either by using the pharmacological inhibitor camostat mesilate (CM), or by genetic down-regulation using matriptase hypomorphic mice, were characterized by quantification of secreted collagen and immunostainings.

MEASUREMENTS AND MAIN RESULTS

Matriptase expression and activity were up-regulated in IPF and bleomycin-induced pulmonary fibrosis. In cultured human pulmonary fibroblasts, matriptase expression was significantly induced by transforming growth factor-β. Furthermore, matriptase elicited signaling via protease-activated receptor-2 (PAR-2), and promoted fibroblast activation, proliferation, and migration. In the experimental bleomycin model, matriptase depletion, by the pharmacological inhibitor CM or by genetic down-regulation, diminished lung injury, collagen production, and transforming growth factor-β expression and signaling.

CONCLUSIONS

These results implicate increased matriptase expression and activity in the pathogenesis of pulmonary fibrosis in human IPF and in an experimental mouse model. Overall, targeting matriptase, or treatment by CM, which is already in clinical use for other diseases, may represent potential therapies for IPF.

Oral delivery of macromolecular drugs: Where we are after almost 100years of attempts

Since the first attempt to administer insulin orally in humans more than 90years ago, the oral delivery of macromolecular drugs (>1000g/mol) has been rather disappointing. Although several clinical pilot studies have demonstrated that the oral absorption of macromolecules is possible, the bioavailability remains generally low and variable. This article reviews the formulations and biopharmaceutical aspects of orally administered biomacromolecules on the market and in clinical development for local and systemic delivery. The most successful approaches for systemic delivery often involve a combination of enteric coating, protease inhibitors and permeation enhancers in relatively high amounts. However, some of these excipients have induced local or systemic adverse reactions in preclinical and clinical studies, and long-term studies are often missing. Therefore, strategies aimed at increasing the oral absorption of macromolecular drugs should carefully take into account the benefit-risk ratio. In the absence of specific uptake pathways, small and potent peptides that are resistant to degradation and that present a large therapeutic window certainly represent the best candidates for systemic absorption. While we acknowledge the need for systemically delivering biomacromolecules, it is our opinion that the oral delivery to local gastrointestinal targets is currently more promising because of their accessibility and the lacking requirement for intestinal permeability enhancement.

Effect of Fetal Membrane-Derived Mesenchymal Stem Cell Transplantation in Rats With Acute and Chronic Pancreatitis

OBJECTIVES

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine and can be isolated from fetal membranes (FMs), particularly amniotic membranes. We investigated the effect of rat FM-derived MSCs (rFM-MSCs) and human amnion-derived MSCs (hAMSCs) on the inflammatory reaction in vitro and therapeutic effects in rats with acute and chronic pancreatitis.

METHODS

Effect of rFM-MSCs or hAMSC-conditioned medium was investigated in vitro. Acute pancreatitis was induced by intraductal injection of 4% taurocholate, and rFM-MSCs were transplanted intravenously. Chronic pancreatitis was induced by intravenous injection of 5 mg/kg dibutyltin dichloride, and hAMSCs were transplanted intravenously.

RESULTS

The inflammatory reaction of macrophages induced by lipopolysaccharide and trypsin was significantly suppressed by rFM-MSC coculture. Pancreatic acinar cell injury induced by cerulein was significantly ameliorated by hAMSC-conditioned medium. Pancreatic stellate cell activation induced by tumor necrosis factor-α was significantly decreased by hAMSC-conditioned medium. Transplantation of rFM-MSCs significantly reduced the histological score and infiltration of CD68-positive macrophages in the rat pancreas. The hAMSC transplantation significantly decreased the expression of MCP-1 and attenuated the downregulation of amylase expression in the pancreas.

CONCLUSIONS

Transplantation of FM-MSCs and AMSCs suppressed the inflammatory reaction of acute and chronic pancreatitis in rats.

A Novel, Poly(Ethyl Ethylene Ether) Inhibitor to Trypsin from Marine Cyanobacteria, Lyngbya confervoides

A novel, poly(ethyl ethylene ether) inhibitor to trypsin was purified from marine cyanobacteria, Lyngbya confervoides from the coastal areas of Thalassery, North Kerala. The kinetics and the thermodynamic parameters of its interactions with the enzyme were also studied. It was demonstrated that the substrate binding, catalytic triad of the enzyme could be blocked by the inhibitor, as expressed by molecular simulation studies. The study also showed that the cyanobacterial group could prove to be a potential source of novel enzyme inhibitors for various applications.

A sustained prostacyclin analog, ONO-1301, attenuates pancreatic fibrosis in experimental chronic pancreatitis induced by dibutyltin dichloride in rats

BACKGROUND

ONO-1301, a novel sustained-release prostacyclin agonist, has an anti-fibrotic effect on the lungs, heart, and kidneys that is partly associated with the induction of hepatocyte growth factor (HGF). This study examined the anti-fibrotic effect of ONO-1301 on chronic pancreatitis (CP) progression.

METHODS

CP was induced in rats in vivo by dibutyltin dichloride (DBTC). Seven days after DBTC injection (day 7), a slow-release form of ONO-1301 (10 mg/kg; ONO-1301-treated group) or vehicle (DBTC-treated group) was injected. On days 14 and 28, we evaluated the histopathological CP score and mRNA expressions of HGF, cytokines, and collagen in the pancreas by real-time RT-PCR. In vitro, monocytes and pancreatic stellate cells (PSCs) were isolated from normal rat spleen and pancreas, respectively. The cytokine and collagen expressions of monocytes and PSCs were detected by real-time RT-PCR, and PSCs proliferation was examined by BrdU assay.

RESULTS

Histopathological CP scores in vivo improved in the ONO-1301-treated group compared to the DBTC-treated group, particularly inflammatory cell infiltration on day 14 and interstitial fibrosis on day 28. HGF mRNA increased significantly after ONO-1301 administration, whereas IL-1β, TNF-α, TGF-β, MCP-1, and collagen mRNA decreased significantly. Cytokine expression in monocytes was suppressed in vitro not only by HGF, but also ONO-1301 alone. However, neither ONO-1301 nor HGF affected the proliferation, or cytokine or collagen expression of PSCs.

CONCLUSIONS

ONO-1301 suppresses pancreatic fibrosis in the DBTC-induced CP model by inhibiting monocyte activity not only with induction of HGF but also by ONO-1301 itself.

Reduction of fibrosis in dibutyltin dichloride-induced chronic pancreatitis using rat umbilical mesenchymal stem cells from Wharton's jelly

OBJECTIVES

The objective of this study was to investigate the effects of rat umbilical cord mesenchymal stem cells (UCMSCs) from Wharton's jelly on dibutyltin dichloride (DBTC)-induced chronic pancreatitis (CP) and subsequent pancreatic fibrosis in rats.

METHODS

A rat model of CP induced by DBTC was used. Male Sprague-Dawley rats were randomly divided into 4 groups: the control, DBTC, DBTC + UCMSCs, and control + UCMSC groups. Umbilical cord mesenchymal stem cells were administered intravenously on day 5 after the administration of DBTC. On days 14 and 28, the rats were evaluated morphologically and biochemically. The expression levels of inflammatory cytokines and chemokines in the pancreatic tissues of different groups were evaluated using quantitative real-time polymerase chain reaction. The activation of pancreatic stellate cells was estimated by immunochemistry and Western blot analysis of α-smooth muscle actin.

RESULTS

Umbilical cord mesenchymal stem cells were detected in inflamed pancreatic tissues. Umbilical cord mesenchymal stem cell treatment improved the histological scores and alleviated the fibrosis of pancreas samples, The expression of cytokines in the DBTC + UCMSC group was significantly lower than that in the DBTC group. Also, pancreatic stellate cell activation was inhibited by UCMSC treatment.

CONCLUSIONS

Xenogeneic transplantation of UCMSCs is a novel approach for the treatment of CP and subsequent fibrosis. Umbilical cord mesenchymal stem cells may be a promising therapeutic intervention for human CP in the future.

The antifibrotic effect of a serine protease inhibitor in the kidney

Interstitial fibrosis is a final common pathway for the progression of chronic kidney diseases. Activated fibroblasts have an extremely important role in the progression of renal fibrosis, and transforming growth factor (TGF)-β₁ is a major activator of fibroblasts. Since previous reports have indicated that serine protease inhibitors have a potential to inhibit TGF-β₁ signaling in vitro, we hypothesized that a synthetic serine protease inhibitor, camostat mesilate (CM), could slow the progression of renal fibrosis. TGF-β₁ markedly increased the phosphorylation of TGF-β type I receptor, ERK 1/2, and Smad2/3 and the levels of profibrotic markers, such as α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), and plasminogen activator inhibitor-1, in renal fibroblasts (NRK-49F cells), and they were all significantly reduced by CM. In protocol 1, 8-wk-old male Sprague-Dawley rats were subjected to unilateral ureteral obstruction (UUO) and were concurrently treated with a slow-release pellet of CM or vehicle for 14 days. Protocol 2 was similar to protocol 1 except that CM was administered 7 days after UUO. CM substantially improved renal fibrosis as determined by sirius red staining, collagen expression, and hydroxyproline levels. The phosphorylation of ERK1/2 and Smad2/3 and the levels of α-SMA, CTGF, promatrix metalloproteinase-2, and matrix metalloproteinase-2 were substantially increased by UUO, and they were all significantly attenuated by CM. These antifibrotic effects of CM were also observed in protocol 2. Our present results suggest the possibility that CM might represent a new class of therapeutic drugs for the treatment of renal fibrosis through the suppression of TGF-β₁ signaling.

Effect of a serine protease inhibitor on the progression of chronic renal failure

The number of the chronic renal failure (CRF) patients is increasing explosively. Hypertension, proteinuria, inflammation, fibrosis, and oxidative stress are intertwined in a complicated manner that leads to the progression of CRF. However, the therapeutic strategies to delay its progression are limited. Since serine proteases are involved in many processes that contribute to these risk factors, we investigated the effects of a synthetic serine protease inhibitor, camostat mesilate (CM), on the progression of CRF in 5/6 nephrectomized (Nx) rats. Eighteen male Sprague-Dawley rats were divided into three groups: a sham-operated group ( n = 6), a vehicle-treated Nx group ( n = 6), and a CM-treated Nx group ( n = 6). Following the 9-wk study period, both proteinuria and serum creatinine levels were substantially increased in the vehicle-treated Nx group, and treatment with CM significantly reduced proteinuria and serum creatinine levels. The levels of podocyte-associated proteins in glomeruli, such as nephrin and synaptopodin, were markedly decreased by 5/6 nephrectomy, and this was significantly ameliorated by CM. CM also suppressed the levels of inflammatory and fibrotic marker mRNAs including transforming growth factor-β1, TNF-α, collagen types I, III, and IV, and reduced glomerulosclerosis, glomerular hypertrophy, and interstitial fibrosis in histological studies. Furthermore, CM decreased the expression of NADPH oxidase component mRNAs, as well as reactive oxygen species generation and advanced oxidative protein product levels. Our present results strongly suggest the possibility that CM could be a useful therapeutic agent against the progression of CRF.

Pancreatic stellate cells: a starring role in normal and diseased pancreas

While the morphology and function of cells of the exocrine and endocrine pancreas have been studied over several centuries, one important cell type in the gland, the pancreatic stellate cell (PSC), had remained undiscovered until as recently as 20 years ago. Even after its first description in 1982, it was to be another 16 years before its biology could begin to be studied, because it was only in 1998 that methods were developed to isolate and culture PSCs from rodent and human pancreas. PSCs are now known to play a critical role in pancreatic fibrosis, a consistent histological feature of two major diseases of the pancreas—chronic pancreatitis and pancreatic cancer. In health, PSCs maintain normal tissue architecture via regulation of the synthesis and degradation of extracellular matrix (ECM) proteins. Recent studies have also implied other functions for PSCs as progenitor cells, immune cells or intermediaries in exocrine pancreatic secretion in humans. During pancreatic injury, PSCs transform from their quiescent phase into an activated, myofibroblast-like phenotype that secretes excessive amounts of ECM proteins leading to the fibrosis of chronic pancreatitis and pancreatic cancer. An ever increasing number of factors that stimulate and/or inhibit PSC activation via paracrine and autocrine pathways are being identified and characterized. It is also now established that PSCs interact closely with pancreatic cancer cells to facilitate cancer progression. Based on these findings, several therapeutic strategies have been examined in experimental models of chronic pancreatitis as well as pancreatic cancer, in a bid to inhibit/retard PSC activation and thereby alleviate chronic pancreatitis or reduce tumor growth in pancreatic cancer. The challenge that remains is to translate these pre-clinical developments into clinically applicable treatments for patients with chronic pancreatitis and pancreatic cancer.

The fibrosis of chronic pancreatitis: new insights into the role of pancreatic stellate cells

SIGNIFICANCE

Prominent fibrosis is a major histological feature of chronic pancreatitis, a progressive necroinflammatory condition of the pancreas, most commonly associated with alcohol abuse. Patients with this disease often develop exocrine and endocrine insufficiency characterized by maldigestion and diabetes. Up until just over a decade ago, there was little understanding of the pathogenesis of pancreatic fibrosis in chronic pancreatitis.

RECENT ADVANCES

In recent times, significant progress has been made in this area, mostly due to the identification, isolation, and characterization of the cells, namely pancreatic stellate cells (PSCs) that are now established as key players in pancreatic fibrogenesis. In health, PSCs maintain normal tissue architecture via regulation of the synthesis and degradation of extracellular matrix (ECM) proteins. During pancreatic injury, PSCs transform into an activated phenotype that secretes excessive amounts of the ECM proteins that comprise fibrous tissue.

CRITICAL ISSUES

This Review summarizes current knowledge and critical aspects of PSC biology which have been increasingly well characterized over the past few years, particularly with respect to the response of PSCs to factors that stimulate or inhibit their activation and the intracellular signaling pathways governing these processes. Based on this knowledge, several therapeutic strategies have been examined in experimental models of pancreatic fibrosis, demonstrating that pancreatic fibrosis is a potentially reversible condition, at least in early stages.

FUTURE DIRECTIONS

These will involve translation of the laboratory findings into effective clinical approaches to prevent/inhibit PSC activation so as to prevent, retard, or reverse the fibrotic process in pancreatitis.

Phenotypic changes in mouse pancreatic stellate cell Ca2+ signaling events following activation in culture and in a disease model of pancreatitis

The specific characteristics of intracellular Ca 2+ signaling and the downstream consequences of these events were investigated in mouse pancreatic stellate cells (PSC) in culture and in situ using multiphoton microscopy in pancreatic lobules. PSC undergo a phenotypic transformation from a quiescent state to a myofibroblast-like phenotype in culture. This is believed to parallel the induction of an activated state observed in pancreatic disease such as chronic pancreatitis and pancreatic cancer. By day 7 in culture, the complement of cell surface receptors coupled to intracellular Ca 2+ signaling was shown to be markedly altered. Specifically, protease-activated receptors (PAR) 1 and 2, responsive to thrombin and trypsin, respectively, and platelet-derived growth factor (PDGF) receptors were expressed only in activated PSC (aPSC). PAR-1, ATP, and PDGF receptor activation resulted in prominent nuclear Ca 2+ signals. Nuclear Ca 2+ signals and aPSC proliferation were abolished by expression of parvalbumin targeted to the nucleus. In pancreatic lobules, PSC responded to agonists consistent with the presence of only quiescent PSC. aPSC were observed following induction of experimental pancreatitis. In contrast, in a mouse model of pancreatic disease harboring elevated K-Ras activity in acinar cells, aPSC were present under control conditions and their number greatly increased following induction of pancreatitis. These data are consistent with nuclear Ca 2+ signaling generated by agents such as trypsin and thrombin, likely present in the pancreas in disease states, resulting in proliferation of "primed" aPSC to contribute to the severity of pancreatic disease.

Chronic pancreatitis: potential future interventions

Chronic pancreatitis is a common disorder of which the underlying pathogenic mechanisms still are incompletely understood. In the last decade, increasing evidence has shown that activated pancreatic stellate cells play a key role in the fibrosis development associated with chronic pancreatitis as well as pancreatic cancer. During pancreatic injury or inflammation, quiescent stellate cells undergo a phenotypic transformation, characterized by smooth muscle alpha-actin expression and increased synthesis of extracellular matrix proteins. Hitherto, specific therapies to prevent or reverse pancreatic fibrosis are unavailable. This review addresses current insights into pathological mechanisms underlying chronic pancreatitis and their applicability as concerns the development of potential future therapeutic approaches.

Efficacy of camostat mesilate against dyspepsia associated with non-alcoholic mild pancreatic disease

BACKGROUND

The aim of the present study was to examine the potential efficacy of camostat mesilate, a protease inhibitor, against dyspepsia associated with non-alcoholic mild pancreatic disease.

METHODS

Patients with upper abdominal pain suggesting pancreatic disease (persistent over hours, pain aggravated by ingestion of food, epigastric pain radiating to the back), without a history of alcohol consumption and who exhibited no abnormalities regarding serum amylase and lipase, ultrasonography, CT and upper gastrointestinal endoscopy, were prescribed 200 mg camostat mesilate three times daily for 2 weeks. The patients were subjected to endoscopic ultrasonography (EUS) while under treatment and were distributed into those who had 4 or more suggestive findings of chronic pancreatitis (suspected pancreatic disease group), 2 or 3 (equivalent group) and those with 1 or no findings (control group). Symptom severity was recorded before and after treatment using a 10-cm visual analog scale (VAS).

RESULTS

Among 95 patients, 40 were in the suspected pancreatic disease group, 30 were in the equivalent group and 25 served as controls. A significant intra- and intergroup improvement of symptoms was observed not only in the suspected pancreatic disease group but also in the equivalent group.

CONCLUSIONS

Camostat mesilate may serve as a therapeutic agent for patients with dyspepsia associated with mild pancreatic disease, who do not habitually drink alcohol.