A small molecule MST1/2 inhibitor accelerates murine liver regeneration with improved survival in models of steatohepatitis.

Dysfunctional liver regeneration following surgical resection remains a major cause of postoperative mortality and has no therapeutic options. Without targeted therapies, the current treatment paradigm relies on supportive therapy until homeostasis can be achieved. Pharmacologic acceleration of regeneration represents an alternative therapeutic avenue. Therefore, we aimed to generate a small molecule inhibitor that could accelerate liver regeneration with an emphasis on diseased models, which represent a significant portion of patients who require surgical resection and are often not studied. Utilizing a clinically approved small molecule inhibitor as a parent compound, standard medicinal chemistry approaches were utilized to generate a small molecule inhibitor targeting serine/threonine kinase 4/3 (MST1/2) with reduced off-target effects. This compound, mCLC846, was then applied to preclinical models of murine partial hepatectomy, which included models of diet-induced metabolic dysfunction-associated steatohepatitis (MASH). mCLC846 demonstrated on target inhibition of MST1/2 and reduced epidermal growth factor receptor inhibition. The inhibitory effects resulted in restored pancreatic beta-cell function and survival under diabetogenic conditions. Liver-specific cell-line exposure resulted in Yes-associated protein activation. Oral delivery of mCLC846 perioperatively resulted in accelerated murine liver regeneration and improved survival in diet-induced MASH models. Bulk transcriptional analysis of regenerating liver remnants suggested that mCLC846 enhanced the normal regenerative pathways and induced them following liver resection. Overall, pharmacological acceleration of liver regeneration with mCLC846 was feasible, had an acceptable therapeutic index, and provided a survival benefit in models of diet-induced MASH.

Enteroviral infections are not associated with type 2 diabetes.

Introduction: For more than a century, enteroviral infections have been associated with autoimmunity and type 1 diabetes (T1D). Uncontrolled viral response pathways repeatedly presented during childhood highly correlate with autoimmunity and T1D. Virus responses evoke chemokines and cytokines, the "cytokine storm" circulating through the body and attack cells especially vulnerable to inflammatory destruction. Intra-islet inflammation is a major trigger of ß-cell failure in both T1D and T2D. The genetic contribution of islet inflammation pathways is apparent in T1D, with several mutations in the interferon system. In contrast, in T2D, gene mutations are related to glucose homeostasis in ß cells and insulin-target tissue and rarely within viral response pathways. Therefore, the current study evaluated whether enteroviral RNA can be found in the pancreas from organ donors with T2D and its association with disease progression. Methods: Pancreases from well-characterized 29 organ donors with T2D and 15 age- and BMI-matched controls were obtained from the network for pancreatic organ donors with diabetes and were analyzed in duplicates. Single-molecule fluorescence in-situ hybridization analyses were performed using three probe sets to detect positive-strand enteroviral RNA; pancreas sections were co-stained by classical immunostaining for insulin and CD45. Results: There was no difference in the presence or localization of enteroviral RNA in control nondiabetic and T2D pancreases; viral infiltration showed large heterogeneity in both groups ranging from 0 to 94 virus+ cells scattered throughout the pancreas, most of them in the exocrine pancreas. Very rarely, a single virus+ cell was found within islets or co-stained with CD45+ immune cells. Only one single T2D donor presented an exceptionally high number of viruses, similarly as seen previously in T1D, which correlated with a highly reduced number of ß cells. Discussion: No association of enteroviral infection in the pancreas and T2D diabetes could be found. Despite great similarities in inflammatory markers in islets in T1D and T2D, long-term enteroviral infiltration is a distinct pathological feature of T1D-associated autoimmunity and in T1D pancreases.

Abnormal acinar-ß-cell crosstalk in type 2 diabetes.

Cellular crosstalk plays a vital role in maintaining pancreas homeostasis. Recently, in Cell Metabolism, Basile et al. demonstrated that aberrant upregulation of acinar-cell-specific pancreatic elastase CELA3B within endocrine islets reduces ß-cell viability in type 2 diabetes (T2D). This identifies detrimental acinar-ß-cell crosstalk as a novel pathogenic mechanism in diabetes.

Localization of enteroviral RNA within the pancreas in donors with T1D and T1D-associated autoantibodies.

Enteroviral infections have been associated with autoimmunity and type 1 diabetes (T1D), but reliable methods to ascertain localization of single infected cells in the pancreas were missing. Using a single-molecule-based fluorescent in situ hybridization (smFISH) method, we detected increased virus infection in pancreases from organ donors with T1D and with disease-associated autoantibodies (AAb+). Although virus-positive ß cells are found at higher frequency in T1D pancreases, compared to control donors, but are scarce, most virus-positive cells are scattered in the exocrine pancreas. Augmented CD45+ lymphocytes in T1D pancreases show virus positivity or localization in close proximity to virus-positive cells. Many more infected cells were also found in spleens from T1D donors. The overall increased proportion of virus-positive cells in the pancreas of AAb+ and T1D organ donors suggests that enteroviruses are associated with immune cell infiltration, autoimmunity, and ß cell destruction in both preclinical and diagnosed T1D.

The Hippo kinase LATS2 impairs pancreatic ß-cell survival in diabetes through the mTORC1-autophagy axis.

Diabetes results from a decline in functional pancreatic ß-cells, but the molecular mechanisms underlying the pathological ß-cell failure are poorly understood. Here we report that large-tumor suppressor 2 (LATS2), a core component of the Hippo signaling pathway, is activated under diabetic conditions and induces ß-cell apoptosis and impaired function. LATS2 deficiency in ß-cells and primary isolated human islets as well as ß-cell specific LATS2 ablation in mice improves ß-cell viability, insulin secretion and ß-cell mass and ameliorates diabetes development. LATS2 activates mechanistic target of rapamycin complex 1 (mTORC1), a physiological suppressor of autophagy, in ß-cells and genetic and pharmacological inhibition of mTORC1 counteracts the pro-apoptotic action of activated LATS2. We further show a direct interplay between Hippo and autophagy, in which LATS2 is an autophagy substrate. On the other hand, LATS2 regulates ß-cell apoptosis triggered by impaired autophagy suggesting an existence of a stress-sensitive multicomponent cellular loop coordinating ß-cell compensation and survival. Our data reveal an important role for LATS2 in pancreatic ß-cell turnover and suggest LATS2 as a potential therapeutic target to improve pancreatic ß-cell survival and function in diabetes.

SARS-CoV-2 and pancreas: a potential pathological interaction?

The widespread extrapulmonary complications of coronavirus disease 2019 (COVID-19) have gained momentum; the pancreas is another major target for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we take a closer look into potential pathological interactions. We provide an overview of the current knowledge and understanding of SARS-CoV-2 infection of the pancreas with a special focus on pancreatic islets and propose direct, indirect, and systemic mechanisms for pancreas injury as result of the COVID-19-diabetes fatal bidirectional relationship.

Inhibition of PHLPP1/2 phosphatases rescues pancreatic ß-cells in diabetes.

Pancreatic ß-cell failure is the key pathogenic element of the complex metabolic deterioration in type 2 diabetes (T2D); its underlying pathomechanism is still elusive. Here, we identify pleckstrin homology domain leucine-rich repeat protein phosphatases 1 and 2 (PHLPP1/2) as phosphatases whose upregulation leads to ß-cell failure in diabetes. PHLPP levels are highly elevated in metabolically stressed human and rodent diabetic ß-cells. Sustained hyper-activation of mechanistic target of rapamycin complex 1 (mTORC1) is the primary mechanism of the PHLPP upregulation linking chronic metabolic stress to ultimate ß-cell death. PHLPPs directly dephosphorylate and regulate activities of ß-cell survival-dependent kinases AKT and MST1, constituting a regulatory triangle loop to control ß-cell apoptosis. Genetic inhibition of PHLPPs markedly improves ß-cell survival and function in experimental models of diabetes in vitro, in vivo, and in primary human T2D islets. Our study presents PHLPPs as targets for functional regenerative therapy of pancreatic ß cells in diabetes.

LDHA is enriched in human islet alpha cells and upregulated in type 2 diabetes.

The lactate dehydrogenase isoform A (LDHA) is a key metabolic enzyme that preferentially catalyzes the conversion of pyruvate to lactate. Whereas LDHA is highly expressed in many tissues, its expression is turned off in the differentiated adult ß-cell within the pancreatic islets. The repression of LDHA under normal physiological condition and its inappropriate upregulation under a diabetogenic environment is well-documented in rodent islets/ß-cells but little is known about LDHA expression in human islet cells and whether its abundance is altered under diabetic conditions. Analysis of public single-cell RNA-seq (sc-RNA seq) data as well as cell type-specific immunolabeling of human pancreatic islets showed that LDHA was mainly localized in human α-cells while it is expressed at a very low level in ß-cells. Furthermore, LDHA, both at mRNA and protein, as well as lactate production is upregulated in human pancreatic islets exposed to chronic high glucose treatment. Microscopic analysis of stressed human islets and autopsy pancreases from individuals with type 2 diabetes (T2D) showed LDHA upregulation mainly in human α-cells. Pharmacological inhibition of LDHA in isolated human islets enhanced insulin secretion under physiological conditions but did not significantly correct the deregulated secretion of insulin or glucagon under diabetic conditions.

Enteroviruses and T1D: Is It the Virus, the Genes or Both which Cause T1D.

Type 1 diabetes (T1D) is a chronic autoimmune disorder that results from the selective destruction of insulin-producing ß-cells in the pancreas. Up to now, the mechanisms triggering the initiation and progression of the disease are, in their complexity, not fully understood and imply the disruption of several tolerance networks. Viral infection is one of the environmental factors triggering diabetes, which is initially based on the observation that the disease's incidence follows a periodic pattern within the population. Moreover, the strong correlation of genetic susceptibility is a prerequisite for enteroviral infection associated islet autoimmunity. Epidemiological data and clinical findings indicate enteroviral infections, mainly of the coxsackie B virus family, as potential pathogenic mechanisms to trigger the autoimmune reaction towards ß-cells, resulting in the boost of inflammation following ß-cell destruction and the onset of T1D. This review discusses previously identified virus-associated genetics and pathways of ß-cell destruction. Is it the virus itself which leads to ß-cell destruction and T1D progression? Or is it genetic, so that the virus may activate auto-immunity and ß-cell destruction only in genetically predisposed individuals?

Neratinib protects pancreatic beta cells in diabetes.

The loss of functional insulin-producing ß-cells is a hallmark of diabetes. Mammalian sterile 20-like kinase 1 (MST1) is a key regulator of pancreatic ß-cell death and dysfunction; its deficiency restores functional ß-cells and normoglycemia. The identification of MST1 inhibitors represents a promising approach for a ß-cell-protective diabetes therapy. Here, we identify neratinib, an FDA-approved drug targeting HER2/EGFR dual kinases, as a potent MST1 inhibitor, which improves ß-cell survival under multiple diabetogenic conditions in human islets and INS-1E cells. In a pre-clinical study, neratinib attenuates hyperglycemia and improves ß-cell function, survival and ß-cell mass in type 1 (streptozotocin) and type 2 (obese Leprdb/db) diabetic mouse models. In summary, neratinib is a previously unrecognized inhibitor of MST1 and represents a potential ß-cell-protective drug with proof-of-concept in vitro in human islets and in vivo in rodent models of both type 1 and type 2 diabetes.

Zinc supplementation of vitrification medium improves in vitro maturation and fertilization of oocytes derived from vitrified-warmed mouse ovaries.

Oocyte cryopreservation is an approach for fertility preservation for normal women and cancer patients facing chemo and radiotherapy. The present study evaluated the effect of adding zinc chloride to the vitrification medium used for whole mouse ovaries and then assessing the in vitro maturation and fertilization of oocytes when they were subsequently extracted from these vitrified ovarian tissues. Four vitrification solutions with 0, 100,150 and 200 µg/dl zinc (V0, V1, V2 and V3 respectively) were compared. The viability of oocytes isolated from ovaries vitrified-warmed in the highest concentration of zinc (V3) was significantly higher after 24 than in the control V0 group (72.99 vs 85.97). Progression to the MII stage, fertilization and cleavage by 48 h was also higher in the V3 than V0 control group (35.55 vs 44.73), (47.67 vs 63.74), (28.72 vs 43.03) (P < 0.05) respectively. These results indicate that supplementation of vitrification medium for intact ovaries with zinc can improve the oocyte viability and in vitro maturation-fertilization rate.