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Background: An increasing number of coronavirus disease 2019 (COVID-19) related autoimmune hepatitis (AIH) and autoimmune liver disease (AILD) has been already described so far in the last three years. This rise has set up some diagnostic and therapeutic concerns, although steroid therapy has mostly been efficient, avoiding main significant side effects., Case Report: We report the case of a 52-year-old subject displaying liver function impairment at the laboratory tests while positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) swab. Needle liver biopsy showed severe portal inflammation, interface hepatitis, lobular inflammation, abundant plasma cells, bridging necrosis, endothelialitis, bile duct vanishing disease, and ductular reaction. The diagnosis of autoimmune liver disease (AILD) was performed. After a month of steroid and ursodeoxycholic acid medications, liver function fully recovered. Azathioprine was introduced, and steroids were gradually reduced., Conclusions: Probably triggered by the SARS-CoV-2-induced cytokine storm, the association between COVID-19 and autoimmune-related inflammatory injury may display a particular paradigm of AILD pathogenesis.

Objective: The atherosclerotic plaque is a complex dynamic pathological lesion of the arterial wall, characterized by multiple elementary lesions of different diagnostic and prognostic significance. Fibrous cap thickness, lipid necrotic core dimension, inflammation, intra-plaque hemorrhage (IPH), plaque neovascularization and endothelial dysfunction (erosions) are generally considered the most relevant morphological details of plaque morphology. In this review, the most relevant features able to discriminate between stable and vulnerable plaques at histological level are discussed., Subjects and Methods: Retrospectively, we have evaluated the laboratory results from one hundred old histological samples from patients treated with carotid endarterectomy. These results were analyzed to assess elementary lesions that characterize stable and unstable plaques., Results: A thin fibrous cap (<65 micron), loss of smooth muscle cells, collagen depletion, a large lipid-rich necrotic core, infiltrating macrophages, IPH and intra-plaque vascularization are identified as the most important risk factors associated with plaque rupture., Conclusions: Immunohistochemistry for smooth muscle actin (smooth muscle cell marker) and for CD68 (marker of monocytes/macrophages) and glycophorin (marker of red blood cells) are suggested as useful tools for an in deep characterization of any carotid plaque and for distinguishing plaque phenotypes at histology. Since patients with a carotid vulnerable plaque are at higher risk of developing vulnerable plaques in other arteries as well, the definition of the vulnerability index is underlined, in order to stratify patients at higher risk for undergoing cardiovascular events.

Background: Persistent polyclonal B-cell lymphocytosis is a rare nonmalignant disorder characterized by mild persistent lymphocyte proliferation with possible evolution to aggressive lymphoma. Its biology is not well known, but it is characterized by a specific immunophenotype with rearrangement of the BCL-2/IGH gene, whereas amplification of the BCL-6 gene has rarely been reported. Given the paucity of reports, it has been hypothesized that this disorder is associated with poor pregnancy outcomes., Case Report: To our knowledge, only two successful pregnancies have been described in women with this condition. We report the third successful pregnancy in a patient with PPBL and the first with amplification of the BCL-6 gene., Conclusions: PPBL is still a poorly understood clinical condition with insufficient data to demonstrate an adverse effect on pregnancy. The role of BCL-6 dysregulation in the pathogenesis of PPBL and its prognostic significance are still unknown. Evolution into aggressive clonal lymphoproliferative disorders is possible and prolonged hematologic follow-up is warranted in patients with this rare clinical disorder.

Objective: Due to the high mortality rate of COVID-19, the assessment of BNT162b2 SARS-CoV-2 mRNA vaccine (Pfizer-BioNTech) efficacy in allogeneic hematopoietic stem cell transplant (HSCT) recipients is mandatory., Patients and Methods: We conducted a single-center pilot study with the main objective of evaluating the immunogenicity of the BNT162b2 mRNA vaccine in 31 hematological patients who underwent hematopoietic stem cell transplantation within the previous 12 months and/or were affected by chronic graft-vs.-host-disease (cGVHD), by the assessment of antibody levels at 30-45 days after the second dose of vaccine., Results: After the second dose of vaccine, 23 out of 31 patients (74%) showed a positive immune response. The presence of severe cGVHD or Ig deficiency identified 7 out of 8 (85%) of non-responders. The median absolute cluster of differentiation 19 (CD19) count was significantly lower in non-responders vs. responders (109/µl vs. 351/µl). Underlying pathology, comorbidities, type of donor, time intervals from transplant and cluster of differentiation 3/cluster of differentiation 4/cluster of differentiation 8 (CD3/CD4/CD8) subsets were not significantly associated with an effective immune response to vaccination., Conclusions: Despite the limited sample of patients enrolled, our findings suggest that hypogammaglobulinemia and cGVHD could be associated with poor humoral response to the BNT162b2.

Objective: L1  cell adhesion molecule (L1CAM) is a glycoprotein characterized by three components: an extracellular region, a transmembrane segment, and a cytoplasmic tail. L1CAM is expressed in multiple human cells, including neurons. The neural cell adhesion molecule L1 has been implicated in a variety of neurologic processes, including neuritogenesis and cerebellar cell migration. The presence of L1CAM on the surface of nerve cells allows the adhesion of neurons among them. Furthermore, when it is bound to itself or to other proteins, L1-CAM induces signals inside the cell. The aim of this work was to study L1CAM expression in the human spinal cord during development, at different gestational ages, through immunohistochemistry., Materials and Methods: Immunohistochemical analysis for L1CAM was performed in five human spinal cord samples, including three embryos and two fetuses of different gestational ages, ranging from 8 to 12 weeks., Results: L1CAM expression was detected in all 5 spinal cords examined in this study. The adhesion molecule was found in the vast majority of cells. The highest levels of immunoreactivity for L1CAM were detected at the periphery of the developing organs, in the spinal cord zones occupied by sensory and motor fibers. In the alar and basal columns, immunoreactivity for L1CAM was characterized by a reticular pattern, being mainly expressed in axons. Strong reactivity of L1CAM was also found in extracellular vesicles. This extracellular localization might indicate the ability of L1CAM to mediate the transduction of extracellular signals that support axon outgrowth., Conclusions: The high reactivity of L1cam in the axons of developing neurons in the fetal spinal cord confirms previous studies on the ability of L1CAM to promote axon sprouting and branching in the developing nervous system. In this work, a new actor is reported to have a role in the complex field of human spinal cord development: L1CAM, whose expression is highly found in the developing neuronal and glial precursors.

Objective: L1 cell adhesion molecule (L1CAM) is a member of the immunoglobulin superfamily of cell adhesion molecules. The present study investigated the expression of L1CAM during the development in the fetal human kidney at different gestational ages, to reach a better knowledge on the role of L1CAM in renal morphogenesis., Materials and Methods: The immunohistochemical analysis for L1CAM was performed in 24 fetal kidneys of different gestational ages, ranging from 10 to 38 weeks. L1CAM expression was observed in all 24 kidneys examined., Results: Immunoreactivity for L1CAM was restricted to the collecting tubules, of the developing fetal kidneys. Moreover, L1CAM was detected in the ureteric bud tips, near the subcapsular metanephric mesenchymal stem/progenitor cells. L1CAM was also expressed in the collecting tubules undergoing fusion with the distal tubules of the developing nephrons. L1CAM was mainly expressed along the cell membrane. In fetal kidneys in which the renal pelvis was observed, epithelial cells of the renal pelvis showed strong membranous reactivity for L1CAM., Conclusions: Our study shows that L1CAM is expressed in all stages of human kidney nephrogenesis, being restricted to the renal structures derived from the ureteric bud. The expression of L1CAM in the cells of the ureteric bud tips suggests a major role for this adhesion molecule in the induction of metanephric mesenchymal cells to undergo mesenchymal-to-epithelial transition and differentiation into new nephrons. The interindividual variability in L1CAM expression observed in this study might be related to different levels of nephrogenesis, suggesting L1CAM involvement in the fetal programming of adult kidney diseases.

The growing incidence of cancers is pushing oncologists to find out new explanations other than the somatic mutation theory, based on the accumulation of DNA mutations. In particular, the embryo-fetal exposure to an increasing number of environmental factors during gestation might represent a trigger able to influence the susceptibility of the newborn to develop cancer later in life. This idea agrees with the fetal programming theory, also known as the Barker hypothesis. Here the role of insulin-like growth factors, thymosin beta-4, and epigenome are discussed as mediators of cancer in prenatal human development. The role of epigenetic factors that during gestation increase the predisposition to develop cancer and the similarities in the gene expression (like MMP9, OPN, TP53 and CDKN2A) between embryonic development and cancer are key factors. Likewise, maternal obesity might be able to re-program embryo-fetal development with long-term changes, including an increased risk to develop neuroblastoma and acute leukemia. Birth weight alone and birth weight corrected for gestational age are proposed as important variables capable of predicting the vulnerability to develop cancers. According to the findings here reported, we hypothesize that cancer prevention should start during gestation by improving the quality of maternal diet. In conclusion, the Barker hypothesis should be applied to cancer as well. Therefore, the identification of the epigenetic factors of cancer appears mandatory, so that the cancer prevention might start in the womb before birth.

Objective: Previous studies have confirmed the key mechanism by which SARS-CoV-2 enters human cells. It is well established that ACE2 is the receptor that can mark the beginning of the infection. In light of this, the organs that express higher levels of ACE2 are generally considered at higher risk, while those with lower levels should be somehow more protected. This - if related to the scarcity of ace2-expressing cells in the brain - seems to contrast with the presence of a variety of neurological symptoms that follow infection with ace2.  The aim of this work was to analyze ACE2 expression in the human brain, focusing on the choroid plexuses., Patients and Methods: Twenty brain samples were obtained at autopsy from ten human fetuses and from ten adult subjects. All samples were selected to contain the choroid plexus. Specimens were fixed in 10% formalin, routinely processed and paraffin embedded. 5-micron sections were stained with Hematoxylin and Eosin (H&E) and immunostained with a commercial anti-human ACE2 rabbit monoclonal antibody at 1:100 dilution., Results: We analyzed 20 samples by immunohistochemistry, and we noted that, as far as fetal samples are concerned, a strong reactivity for ACE2 was detected in the myxoid stroma of the choroid plexuses and in the endothelial cells in fetuses. The complete absence of the ACE2 marker was detected in epithelial cells, neurons and glial cells of the cerebral cortex, both in fetuses and in adults. Whereas a  strong but selective reactivity for ACE2 was also detected in adult choroid plexuses, mainly localized in the endothelial cells of the choroid capillaries., Conclusions: Our study shows a strong expression of ACE in the fetal and adult brain choroid plexuses. This new histopathological finding may clarify the susceptibility of the human brain to SARS-COV-2 infection. Our data indicate the choroid plexus as the entry gate of virus for in the human brain; therefore, the entrance of SARS-CoV-2 into the cerebrospinal fluid through the choroid plexuses might represent the mechanism utilized by this coronavirus to cause direct injury to brain cells.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare new syndrome occurring after the ChAdOx1 nCoV-19 vaccine immunization. Patients with VITT are characterized by a variable clinical presentation, likewise also the outcome of these patients is very variable. Here we report the lung ultrastructural findings in the course of VITT of a 58-year-old male patient. Alveoli were mainly dilated, irregular in shape, and occupied by a reticular network of fibrin, while interalveolar septa appeared thickened. The proliferation of small capillaries gave rise to plexiform structures and pulmonary capillary hemangiomatosis-like features. Near the alveoli occupied by a dense fibrin network, the medium-sized arteries showed a modified wall and an intraluminal thrombus. This scenario looks quite similar to that found during COVID-19, where the lungs suffer from the attack of the antigen-antibodies complexes and the virus respectively. In both diseases, the final outcome is a severe inflammation, activation of the haemostatic system and fibrinolysis.

The risk stratification of young adults between subjects who will develop a mild form of atherosclerosis and subjects who will undergo a severe disease remains inaccurate. In the eighties of the previous century, David JP Barker has demonstrated the relationship between fetal conditions and occurrence of pathologies in adulthood. In this paper, the multiple evidence that might explain the increased susceptibility to severe forms of atherosclerosis, including stroke and cardiac infarct, in subjects who underwent intrauterine growth restriction (IUGR) will be analyzed. Specifically, we will review those inter-connected data indicating an association between a low weight at birth and an adult phenotype which might favor a severe outcome of atherosclerosis. Young and adult subjects born too small (IUGR) or too early (pre-terms) might represent a subgroup of "at risk subjects", more susceptible toward severe forms of atherosclerosis. Given that low birth weight (LBW) may be considered a surrogate of IUGR, this phenotypic feature could be considered among those indispensable clinical data collected in every patient presenting with atherosclerosis, irrespectively of age. According to the hypothesis that structural arterial changes might represent the link between LBW and susceptibility to atherosclerosis later in life, we suggest that the prevention of atherosclerosis should begin at birth. Regenerative and physiological substances such as thymosin Beta-4 could be challenged for a new "arterial regenerative medicine" in the perinatal period. The goal of this new approach should be the reinforcement of the structure of the arterial wall, allowing LBW newborns to avoid the most severe complications of atherosclerosis later in life: a dream that our research could contribute to bringing to life.

Arterial thromboembolic complications reported in patients with COVID-19 infection suggested that SARS-CoV-2 can trigger atherosclerotic plaque vulnerability. While endothelial cells in healthy subjects protect against thrombus formation, after injury they show prothrombotic activity. In addition, it has been hypothesized that "cytokine storm" might stimulate the production of neo-platelets triggering an abnormal "immunothrombosis" responsible for the hypercoagulable state induced in COVID-19 patients. The aim of this study is to report a case of severe COVID-19 infection characterized by the occurrence of microthrombosis in the vasa vasorum of the aorta. A 67-year-old male patient, in good health status and without comorbidities, who underwent a severe COVID-19 infection with fatal outcome, showed scattered aortic atherosclerotic plaques, characterized by multiple occlusive micro-thromboses in the vasa vasorum, spread out lymphocytic infiltrates and foci of endotheliitis and endothelial detachment. This case report confirms the previously described thrombotic involvement of vasa vasorum in COVID-19. The occurrence of the synchronous damage involving both the lumen surface (endothelial dysfunction, endotheliitis and endothelial detachment) and the adventitia (inflammation and occlusive thrombosis of vasa vasorum) could be the key points related to the fatal outcome of the SARS-CoV-2 patients. In our opinion, vasa vasorum thrombosis may thus initiate an atherogenic process that could be characterized by a much more rapid development.

Objective: Liver injury has been reported in patients with COVID-19. This condition is characterized by severe outcome and could be related with the ability of SARS-CoV-2 to activate cytotoxic T cells. The purpose of this study is to show the histological and scanning electron microscopy features of liver involvement in COVID-19 to characterize the liver changes caused by the activation of multiple molecular pathways following this infection., Patients and Methods: Liver biopsies from 4 patients (3 post-mortems and 1 in vivo) with COVID-19 were analyzed with histology and by scanning electron microscopy., Results: The liver changes showed significant heterogeneity. The first case showed ground glass hepatocytes and scattered fibrin aggregates in the sinusoidal lumen. The second evidenced intra-sinusoidal thrombi. The third was characterized by sinusoidal dilatation, atrophy of hepatocytes, Disse's spaces dilatation and intra-sinusoidal aggregates of fibrin and red blood cells. The fourth case exhibited diffuse fibrin aggregates in the dilated Disse spaces and microthrombi in the sinusoidal lumen., Conclusions: In COVID-19-related liver injury, a large spectrum of pathological changes was observed. The most peculiar features were very mild inflammation, intra-sinusoidal changes, including sinusoidal dilatation, thrombotic sinusoiditis and diffuse intra-sinusoidal fibrin deposition. These findings suggested that a thrombotic sinusoiditis followed by a local diffuse intra-vascular (intra-sinusoidal) coagulation could be the typical features of the SARS-CoV-2-related liver injury.

The risk stratification of young adults between subjects who will develop a mild form COVID-19 and subjects who will undergo a severe disease remains inaccurate. In this review, we propose that the Barker hypothesis might explain the increased susceptibility to severe forms of COVID-19 in subjects who underwent intrauterine growth restriction (IUGR). In this paper evidence indicating an association between a low birth weight and an adult phenotype which might favor a severe outcome of SARS-CoV-2 infection are presented: lower lung functional capacity; increased respiratory morbidity; changes in fibrinogen and Factor VII serum levels and dysregulation of the hemostasis and thrombosis system; acquisition of a pro-thrombotic phenotype; low nephron number, with decreased ability to sustain renal function and increased renal morbidity; heart remodeling, with a less efficient cardiac function; endothelial dysfunction, a risk factor for the insurgence of the multiple organ failure; remodeling of arteries, with changes in the elastic properties of the arterial wall, predisposing to the insurgence and progression of atherosclerosis; dysfunction of the innate immune system, a risk factor for immune diseases in adulthood. These data suggest that young and adult subjects born too small (IUGR) or too early (pre-terms) might represent a subgroup of "at risk subjects", more susceptible toward severe forms of COVID-19. Given that LBW may be considered a surrogate of IUGR, this phenotypic marker should be included among the indispensable clinical data collected in every patient presenting with SARS-COV-2 infection, irrespectively of his/her age.

Objective: Vaccine-induced immune thrombocytopenia (VITT) is a new syndrome occurring primarily in healthy young adults, with a female predominance, after receiving the first dose of ChAdOx1 nCoV-19 vaccine. We describe VITT syndrome characterized by severe thrombosis and thrombocytopenia found in our patient, with fatal outcome., Case Report: A 58-year-old man, after 13 days from the first administration of ChAdOx1 nCoV-19 vaccine (AstraZeneca), presented with abdominal pain, diarrhea and vomitus. Laboratory tests revealed a severe thrombocytopenia, low fibrinogen serum levels and marked increase of D-dimer serum levels. The patient quickly developed a multiple organ failure, till death, three days after the hospital admission., Results: At histology, in the lungs, interalveolar septa appeared thickened with microthrombi in the capillaries and veins. Interalveolar septa appeared thickened and showed vascular proliferation. Thrombi were detected in the capillaries of glomerular tufts. In the hearth, thrombi were observed in veins and capillaries. In the liver, voluminous fibrin thrombi were diffusely observed in the branches of the portal vein. Microthrombi were also found in the vasa vasorum of the wall of abdominal aorta. In the brain, microthrombi were observed in the capillaries of the choroid plexuses. Diffuse hemorrhagic necrosis was observed in the intestinal wall with marked congestion of the venous vessels., Conclusions: In our patient, the majority of data necessary for a VITT final diagnosis were present: thrombocytopenia and thrombosis in pulmonary, portal, hepatic, renal and mesenteric veins, associated with a marked increase of D-dimer serum levels. The finding of cerebral thrombosis in choroid plexuses, is a new finding in VITT. These features are suggestive for a very aggressive form of VITT.

Objective: Acute respiratory distress syndrome (ARDS) is characterized by quantitative and qualitative changes in surfactant composition, leading to surfactant dysregulation with alveolar collapse and acute respiratory hypoxic failure. Recently, surfactant has been hypothesized to play a relevant role in COVID-19, representing a strong defender against SARS-CoV-2 infection. The aim of our work was the study of immunohistochemical surfactant expression in the lungs of patients died following SARS-CoV-2 ARDS, in order to shed light on a possible therapeutic surfactant administration., Patients and Methods: We investigated four patients who died due to ARDS following SARS-COV-2 infection and four patients submitted to lung biopsy, in the absence of SARS-CoV-2 infection. In all 8 cases, lung specimens were immunostained with anti-surfactant protein A (SP-A) and B (SP-B)., Results: In control subjects, reactivity for SP-B was restricted to type II alveolar cells. Immunostaining for SP-A was observed on the surface of alveolar spaces. In the COVID-19 positive lungs, immunoreactivity for SP-B was similar to that observed in control lungs; SP-A was strongly expressed along the alveolar wall. Moreover, dense aggregates of SP-A positive material were observed in the alveolar spaces., Conclusions: Our immunohistochemical data show the dysregulation of surfactant production in COVID-19 patients, particularly regarding SP-A expression. The increased presence of SP-A in condensed masses inside alveolar spaces could invalidate the therapeutic efficacy of the treatment with exogenous surfactant.

Objective: In human pathology, SARS-CoV-2 utilizes multiple molecular pathways to determine structural and biochemical changes within the different organs and cell types. The clinical picture of patients with COVID-19 is characterized by a very large spectrum. The reason for this variability has not been clarified yet, causing the inability to make a prognosis on the evolution of the disease., Materials and Methods: PubMed search was performed focusing on the role of ACE 2 receptors in allowing the viral entry into cells, the role of ACE 2 downregulation in triggering the tissue pathology or in accelerating previous disease states, the role of increased levels of Angiotensin II in determining endothelial dysfunction and the enhanced vascular permeability, the role of the dysregulation of the renin angiotensin system in COVID-19 and the role of cytokine storm., Results: The pathological changes induced by SARS-CoV-2 infection in the different organs, the correlations between the single cell types targeted by the virus in the different human organs and the clinical consequences, COVID-19 chronic pathologies in liver fibrosis, cardiac fibrosis and atrial arrhythmias, glomerulosclerosis and pulmonary fibrosis, due to the systemic fibroblast activation induced by angiotensin II are discussed., Conclusions: The main pathways involved showed different pathological changes in multiple tissues and the different clinical presentations. Even if ACE2 is the main receptor of SARS-CoV-2 and the main entry point into cells for the virus, ACE2 expression does not always explain the observed marked inter-individual variability in clinical presentation and outcome, evidencing the complexity of this disorder. The proper interpretation of the growing data available might allow to better classifying COVID-19 in human pathology.