Preliminary Post-Mortem COVID-19 Evidence of Endothelial Injury and Factor VIII Hyperexpression

Abstract

(1) Background: The current outbreak of COVID-19 infection is an ongoing challenge and a major threat to public health that requires surveillance, prompt diagnosis, as well as research efforts to understand the viral pathogenesis. Despite this, to date, very few studies have been performed concerning autoptic specimens. Therefore, this study aimed: (i) to reiterate the importance of the autoptic examination, the only method able to precisely define the cause of death; (ii) to provide a complete post-mortem histological and immunohistochemical investigation pattern capable of diagnosing death from COVID-19 infection. (2) Methods: In this paper, the lung examination of two subjects who died from COVID-19 are discussed, comparing the obtained data with those of the control, a newborn who died from pneumonia in the same pandemic period. (3) Results: The results of the present study suggest that COVID-19 infection can cause different forms of acute respiratory distress syndrome (ARDS), due to diffuse alveolar damage and diffuse endothelial damage. Nevertheless, different patterns of cellular and cytokine expression are associated with anti-COVID-19 antibody positivity, compared to the control case. Moreover, in both case studies, it is interesting to note that COVID-19, ACE2 and FVIII positivity was detected in the same fields. (4) Conclusions: COVID-19 infection has been initially classified as exclusively interstitial pneumonia with varying degrees of severity. Subsequently, vascular biomarkers showed that it can also be considered a vascular disease. The data on Factor VIII discussed in this paper, although preliminary and limited in number, seem to suggest that the thrombogenicity of Sars-CoV2 infection might be linked to widespread endothelial damage. In this way, it would be very important to investigate the pro-coagulative substrate both in all subjects who died and in COVID-19 survivors. This is because it may be hypothesized that the different patterns with which the pathology is expressed could depend on different individual susceptibility to infection or a different personal genetic-clinical background. In light of these findings, it would be important to perform more post-mortem investigations in order to clarify all aspects of the vascular hypothesis in the COVID-19 infection.

Keywords: COVID-19; COVID-19 diagnostic; autopsy; forensic pathology; forensic science; immunohistochemistry; post-mortem examination.

Figure 1

Lungs of Case 1 (A,B): the left lung had a greater volume while the right lung showed normal volume and shape (A). The lungs showed bilateral pulmonary edema and the left one presented patches of dark hemorrhage (B). Lungs of Case 2 (C,D). Lungs of the Control Case (E,F).

Figure 2

H&E staining: left lung of Case 1 (cm 26 × 20 × 8 and g 1465) showing unilateral diffuse alveolar damage with a focus on a microthrombus and surrounding lung tissue characterized by severe organizing pneumonia. Sample from lungs of Case 2 (left: cm 26.5 × 17 × 2.5 and g 1000; right: cm 26 × 17.5 × 3 and g 1040): showing bilateral diffuse alveolar damage with alveolar protein and fibrinous exudate, associated with wall thickening and abundant macrophagic alveolar infiltrate. Sample from lungs of CTL (left: 7 × 5 × 1.5 cm and 31 g; right: 6 × 5.5 × 2.5 cm and 29 g): showing bilateral interstitial pneumonia, consisting mainly of monocytic-macrophage cells, plasma cells, and rare granulocytes.

Figure 3

Masson’s trichrome stain: left lung of Case 1 confirmed the microthrombus and there was the presence of a modest deposit of perivasal fibrin in blue. Sample from lungs of Case 2 showed the presence of hyaline membranes, almost ubiquitous. Sample from lungs of CTL: Masson’s trichrome stain confirmed the H&E findings.

Figure 4

Immunohistochemical findings (20x): arrows show focal positivity; in the other pictures the positivity for each antibody appears diffuse. In particular, very strong positivity for the anti-COVID-19 Ab in both Cases 1 and 2; weak positivity for the anti-CD-4 Ab in both Cases 1 and 2; CD-8+ lymphocytes were located predominantly in the interstitial spaces and around larger bronchioles in both Cases 1 and 2; Anti-CD-20 and anti-CD-68 strong positivity in Cases 1 and 2 confirm the histochemical microscopic data of the presence of plasma cells and macrophages; anti CD-79 Ab shows the highest positivity in Case 1, being completely negative in Case 2. The Control Case showed the picture of interstitial pneumonia with a prevalent macrophagic and lymphoplasmatic cellularity: COVID-19 negative; Ab-anti-CD-20 and Ab-anti-CD-68 positive.

Figure 5

Immunohistochemical findings (20×): Ab-anti-ACE2 showing high positivity in both Cases 1 and 2, instead Ab-anti-FVIII shows the highest positivity in Case 1, being completely negative in the Control case. Moreover, the Ab-anti-ACE2, Ab-anti-FVIII, and Ab anti-COVID-19 in Figure 4, located in the same site. Ab-anti-IL6 and Ab-anti-TNFα was positive in all samples.