Low Percentage of Perforin-Expressing NK Cells during Severe SARS-CoV-2 Infection: Consumption Rather than Primary Deficiency

Genetic defects in the ability to deliver effective perforin have been reported in patients with hemophagocytic lymphohistiocytosis. We tested the hypothesis that a primary perforin deficiency might also be causal in severe SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to intensive care units or non-intensive care units and age- and sex-matched healthy controls. Compared with healthy controls, the percentage of perforin-expressing CD3-CD56+ NK cells quantified by flow cytometry was low in COVID-19 patients (69.9 ± 17.7 versus 78.6 ± 14.6%, p = 0.026). There was no correlation between the proportions of perforin-positive NK cells and T8 lymphocytes. Moreover, the frequency of NK cells producing perforin was neither linked to disease severity nor predictive of death. Although IL-6 is known to downregulate perforin production in NK cells, we did not find any link between perforin expression and IL-6 plasma level. However, we unveiled a negative correlation between the degranulation marker CD107a and perforin expression in NK cells (r = -0.488, p = 10-4). PRF1 gene expression and the frequency of NK cells harboring perforin were normal in patients 1 y after acute SARS-CoV-2 infection. A primary perforin defect does not seem to be a driver of COVID-19 because NK perforin expression is 1) linked neither to T8 perforin expression nor to disease severity, 2) inversely correlated with NK degranulation, and 3) normalized at distance from acute infection. Thus, the cause of low frequency of perforin-positive NK cells appears, rather, to be consumption.

T4 apoptosis in the acute phase of SARS-CoV-2 infection predicts long COVID

Background

As about 10% of patients with COVID-19 present sequelae, it is important to better understand the physiopathology of so-called long COVID.

Method

To this aim, we recruited 29 patients hospitalized for SARS-CoV-2 infection and, by Luminex®, quantified 19 soluble factors in their plasma and in the supernatant of their peripheral blood mononuclear cells, including inflammatory and anti-inflammatory cytokines and chemokines, Th1/Th2/Th17 cytokines, and endothelium activation markers. We also measured their T4, T8 and NK differentiation, activation, exhaustion and senescence, T cell apoptosis, and monocyte subpopulations by flow cytometry. We compared these markers between participants who developed long COVID or not one year later.

Results

None of these markers was predictive for sequelae, except programmed T4 cell death. T4 lymphocytes from participants who later presented long COVID were more apoptotic in culture than those of sequelae-free participants at Month 12 (36.9 ± 14.7 vs. 24.2 ± 9.0%, p = 0.016).

Conclusions

Our observation raises the hypothesis that T4 cell death during the acute phase of SARS-CoV-2 infection might pave the way for long COVID. Mechanistically, T4 lymphopenia might favor phenomena that could cause sequelae, including SARS-CoV-2 persistence, reactivation of other viruses, autoimmunity and immune dysregulation. In this scenario, inhibiting T cell apoptosis, for instance, by caspase inhibitors, could prevent long COVID.

Repetitive mRNA vaccination is required to improve the quality of broad-spectrum anti-SARS-CoV-2 antibodies in the absence of CXCL13

Since the initial spread of severe acute respiratory syndrome coronavirus 2 infection, several viral variants have emerged and represent a major challenge for immune control, particularly in the context of vaccination. We evaluated the quantity, quality, and persistence of immunoglobulin G (IgG) and IgA in individuals who received two or three doses of messenger RNA (mRNA) vaccines, compared with previously infected vaccinated individuals. We show that three doses of mRNA vaccine were required to match the humoral responses of preinfected vaccinees. Given the importance of antibody-dependent cell-mediated immunity against viral infections, we also measured the capacity of IgG to recognize spike variants expressed on the cell surface and found that cross-reactivity was also strongly improved by repeated vaccination. Last, we report low levels of CXCL13, a surrogate marker of germinal center activation and formation, in vaccinees both after two and three doses compared with preinfected individuals, providing a potential explanation for the short duration and low quality of Ig induced.

Low perforin expression in CD8+ T lymphocytes during the acute phase of severe SARS-CoV-2 infection predicts long COVID

T cell cytotoxicity plays a major role in antiviral immunity. Anti-SARS-CoV-2 immunity may determine acute disease severity, but also the potential persistence of symptoms (long COVID). We therefore measured the expression of perforin, a cytotoxic mediator, in T cells of patients recently hospitalized for SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to Intensive Care Units (ICUs) or non-ICU, and 29 age- and sex-matched healthy controls (HCs). Amounts of intracellular perforin and granzyme-B, as well as cell surface expression of the degranulation marker CD107A were determined by flow cytometry. The levels of 15 cytokines in plasma were measured by Luminex. The frequency of perforin-positive T4 cells and T8 cells was higher in patients than in HCs (9.9 ± 10.1% versus 4.6 ± 6.4%, p = 0.006 and 46.7 ± 20.6% vs 33.3 ± 18.8%, p = 0.004, respectively). Perforin expression was neither correlated with clinical and biological markers of disease severity nor predictive of death. By contrast, the percentage of perforin-positive T8 cells in the acute phase of the disease predicted the onset of long COVID one year later. A low T8 cytotoxicity in the first days of SARS-CoV-2 infection might favor virus replication and persistence, autoimmunity, and/or reactivation of other viruses such as Epstein-Barr virus or cytomegalovirus, paving the way for long COVID. Under this hypothesis, boosting T cell cytotoxicity during the acute phase of the infection could prevent delayed sequelae.

Low quantity and quality of anti-spike humoral response is linked to CD4 T-cell apoptosis in COVID-19 patients

In addition to an inflammatory reaction, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-infected patients present lymphopenia, which we recently reported as being related to abnormal programmed cell death. As an efficient humoral response requires CD4 T-cell help, we hypothesized that the propensity of CD4 T cells to die may impact the quantity and quality of the humoral response in acutely infected individuals. In addition to specific immunoglobulins (Ig)A, IgM, and IgG against SARS-CoV-2 nucleocapsid (N), membrane (M), and spike (S1) proteins, we assessed the quality of IgG response by measuring the avidity index. Because the S protein represents the main target for neutralization and antibody-dependent cellular cytotoxicity responses, we also analyzed anti-S-specific IgG using S-transfected cells (S-Flow). Our results demonstrated that most COVID-19 patients have a predominant IgA anti-N humoral response during the early phase of infection. This specific humoral response preceded the anti-S1 in time and magnitude. The avidity index of anti-S1 IgG was low in acutely infected individuals compared to convalescent patients. We showed that the percentage of apoptotic CD4 T cells is inversely correlated with the levels of specific IgG antibodies. These lower levels were also correlated positively with plasma levels of CXCL10, a marker of disease severity, and soluble Fas ligand that contributes to T-cell death. Finally, we found lower S-Flow responses in patients with higher CD4 T-cell apoptosis. Altogether, these results demonstrate that individuals with high levels of CD4 T-cell apoptosis and CXCL10 have a poor ability to build an efficient anti-S response. Consequently, preventing CD4 T-cell death might be a strategy for improving humoral response during the acute phase, thereby reducing COVID-19 pathogenicity.

Angiotensin II induces reactive oxygen species, DNA damage, and T cell apoptosis in severe COVID-19

Background

Lymphopenia is predictive of survival in patients with coronavirus disease 2019 (COVID-19).

Objective

The aim of this study was to understand the cause of the lymphocyte count drop in severe forms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Methods

Monocytic production of reactive oxygen species (ROSs) and T-cell apoptosis were measured by flow cytometry, DNA damage in PBMCs was measured by immunofluorescence, and angiotensin II (AngII) was measured by ELISA in patients infected with SARS-CoV-2 at admission to an intensive care unit (ICU) (n = 29) or not admitted to an ICU (n = 29) and in age- and sex-matched healthy controls.

Results

We showed that the monocytes of certain patients with COVID-19 spontaneously released ROSs able to induce DNA damage and apoptosis in neighboring cells. Of note, high ROS production was predictive of death in ICU patients. Accordingly, in most patients, we observed the presence of DNA damage in up to 50% of their PBMCs and T-cell apoptosis. Moreover, the intensity of this DNA damage was linked to lymphopenia. SARS-CoV-2 is known to induce the internalization of its receptor, angiotensin-converting enzyme 2, which is a protease capable of catabolizing AngII. Accordingly, in certain patients with COVID-19 we observed high plasma levels of AngII. When looking for the stimulus responsible for their monocytic ROS production, we revealed that AngII triggers ROS production by monocytes via angiotensin receptor I. ROSs released by AngII-activated monocytes induced DNA damage and apoptosis in neighboring lymphocytes.

Conclusion

We conclude that T-cell apoptosis provoked via DNA damage due to the release of monocytic ROSs could play a major role in COVID-19 pathogenesis.

Diagnosis of bone metastases in breast cancer: Lesion-based sensitivity of dual-time-point FDG-PET/CT compared to low-dose CT and bone scintigraphy

We compared lesion-based sensitivity of dual-time-point FDG-PET/CT, bone scintigraphy (BS), and low-dose CT (LDCT) for detection of various types of bone metastases in patients with metastatic breast cancer. Prospectively, we included 18 patients with recurrent breast cancer who underwent dual-time-point FDG-PET/CT with LDCT and BS within a median time interval of three days. A total of 488 bone lesions were detected on any of the modalities and were categorized by the LDCT into osteolytic, osteosclerotic, mixed morphologic, and CT-negative lesions. Lesion-based sensitivity was 98.2% (95.4-99.3) and 98.8% (96.8-99.5) for early and delayed FDG-PET/CT, respectively, compared with 79.9% (51.1-93.8) for LDCT, 76.0% (36.3-94.6) for BS, and 98.6% (95.4-99.6) for the combined BS+LDCT. BS detected only 51.2% of osteolytic lesions which was significantly lower than other metastatic types. SUVs were significantly higher for all lesion types on delayed scans than on early scans (P<0.0001). Osteolytic and mixed-type lesions had higher SUVs than osteosclerotic and CT-negative metastases at both time-points. FDG-PET/CT had significantly higher lesion-based sensitivity than LDCT and BS, while a combination of the two yielded sensitivity comparable to that of FDG-PET/CT. Therefore, FDG-PET/CT could be considered as a sensitive one-stop-shop in case of clinical suspicion of bone metastases in breast cancer patients.

Pulmonary arteriovenous malformations: a radiological and clinical investigation of 136 patients with long-term follow-up

AIM

To assess the clinical outcome of patients with and without hereditary haemorrhagic telangiectasia (HHT) after embolisation of pulmonary arteriovenous malformations (PAVM) from a single national centre.

MATERIALS AND METHODS

The present register-based observational study including all patients with PAVM treated with embolisation at a reference centre for HHT and PAVM was undertaken over a 20-year period. Demographic data, HHT genotyping, clinical presentation, and outcome were registered. Patients with HHT were compared to the patients without HHT. Clinical examination, contrast-enhanced echocardiography, and computed tomography (CT) were used to assess the clinical outcome at follow-up.

RESULTS

One hundred and thirty-six patients with 339 PAVM underwent embolisation during the study period: 22 did not have HHT; 62% had HHT1, 10% had HHT2, 4% had JP-HHT, 8% had clinical HHT without identified genetic mutations. Solitary PAVM were more common among patients without HHT than with HHT. Mean follow-up after the first embolisation was 58 months. Mean age at first embolisation was 46.5 years, and at last follow-up 51.8 years. The clinical success without shunt at follow-up was 87%. The 30-day mortality related to the embolisation was 0%. Twenty patients died during follow-up (mean age 69 years). Most patients could be treated during one session, but many will need a long follow-up with repeated clinical examinations and embolisation.

CONCLUSION

The majority of patients referred for embolisation of PAVM had HHT. Multiple PAVM is associated with HHT. Patients with PAVM should be screened for HHT and patients with HHT for PAVM. Embolisation is a safe procedure with high clinical success.

[Positron emission tomography/computed tomography for diagnosing a rare genetic disease in an infant]

Generalized arterial calcification of infancy is a very rare genetic disorder characterized by arterial calcifications. The symptoms are apparent within the first few weeks of life and the disease shows high mortality rates. This case report describes the clinical presentation, the radiological findings and the treatments challenges.

[18F]Fluorodeoxyglucose (FDG)-Positron Emission Tomography (PET)/Computed Tomography (CT) in Suspected Recurrent Breast Cancer: A Prospective Comparative Study of Dual-Time-Point FDG-PET/CT, Contrast-Enhanced CT, and Bone Scintigraphy

PURPOSE

To prospectively investigate the diagnostic accuracy of [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) with dual-time-point imaging, contrast-enhanced CT (ceCT), and bone scintigraphy (BS) in patients with suspected breast cancer recurrence.

PATIENTS AND METHODS

One hundred women with suspected recurrence of breast cancer underwent 1-hour and 3-hour FDG-PET/CT, ceCT, and BS within approximately 10 days. The study was powered to estimate the precision of the individual imaging tests. Images were visually interpreted using a four-point assessment scale, and readers were blinded to other test results. The reference standard was biopsy along with treatment decisions and clinical follow-up (median, 17 months).

RESULTS

FDG-PET/CT resulted in no false negatives and fewer false positives than the other imaging techniques. Accuracy of results were similar for 1-hour and 3-hour FDG-PET/CT. For distant recurrence, the area under the receiver operating curve was 0.99 (95% CI, 0.97 to 1) for FDG-PET/CT, 0.84 (95% CI, 0.73 to 0.94) for ceCT, and 0.86 (95% CI, 0.77 to 0.94) for the combined ceCT+BS. Of 100 patients, 22 (22%) were verified with distant recurrence, and 18 of these had bone involvement. Nineteen patients (19%) had local recurrence only. In exploratory analyses, diagnostic accuracy of FDG-PET/CT was better than ceCT alone or ceCT combined with BS in diagnosing distant, bone, and local recurrence, shown by a greater area under the receiver operating curve and higher sensitivity, specificity, and superior likelihood ratios.

CONCLUSION

FDG-PET/CT was accurate in diagnosing recurrence in breast cancer patients. It allowed for distant recurrence to be correctly ruled out and resulted in only a small number of false-positive cases. Exploratory findings suggest that FDG-PET/CT has greater accuracy than conventional imaging technologies in this patient group.

Endovascular repair of postoperative vascular graft related complications after aorto-iliac surgery

AIM

Para-anastomotic aneurysms, leakage due to anastomotic failure, aorto- and arterioenteric fistulas are some of the serious complications after aorto-iliac surgical reconstructions. Treatment of these complications is challenging and is either done by open surgery or by endovascular therapy. The mortality and morbidity is higher compared to the initial treatment. We present twelve patients with these complications which were treated by an endovascular approach.

METHODS

From January 2008 through January 2013 our radiological records were searched for cases with post surgical vascular complications treated with endovascular intervention. These comprised of anastomotic pseudoaneurysm, suture leakage and arterial enteric fistulas. Patients with limb occlusions were not included in this study.

RESULTS

Twelve patients with graft related complications treated with endovascular intervention were recorded. There were four women and eight men with a mean age 75,3 years (range 48-80). At the time of diagnosis, 9 patients (75%) had symptoms and three (25%) was incidentally discovered. Six patients had leakage due to suture failure. All infective parameters were within normal limits. Four patients presented with anastomotic pseudoaneurysms without leak, of which three had proximal anastomotic pseudoaneurysms and one had distal iliac anastomotic pseudoaneurysm. Implanted stent graft were Endurant (Medtronic) bifurcated endoprostheses in three patients and Excluder (Gore) prosthesis in a two cases. Tubular Medtronic endoprosthesis was implanted in one case and in two cases aortic cuff was used. Fluency periphery stent grafts were used in four cases. There was a 100% technical success. Intervention related early mortality was 8%. One patient with pseudoaneurysm died 28 months after endovascular treatment because of cardiac infarct and one patient with previously infected arterio-enteric fistula and advanced malignancy died 7 months after second endovascular treatment. Overall the mortality was 25%. There was no procedure related morbidity or complications during hospitalization and follow-up of mean 12, 3 months (range 1-36 months) in the other 9 patients. There were no complications like endoleaks or limb occlusions.

CONCLUSION

Endovascular treatment of vascular graft related postsurgical complications is a valuable therapeutic option followed by lower mortality and morbidity rates compared with re-operation. Short and midterm follow-up is without severe complications and if it occurs most of them can be treated by endovascular means again.

Endovascular treatment of superior vena cava syndrome

AIM

The aim of this study was to report our experience with palliative stent treatment of superior vena cava syndrome.

METHODS

Between January 2008 and December 2009, 30 patients (mean age 60.7 years) were treated with stents because of stenosed superior vena cava. All patients presented clinically with superior vena cava syndrome and according caval stenosis confirmed by computed tomography. The causes of stenoses were non-small cell carcinoma in 22 patients and small cell carcinoma in 8 patients.

RESULTS

In all patients the stents were placed as intended in all patients there was an immediate clinical improvement with considerable reduction in the edema of upper extremities and head. There was, however, continous dyspnea in five patients (17%) and two patients (7%) had persistent visible collateral venous circulations on the upper chest. There were no stent associated complications. All patients were followed clinically till death and the median follow-up period was 2.8 months (15-420 days). During follow-up three cases of stent thrombosis (one complete and two partial thrombosis) were observed.

CONCLUSION

Palliative care with stent implantation for superior vena cava syndrome is a minimal invasive and safe procedure with good clinical effect giving the patients a significant better quality of their residual life.