Combination of a SARS-CoV-2 IgG Assay and RT-PCR for Improved COVID-19 Diagnosis.

BACKGROUND: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is generally diagnosed by reverse transcription (RT)-PCR or serological assays. The SARS-CoV-2 viral load decreases a few days after symptom onset. Thus, the RT-PCR sensitivity peaks at three days after symptom onset (approximately 80%). We evaluated the performance of the ARCHITECT® SARS-CoV-2 IgG assay (henceforth termed IgG assay; Abbott Laboratories, Lake County, IL, USA), and the combination of RT-PCR and the IgG assay for COVID-19 diagnosis. METHODS: In this retrospective study, 206 samples from 70 COVID-19 cases at two hospitals in Tokyo that were positive using RT-PCR were used to analyze the diagnostic sensitivity. RT-PCR-negative (N=166), COVID-19-unrelated (N=418), and Japanese Red Cross Society (N=100) samples were used to evaluate specificity. RESULTS: Sensitivity increased daily after symptom onset and exceeded 84.4% after 10 days. Specificity ranged from 98.2% to 100% for samples from the three case groups. Seroconversion was confirmed from 9 to 20 days after symptom onset in 18 out of 32 COVID-19 cases with multiple samples and from another case with a positive result in the IgG assay for the first available sample. CONCLUSIONS: The combination of RT-PCR and IgG assay improves the robustness of laboratory diagnostics by compensating for the limitations of each method.

Upregulation of osteopontin expression via the interaction of macrophages and fibroblasts under IL-1b stimulation.

BACKGROUND: Fibrosis is attributed to dysregulation of tissue-remodeling. In remodeling areas, fibroblasts and macrophages actively make contact with each other. Osteopontin (OPN) is a pro-fibrotic molecule, whose expression is upregulated by interleukin (IL)-1ß via secretion of its downstream cytokines, such as IL-6. Here, we investigated the effect of interaction between fibroblasts and macrophages under IL-1ß stimulation on the expression of OPN. METHODS: We used human lung fibroblasts and THP-1 macrophages differentiated from THP-1 cells using phorbol 12-myristate 13-acetate. These cells were either cultured alone or co-cultured under IL-1ß stimulation. Secretion of OPN and IL-6 were examined by enzyme-linked immunosorbent assay, and mRNA expression was assessed by quantitative real-time PCR. The effects of siRNA against IL-6 or OPN on OPN expression were evaluated. RESULTS: OPN expression increased when fibroblasts and THP-1 macrophages were co-cultured under IL-1ß stimulation. The siRNA against IL-6 in fibroblasts suppressed the upregulation of OPN expression during co-culture, whereas siRNA against IL-6 in THP-1 macrophages did not. The upregulation of expression of OPN mRNA in fibroblasts or THP-1 macrophages when co-cultured under IL-1ß stimulation was mediated by IL-6 from fibroblasts. OPN from THP-1 macrophages was involved in the increase of OPN expression in fibroblasts. CONCLUSIONS: The present study revealed the crosstalk between fibroblasts and THP-1 macrophages under IL-1ß stimulation, where IL-6 from fibroblasts, stimulated by IL-1ß, upregulated OPN expression in fibroblasts themselves via increase in OPN from THP-1 macrophages. The fibroblasts/macrophages network may induce activation or qualitative changes in both cells, which contributes to inflammation-associated fibrosis.

Acute Myeloid Leukemia in a Patient With X-linked Severe Combined Immunodeficiency.

Severe combined immunodeficiency (SCID) is a defect in the differentiation and function of T cells. An increased malignancy risk, mainly lymphatic malignancy, has been described in patients with SCID. We report a patient with X-linked SCID who developed acute myeloid leukemia, derived from the recipient with somatic NRAS mutation 4 months after cord blood transplantation (CBT). Loss of heterozygosity phenomenon of the recipient at 6q14 locus was observed at 2 months post-CBT and progressed to 6q deletion (6q-) chromosome abnormality. Somatic NRAS mutation was detected at 3 months post-CBT. Thus, 6q- and NRAS mutation were strongly associated with the leukemic transformation in our patient.

IL-6 trans-signaling is another pathway to upregulate Osteopontin.

BACKGROUND: Osteopontin (OPN) is a pro-fibrotic molecule upregulated by pro-inflammatory cytokines. Interleukin (IL)-6 functions downstream of IL-1ß and has unique signal pathways: classic- or trans-signaling via membrane-bound IL-6R or soluble IL-6R (sIL-6R). We investigated the effect of IL-6 trans-signaling on the upregulation of OPN. METHODS: We used THP-1 cells and THP-1 macrophages differentiated from THP-1 cells using phorbol 12-myristate 13-acetate (PMA). After IL-1ß stimulation, expression of OPN, IL-6, sIL-6R, and a disintegrin and metalloproteinase 17 (ADAM17) was examined by ELISA and quantitative PCR. The effects of anti-human IL-6 neutralizing antibody, soluble gp130 (sgp130, IL-6 trans-signaling-specific inhibitor), TAPI-1 (ADAM inhibitor) and siRNA against IL-6R or ADAM17 on OPN expression were evaluated. RESULTS: IL-1ß increased OPN and induced IL-6 in THP-1 macrophages. Anti-IL-6 neutralizing antibody and siRNA against IL-6R inhibited OPN upregulation induced by IL-1ß. TAPI-1 significantly inhibited the increase in sIL-6R induced by IL-1ß. Treatment with sgp130 attenuated OPN elevation by IL-1ß, whereas sgp130 did not change OPN levels in THP-1 macrophages without IL-1ß stimulation. ADAM17 was expressed in THP-1 macrophages and THP-1 cells and IL-1ß stimulation significantly increased ADAM17 expression, regardless of PMA treatment. TAPI-1 and siRNA against ADAM17 significantly inhibited OPN increased by IL-1ß. CONCLUSIONS: IL-6 and sIL-6R induced by IL-1ß may trigger IL-6 trans-signaling, contributing to the upregulation of OPN in THP-1 macrophages. Macrophages may be used as a source of IL-6 and sIL-6R and evoke IL-6 trans-signaling.