TLR2 and TLR7 mediate distinct immunopathological and antiviral plasmacytoid dendritic cell responses to SARS-CoV-2 infection

Understanding the molecular pathways driving the acute antiviral and inflammatory response to SARS-CoV-2 infection is critical for developing treatments for severe COVID-19. Here, we find decreasing number of circulating plasmacytoid dendritic cells (pDCs) in COVID-19 patients early after symptom onset, correlating with disease severity. pDC depletion is transient and coincides with decreased expression of antiviral type I IFNα and of systemic inflammatory cytokines CXCL10 and IL-6. Using an in vitro stem cell-based human pDC model, we further demonstrate that pDCs, while not supporting SARS-CoV-2 replication, directly sense the virus and in response produce multiple antiviral (interferons: IFNα and IFNλ1) and inflammatory (IL-6, IL-8, CXCL10) cytokines that protect epithelial cells from de novo SARS-CoV-2 infection. Via targeted deletion of virus-recognition innate immune pathways, we identify TLR7-MyD88 signaling as crucial for production of antiviral interferons, whereas TLR2 is responsible for the inflammatory IL-6 response. We further show that SARS-CoV-2 engages the receptor neuropilin-1 on pDCs to selectively mitigate the antiviral interferon response, but not the IL-6 response, suggesting neuropilin-1 as potential therapeutic target for stimulation of TLR7-mediated antiviral protection.

Cell-Extrinsic Priming Increases Permissiveness of CD4+ T Cells to Human Immunodeficiency Virus Infection by Increasing C-C Chemokine Receptor Type 5 Co-receptor Expression and Cellular Activation Status

The chemokine receptor CCR5 is expressed on multiple cell types, including macrophages, dendritic cells, and T cells, and is the major co-receptor used during HIV transmission. Using a standard αCD3/CD28 in vitro stimulation protocol to render CD4+ T cells from PBMCs permissive to HIV infection, we discovered that the percentage of CCR5⁺ T cells was significantly elevated in CD4+ T cells when stimulated in the presence of peripheral blood mononuclear cells (PBMCs) as compared to when stimulated as purified CD4+ T cells. This indicated that environmental factors unique to the T-PBMCs condition affect surface expression of CCR5 on CD4+ T cells. Conditioned media from αCD3/CD28-stimulated PBMCs induced CCR5 expression in cultures of unstimulated cells. Cytokine profile analysis of these media suggests IL-12 as an inducer of CCR5 expression. Mass cytometric analysis showed that stimulated T-PBMCs exhibited a uniquely activated phenotype compared to T-Pure. In line with increased CCR5 expression and activation status in stimulated T-PBMCs, CD4+ T cells from these cultures were more susceptible to infection by CCR5-tropic HIV-1 as compared with T-Pure cells. These results suggest that in order to increase ex vivo infection rates of blood-derived CD4+ T cells, standard stimulation protocols used in HIV infection studies should implement T-PBMCs or purified CD4+ T cells should be supplemented with IL-12.

A randomized, double-blinded, placebo-controlled, parallel trial of vitamin D3 supplementation in adult patients with migraine

BACKGROUND

Vitamin D levels have been linked to certain pain states, including migraine. This study investigated whether vitamin D supplementation would be beneficial for adult patients with migraine (ClinicalTrials.gov Identifier: NCT01695460).

METHODS

A randomized, double-blinded, placebo-controlled parallel trial was conducted in migraine patients (36 women and 12 men, 18-65 years of age). A 4-week baseline period was conducted before randomization to 24 weeks of treatment. Participants were assigned to receive D3-Vitamin (n = 24, 18 women and 6 men, 100 μg/day D3-Vitamin) or placebo (n = 24, 18 women and 6 men). Migraine attacks and related symptoms were assessed by self-reported diaries. The response rate (i.e. experiencing a 50% or greater reduction in migraine frequency from baseline to week 24), change in migraine severity, and number of migraine days were recorded. Changes in migraine-related symptoms, HIT-6^TM scores, and pain sensitivity tests (pressure pain threshold and temporal summation) were also evaluated. Serum levels of both 25 (OH)D and 1,25 (OH)₂D were assessed from baseline to week 24.

RESULTS

The number of headache days changed from 6.14 ± 3.60 in the treatment group and 5.72 ± 4.52 in the placebo group at baseline to 3.28 ± 3.24 and 4.93 ± 3.24 by the end of the trial, respectively. Migraine patients on D3-Vitamin demonstrated a significant decrease (p < .001) in migraine frequency from baseline to week 24 compared with placebo. However, migraine severity, pressure pain thresholds, or temporal summation did not show a significant change. 25(OH)D levels increased significantly for the D3-Vitamin group during the first 12 weeks of treatment. There was no significant change in 1,25(OH)₂D. No side-effects were reported or noted.

CONCLUSIONS

D3-Vitamin was superior to placebo in reducing migraine days in migraine patients. Larger studies are required to confirm that vitamin D₃ might be one of the prophylactic options for adult patients with migraine.

Multiple Homozygous Variants in the STING-Encoding TMEM173 Gene in HIV Long-Term Nonprogressors

Among HIV-infected individuals, long-term nonprogressor (LTNP) patients experience slow CD4 T cell decline and almost undetectable viral load for several years after primary acquisition of HIV. Type I IFN has been suggested to play a pathogenic role in HIV pathogenesis, and therefore diminished IFN responses may underlie the LTNP phenotype. In this study, we examined the presence and possible immunological role of multiple homozygous single-nucleotide polymorphisms in the stimulator of IFN genes (STING) encoding gene TMEM173 involved in IFN induction and T cell proliferation in HIV LTNP patients. We identified LTNPs through the Danish HIV Cohort and performed genetic analysis by Sanger sequencing, covering the R71H-G230A-R293Q (HAQ) single-nucleotide polymorphisms in TMEM173 This was followed by investigation of STING mRNA and protein accumulation as well as innate immune responses and proliferation following STING stimulation and infection with replication-competent HIV in human blood-derived cells. We identified G230A-R293Q/G230A-R293Q and HAQ/HAQ homozygous TMEM173 variants in 2 out of 11 LTNP patients. None of the 11 noncontrollers on antiretroviral treatment were homozygous for these variants. We found decreased innate immune responses to DNA and HIV as well as reduced STING-dependent inhibition of CD4 T cell proliferation, particularly in the HAQ/HAQ HIV LTNP patients, compared with the age- and gender-matched noncontrollers on antiretroviral treatment. These findings suggest that homozygous HAQ STING variants contribute to reduced inhibition of CD4 T cell proliferation and a reduced immune response toward DNA and HIV, which might result in reduced levels of constitutive IFN production. Consequently, the HAQ/HAQ TMEM173 genotype may contribute to the slower disease progression characteristic of LTNPs.

Ossifying fibromyxoid tumour of soft parts, with focus on unusual clinicopathological features

AIMS

Ossifying fibromyxoid tumour is a rare lesion that generally occurs in the soft tissues of proximal limbs/girdle, or head and neck. Histologically, it usually consists of bland, mitotically inactive, S100+ cells in a fibromyxoid matrix with a characteristic peripheral ossification. However, we present two cases that deviated from this pattern.

MATERIAL AND METHODS

One tumour, which was removed from the axilla of a 55-year-old female, was unusual in its large size (120 mm in diameter) and in its restriction of bone formation to its central zones. The other tumour, which occurred in a 62-year-old female, was remarkable in its acral location on the hand and high mitotic activity (four mitoses per high-power field). These features caused concern and follow-up of the patients was recommended. So far there have been no recurrences (25 and 18 months after surgery, respectively). An additional previously undescribed feature was the presence of fibronexus-like structures by electron microscopy in the second case. However, a myofibroblastic phenotype was not supported by the immunohistochemical findings.

CONCLUSION

Though a distinct entity, ossifying fibromyxoid tumour may exhibit a wider clinicopathological spectrum than generally recognized.

Decreased bone density of the distal femur after uncemented knee arthroplasty. A 1-year follow-up of 29 knees

We measured the early adaptive bone remodeling of the distal femur prospectively for 1 year after uncemented total knee arthroplasty (TKA) in 29 knees with primary arthrosis. 18 patients were randomized to receive a PCA Modular femoral component (n 9) or a modified version of the same prosthesis (n 9) with an altered location of the porous coating. The other 11 patients (n 11) formed a consecutive series with the Duracon femoral component. In the trabecular bone above the femoral component, bone mineral density (BMD) was measured in 2 regions of interest (ROI) anteriorly to the fixation pegs (ROI 1) and above the pegs (ROI 2), using dual photon absorptiometry (DPA). There were no differences between the Modular component and the modified version regarding the postoperative decrease in BMD. There was a decrease in BMD in both ROI 1 and ROI 2 with all 3 different femoral components, and in both ROIs the highest bone loss rate was observed during the first 3 months after surgery. On average (n 29), a significant bone loss of 44% and 19% in ROI 1 and ROI 2, respectively, was reached at the 1-year follow-up, compared to the initial values. A decrease of this magnitude in BMD in the anterior distal femur 1 year after TKA may be an important determinant of periprosthetic fracture and later failure of the femoral component. In this experimental set-up, a modified femoral component with an altered location of the porous coating did not influence the development of bone loss.

Effects of gentamicin and monomer on bone. An in vitro study

Gentamicin-loaded bone cement is used with increasing frequency in primary and revision arthroplasty. Considering the high local concentration and the well-known toxic effect of gentamicin on the kidney, a similar inhibiting effect on bone tissue might be expected. In a series of in vitro studies using paired mouse calvaries cultured for 2 days, the authors found a dose-dependent decrease in the release of previously incorporated calcium-45 (45Ca) or tritiated proline and a decrease in alkaline phosphatase activity. In combination with methylmethacrylate, a small additional reduction in 45Ca release and a marked decrease in alkaline phosphatase activity were recorded. These results indicate that released gentamicin and monomer from antibiotic-supplemented bone cement depresses bone turnover and might thus play an important part in the pathogenesis of loosening.

Depressive effects of acrylic cement components on bone metabolism. Isotope release and phosphatase production studied in vitro

In vitro methyl methacrylate bone cement components were found to depress the release of radioactive calcium and proline as well as the activity of both alkaline and acid phosphatases. These effects were dose dependent and reached levels observed for dead bone. These observations may reflect part of the pathogenesis of loosening of joint replacements involving the use of bone cement.

Influence of diphenylhydantoin on isotope release and bone enzymes in vitro

The acute effect of diphenylhydantoin isotope release in an in vitro system using mouse calvaries was studied. A depressive effect on bone resorption was found involving radioactive calcium as well as tritiated proline. Bone resorption and formation were further investigated by semiquantitative histochemistry. Depressed activity of both alkaline and acid phosphatase was found, indicating a direct inhibitory effect of diphenylhydantoin on bone turnover.

A note on the likelihood equation in the ABO blood group system

Some sufficient conditions on the data for the likelihood equation of the ABO blood-group system to have a unique solution, the maximum-likelihood estimate, are given. The simplest of these conditions is that the frequency of the blood group O in the sample shall exceed 1/8. This condition will hold for most samples.