Long-termin vitromaintenance of plasma cells in a hydrogel-enclosed human bone marrow microphysiological 3D model system.

Plasma cells (PCs) in bone marrow (BM) play an important role in both protective and pathogenic humoral immune responses, e.g. in various malignant and non-malignant diseases such as multiple myeloma, primary and secondary immunodeficiencies and autoimmune diseases. Dedicated microenvironmental niches in the BM provide PCs with biomechanical and soluble factors that support their long-term survival. There is a high need for appropriate and robust model systems to better understand PCs biology, to develop new therapeutic strategies for PCs-related diseases and perform targeted preclinical studies with high predictive value. Most preclinical data have been derived fromin vivostudies in mice, asin vitrostudies of human PCs are limited due to restricted survival and functionality in conventional 2D cultures that do not reflect the unique niche architecture of the BM. We have developed a microphysiological, dynamic 3D BM culture system (BM-MPS) based on human primary tissue (femoral biopsies), mechanically supported by a hydrogel scaffold casing. While a bioinert agarose casing did not support PCs survival, a photo-crosslinked collagen-hyaluronic acid (Col-HA) hydrogel preserved the native BM niche architecture and allowed PCs survivalin vitrofor up to 2 weeks. Further, the Col-HA hydrogel was permissive to lymphocyte migration into the microphysiological system´s circulation. Long-term PCs survival was related to the stable presence in the culture of soluble factors, as APRIL, BAFF, and IL-6. Increasing immunoglobulins concentrations in the medium confirm their functionality over culture time. To the best of our knowledge, this study is the first report of successful long-term maintenance of primary-derived non-malignant PCsin vitro. Our innovative model system is suitable for in-depthin vitrostudies of human PCs regulation and exploration of targeted therapeutic approaches such as CAR-T cell therapy or biologics.

Extracellular CIRP co-stimulated T cells through IL6R/STAT3 in pediatric IgA vasculitis.

Immunoglobulin A vasculitis (IgAV) is the most common vasculitis of childhood. Disordered immune responses play important roles in its pathogenesis, but the comprehensive immune profile of the disease and the underlying mechanisms are still largely unknown. Here we found a potential disease biomarker cold inducible RNA binding protein (CIRP) in our pediatric IgAV cohort. Serum CIRP level in these patients were elevated and positively correlated with the increased early memory (CD45RA+CD62L+CD95+) T cells revealed using multicolor flow cytometry. Immune phenotyping of the patients showed they had more activated T cells with higher IL6Ra expression. T cell culture experiment showed CIRP further activated both human CD4+ and CD8+ T cells as indicated by increased perforin secretion and phosphorylation of STAT3. Blockade of IL6Rα attenuated CIRP-induced T cell toxicity in vitro. RNA-sequencing data further supported CIRP stimulation promoted human T cell activation and migration, fueled inflammation through the JAK-STAT signaling pathway. Therefore, IL6Ra-mediated T cell activation by extracellular CIRP may contribute to pathogenesis of IgAV in children, both CIRP and IL6Ra could be new therapeutic targets for IgAV.

In Vitro Transcribed mRNA Immunogenicity Induces Chemokine-Mediated Lymphocyte Recruitment and Can Be Gradually Tailored by Uridine Modification.

Beyond SARS-CoV2 vaccines, mRNA drugs are being explored to overcome today's greatest healthcare burdens, including cancer and cardiovascular disease. Synthetic mRNA triggers immune responses in transfected cells, which can be reduced by chemically modified nucleotides. However, the side effects of mRNA-triggered immune activation on cell function and how different nucleotides, such as the N1-methylpseudouridine (m1Ψ) used in SARS-CoV2 vaccines, can modulate cellular responses is not fully understood. Here, cellular responses toward a library of uridine-modified mRNAs are investigated in primary human cells. Targeted proteomics analyses reveal that unmodified mRNA induces a pro-inflammatory paracrine pattern marked by the secretion of chemokines, which recruit T and B lymphocytes toward transfected cells. Importantly, the magnitude of mRNA-induced changes in cell function varies quantitatively between unmodified, Ψ-, m1Ψ-, and 5moU-modified mRNA and can be gradually tailored, with implications for deliberately exploiting this effect in mRNA drug design. Indeed, both the immunosuppressive effect of stromal cells on T-cell proliferation, and the anti-inflammatory effect of IL-10 mRNA are enhanced by appropriate uridine modification. The results provide new insights into the effects of mRNA drugs on cell function and cell-cell communication and open new possibilities to tailor mRNA-triggered immune activation to the desired pro- or anti-inflammatory application.

Integration of ζ-deficient CARs into the CD3ζ gene conveys potent cytotoxicity in T and NK cells.

ABSTRACT: Chimeric antigen receptor (CAR)-redirected immune cells hold significant therapeutic potential for oncology, autoimmune diseases, transplant medicine, and infections. All approved CAR-T therapies rely on personalized manufacturing using undirected viral gene transfer, which results in nonphysiological regulation of CAR-signaling and limits their accessibility due to logistical challenges, high costs and biosafety requirements. Random gene transfer modalities pose a risk of malignant transformation by insertional mutagenesis. Here, we propose a novel approach utilizing CRISPR-Cas gene editing to redirect T cells and natural killer (NK) cells with CARs. By transferring shorter, truncated CAR-transgenes lacking a main activation domain into the human CD3ζ (CD247) gene, functional CAR fusion-genes are generated that exploit the endogenous CD3ζ gene as the CAR's activation domain. Repurposing this T/NK-cell lineage gene facilitated physiological regulation of CAR expression and redirection of various immune cell types, including conventional T cells, TCRγ/δ T cells, regulatory T cells, and NK cells. In T cells, CD3ζ in-frame fusion eliminated TCR surface expression, reducing the risk of graft-versus-host disease in allogeneic off-the-shelf settings. CD3ζ-CD19-CAR-T cells exhibited comparable leukemia control to TCRα chain constant (TRAC)-replaced and lentivirus-transduced CAR-T cells in vivo. Tuning of CD3ζ-CAR-expression levels significantly improved the in vivo efficacy. Notably, CD3ζ gene editing enabled redirection of NK cells without impairing their canonical functions. Thus, CD3ζ gene editing is a promising platform for the development of allogeneic off-the-shelf cell therapies using redirected killer lymphocytes.

Increased Expression of Proinflammatory Genes in Peripheral Blood Cells Is Associated with Cardiac Cachexia in Patients with Heart Failure with Reduced Ejection Fraction.

Background: Cardiac cachexia (CC) in chronic heart failure with reduced ejection fraction (HFrEF) is characterized by catabolism and inflammation predicting poor prognosis. Levels of responsible transcription factors like signal transducer and activator of transcription (STAT)1, STAT3, suppressor of cytokine signaling (SOCS)1 and SOCS3 in peripheral blood cells (PBC) are underinvestigated in CC. Expression of mediators was related to patients' functional status, body composition (BC) and metabolic gene expression in skeletal muscle (SM). Methods: Gene expression was quantified by qRT-PCR in three cohorts: non-cachectic patients (ncCHF, n = 19, LVEF 31 ± 7%, BMI 30.2 ± 5.0 kg/m2), cachectic patients (cCHF; n = 18, LVEF 27 ± 7%, BMI 24.3 ± 2.5 kg/m2) and controls (n = 17, LVEF 70 ± 7%, BMI 27.6 ± 4.6 kg/m2). BC was assessed by dual-energy X-ray absorptiometry. Blood inflammatory markers were measured. We quantified solute carrier family 2 member 4 (SLC2A4) and protein degradation by expressions of proteasome 20S subunit beta 2 and calpain-1 catalytic subunit in SM biopsies. Results: TNF and IL-10 expression was higher in cCHF than in ncCHF and controls (all p < 0.004). cCHF had a lower fat mass index (FMI) and lower fat-free mass index (FFMI) compared to ncCHF and controls (p < 0.05). STAT1 and STAT3 expression was higher in cCHF vs. ncCHF or controls (1.1 [1.6] vs. 0.8 [0.9] vs. 0.9 [1.1] RU and 4.6 [5.5] vs. 2.5 [4.8] vs. 3.0 [4.2] RU, all ANOVA-p < 0.05). The same applied for SOCS1 and SOCS3 expression (1.1 [1.5] vs. 0.4 [0.4] vs. 0.4 [0.5] and 0.9 [3.3] vs. 0.4 [1.1] vs. 0.8 [0.9] RU, all ANOVA-p < 0.04). In cCHF, higher TNF and STAT1 expression was associated with lower FMI (r = 0.5, p = 0.053 and p < 0.05) but not with lower FFMI (p > 0.4). In ncCHF, neither cytokine nor STAT/SOCS expression was associated with BC (all p > 0.3). SLC2A4 was upregulated in SM of cCHF vs. ncCHF (p < 0.03). Conclusions: Increased STAT1, STAT3, SOCS1 and SOCS3 expression suggests their involvement in CC. In cCHF, higher TNF and STAT-1 expression in PBC were associated with lower FMI. Increased SLC2A4 in cachectic SM biopsies indicates altered glucose metabolism.

PACE: randomized, controlled, multicentre, multinational, phase III study of PLX-PAD for critical limb ischaemia in patients unsuitable for revascularization: randomized clinical trial.

BACKGROUND: Revascularization is the primary treatment modality for chronic limb-threatening ischaemia (CLTI), but is not feasible in all patients. PLX-PAD is an off-the-shelf, placental-derived, mesenchymal stromal cell-like cell therapy. This study aimed to evaluate whether PLX-PAD would increase amputation-free survival in people with CLTI who were not candidates for revascularization. METHODS: People with CLTI and minor tissue loss (Rutherford 5) who were unsuitable for revascularization were entered into a randomized, parallel-group, placebo-controlled, multinational, blinded, trial, in which PLX-PAD was compared with placebo (2 : 1 randomization), with 30 intramuscular injections (0.5 ml each) into the index leg on days 0 and 60. Planned follow-up was 12-36 months, and included vital status, amputations, lesion size, pain and quality-of-life assessments, haemodynamic parameters, and adverse events. RESULTS: Of 213 patients enrolled, 143 were randomized to PLX-PAD and 70 to placebo. Demographics and baseline characteristics were balanced. Most patients were Caucasian (96.2%), male (76.1%), and ambulatory (85.9%). Most patients (76.6%) reported at least one adverse event, which were mostly expected events in CLTI, such as skin ulcer or gangrene. The probability of major amputation or death was similar for placebo and PLX-PAD (33 and 28.6% respectively; HR 0.93, 95% c.i. 0.53 to 1.63; P = 0.788). Revascularization and complete wound healing rates were similar in the two groups. A post hoc analysis of a subpopulation of 121 patients with a baseline haemoglobin A1c level below 6.5% showed improved 12-month amputation-free survival (HR 0.46, 0.21 to 0.99; P = 0.048). CONCLUSION: Although there was no evidence that PLX-PAD reduced amputation-free survival in the entire study population, benefit was observed in patients without diabetes mellitus or whose diabetes was well controlled; this requires confirmation in further studies. Trial registration: NCT03006770 (http://www.clinicaltrials.gov); 2015-005532-18 (EudraCT Clinical Trials register - Search for 2015-005532-18).

Tacrolimus After rATG and Infliximab Induction Immunosuppression-RIMINI Trial.

BACKGROUND: Infliximab selectively targets recently activated effector cells and, as an induction agent, might enable the safe elimination of mycophenolate from maintenance immunosuppression in kidney transplantation. METHODS: This is a phase II international multicenter open-label single-arm confidence interval (CI)-based clinical trial of the BIO-DrIM EU consortium aimed at assessing the efficacy and safety of rabbit antithymocyte globulin and infliximab induction in kidney transplantation. Sixty-seven primary kidney transplant recipients at low risk (panel-reactive antibodies <20%, no donor-specific antibodies [DSA]) received rabbit antithymocyte globulin (2 × 1.5 mg/kg, postoperative days 0 and 1) and infliximab (5 mg/kg, postoperative day 2), followed by mycophenolate-free tacrolimus-based immunosuppression for 12 mo. The primary endpoint was efficacy failure, defined as a composite of acute rejection, graft loss, or poor graft function (estimated glomerular filtration rate <40 mL/min) at 12 mo and was based on the endpoint of the comparator study. Additionally, a historical propensity-matched control cohort was established. RESULTS: Primary endpoint occurred in 22 of 67 patients (32.84%), with upper bound of an exact 1-sided 95% CI of 43.47%, which met the predefined criteria (efficacy failure of <40% and upper-bound 95% CI of <50%) and was similar in the historical matched cohort. By 12 mo, 79.1% of patients remained on the study protocol. Lower rates of BK replication (6% versus 22.4%; P = 0.013) but higher rates of de novo DSAs (11.9% versus 1.5%; P = 0.039) were observed in the study cohort. CONCLUSIONS: A similar efficacy of the study immunosuppression regimen to the comparator study and the historical matched cohort was found. However, a higher de novo DSA emergence points to an increased risk of antibody-mediated rejection (NCT04114188).

Integration of ζ-deficient CARs into the CD3-zeta gene conveys potent cytotoxicity in T and NK cells.

Chimeric antigen receptor (CAR)-reprogrammed immune cells hold significant therapeutic potential for oncology, autoimmune diseases, transplant medicine, and infections. All approved CAR-T therapies rely on personalized manufacturing using undirected viral gene transfer, which results in non-physiological regulation of CAR-signaling and limits their accessibility due to logistical challenges, high costs and biosafety requirements. Here, we propose a novel approach utilizing CRISPR-Cas gene editing to redirect T cells and natural killer (NK) cells with CARs. By transferring shorter, truncated CAR-transgenes lacking a main activation domain into the human CD3 ζ (CD247) gene, functional CAR fusion-genes are generated that exploit the endogenous CD3 ζ gene as the CAR's activation domain. Repurposing this T/NK-cell lineage gene facilitated physiological regulation of CAR-expression and reprogramming of various immune cell types, including conventional T cells, TCRγ/δ T cells, regulatory T cells, and NK cells. In T cells, CD3 ζ in-frame fusion eliminated TCR surface expression, reducing the risk of graft-versus-host disease in allogeneic off-the-shelf settings. CD3 ζ-CD19-CAR-T cells exhibited comparable leukemia control to T cell receptor alpha constant ( TRAC )-replaced and lentivirus-transduced CAR-T cells in vivo . Tuning of CD3 ζ-CAR-expression levels significantly improved the in vivo efficacy. Compared to TRAC -edited CAR-T cells, integration of a Her2-CAR into CD3 ζ conveyed similar in vitro tumor lysis but reduced susceptibility to activation-induced cell death and differentiation, presumably due to lower CAR-expression levels. Notably, CD3 ζ gene editing enabled reprogramming of NK cells without impairing their canonical functions. Thus, CD3 ζ gene editing is a promising platform for the development of allogeneic off-the-shelf cell therapies using redirected killer lymphocytes. Key points: Integration of ζ-deficient CARs into CD3 ζ gene allows generation of functional TCR-ablated CAR-T cells for allogeneic off-the-shelf use CD3 ζ-editing platform allows CAR reprogramming of NK cells without affecting their canonical functions.

Measuring translational research impact requires reaching beyond current metrics.

Translational impact assessment is key to selecting those biomedical research discoveries most likely to be converted into viable new products to improve human health. However, metrics for translational success are variable, are not limited to commercial success, and may not be relevant to every case or institution. Societal impact is a top translational priority in a globalized society.

The spinal cord injury-induced immune deficiency syndrome: results of the SCIentinel study.

Infections are prevalent after spinal cord injury (SCI), constitute the main cause of death and are a rehabilitation confounder associated with impaired recovery. We hypothesize that SCI causes an acquired lesion-dependent (neurogenic) immune suppression as an underlying mechanism to facilitate infections. The international prospective multicentre cohort study (SCIentinel; protocol registration DRKS00000122; n = 111 patients) was designed to distinguish neurogenic from general trauma-related effects on the immune system. Therefore, SCI patient groups differing by neurological level, i.e. high SCI [thoracic (Th)4 or higher]; low SCI (Th5 or lower) and severity (complete SCI; incomplete SCI), were compared with a reference group of vertebral fracture (VF) patients without SCI. The primary outcome was quantitative monocytic Human Leukocyte Antigen-DR expression (mHLA-DR, synonym MHC II), a validated marker for immune suppression in critically ill patients associated with infection susceptibility. mHLA-DR was assessed from Day 1 to 10 weeks after injury by applying standardized flow cytometry procedures. Secondary outcomes were leucocyte subpopulation counts, serum immunoglobulin levels and clinically defined infections. Linear mixed models with multiple imputation were applied to evaluate group differences of logarithmic-transformed parameters. Mean quantitative mHLA-DR [ln (antibodies/cell)] levels at the primary end point 84 h after injury indicated an immune suppressive state below the normative values of 9.62 in all groups, which further differed in its dimension by neurological level: high SCI [8.95 (98.3% confidence interval, CI: 8.63; 9.26), n = 41], low SCI [9.05 (98.3% CI: 8.73; 9.36), n = 29], and VF without SCI [9.25 (98.3% CI: 8.97; 9.53), n = 41, P = 0.003]. Post hoc analysis accounting for SCI severity revealed the strongest mHLA-DR decrease [8.79 (95% CI: 8.50; 9.08)] in the complete, high SCI group, further demonstrating delayed mHLA-DR recovery [9.08 (95% CI: 8.82; 9.38)] and showing a difference from the VF controls of -0.43 (95% CI: -0.66; -0.20) at 14 days. Complete, high SCI patients also revealed constantly lower serum immunoglobulin G [-0.27 (95% CI: -0.45; -0.10)] and immunoglobulin A [-0.25 (95% CI: -0.49; -0.01)] levels [ln (g/l × 1000)] up to 10 weeks after injury. Low mHLA-DR levels in the range of borderline immunoparalysis (below 9.21) were positively associated with the occurrence and earlier onset of infections, which is consistent with results from studies on stroke or major surgery. Spinal cord injured patients can acquire a secondary, neurogenic immune deficiency syndrome characterized by reduced mHLA-DR expression and relative hypogammaglobulinaemia (combined cellular and humoral immune deficiency). mHLA-DR expression provides a basis to stratify infection-risk in patients with SCI.

CAR NK-92 cell-mediated depletion of residual TCR+ cells for ultrapure allogeneic TCR-deleted CAR T-cell products.

Graft-versus-host disease (GVHD) is a major risk of the administration of allogeneic chimeric antigen receptor (CAR)-redirected T cells to patients who are HLA unmatched. Gene editing can be used to disrupt potentially alloreactive T-cell receptors (TCRs) in CAR T cells and reduce the risk of GVHD. Despite the high knockout rates achieved with the optimized methods, a subsequent purification step is necessary to obtain a safe allogeneic product. To date, magnetic cell separation (MACS) has been the gold standard for purifying TCRα/ß- CAR T cells, but product purity can still be insufficient to prevent GVHD. We developed a novel and highly efficient approach to eliminate residual TCR/CD3+ T cells after TCRα constant (TRAC) gene editing by adding a genetically modified CD3-specific CAR NK-92 cell line during ex vivo expansion. Two consecutive cocultures with irradiated, short-lived, CAR NK-92 cells allowed for the production of TCR- CAR T cells with <0.01% TCR+ T cells, marking a 45-fold reduction of TCR+ cells compared with MACS purification. Through an NK-92 cell-mediated feeder effect and circumventing MACS-associated cell loss, our approach increased the total TCR- CAR T-cell yield approximately threefold while retaining cytotoxic activity and a favorable T-cell phenotype. Scaling in a semiclosed G-Rex bioreactor device provides a proof-of-principle for large-batch manufacturing, allowing for an improved cost-per-dose ratio. Overall, this cell-mediated purification method has the potential to advance the production process of safe off-the-shelf CAR T cells for clinical applications.

Combining different CRISPR nucleases for simultaneous knock-in and base editing prevents translocations in multiplex-edited CAR T cells.

BACKGROUND: Multiple genetic modifications may be required to develop potent off-the-shelf chimeric antigen receptor (CAR) T cell therapies. Conventional CRISPR-Cas nucleases install sequence-specific DNA double-strand breaks (DSBs), enabling gene knock-out or targeted transgene knock-in. However, simultaneous DSBs provoke a high rate of genomic rearrangements which may impede the safety of the edited cells. RESULTS: Here, we combine a non-viral CRISPR-Cas9 nuclease-assisted knock-in and Cas9-derived base editing technology for DSB free knock-outs within a single intervention. We demonstrate efficient insertion of a CAR into the T cell receptor alpha constant (TRAC) gene, along with two knock-outs that silence major histocompatibility complexes (MHC) class I and II expression. This approach reduces translocations to 1.4% of edited cells. Small insertions and deletions at the base editing target sites indicate guide RNA exchange between the editors. This is overcome by using CRISPR enzymes of distinct evolutionary origins. Combining Cas12a Ultra for CAR knock-in and a Cas9-derived base editor enables the efficient generation of triple-edited CAR T cells with a translocation frequency comparable to unedited T cells. Resulting TCR- and MHC-negative CAR T cells resist allogeneic T cell targeting in vitro. CONCLUSIONS: We outline a solution for non-viral CAR gene transfer and efficient gene silencing using different CRISPR enzymes for knock-in and base editing to prevent translocations. This single-step procedure may enable safer multiplex-edited cell products and demonstrates a path towards off-the-shelf CAR therapeutics.

Immuno-engineered mRNA combined with cell adhesive niche for synergistic modulation of the MSC secretome.

In vitro transcribed (IVT-)mRNA has entered center stage for vaccine development due to its immune co-stimulating properties. Given the widely demonstrated safety of IVT-mRNA-based vaccines, we aimed to adopt IVT-mRNA encoding VEGF for secretory phenotype modulation of therapeutic cells. However, we observed that the immunogenicity of IVT-mRNA impairs the endogenous secretion of pro-angiogenic mediators from transfected mesenchymal stromal cells, instead inducing anti-angiogenic chemokines. This inflammatory secretome modulation limits the application potential of unmodified IVT-mRNA for cell therapy manufacturing, pro-angiogenic therapy and regenerative medicine. To uncouple immunogenicity from the protein expression functionality, we immuno-engineered IVT-mRNA with different chemically modified ribonucleotides. 5-Methoxy-uridine-modification of IVT-mRNA rescued the endogenous secretome pattern of transfected cells and prolonged secretion of IVT-mRNA-encoded VEGF. We found that high secretion of IVT-mRNA-encoded protein further depends on optimized cell adhesion. Cell encapsulation in a collagen-hyaluronic acid hydrogel increased secretion of IVT-mRNA-encoded VEGF and augmented the endogenous secretion of supporting pro-angiogenic mediators, such as HGF. Integrating minimally immunogenic mRNA technology with predesigned matrix-derived cues allows for the synergistic combination of multiple dimensions of cell manipulation and opens routes for biomaterial-based delivery of mRNA-engineered cell products. Such multimodal systems could present a more biologically relevant way to therapeutically address complex multifactorial processes such as tissue ischemia, angiogenesis, and regeneration.

Neutrophilic granulocyte-derived B-cell activating factor supports B cells in skin lesions in hidradenitis suppurativa.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by painful inflamed nodules, abscesses, and pus-draining tunnels appearing in axillary, inguinal, and perianal skin areas. HS lesions contain various types of immigrated immune cells. OBJECTIVE: This study aimed to characterize mediators that support lesional B/plasma cell persistence in HS. METHODS: Skin samples from several cohorts of HS patients and control cohorts were assessed by mRNA sequencing, quantitative PCR on reverse-transcribed RNA, flow cytometry, and immunohistofluorescence. Blood plasma and cultured skin biopsy samples, keratinocytes, dermal fibroblasts, neutrophilic granulocytes (neutrophils), monocytes, and B cells were analyzed. Complex systems biology approaches were used to evaluate bulk and single-cell RNA sequencing data. RESULTS: Proportions of B/plasma cells, neutrophils, CD8+ T cells, and M0 and M1 macrophages were elevated in HS lesions compared to skin of healthy and perilesional intertriginous areas. There was an association between B/plasma cells, neutrophils, and B-cell activating factor (BAFF, aka TNFSF13B). BAFF was abundant in HS lesions, particularly in nodules and abscesses. Among the cell types present in HS lesions, myeloid cells were the main BAFF producers. Mechanistically, granulocyte colony-stimulating factor in the presence of bacterial products was the major stimulus for neutrophils' BAFF secretion. Lesional upregulation of BAFF receptors was attributed to B cells (TNFRSF13C/BAFFR and TNFRSF13B/TACI) and plasma cells (TNFRSF17/BCMA). Characterization of the lesional BAFF pathway revealed molecules involved in migration/adhesion (eg, CXCR4, CD37, CD53, SELL), proliferation/survival (eg, BST2), activation (eg, KLF2, PRKCB), and reactive oxygen species production (eg, NCF1, CYBC1) of B/plasma cells. CONCLUSION: Neutrophil-derived BAFF supports B/plasma cell persistence and function in HS lesions.

Complex Spatio-Temporal Interplay of Distinct Immune and Bone Cell Subsets during Bone Fracture Healing.

BACKGROUND: The healing of a bone injury is a highly complex process involving a multitude of different tissue and cell types, including immune cells, which play a major role in the initiation and progression of bone regeneration. METHODS: We histologically analyzed the spatio-temporal occurrence of cells of the innate immune system (macrophages), the adaptive immune system (B and T lymphocytes), and bone cells (osteoblasts and osteoclasts) in the fracture area of a femoral osteotomy over the healing time. This study was performed in a bone osteotomy gap mouse model. We also investigated two key challenges of successful bone regeneration: hypoxia and revascularization. RESULTS: Macrophages were present in and around the fracture gap throughout the entire healing period. The switch from initially pro-inflammatory M1 macrophages to the anti-inflammatory M2 phenotype coincided with the revascularization as well as the appearance of osteoblasts in the fracture area. This indicates that M2 macrophages are necessary for the restoration of vessels and that they also play an orchestrating role in osteoblastogenesis during bone healing. The presence of adaptive immune cells throughout the healing process emphasizes their essential role for regenerative processes that exceeds a mere pathogen defense. B and T cells co-localize consistently with bone cells throughout the healing process, consolidating their crucial role in guiding bone formation. These histological data provide, for the first time, comprehensive information about the complex interrelationships of the cellular network during the entire bone healing process in one standardized set up. With this, an overall picture of the spatio-temporal interplay of cellular key players in a bone healing scenario has been created. CONCLUSIONS: A spatio-temporal distribution of immune cells, bone cells, and factors driving bone healing at time points that are decisive for this process-especially during the initial steps of inflammation and revascularization, as well as the soft and hard callus phases-has been visualized. The results show that the bone healing cascade does not consist of five distinct, consecutive phases but is a rather complex interrelated and continuous process of events, especially at the onset of healing.

Immuno-cardio-oncology: Killing two birds with one stone?

Inflammation and a dysregulated immune system are common denominators of cancer and cardiovascular disease (CVD). Immuno-cardio-oncology addresses the interconnected immunological aspect in both cancer and CVD and the integration of immunotherapies and anti-inflammatory therapies in both distinct disease entities. Building on prominent examples of convergent inflammation (IL-1ß biology) and immune disbalance (CD20 cells) in cancer and CVD/heart failure, the review tackles both the roadblocks and opportunities of repurposed use of IL-1ß drugs and anti-CD20 antibodies in both fields, and discusses the use of advanced therapies e.g. chimeric antigen receptor (CAR) T cells, that can address the raising burden of both cancer and CVD. Finally, it is discussed how inspired by precision medicine in oncology, the use of biomarker-driven patient stratification is needed to better guide anti-inflammatory/immunomodulatory therapeutic interventions in cardiology.

Extra-hematopoietic immunomodulatory role of the guanine-exchange factor DOCK2.

Stromal cells interact with immune cells during initiation and resolution of immune responses, though the precise underlying mechanisms remain to be resolved. Lessons learned from stromal cell-based therapies indicate that environmental signals instruct their immunomodulatory action contributing to immune response control. Here, to the best of our knowledge, we show a novel function for the guanine-exchange factor DOCK2 in regulating immunosuppressive function in three human stromal cell models and by siRNA-mediated DOCK2 knockdown. To identify immune function-related stromal cell molecular signatures, we first reprogrammed mesenchymal stem/progenitor cells (MSPCs) into induced pluripotent stem cells (iPSCs) before differentiating these iPSCs in a back-loop into MSPCs. The iPSCs and immature iPS-MSPCs lacked immunosuppressive potential. Successive maturation facilitated immunomodulation, while maintaining clonogenicity, comparable to their parental MSPCs. Sequential transcriptomics and methylomics displayed time-dependent immune-related gene expression trajectories, including DOCK2, eventually resembling parental MSPCs. Severe combined immunodeficiency (SCID) patient-derived fibroblasts harboring bi-allelic DOCK2 mutations showed significantly reduced immunomodulatory capacity compared to non-mutated fibroblasts. Conditional DOCK2 siRNA knockdown in iPS-MSPCs and fibroblasts also immediately reduced immunomodulatory capacity. Conclusively, CRISPR/Cas9-mediated DOCK2 knockout in iPS-MSPCs also resulted in significantly reduced immunomodulation, reduced CDC42 Rho family GTPase activation and blunted filopodia formation. These data identify G protein signaling as key element devising stromal cell immunomodulation.

Local immune cell contributions to fracture healing in aged individuals - A novel role for interleukin 22.

With increasing age, the risk of bone fractures increases while regenerative capacity decreases. This variation in healing potential appears to be linked to adaptive immunity, but the underlying mechanism is still unknown. This study sheds light on immunoaging/inflammaging, which impacts regenerative processes in aging individuals. In an aged preclinical model system, different levels of immunoaging were analyzed to identify key factors that connect immunoaged/inflammaged conditions with bone formation after long bone fracture. Immunological facets, progenitor cells, the microbiome, and confounders were monitored locally at the injury site and systemically in relation to healing outcomes in 12-month-old mice with distinct individual levels of immunoaging. Bone tissue formation during healing was delayed in the immunoaged group and could be associated with significant changes in cytokine levels. A prolonged and amplified pro-inflammatory reaction was caused by upregulated immune cell activation markers, increased chemokine receptor availability and a lack of inhibitory signaling. In immunoaged mice, interleukin-22 was identified as a core cell signaling protein that played a central role in delayed healing. Therapeutic neutralization of IL-22 reversed this specific immunoaging-related disturbed healing. Immunoaging was found to be an influencing factor of decreased regenerative capacity in aged individuals. Furthermore, a novel therapeutic strategy of neutralizing IL-22 may successfully rejuvenate healing in individuals with advanced immune experiences.

A prospective observational study of post-COVID-19 chronic fatigue syndrome following the first pandemic wave in Germany and biomarkers associated with symptom severity.

A subset of patients has long-lasting symptoms after mild to moderate Coronavirus disease 2019 (COVID-19). In a prospective observational cohort study, we analyze clinical and laboratory parameters in 42 post-COVID-19 syndrome patients (29 female/13 male, median age 36.5 years) with persistent moderate to severe fatigue and exertion intolerance six months following COVID-19. Further we evaluate an age- and sex-matched postinfectious non-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome cohort comparatively. Most post-COVID-19 syndrome patients are moderately to severely impaired in daily live. 19 post-COVID-19 syndrome patients fulfill the 2003 Canadian Consensus Criteria for myalgic encephalomyelitis/chronic fatigue syndrome. Disease severity and symptom burden is similar in post-COVID-19 syndrome/myalgic encephalomyelitis/chronic fatigue syndrome and non-COVID-19/myalgic encephalomyelitis/chronic fatigue syndrome patients. Hand grip strength is diminished in most patients compared to normal values in healthy. Association of hand grip strength with hemoglobin, interleukin 8 and C-reactive protein in post-COVID-19 syndrome/non-myalgic encephalomyelitis/chronic fatigue syndrome and with hemoglobin, N-terminal prohormone of brain natriuretic peptide, bilirubin, and ferritin in post-COVID-19 syndrome/myalgic encephalomyelitis/chronic fatigue syndrome may indicate low level inflammation and hypoperfusion as potential pathomechanisms.