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The lung is constantly exposed to the outside world and optimal adaptation of immune responses is crucial for efficient pathogen clearance. However, mechanisms that lead to lung-associated macrophages' functional and developmental adaptation remain elusive. To reveal such mechanisms, we developed a reductionist model of environmental intranasal β-glucan exposure, allowing for the detailed interrogation of molecular mechanisms of pulmonary macrophage adaptation. Employing single-cell transcriptomics, high-dimensional imaging and flow cytometric characterization paired with in vivo and ex vivo challenge models, we reveal that pulmonary low-grade inflammation results in the development of apolipoprotein E (ApoE)-dependent monocyte-derived alveolar macrophages (ApoE + CD11b + AMs). ApoE + CD11b + AMs expressed high levels of CD11b, ApoE, Gpnmb and Ccl6, were glycolytic, highly phagocytic and produced large amounts of interleukin-6 upon restimulation. Functional differences were cell intrinsic, and myeloid cell-specific ApoE ablation inhibited Ly6c + monocyte to ApoE + CD11b + AM differentiation dependent on macrophage colony-stimulating factor secretion, promoting ApoE + CD11b + AM cell death and thus impeding ApoE + CD11b + AM maintenance. In vivo, β-glucan-elicited ApoE + CD11b + AMs limited the bacterial burden of Legionella pneumophilia after infection and improved the disease outcome in vivo and ex vivo in a murine lung fibrosis model. Collectively these data identify ApoE + CD11b + AMs generated upon environmental cues, under the control of ApoE signaling, as an essential determinant for lung adaptation enhancing tissue resilience., (© 2024. The Author(s).)

Antisynthease syndrome (ASSD) is a rare, complex and understudied autoimmune disease. Internet-based studies can overcome barriers of traditional on-site research and are therefore very appealing for rare diseases. The aim of this study was to investigate patient-reported symptoms, diagnostic delay, symptoms, medical care, health status, working status, disease knowledge and willingness to participate in research of ASSD patients by conducting an international web-based survey. The multilingual questionnaire was created by an international group of rheumatologists and patients and distributed online. 236 participants from 22 countries completed the survey. 184/236 (78.0%) were female, mean age (SD) was 49.6 years (11.3) and most common antisynthetase antibody was Jo-1 (169/236, 71.6%). 79/236 (33.5%) reported to work full-time. Median diagnostic delay was one year. The most common symptom at disease onset was fatigue 159/236 (67.4%), followed by myalgia 130/236 (55.1%). The complete triad of myositis, arthritis and lung involvement verified by a clinician was present in 42/236 (17.8%) at disease onset and in 88/236 (37.3%) during the disease course. 36/236 (15.3%) reported to have been diagnosed with fibromyalgia and 40/236 (16.3%) with depression. The most reported immunosuppressive treatments were oral corticosteroids 179/236 (75.9%), followed by rituximab 85/236 (36.0%). 73/236 (30.9%) had received physiotherapy treatment. 71/236 (30.1%) reported to know useful online information sources related to ASSD. 223/236 (94.5%) were willing to share health data for research purposes once a year. Our results reiterate that internet-based research is invaluable for cooperating with patients to foster knowledge in rare diseases., (© 2023. The Author(s).)

There have been three randomized controlled trials on autologous hematopoietic stem cell transplantation (AHSCT) in systemic sclerosis (SSc) that demonstrated significant superiority with respect to survival, improvement of cutaneous fibrosis, lung function and quality of life compared to standard treatment; however, these advantages must be carefully weighed against the transplantation-related risks. For this reason, an expert group from the stem cell therapy working party of the German Society for Rheumatology (DGRh) has now developed recommendations for the use of AHSCT in SSc. Based on the high-quality evidence, AHSCT is considered as the standard option for the treatment of selected SSc patients. Potential candidates for AHSCT are those with early, rapidly progressive, diffuse cutaneous SSc with visceral manifestations who have not yet developed severe damage to internal organs. A close cooperation between rheumatologists and transplantation centers is crucial for optimizing patient selection and treatment outcomes.

Background: Digital ulcers (DU) affect up to 60 % of patients with systemic sclerosis (SSc) and have a considerable impact on quality of life and morbidity. It is unclear to what extent authorised medicines are used, and if therapy guidelines are implemented in everyday practice., Method: This retrospective health care study examined current standards of treatment for therapy and prevention of SSc-associated DU in an online survey with 83 physicians. Additionally, data from 161 case studies of SSc patients with DU were analysed, and the effect of DU treatment on the course of the disease determined., Results: For treatment and prevention of active DU, physicians predominantly indicated topical therapies, calcium channel blockers, iloprost and endothelin receptor antagonists. According to the case studies, 90 % of episodes with acute DU were treated with bosentan and iloprost in mono- or combination therapy. Preventive treatment was only administered during 50 % of episodes without DU, even after three or more phases with active DU. For the prevention of new DU, bosentan was used in mono- or combination therapy in 57 % of episodes without DU. Bosentan therapy during prevention shortened the following acute phase by 32 %. Additionally, continuous treatment with bosentan in acute and prevention phases reduced the duration of the following acute phase and increased the time to onset of new DU by 16 %. Moreover, bosentan stabilised the number of new DU., Conclusion: In summary, these data confirm the efficacy of bosentan in preventing new DU when used in DU-free episodes and possibly also in phases of acute DU. Therapy recommendations for the treatment of DU are currently not fully implemented. In the future, even more attention should be paid to DU therapy.

Large data bases and the projects arising from them have led to a much improved understanding of systemic sclerosis over the last decade. Serology has developed further so that more autoantibodies are available for routine testing. Capillary microscopy has become standard and relevant progress has also been made in therapy. Many diagnostic terms found in medical documentation do not adequately reflect this progress. The nomenclature is inconsistent and, therefore, confusing. The international classification of diseases (ICD) nomenclature is, from our point of view, also in need of improvement. This article aims to reestablish a common German language standard for systemic sclerosis, which reflects current knowledge and is suitable for implementation in the clinical routine.

Objective: To search for novel autoantibodies in patients with rheumatoid arthritis (RA) in an effort to better understand the processes of joint destruction in this disease., Methods: Using a modified SEREX technique and complementary DNA derived from RA synovium, serpin E2 was identified as a novel autoantigen and was analyzed by immunohistochemistry. Levels of anti-serpin E2 autoantibodies in serum and synovial fluid from patients with RA, osteoarthritis (OA), psoriatic arthritis, and ankylosing spondylitis, and/or from healthy individuals were assessed by enzyme-linked immunosorbent assay. Since serpin E2 is an inhibitor of serine proteases, we studied the inhibitory activity of serpin E2 toward its target, urokinase plasminogen activator (uPA), in vitro in the presence of isolated anti-serpin E2 autoantibodies and in vivo using the uPA activity assay., Results: We identified autoantibodies against serpin E2 by the SEREX technique. Serpin E2 was overexpressed in RA synovial tissues as compared with OA synovial tissues. Significantly higher levels of anti-serpin E2 autoantibodies were present in samples of synovial fluid (28%) and serum (22%) from RA patients as compared with OA patients (0 and 6%, respectively) or with healthy individuals (6% of sera). Most importantly, anti-serpin E2 autoantibodies isolated from RA sera reversed the inhibitory activity of serpin E2 by 70%. Furthermore, the levels of anti-serpin E2 autoantibodies correlated with the uPA activity in vivo., Conclusion: This study characterizes a functional property of a novel autoantibody in RA. Since anti-serpin E2 autoantibodies interfere with the inhibitory activity of serpin E2 toward serine proteases, they might facilitate the joint destruction in RA.

Systemic sclerosis (SSc) is a fibrosing connective tissue disease with significantly increased mortality. Therapeutic options to treat fibrosis are limited. The small molecule tyrosine kinase inhibitor imatinib and related drugs such as dasatinib and nilotinib target simultaneously two of the major profibrotic pathways, TGFbeta- and PDGF- signaling. Imatinib, dasatinib and nilotinib inhibit collagen synthesis in cultured fibroblasts and have potent anti-fibrotic effects in animal models of different fibrotic diseases. Moreover, several case reports, case series and uncontrolled studies on patients with SSc, mixed connective tissue disease, nephrogenic systemic fibrosis and in particular sclerodermatous graft versus host disease (cGvHD) report regression of fibrosis and good tolerability. However, the results of larger controlled trials, which are currently ongoing, are needed before any conclusions on efficacy and tolerability can be drawn. Until the results of these trials are available, we discourage off-label use of Imatinib in single patients.

Systemic sclerosis (SSc) is characterised by a progressive microangiopathy that contributes significantly to the morbidity of patients with SSc. Besides insufficient angiogenesis, defective vasculogenesis with altered numbers of endothelial precursor cells (EPCs) might also contribute to the vascular pathogenesis of SSc. However, different protocols for isolation, enrichment, culture and quantification of EPCs are currently used, which complicate comparison and interpretation of the results from different studies. The aim of the European League Against Rheumatism Scleroderma Trials and Research (EUSTAR) group expert panel was to provide recommendations for standardisation of future research on EPCs. Consensus statements and recommendations were developed in a face to face meeting by an expert panel of the basic science working group of EUSTAR. The findings were: cardiovascular risk factors and medications such as statins should be described in detail. A detailed description of methods considering isolation, culture, enrichment and detection of EPCs should be given. For in vitro culture of EPCs, no protocol has been shown to be superior to another, but coating with laminin and type IV collagen would resemble most closely the situation in vivo. The endothelial phenotype should be confirmed in all in vitro cultures at the end of the culture period. We recommend using CD133, vascular endothelial growth factor type 2 receptor (VEGFR2) and CD34 in combination with a viability marker for quantification of EPCs in the blood. Finally, exact standard operating procedures for fluorescence-activated cell sorting (FACS) analysis are given that should be strictly followed. In summary, the EUSTAR recommendations will help to unify EPC research and allow better comparison between the results of different studies.

Activation of the immune system and increased synthesis of extracellular matrix proteins by fibroblasts are hallmarks in the pathogenesis of SSc. The molecular mechanisms underlying the infiltration of inflammatory cells into the skin and the subsequent activation of fibroblasts are still largely unknown. Chemokines are a family of small molecules that are classified according to the position of the NH(2)-terminal cysteine motif. Recent data indicate that chemokines and in particular two members of the subfamily of monocyte chemoattractant proteins, MCP-1 (CCL-2) and MCP-3 (CCL-7), might be involved in the pathogenesis of SSc. MCP-1 and -3 are overexpressed by SSc fibroblasts and in skin lesions from SSc patients compared to healthy controls. MCP-1 and -3 are chemotactic for inflammatory cells and stimulate their migration into the skin. In addition to their pro-inflammatory effects, MCP-1 and -3 contribute to tissue fibrosis by activating the synthesis of extracellular matrix proteins in SSc fibroblasts. Therapeutic strategies targeting MCP-1 have revealed promising results in several animal models of SSc. Antagonists against the receptor CCR2 are currently tested in clinical trials of a variety of diseases and also represent interesting candidates for target-directed therapy in SSc.

Tissue fibrosis is a major cause of morbidity and mortality in SSc. An increasing number of promising molecular targets for anti-fibrotic therapies have been described recently. However, the number of patients eligible for clinical trials is limited in SSc. The present article discusses criteria to select the most promising molecular targets for clinical trials in SSc. Based on consensus among experts, important criteria for the selection of molecular-based therapies were as follows: First, there should be strong experimental evidence that targeting the molecule of interest inhibits fibrosis. Optimally, the anti-fibrotic effects should be confirmed in at least two complementary animal models of SSc. Second, inhibitors of the molecule of interest should be clinically available. Third, clinical experience with the drug of interest in other diseases hastens the initiation of clinical trials and reduces the risk of unexpected side-effects. Finally, funding for clinical trials with the drug of interest in SSc should be available. We propose that the priority of novel targets for evaluation in clinical trials in SSc might be selected based on these consensus criteria.

Tissue fibrosis is a major cause of death in SSc, but therapies that target selectively fibrosis are not yet available for routine clinical use. Recent pre-clinical studies suggest that selective tyrosine kinase inhibitors that target c-Abl, PDGF receptor or Src kinases might be promising targets for anti-fibrotic approaches. Dual inhibition of c-Abl and PDGF receptor by imatinib and nilotinib, and inhibition of Src kinases either selectively by SU6656 or in combination with c-Abl and PDGF by dasatinib exerted potent anti-fibrotic effects. Imatinib, nilotinib, dasatinib and SU6656 reduced dose-dependently the synthesis of extracellular matrix protein in human dermal fibroblasts in vitro and prevented fibrosis in the mouse model of bleomycin-induced skin fibrosis. Clinical data from patients with chronic myelogenous leukaemia suggest that imatinib, nilotinib and dasatinib are well tolerated. Based on the promising pre-clinical data, imatinib is currently evaluated in clinical trials for the treatment of fibrosis in SSc and trials with other tyrosine kinase inhibitors are in preparation.

Vascular abnormalities are a major component of SSc, but little is known about the events or mechanisms that initiate vascular injury and prevent its repair. In SSc, angiogenesis is incomplete or lacking despite the increased expression of a large array of pro-angiogenic factors such as VEGF. Conflicting results have recently been published concerning the presence and role of vasculogenesis and circulating endothelial progenitor cells in SSc. It remains to be established if these endothelial progenitor cells are a marker of endothelial disease or a cause of insufficient vascular repair. Human mesenchymal stem cells (MSCs) may be an alternative source for endothelial progenitor cells, and it has been observed that the angiogenic potential of endothelial-like MSCs is reduced. Other mechanisms of vascular damage include oxidative stress and factors released from activated platelets. In addition, growth factors such as ET-1 and PDGF induce proliferation of vascular smooth muscle cells resulting in intimal thickening. For the development of new therapeutic strategies, it is important to realize that the different vascular pathologies--uncompensated loss of capillaries on one hand and vascular remodelling with a proliferative vasculopathy on the other--might require different treatment approaches.

The term Raynaud's phenomenon describes an abnormal vasospastic response to cold or emotional stress. It is a common condition with a prevalence of 3-5% of the population. Clinically, Raynaud's phenomenon manifests as sharply demarcated colour changes of the skin of the digits that is often accompanied by paraesthesia. Raynaud's phenomenon can be subdivided into primary, or idiopathic, and secondary forms, in the latter of which associated diseases or causes can be identified. The pathogenesis of the disease is incompletely understood. Pathologic changes have been observed primarily in vascular smooth muscle cells, endothelial cells and perineuronal microvasculature. Current therapeutic strategies include supportive treatments, topical therapeutic approaches and systemic medication. Drug therapies with proven efficacy include calcium channel blockers, prostacyclin analogues, fluoxetine, losartan and sildenafil.

In contrast to vasculogenesis, angiogenesis is defined as the formation of new vessels from preexisting ones. Physiologically, this multistep process occurs in adults during the reproductive cycle and during pregnancy, pathophysiologically it can be found in wound healing, inflammation and carcinogenesis. The underlying mechanisms are vasodilatation and increasing permeability, destabilization of vessel walls and degradation of extracellular matrix, followed by the proliferation and migration of endothelial cells. Migrated endothelial cells form vascular tubes at sites of ischemia and these tubes are finally stabilized by pericytes and smooth muscle cells. This process is controlled by a complex interaction of angiogenic and angiostatic factors. In contrast to carcinogenesis, the role of angiogenesis for the pathogenesis and therapy of rheumatic diseases is less understood. Two examples for pathologically disturbed angiogenesis, rheumatoid arthritis and systemic sclerosis, are discussed in this review with respect to therapeutic options.

In addition to inflammatory infiltrates and an accumulation of extracellular matrix proteins, vascular changes are a hallmark in the pathogenesis of systemic sclerosis (SSc). Consistent with the ongoing endothelial cell apoptosis, several markers of EC damage are up-regulated in the serum of SSc patients. Surprizingly, vascular endothelial growth factor (VEGF), a very potent angiogenic molecule, is overexpressed in SSc patients despite the insufficient angiogenesis. VEGF can protect patients from fingertip ulcers, but a prolonged overexpression of VEGF might have paradoxical effects leading to the formation of irregular vessels similar to that observed in SSc. Besides defective angiogenesis, recent studies suggest that vasculogenesis is also impaired in SSc patients with reduced numbers and functional defects of endothelial progenitor cells.

Microparticles are small membrane vesicles released from the cell membrane by exogenous budding. To elucidate the interactions of microparticles with macrophages, the effect of microparticles released from Jurkat T cells on RAW 264.7 cells was determined. Microparticles were isolated by differential centrifugation, using FACS analysis with annexin V and cell surface markers for identification. Various inducers of apoptosis increased the release of microparticles from Jurkat cells up to 5-fold. The released microparticles were then cultured with RAW 264.7 cells. As shown by confocal microscopy and FACS analysis, RAW 264.7 macrophages cleared microparticles by phagocytosis. In addition, microparticles induced apoptosis in RAW 264.7 cells in a dose-dependent manner with up to a 5-fold increase of annexin V positive cells and 9-fold increase in caspase 3 activity. Cell proliferation as determined by the MTT test was also reduced. Furthermore, microparticles stimulated the release of microparticles from macrophages. These effects were specific for macrophages, since no apoptosis was observed in NIH 3T3 and L929 cells. These findings indicate that microparticles can induce macrophages to undergo apoptosis, in turn resulting in a further increase of microparticles. The release of microparticles from apoptotic cells may therefore represent a novel amplification loop of cell death.

Systemic sclerosis (SSc, scleroderma) is a connective tissue disease of unknown etiology. Perivascular inflammatory infiltrates and endothelial apoptosis with an impaired angiogenesis are observed in early stages of the disease, whereas later stages are characterized by an excessive accumulation of extracellular matrix proteins in the skin and various internal organs. Consistent with the ongoing endothelial cell damage, various markers of endothelial cells such as endothelin-1, sICAM-1, s-VCAM-1 and thrombomodulin are found in high levels in the serum of SSc patients. Surprisingly, the vascular endothelial growth factor (VEGF), a potent angiogenic molecule, is overexpressed in the skin of patients with SSc despite insufficient angiogenesis. Interestingly, patients suffering from diffuse SSc and patients without finger tip ulcers show higher VEGF levels compared to age- and sex-matched controls. These results indicate that a controlled overexpression of VEGF might help to protect against the manifestation of ischemic conditions. On the other hand, data from animal models indicate that a long-term, uncontrolled overexpression of VEGF might have paradox effects on the formation of new vessels leading to capillary changes similar to those observed in SSc. In addition to the impaired angiogenesis, defective vasculogenesis might contribute to the vascular symptoms of SSc.

The vascular system that ensures an adequate blood flow is required to provide the cells with sufficient supply of nutrients and oxygen. Two different mechanisms of the formation of new vessels can be distinguished: vasculogenesis, the formation of the first primitive vascular plexus de novo and angiogenesis, the formation of new vessels from preexisting ones. Both processes are regulated by a delicate balance of pro- and anti-angiogenic factors. Physiologically, angiostatic mediators outweigh the angiogenic molecules and angiogenesis does not occur. Under certain conditions such as tumor formation or wound healing, the positive regulators of angiogenesis predominate and the endothelium becomes activated. Angiogenesis is initiated by vasodilatation and an increased permeability. After destabilization of the vessel wall, endothelial cells proliferate, migrate and form a tube, which is finally stabilized by pericytes and smooth muscle cells. Numerous soluble growth factors and inhibitors, cytokines and proteases as well as extracellular matrix proteins and adhesion molecules strictly control this multi-step process. The properties and interactions of angiogenic molecules such as VEGFs, FGFs, angiopoietins, PDGF, angiogenin, angiotropin, HGF, CXC chemokines with ELR motif, PECAM-1, integrins and VE-cadherin as well as angiostatic key players such as angiostatin, endostatin, thrombospondin, CXC chemokines without ELR motif, PEDF are discussed in this review with respect to their molecular impact on angiogenesis.