Comparative safety of high-efficacy disease-modifying therapies in relapsing-remitting multiple sclerosis: a systematic review and network meta-analysis.

OBJECTIVE: This study aimed to compare the safety profile of high-efficacy disease-modifying therapies (DMTs) natalizumab, fingolimod, alemtuzumab, cladribine, ocrelizumab, ofatumumab, ozanimod, as well as a potentially high-efficacy DMT, ponesimod, in adult patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: A systematic review with frequentist network meta-analysis (NMA) was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We included randomized controlled trials (RCTs) with at least 48-week follow-up investigating the use of natalizumab, fingolimod, alemtuzumab, cladribine, ocrelizumab, ofatumumab, ozanimod, and ponesimod, as well as other DMTs, in adult patients with RRMS. Eligible studies were identified by two reviewers in MEDLINE (via PubMed), EMBASE, and Cochrane Library. The Cochrane Collaboration tool to assess the risk of bias for RCTs was used. RESULTS: A total of 33 RCTs were included in the systematic review and NMA. A higher rate of adverse events (AEs) was revealed for alemtuzumab versus all other high-efficacy DMTs; for alemtuzumab (average probability of an event: 98.2%) versus placebo (86.2%); for cladribine (3.5 mg; 90.5%) versus ozanimod (1 mg; 84.2%) and placebo; as well as for ocrelizumab (95.5%) versus ozanimod, ofatumumab (88.9%), fingolimod (87.4%), natalizumab (82.8%), and placebo. No significant differences were found between drugs in terms of serious AEs except for cladribine (3.5 mg, 17.3%) versus ocrelizumab (10.3%) and ofatumumab (16.6%) versus ocrelizumab. Significant differences in AEs leading to the discontinuation of study drug were found only for ponesimod (10.1%) versus alemtuzumab (12 mg, 3.0%) and placebo (4.2%). No differences were found in terms of upper respiratory tract infections, nasopharyngitis, fatigue, and nausea between individual high-efficacy DMTs as well as between DMTs and placebo. The results of the NMA indicated a higher risk of infections for alemtuzumab (12 mg) versus ocrelizumab, for cladribine (3.5 mg) versus ofatumumab and placebo, and for ofatumumab versus placebo. For serious infections and urinary tract infections, a significant increase was found only for alemtuzumab (12 mg) versus ocrelizumab, while no differences were found between the other DMTs or between DMTs and placebo. Headache was more common for alemtuzumab (12 mg) as compared with all the other high-efficacy DMTs and placebo, as well as for cladribine versus natalizumab and fingolimod versus natalizumab. CONCLUSION: The commonly reported AEs are generally similar among high-efficacy DMTs. However, based on P scores for most analyzed endpoints, natalizumab and ocrelizumab were shown to be the safest DMTs. Considering the limitations of indirect comparisons, further research is needed to confirm our findings, preferably head-to-head RCTs and large observational studies.

Secretory Leukocyte Protease Inhibitor Is Present in Circulating and Tissue-Recruited Human Eosinophils and Regulates Their Migratory Function.

Eosinophils and secretory leukocyte protease inhibitor (SLPI) are both associated with Th2 immune responses and allergic diseases, but whether the fact that they are both implicated in these conditions is pathophysiologically related remains unknown. Here we demonstrate that human eosinophils derived from normal individuals are one of the major sources of SLPI among circulating leukocytes. SLPI was found to be stored in the crystalline core of eosinophil granules, and its dislocation/rearrangement in the crystalline core likely resulted in changes in immunostaining for SLPI in these cells. High levels of SLPI were also detected in blood eosinophils from patients with allergy-associated diseases marked by eosinophilia. These include individuals with eosinophilic granulomatosis with polyangiitis (EGPA) and atopic dermatitis (AD), who were also found to have elevated SLPI levels in their plasma. In addition to the circulating eosinophils, diseased skin of AD patients also contained SLPI-positive eosinophils. Exogenous, recombinant SLPI increased numbers of migratory eosinophils and supported their chemotactic response to CCL11, one of the key chemokines that regulate eosinophil migratory cues. Together, these findings suggest a role for SLPI in controlling Th2 pathophysiologic processes via its impact on and/or from eosinophils.

Differences in Staining for Neutrophil Elastase and its Controlling Inhibitor SLPI Reveal Heterogeneity among Neutrophils in Psoriasis.

Neutrophils are broadly classified into conventional neutrophils (PMNs) and low-density granulocytes (LDGs). LDGs are better than PMNs at generating neutrophil extracellular traps (NETs), which may contribute to the pathology of autoimmune diseases. We hypothesized that LDGs and PMNs differ in their levels of unrestrained NE that supports NET generation. Here, we show that individuals with psoriasis contain elevated levels of LDGs and that in contrast to PMNs, the LDGs display higher staining for NE and lower staining for its inhibitor SLPI. The heterogeneity between blood-derived LDGs and PMNs was somewhat reminiscent of the differences in the NE and SLPI staining patterns observed in psoriasis skin-infiltrating neutrophils. Distinctive staining for NE and SLPI in LDGs and PMNs did not result from differences in their protein levels nor manifested in higher total proteolytic activity of NE in LDGs; rather, it likely depended on different cytosolic sequestration of these proteins. The disparate profile of NE and SLPI in LDGs and PMNs coincided with altered migratory responses of these cells to cutaneous chemoattractants. Collectively, differential NE and SLPI staining identifies common attributes of both circulating and skin-infiltrating neutrophils, which may guide neutrophil migration to distinct skin regions and determine the localization of LDGs-mediated cutaneous pathology.

Differential expansion of circulating human MDSC subsets in patients with cancer, infection and inflammation.

BACKGROUND: Myeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells. METHODS: We developed, tested, executed and optimized a standard operating procedure for the isolation and immunophenotyping of MDSC using blood from healthy donors. We applied this procedure to the blood of almost 400 patients and controls with different solid tumors and non-malignant diseases. The latter included viral infections such as HIV and hepatitis B virus, but also psoriasis and cardiovascular disorders. RESULTS: We observed that the frequency of MDSC in healthy donors varied substantially between centers and was influenced by technical aspects such as the anticoagulant and separation method used. Expansion of polymorphonuclear (PMN)-MDSC exceeded the expansion of monocytic MDSC (M-MDSC) in five out of six solid tumors. PMN-MDSC expansion was more pronounced in cancer compared with infection and inflammation. Programmed death-ligand 1 was primarily expressed in M-MDSC and e-MDSC and was not upregulated as a consequence of disease. LOX-1 expression was confined to PMN-MDSC. CONCLUSIONS: This study provides improved technical protocols and workflows for the multi-center analysis of circulating human MDSC subsets. Application of these workflows revealed a predominant expansion of PMN-MDSC in solid tumors that exceeds expansion in chronic infection and inflammation.

Eosinophils Regulate Interferon Alpha Production in Plasmacytoid Dendritic Cells Stimulated with Components of Neutrophil Extracellular Traps.

Eosinophils constitute an important component of helminth immunity and are not only associated with various allergies but are also linked to autoinflammatory disorders, including the skin disease psoriasis. Here we demonstrate the functional relationship between eosinophils and plasmacytoid dendritic cells (pDCs) as related to skin diseases. We previously showed that pDCs colocalize with neutrophil extracellular traps (NETs) in psoriatic skin. Here we demonstrate that eosinophils are found in psoriatic skin near neutrophils and NETs, suggesting that pDC responses can be regulated by eosinophils. Eosinophils inhibited pDC function in vitro through a mechanism that did not involve cell contact but depended on soluble factors. In pDCs stimulated by specific NET components, eosinophil-conditioned media attenuated the production of interferon α (IFNα) but did not affect the maturation of pDCs as evidenced by the unaltered expression of the costimulatory molecules CD80 and CD86. As pDCs and IFNα play a key role in autoimmune skin inflammation, these data suggest that eosinophils may influence autoinflammatory responses through their impact on the production of IFNα by pDCs.

Inhibitors of Serine Proteases in Regulating the Production and Function of Neutrophil Extracellular Traps.

Neutrophil extracellular traps (NETs), DNA webs released into the extracellular environment by activated neutrophils, are thought to play a key role in the entrapment and eradication of microbes. However, NETs are highly cytotoxic and a likely source of autoantigens, suggesting that NET release is tightly regulated. NET formation involves the activity of neutrophil elastase (NE), which cleaves histones, leading to chromatin decondensation. We and others have recently demonstrated that inhibitors of NE, such as secretory leukocyte protease inhibitor (SLPI) and SerpinB1, restrict NET production in vitro and in vivo. SLPI was also identified as a NET component in the lesional skin of patients suffering from the autoinflammatory skin disease psoriasis. SLPI-competent NET-like structures (a mixture of SLPI with neutrophil DNA and NE) stimulated the synthesis of interferon type I (IFNI) in plasmacytoid dendritic cells (pDCs) in vitro. pDCs uniquely respond to viral or microbial DNA/RNA but also to nucleic acids of "self" origin with the production of IFNI. Although IFNIs are critical in activating the antiviral/antimicrobial functions of many cells, IFNIs also play a role in inducing autoimmunity. Thus, NETs decorated by SLPI may regulate skin immunity through enhancing IFNI production in pDCs. Here, we review key aspects of how SLPI and SerpinB1 can control NET production and immunogenic function.