Incidence of Interstitial Lung Disease in Patients With Rheumatoid Arthritis Treated With Biologic and Targeted Synthetic Disease-Modifying Antirheumatic Drugs.

Importance: Current data are lacking regarding the risk of biologic and targeted synthetic disease-modifying antirheumatic drug (b/tsDMARD) use on the development of interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA). Objective: To determine the risk of developing ILD in patients with RA undergoing treatment with different b/tsDMARDs. Design, Setting, and Participants: Retrospective cohort study using claims data from the Optum Clinformatics Data Mart between December 2003 and December 2019. Adult patients with RA, 1 year or more of continuous enrollment, treatment with a b/tsDMARD of interest, and without preexisting ILD were included. Data were analyzed from October 2021 to April 2022. Exposures: New administration of adalimumab, abatacept, rituximab, tocilizumab, or tofacitinib. Main Outcomes and Measures: Crude incidence rates (IRs) for the development of ILD were calculated. The risk of ILD across different b/tsDMARDs was compared using Cox-regression models. A sensitivity analysis using a prevalent new-user cohort design compared patients treated with tofacitinib and adalimumab. Results: A total of 28 559 patients with RA (mean [SD] age 55.6 [13.7] years; 22 158 female [78%]) were treated with adalimumab (13 326 patients), abatacept (5676 patients), rituximab (5444 patients), tocilizumab (2548 patients), or tofacitinib (1565 patients). Crude IRs per 1000 person-years for ILD were 3.43 (95% CI 2.85-4.09) for adalimumab, 4.46 (95% CI 3.44-5.70) for abatacept, 6.15 (95% CI 4.76-7.84) for rituximab, 5.05 (95% CI 3.47-7.12) for tocilizumab, and 1.47 (95% CI 0.54-3.27) for tofacitinib. After multiple adjustments, compared with patients treated with adalimumab, patients treated with tofacitinib had a lower risk of ILD (adjusted hazard ratio [aHR] 0.31; 95% CI, 0.12-0.78; P = .009). In a prevalent new-user cohort analysis, patients treated with tofacitinib had 68% reduced risk of ILD compared with adalimumab (aHR 0.32; 95% CI 0.13-0.82; P < .001). In an adjusted model, there was a 69% reduced risk of ILD in patients treated with tofacitinib compared with patients treated with adalimumab. Conclusions and Relevance: In this retrospective cohort of patients with RA, patients treated with tofacitinib had the lowest incidence of ILD compared with patients treated with all bDMARDs evaluated, and patients treated with tofacitinib had a reduced risk of ILD compared with patients treated with adalimumab after adjusting for important covariates. Additional prospective studies are needed to better understand the role tofacitinib may play in preventing ILD in patients with RA. These results, while significant, should be interpreted with caution given the fairly small sample size of the tofacitinib group.

Inflammasome Activation Can Mediate Tissue-Specific Pathogenesis or Protection in Staphylococcus aureus Infection.

Staphylococcus aureus is a Gram-positive coccus that interacts with human hosts on a spectrum from quiet commensal to deadly pathogen. S. aureus is capable of infecting nearly every tissue in the body resulting in cellulitis, pneumonia, osteomyelitis, endocarditis, brain abscesses, bacteremia, and more. S. aureus has a wide range of factors that promote infection, and each site of infection triggers a different response in the human host. In particular, the different patterns of inflammasome activation mediate tissue-specific pathogenesis or protection in S. aureus infection. Although still a nascent field, understanding the unique host-pathogen interactions in each infection and the role of inflammasomes in mediating pathogenesis may lead to novel strategies for treating S. aureus infections. Reviews addressing S. aureus virulence and pathogenesis (Thammavongsa et al. 2015), as well as epidemiology and pathophysiology (Tong et al. 2015), have recently been published. This review will focus on S. aureus factors that activate inflammasomes and their impact on innate immune signaling and bacterial survival.

Functional Amyloid Signaling via the Inflammasome, Necrosome, and Signalosome: New Therapeutic Targets in Heart Failure.

As the most common cause of death and disability, globally, heart disease remains an incompletely understood enigma. A growing number of cardiac diseases are being characterized by the presence of misfolded proteins underlying their pathophysiology, including cardiac amyloidosis and dilated cardiomyopathy (DCM). At least nine precursor proteins have been implicated in the development of cardiac amyloidosis, most commonly caused by multiple myeloma light chain disease and disease-causing mutant or wildtype transthyretin (TTR). Similarly, aggregates with PSEN1 and COFILIN-2 have been identified in up to one-third of idiopathic DCM cases studied, indicating the potential predominance of misfolded proteins in heart failure. In this review, we present recent evidence linking misfolded proteins mechanistically with heart failure and present multiple lines of new therapeutic approaches that target the prevention of misfolded proteins in cardiac TTR amyloid disease. These include multiple small molecule pharmacological chaperones now in clinical trials designed specifically to support TTR folding by rational design, such as tafamidis, and chaperones previously developed for other purposes, such as doxycycline and tauroursodeoxycholic acid. Last, we present newly discovered non-pathological "functional" amyloid structures, such as the inflammasome and necrosome signaling complexes, which can be activated directly by amyloid. These may represent future targets to successfully attenuate amyloid-induced proteotoxicity in heart failure, as the inflammasome, for example, is being therapeutically inhibited experimentally in autoimmune disease. Together, these studies demonstrate multiple novel points in which new therapies may be used to primarily prevent misfolded proteins or to inhibit their downstream amyloid-mediated effectors, such as the inflammasome, to prevent proteotoxicity in heart failure.

Staphylococcus aureus Leukocidin A/B (LukAB) Kills Human Monocytes via Host NLRP3 and ASC when Extracellular, but Not Intracellular.

Staphylococcus aureus infections are a growing health burden worldwide, and paramount to this bacterium's pathogenesis is the production of virulence factors, including pore-forming leukotoxins. Leukocidin A/B (LukAB) is a recently discovered toxin that kills primary human phagocytes, though the underlying mechanism of cell death is not understood. We demonstrate here that LukAB is a major contributor to the death of human monocytes. Using a variety of in vitro and ex vivo intoxication and infection models, we found that LukAB activates Caspase 1, promotes IL-1ß secretion and induces necrosis in human monocytes. Using THP1 cells as a model for human monocytes, we found that the inflammasome components NLRP3 and ASC are required for LukAB-mediated IL-1ß secretion and necrotic cell death. S. aureus was shown to kill human monocytes in a LukAB dependent manner under both extracellular and intracellular ex vivo infection models. Although LukAB-mediated killing of THP1 monocytes from extracellular S. aureus requires ASC, NLRP3 and the LukAB-receptor CD11b, LukAB-mediated killing from phagocytosed S. aureus is independent of ASC or NLRP3, but dependent on CD11b. Altogether, this study provides insight into the nature of LukAB-mediated killing of human monocytes. The discovery that S. aureus LukAB provokes differential host responses in a manner dependent on the cellular contact site is critical for the development of anti-infective/anti-inflammatory therapies that target the NLRP3 inflammasome.

Toxoplasma co-opts host cells it does not invade.

Like many intracellular microbes, the protozoan parasite Toxoplasma gondii injects effector proteins into cells it invades. One group of these effector proteins is injected from specialized organelles called the rhoptries, which have previously been described to discharge their contents only during successful invasion of a host cell. In this report, using several reporter systems, we show that in vitro the parasite injects rhoptry proteins into cells it does not productively invade and that the rhoptry effector proteins can manipulate the uninfected cell in a similar manner to infected cells. In addition, as one of the reporter systems uses a rhoptry:Cre recombinase fusion protein, we show that in Cre-reporter mice infected with an encysting Toxoplasma-Cre strain, uninfected-injected cells, which could be derived from aborted invasion or cell-intrinsic killing after invasion, are actually more common than infected-injected cells, especially in the mouse brain, where Toxoplasma encysts and persists. This phenomenon has important implications for how Toxoplasma globally affects its host and opens a new avenue for how other intracellular microbes may similarly manipulate the host environment at large.

CMF70 is a subunit of the dynein regulatory complex.

Flagellar motility drives propulsion of several important pathogens and is essential for human development and physiology. Motility of the eukaryotic flagellum requires coordinate regulation of thousands of dynein motors arrayed along the axoneme, but the proteins underlying dynein regulation are largely unknown. The dynein regulatory complex, DRC, is recognized as a focal point of axonemal dynein regulation, but only a single DRC subunit, trypanin/PF2, is currently known. The component of motile flagella 70 protein, CMF70, is broadly and uniquely conserved among organisms with motile flagella, suggesting a role in axonemal motility. Here we demonstrate that CMF70 is part of the DRC from Trypanosoma brucei. CMF70 is located along the flagellum, co-sediments with trypanin in sucrose gradients and co-immunoprecipitates with trypanin. RNAi knockdown of CMF70 causes motility defects in a wild-type background and suppresses flagellar paralysis in cells with central pair defects, thus meeting the functional definition of a DRC subunit. Trypanin and CMF70 are mutually conserved in at least five of six extant eukaryotic clades, indicating that the DRC was probably present in the last common eukaryotic ancestor. We have identified only the second known subunit of this ubiquitous dynein regulatory system, highlighting the utility of combined genomic and functional analyses for identifying novel subunits of axonemal sub-complexes.

The Trypanosoma brucei flagellum: moving parasites in new directions.

African trypanosomes are devastating human and animal pathogens. Trypanosoma brucei rhodesiense and T. b. gambiense subspecies cause the fatal human disease known as African sleeping sickness. It is estimated that several hundred thousand new infections occur annually and the disease is fatal if untreated. T. brucei is transmitted by the tsetse fly and alternates between bloodstream-form and insect-form life cycle stages that are adapted to survive in the mammalian host and the insect vector, respectively. The importance of the flagellum for parasite motility and attachment to the tsetse fly salivary gland epithelium has been appreciated for many years. Recent studies have revealed both conserved and novel features of T. brucei flagellum structure and composition, as well as surprising new functions that are outlined here. These discoveries are important from the standpoint of understanding trypanosome biology and identifying novel drug targets, as well as for advancing our understanding of fundamental aspects of eukaryotic flagellum structure and function.