Background: Interstitial lung disease (ILD) is one of the leading causes of mortality in patients with systemic sclerosis (SSc). To further understand this patient population, we present the first systematic review on the epidemiology of SSc and SSc-associated ILD (SSc-ILD). Methods: Bibliographic databases and web sources were searched for studies including patients with SSc and SSc-ILD in Europe and North America (United States and Canada). The systematic review was limited to publications in English, German, French, Spanish, Italian, and Portuguese, published between January 1, 2000 and February 29, 2016. For all publications included in the review, the methodologic quality was assessed. For each dimension and region, data availability in terms of quantity and consistency of reported findings was evaluated. Results: Fifty publications reporting epidemiologic data (prevalence, incidence, demographic profile, and survival and mortality) were included; 39 included patients with SSc and 16 included patients with SSc-ILD. The reported prevalence of SSc was 7.2–33.9 and 13.5–44.3 per 100,000 individuals in Europe and North America, respectively. Annual incidence estimates were 0.6–2.3 and 1.4–5.6 per 100,000 individuals in Europe and North America, respectively. Associated ILD was present in ~35% of the patients in Europe and ~52% of the patients in North America. In Europe, a study estimated the prevalence and annual incidence of SSc-ILD at 1.7–4.2 and 0.1–0.4 per 100,000 individuals, respectively. In both Europe and North America, SSc-ILD was diagnosed at a slightly older age than SSc, with both presentations of the disease affecting 2–3 times more women than men. Ten-year survival in patients with SSc was reported at 65–73% in Europe and 54–82% in North America, with cardiorespiratory manifestations (including ILD) associated with poor prognosis. Conclusion: This systematic review confirms that SSc and SSc-ILD are rare, with geographic variation in prevalence and incidence.

Many plant-pathogenic bacteria utilize type II secretion (T2S) systems to secrete degradative enzymes into the extracellular milieu. T2S substrates presumably mediate the degradation of plant cell wall components during the host-pathogen interaction and thus promote bacterial virulence. Previously, the Xps-T2S system from Xanthomonas campestris pv. vesicatoria was shown to contribute to extracellular protease activity and the secretion of a virulence-associated xylanase. The identities and functions of additional T2S substrates from X. campestris pv. vesicatoria, however, are still unknown. In the present study, the analysis of 25 candidate proteins from X. campestris pv. vesicatoria led to the identification of two type II secreted predicted xylanases, a putative protease and a lipase which was previously identified as a virulence factor of X. campestris pv. vesicatoria. Studies with mutant strains revealed that the identified xylanases and the protease contribute to virulence and in planta growth of X. campestris pv. vesicatoria. When analyzed in the related pathogen X. campestris pv. campestris, several T2S substrates from X. campestris pv. vesicatoria were secreted independently of the T2S systems, presumably because of differences in the T2S substrate specificities of the two pathogens. Furthermore, in X. campestris pv. vesicatoria T2S mutants, secretion of T2S substrates was not completely absent, suggesting the contribution of additional transport systems to protein secretion. In line with this hypothesis, T2S substrates were detected in outer membrane vesicles, which were frequently observed for X. campestris pv. vesicatoria. We, therefore, propose that extracellular virulence-associated enzymes from X. campestris pv. vesicatoria are targeted to the Xps-T2S system and to outer membrane vesicles. IMPORTANCEThe virulence of plant-pathogenic bacteria often depends on TS2 systems, which secrete degradative enzymes into the extracellular milieu. T2S substrates are being studied in several plant-pathogenic bacteria, including Xanthomonas campestris pv. vesicatoria, which causes bacterial spot disease in tomato and pepper. Here, we show that the T2S system from X. campestris pv. vesicatoria secretes virulence-associated xylanases, a predicted protease, and a lipase. Secretion assays with the related pathogen X. campestris pv. campestris revealed important differences in the T2S substrate specificities of the two pathogens. Furthermore, electron microscopy showed that T2S substrates from X. campestris pv. vesicatoria are targeted to outer membrane vesicles (OMVs). Our results, therefore, suggest that OMVs provide an alternative transport route for type II secreted extracellular enzymes. Many Gram-negative plant-pathogenic bacteria utilize specialized protein secretion systems to deliver virulence factors, including DNA or bacterial effector proteins, into plant cells (1). The efficient trans-kingdom transport of bacterial effector proteins is often hindered by the rigid plant cell wall, which mainly cons...

Streptococcus pneumoniae is an important bacterial pathogen that causes a range of noninvasive and invasive diseases. The mechanisms underlying variability in the ability of S. pneumoniae to transition from nasopharyngeal colonization to disease-causing pathogen are not well defined. Mucosal-associated invariant T (MAIT) cells are prevalent in mucosal tissues such as the airways and are believed to play an important role in the early response to infection with bacterial pathogens. The ability of MAIT cells to recognize and contain infection with S. pneumoniae is not known. In the present study, we analyzed MAIT-cell responses to infection with clinical isolates of S. pneumoniae serotype 19A, a serotype linked to invasive pneumococcal disease. We found that although MAIT cells were capable of responding to human dendritic and airway epithelial cells infected with S. pneumoniae, the magnitude of response to different serotype 19A isolates was determined by genetic differences in the expression of the riboflavin biosynthesis pathway. MAIT-cell release of cytokines correlated with differences in the ability of MAIT cells to respond to and control S. pneumoniae in vitro and in vivo in a mouse challenge model. Together, these results demonstrate first that there are genetic differences in riboflavin metabolism among clinical isolates of the same serotype and second that these likely determine MAIT-cell function in response to infection with S. pneumoniae. These differences are critical when considering the role that MAIT cells play in early responses to pneumococcal infection and determining whether invasive disease will develop.

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