B cells promote inflammation in obesity and type 2 diabetes through regulation of T-cell function and an inflammatory cytokine profile

Patients with type 2 diabetes (T2D) have disease-associated changes in B-cell function, but the role these changes play in disease pathogenesis is not well established. Data herein show B cells from obese mice produce a proinflammatory cytokine profile compared with B cells from lean mice. Complementary in vivo studies show that obese B cell–null mice have decreased systemic inflammation, inflammatory B- and T-cell cytokines, adipose tissue inflammation, and insulin resistance (IR) compared with obese WT mice. Reduced inflammation in obese/insulin resistant B cell–null mice associates with an increased percentage of anti-inflammatory regulatory T cells (Tregs). This increase contrasts with the sharply decreased percentage of Tregs in obese compared with lean WT mice and suggests that B cells may be critical regulators of T-cell functions previously shown to play important roles in IR. We demonstrate that B cells from T2D (but not non-T2D) subjects support proinflammatory T-cell function in obesity/T2D through contact-dependent mechanisms. In contrast, human monocytes increase proinflammatory T-cell cytokines in both T2D and non-T2D analyses. These data support the conclusion that B cells are critical regulators of inflammation in T2D due to their direct ability to promote proinflammatory T-cell function and secrete a proinflammatory cytokine profile. Thus, B cells are potential therapeutic targets for T2D.     

Clinical features, diagnosis, and management of multiple drug-resistant tuberculosis since 2002

PURPOSE OF REVIEW: Multiple drug-resistant tuberculosis is increasing globally, particularly in Eastern Europe. This review summarizes advances in our understanding of the epidemiology, diagnosis, and treatment of MDRTB in 2002-2003. RECENT FINDINGS: The annual incidence of multiple drug-resistant tuberculosis globally is unknown because systematic drug resistance data have been produced from only 60 countries internationally. Nevertheless, countries with effective tuberculosis programs see approximately 1% multiple drug-resistant tuberculosis among new cases annually. Hot spots with high rates such as countries of the former Soviet Union exist, and modeling of existing data suggests that between 250,000 and 500,000 new MDRTB cases occur globally. Unfortunately, mortality from multiple drug-resistant tuberculosis, particularly with HIV co-infection, remains high, and the global economic costs are also substantial. Research has produced many rapid and novel diagnostic methods for multiple drug-resistant tuberculosis, but culture-based methods remain the mainstay of analyzing resistance to drugs other than isoniazid and rifampicin. Treatment of multiple drug-resistant tuberculosis is prolonged, and survival requires therapy with at least three agents to which the bacteria are susceptible. Individualized therapy forms the gold standard of treatment, but the high laboratory costs associated with this approach have led to studies of standardized treatment in middle-/low-income countries. Studies in Peru examined both approaches with comparable success. Nevertheless, even standardized treatment requires an accurate survey of drug resistance and an understanding and correction of the causes of the high rates of multiple drug-resistant tuberculosis. SUMMARY: The global rates of multiple drug-resistant tuberculosis are unknown. Rapid and early diagnosis of multiple drug-resistant tuberculosis improves survival and is of a public health benefit. Treatment requires prolonged effective combination chemotherapy.     

Genetic and antigenic heterogeneity of infectious bronchitis virus in South America: implications for control programmes

Infectious bronchitis virus (IBV) is a persistent sanitary problem for the South American poultry industry despite extensive vaccination. The IBV single-stranded RNA genome has high rates of mutation and recombination that generate a notorious virus variability. Since most IBV vaccines are type-specific, there is a need for constant surveillance of the circulating lineages and knowledge about their genetic and antigenic properties. Here we present an integrative analysis that provides the pattern of genetic variation of the South American IBV strains and information about their antigenic characteristics. The genetic analysis was performed using the S1 complete coding sequences of all available South American strains, including newly obtained Argentine and Uruguayan field samples. Our phylogenetic and phylodynamic analyses evidence that three main lineages (GI-1, GI-11 and GI-16) are extensively circulating in South American flocks. Strains of the GI-1 lineage (Massachusetts-type) were detected in Argentina, Brazil, Chile and Colombia. The GI-11 lineage is an exclusively South American lineage that emerged in the 1950s, and is the predominant lineage in Brazil and Uruguay at present. The GI-16 lineage emerged around 1979, and is currently circulating in most South American territories (Argentina, Chile, Uruguay, Colombia and Peru). The virus cross-neutralization test performed here reveals very low antigenic relatedness between GI-11 and GI-16 lineages (i.e. they are different serotypes). The results of this study extend our knowledge about the present and past IBV variability in South America and provide relevant elements to improve the control programmes by considering the genetic and antigenic attributes of IBV.     

Intracellular Trafficking of Bordetella pertussis in Human Macrophages

Although Bordetella pertussis has been observed to survive inside macrophages, its ability to resist or evade degradation in phagolysosomes has not been defined. We here investigated the trafficking of B. pertussis upon entry into human macrophages. During the first hours following phagocytosis, a high percentage of bacteria were destroyed within acidic compartments positive for the lysosome-associated membrane proteins (LAMP). However, roughly one-fourth of the bacteria taken up evade this initial killing event, remaining in nonacidic compartments. Forty-eight hours after infection, the number of intracellular bacteria per cell increased, suggesting that B. pertussis is capable of replicating in this type of compartment. Viable bacteria accumulated within phagosomal compartments positive for the early endosomal marker Rab5 but not the late endosomal marker LAMP. Moreover, B. pertussis-containing phagosomes acquired exogenously added transferrin, indicating that intracellular bacteria have access to extracellular components and essential nutrients via the host cell recycling pathway. Overall, these results suggest that B. pertussis survives and eventually replicates in compartments with characteristics of early endosomes, potentially contributing to its extraordinary ability to persist within hosts and populations.Bordetella pertussis colonizes the human respiratory tract, causing a disease known as whooping cough or pertussis, which affects around 4 million people worldwide and causes more than 300,000 deaths each year. Despite high vaccination rates, whooping cough remains a serious threat to human health and its incidence has been increasing in recent years in vaccinated populations. Although some potential contributors to initial colonization have been described, the mechanisms that allow this pathogen to evade immune clearance and to cause the extraordinarily prolonged disease known in China as Bai Ri Ke (100-day cough) are not known.B. pertussis expresses a number of potent virulence factors, adhesins, and toxins (23) with known or predicted roles during infection. Although B. pertussis is described as an extracellular pathogen, several studies indicate that the immunomodulatory properties of several of these virulence factors enable the bacterium to persist within epithelial cells and leukocytes (1, 3, 22, 24), leading to speculation that the infection might also comprise an intracellular stage. The dual extra- and intracellular locations of B. pertussis are also consistent with the reported need for both cellular and humoral immune responses for bacterial elimination from the respiratory tract (12, 17, 33, 38).It is presumed that macrophages play an important role in the clearance of B. pertussis (21). However, in vitro studies indicated that B. pertussis is capable of surviving intracellularly in human macrophages for several days in the absence of opsonins (11). Moreover, B. pertussis was found viable in alveolar macrophage cells of mice for more than 21 days after infection (16). These observations have led to speculation that alveolar macrophages might represent an intracellular niche for B. pertussis (16, 41). The recovery of viable B. pertussis from human hosts several weeks after infection (19, 30) and the observation of B. pertussis within pulmonary alveolar macrophages of HIV-infected children (7) and in infants with confirmed B. pertussis pneumonia (28) provide support for this theory.Efforts to characterize the interaction between B. pertussis and human macrophages have been mainly focused on B. pertussis adherence. Several B. pertussis virulence factors facilitate interaction with phagocytes. B. pertussis fimbriae mediate the binding to the very late antigen 5 receptor on monocytes and macrophages, inducing the upregulation of complement receptor 3 (CR3: CD11b/CD18) (14). CR3 expression is further upregulated by pertussis toxin and filamentous hemagglutinin (FHA) (18, 42). It has been demonstrated that CR3 serves as a docking molecule for B. pertussis binding by FHA (18, 31), which eventually leads to B. pertussis uptake in a nonbactericidal way (15). However, little is known about the fate of B. pertussis inside macrophages. Recent studies by our group showed that neutrophil uptake of B. pertussis in the absence of specific antibodies leads to the failure of lysosomal maturation and bacterial clearance (20). These observations are intriguing evidence that B. pertussis has mechanisms that can allow for evasion of phagolysosome biogenesis. However, short-lived neutrophils are unlikely to provide a prolonged reservoir of bacteria, and evasion of phagolysosome biogenesis in macrophages appears to be an important aspect of the persistence of many other pathogens (9, 10, 29, 40).The aim of this study was to determine the fate of B. pertussis following phagocytosis by macrophages. Although many ingested bacteria were rapidly killed by macrophages, a significant fraction of internalized B. pertussis was capable of evading phagosome-lysosome fusion, surviving for days and eventually replicating in nonacidic compartments with characteristics of early endosomes. These results reveal a pathway that may contribute to both the extraordinarily long persistence of the coughing illness caused by B. pertussis and its ability to persist within largely immune populations.     

Chimerism of allogeneic mesenchymal cells in bone marrow,liver, and spleen after mesenchymal stem cells infusion

Although an infusion of culture‐expanded MSCs is applied in clinic to improve results of HSCs transplantation and for a treatment of musculoskeletal disorders, homing, and engraftment potential of culture‐expanded MSC in humans is still obscure. We report two female patients who received allogeneic BM transplantation as a treatment of hematological diseases and a transplantation of MSCs from third‐party male donors. Both patients died within one yr of infectious complications. Specimens of paraffin‐embedded blocks of tissues from transplanted patients were taken. The aim of the study was to estimate possible homing and engraftment of allogeneic BM‐derived MSCs in some tissues/organs of recipient. Sensitive real‐time quantitative PCR analysis was applied with SRY gene as a target. MSC chimerism was found in BM, liver, and spleen of both patients. We conclude that sensitive RQ‐PCR analysis is acceptable for low‐level chimerism evaluation even in paraffin‐embedded tissue specimens.