Gender differences in appointments to pathology department interim chair positions and subsequent advancement to permanent chair positions.

Females are under-represented as departmental chairs in academic medical centers and identifying ways to increase their numbers in this position would be useful. A previous study of women chairs of pathology showed that 35% of permanent chairs had previously been interim chairs, suggesting that the interim position was a common pathway for women to advance to a permanent chair position. We sought to determine whether it might also be true for males and if not, possible reasons for the difference. Between January 2016 and June 2022, the Association of Pathology Chairs identified 50 people who had served as interim pathology department chairs. Males served as interim chairs more often than females (66% vs 34%), but, within this time frame, female interim chairs were more likely to become permanent chairs than males (47% of females compared to 27% of males). To better understand the difference in the rate of advancement from interim to permanent chair, we surveyed the 50 individuals who had served as interim chairs to explore gender differences in backgrounds, reasons for serving as interim chairs and reasons for seeking or not seeking the permanent chair position. No significant gender differences were found except that male interim chairs were older (59.2 years) than female interim chairs (50.4 years). This study affirms that serving as an interim chair is a common pathway for females to become permanent chairs, while it is less so for males, although the reasons for this difference could not be determined.

Women in Academic Pathology: Pathways to Department Chair.

The Association of Pathology Chairs, an organization of American and Canadian academic pathology departments, has a record percent of women department chairs in its ranks (31%), although still not representative of the percent of women pathology faculty (43%). These women chairs were surveyed to determine what had impeded and what had facilitated their academic advancement before becoming chairs. The 2 most frequently identified impediments to their career advancement were heavy clinical loads and the lack of time, training, and/or funding to pursue research. Related to the second impediment, only one respondent became chair of a department which was in a top 25 National Institutes of Health-sponsored research medical school. Eighty-nine percent of respondents said that they had experienced gender bias during their careers in pathology, and 31% identified gender bias as an important impediment to advancement. The top facilitator of career advancement before becoming chairs was a supportive family. Strikingly, 98% of respondents have a spouse or partner, 75% have children, and 38% had children younger than 18 when becoming chairs. Additional top facilitators were opportunities to attend national meetings and opportunities to participate in leadership. Previous leadership experiences included directing a clinical service, a residency training program, and/or a medical student education program. These results suggest important ways to increase the success of women in academic pathology and increasing the percent of women department chairs, including supporting a family life and providing time, encouragement and resources for research, attending national meetings, and taking on departmental leadership positions.

Life After Being a Pathology Department Chair III: Reflections on the "Afterlife".

The Association of Pathology Chairs Senior Fellows Group provided reflections on activities that have kept them engaged and inspired after stepping down as chair. They offered advice to current chairs who were considering leaving their positions and also to individuals contemplating becoming pathology chairs. A majority (35/41) responded: 60% maintained teaching/mentoring activities; 43% engaged in hobbies; 40% took other administrative positions including deans, medical center chief executive officers, and residency program directors; 31% continued research; 28% wrote books; 20% performed community service; 14% led professional organizations; 14% developed specialized programs; 11% engaged in clinical service; and 11% performed entrepreneurial activities. Most individuals had several of these activities. One-third indicated that those considering becoming chair should be able to place faculty and department needs before their own. One-fourth emphasized the need to know why one wants to become chair, the need to develop clear goals, and the need to know what one wants to accomplish as chair before applying for and accepting the position. More than half (57%) indicated that before stepping down as chair, one should have a clear plan and/or professional goals that can be served by stepping down. Some even suggested that this be in place before applying for the chair. Almost two-thirds (63%) indicated they had no regrets stepping down as chair. These findings may be valuable to those contemplating stepping down from or stepping into any department chair position or other academic leadership role.

What Advice Current Pathology Chairs Seek From Former Chairs.

The 2018 Association of Pathology Chairs annual meeting included a panel discussion of Association of Pathology Chairs senior fellows (former chairs of academic departments of pathology who have remained active in Association of Pathology Chairs) about the type of advice that current (sitting) pathology chairs ask them. To inform the panel discussion, information was obtained from the senior fellows by e-mail and subsequent conference call. Of the 33 respondents, 24 (73%) had provided consultation advice (9, <5; 11, 5-10; 2, 10-20; and 2, >20). Most (>75%) of the consultations were provided face-to-face and outside the framework of Association of Pathology Chairs, with 70% of those seeking advice being well known by the consultant(s). Of the senior fellows providing advice, 71% had themselves sought consultation from former pathology chairs and 75% from nonpathology chairs. Modest correlation was found between the number of consultations senior fellows sought when they were chairs and the number of consultations they subsequently provided. The most frequent topics of consultation were strategic planning, balancing the missions, setting department priorities, recruitment of faculty and staff, conflict management, issues specific to new chairs, and resource (money/space) issues. Those who had provided such advice the longest and to the most people indicated that there was no significant change in the type of questions asked over time. Former department chairs can be a valuable source of counseling for current chairs, and organizations of department chairs should consider formalizing the use of these individuals as consultants to sitting chairs.

Life After Being a Pathology Department Chair II: Lessons Learned.

The 2016 Association of Pathology Chairs annual meeting featured a discussion group of Association of Pathology Chairs senior fellows (former chairs of academic departments of pathology who have remained active in Association of Pathology Chairs) that focused on how they decided to transition from the chair, how they prepared for such transition, and what they did after the transition. At the 2017 annual meeting, the senior fellows (encompassing 481 years of chair service) discussed lessons they learned from service as chair. These lessons included preparation for the chairship, what they would have done differently as chair, critical factors for success as chair, factors associated with failures, stress reduction techniques for themselves and for their faculty and staff, mechanisms for dealing with and avoiding problems, and the satisfaction they derived from their service as chair. It is reasonable to assume that these lessons may be representative of those learned by chairs of other specialties as well as by higher-level academic administrators such as deans, vice presidents, and chief executive officers. Although the environment for serving as a department chair has been changing dramatically, many of the lessons learned by former chairs are still valuable for current chairs of any length of tenure.

Life After Being a Pathology Department Chair: Issues and Opportunities.

Although there is a considerable literature on transition of faculty members to the position of department chair, there is a dearth of publications about transitioning from the chair to other activities including retirement. The Association of Pathology Chairs senior fellows (all of whom are former chairs of academic departments of pathology) made this topic a focus of discussion at the Association of Pathology Chairs 2016 Annual Meeting. Of the 33 senior fellows engaged in this discussion, following their time as chairs, a small majority (18) transitioned to other administrative posts within or outside the university, while the others either returned to the active faculty (7) or retired (8). The motivating factors and influences for transitioning from the chair were probed along with the processes used in executing the transition, such as the development of transition plans. The reasons for selecting the specific type of postchair activity were also investigated. There was extraordinary diversity in the type of post-chair activities pursued. To our knowledge, no other medical specialty has examined these issues, which may be potentially relevant for the career planning of active chairs.

Lethal factor, but not edema factor, is required to cause fatal anthrax in cynomolgus macaques after pulmonary spore challenge.

Inhalational anthrax is caused by inhalation of Bacillus anthracis spores. The ability of B. anthracis to cause anthrax is attributed to the plasmid-encoded A/B-type toxins, edema toxin (edema factor and protective antigen) and lethal toxin (lethal factor and protective antigen), and a poly-d-glutamic acid capsule. To better understand the contribution of these toxins to the disease pathophysiology in vivo, we used B. anthracis Ames strain and isogenic toxin deletion mutants derived from the Ames strain to examine the role of lethal toxin and edema toxin after pulmonary spore challenge of cynomolgus macaques. Lethal toxin, but not edema toxin, was required to induce sustained bacteremia and death after pulmonary challenge with spores delivered via bronchoscopy. After intravenous challenge with bacilli to model the systemic phase of infection, lethal toxin contributed to bacterial proliferation and subsequent host death to a greater extent than edema toxin. Deletion of protective antigen resulted in greater loss of virulence after intravenous challenge with bacilli than deletion of lethal toxin or edema toxin alone. These findings are consistent with the ability of anti-protective antigen antibodies to prevent anthrax and suggest that lethal factor is the dominant toxin that contributes to the escape of significant numbers of bacilli from the thoracic cavity to cause anthrax after inhalation challenge with spores.

Cowpox virus inhibits human dendritic cell immune function by nonlethal, nonproductive infection.

Orthopoxviruses encode multiple proteins that modulate host immune responses. We determined whether cowpox virus (CPXV), a representative orthopoxvirus, modulated innate and acquired immune functions of human primary myeloid DCs and plasmacytoid DCs and monocyte-derived DCs (MDDCs). A CPXV infection of DCs at a multiplicity of infection of 10 was nonproductive, altered cellular morphology, and failed to reduce cell viability. A CPXV infection of DCs did not stimulate cytokine or chemokine secretion directly, but suppressed toll-like receptor (TLR) agonist-induced cytokine secretion and a DC-stimulated mixed leukocyte reaction (MLR). LPS-stimulated NF-κB nuclear translocation and host cytokine gene transcription were suppressed in CPXV-infected MDDCs. Early viral immunomodulatory genes were upregulated in MDDCs, consistent with early DC immunosuppression via synthesis of intracellular viral proteins. We conclude that a nonproductive CPXV infection suppressed DC immune function by synthesizing early intracellular viral proteins that suppressed DC signaling pathways.

The pathogenesis of acute pulmonary viral and bacterial infections: investigations in animal models.

Acute viral and bacterial infections in the lower respiratory tract are major causes of morbidity and mortality worldwide. The proper study of pulmonary infections requires interdisciplinary collaboration among physicians and biomedical scientists to develop rational hypotheses based on clinical studies and to test these hypotheses in relevant animal models. Animal models for common lung infections are essential to understand pathogenic mechanisms and to clarify general mechanisms for host protection in pulmonary infections, as well as to develop vaccines and therapeutics. Animal models for uncommon pulmonary infections, such as those that can be caused by category A biothreat agents, are also very important because the infrequency of these infections in humans limits in-depth clinical studies. This review summarizes our understanding of innate and adaptive immune mechanisms in the lower respiratory tract and discusses how animal models for selected pulmonary pathogens can contribute to our understanding of the pathogenesis of lung infections and to the search for new vaccines and therapies.

Discriminating virulence mechanisms among Bacillus anthracis strains by using a murine subcutaneous infection model.

Bacillus anthracis strains harboring virulence plasmid pXO1 that encodes the toxin protein protective antigen (PA), lethal factor, and edema factor and virulence plasmid pXO2 that encodes capsule biosynthetic enzymes exhibit different levels of virulence in certain animal models. In the murine model of pulmonary infection, B. anthracis virulence was capsule dependent but toxin independent. We examined the role of toxins in subcutaneous (s.c.) infections using two different genetically complete (pXO1(+) pXO2(+)) strains of B. anthracis, strains Ames and UT500. Similar to findings for the pulmonary model, toxin was not required for infection by the Ames strain, because the 50% lethal dose (LD(50)) of a PA-deficient (PA(-)) Ames mutant was identical to that of the parent Ames strain. However, PA was required for efficient s.c. infection by the UT500 strain, because the s.c. LD(50) of a UT500 PA(-) mutant was 10,000-fold higher than the LD(50) of the parent UT500 strain. This difference between the Ames strain and the UT500 strain could not be attributed to differences in spore coat properties or the rate of germination, because s.c. inoculation with the capsulated bacillus forms also required toxin synthesis by the UT500 strain to cause lethal infection. The toxin-dependent phenotype of the UT500 strain was host phagocyte dependent, because eliminating Gr-1(+) phagocytes restored virulence to the UT500 PA(-) mutant. These experiments demonstrate that the dominant virulence factors used to establish infection by B. anthracis depend on the route of inoculation and the bacterial strain.

Effect of Bacillus anthracis virulence factors on human dendritic cell activation.

Bacillus anthracis possesses three primary virulence factors: capsule, lethal toxin (LT), and edema toxin (ET). Dendritic cells (DCs) are critical to innate and acquired immunity and represent potential targets for these factors. We examined the ability of B. anthracis spores and bacilli to stimulate human monocyte-derived DC (MDDC), primary myeloid DC (mDC), and plasmacytoid DC (pDC) cytokine secretion. Exposure of MDDCs and mDCs to spores or vegetative bacilli of the genetically complete strain UT500 induced significantly increased cytokine secretion. Spores lacking genes required for capsule biosynthesis stimulated significantly higher cytokine secretion than UT500 spores from mDCs, but not MDDCs. In contrast, bacilli lacking capsule stimulated significantly higher cytokine secretion than UT500 bacilli in both MDDCs and mDCs. Spores or bacilli lacking both LT and ET stimulated significantly higher cytokine secretion than UT500 spores or bacilli, respectively, in both mDCs and MDDCs. pDCs exposed to spores or bacilli did not produce significant amounts of cytokines even when virulence factors were absent. In conclusion, B. anthracis employs toxins as well as capsule to inhibit human MDDC and mDC cytokine secretion, whereas human pDCs respond poorly even when capsule or both toxins are absent.

Murine innate immune response to virulent toxigenic and nontoxigenic Bacillus anthracis strains.

Effective treatment of anthrax is hampered by our limited understanding of the pathophysiology of Bacillus anthracis infection. We used a genetically complete (pXO1(+) pXO2(+)) virulent B. anthracis strain and four isogenic toxin-null mutants to determine the effects of the anthrax edema toxin (ET; edema factor [EF] plus protective antigen [PA]) and lethal toxin (LT; lethal factor [LF] plus PA) on the host innate response during systemic infection. Using the spleen as an indicator for host response, we found that intravenous inoculation of LT-deficient mutants into C57BL/6 mice significantly increased production of several cytokines over that observed after infection with the parent strain or an EF-deficient mutant. Bacteria producing one or both of the toxins were capable of inducing significant apoptosis of cells present in spleens, whereas apoptosis was greatly reduced in mice infected with nontoxigenic mutants. Mice infected with toxin-producing strains also showed increased splenic neutrophil recruitment compared to mice infected with nontoxigenic strains and neutrophil depletion prior to infection with toxin-producing strains, leading to decreased levels of apoptosis. Together, these studies indicate that anthrax LT suppresses cytokine secretion during infection, but both EF and LF play roles in inducing neutrophil recruitment and enhancing apoptosis. Interestingly, in the absence of LF the effect of EF-induced cell recruitment is further enhanced, perhaps because LF so effectively suppresses the secretion of chemokines.

Characterization of myeloid and plasmacytoid dendritic cells in human lung.

Dendritic cells (DCs) are bone marrow-derived mononuclear cells that play a central role in the initiation of immune responses. Because human lung DCs have been incompletely characterized, we enumerated and phenotyped mononuclear cell populations from excess lung tissue obtained at surgery. Myeloid DCs (MDCs) were identified as CD1c(+)CD11c(+)CD14(-)HLA-DR(+) cells and comprised approximately 2% of low autofluorescent (LAF) mononuclear cells. Plasmacytoid DCs (PDCs) were characterized as CD123(+)CD11c(-)CD14(-)HLA-DR(+) cells and comprised approximately 1.0% of the LAF mononuclear cells. Cells enriched in MDCs expressed CD86, moderate CD80, and little CD40, but cells enriched in PDCs had little to no expression of these three costimulatory molecules. CD11c(+)CD14(-) lineage-negative (MDC-enriched) LAF cells were isolated and shown to be much more potent in stimulating an alloreaction than CD11c(+)CD14(+) lineage-negative (monocyte-enriched) LAF cells. PDC-enriched cells were more capable of responding to a TLR-7 agonist by secreting IFN-alpha than MDC-enriched cells. MDC-enriched cells were either CD123(+) or CD123(-), but both subsets secreted cytokines and chemokines typical of MDC upon stimulation with a TLR-4 agonist and both subsets failed to secrete IFN-alpha upon stimulation with a TLR-7 agonist. By immunohistochemistry, we identified MDCs throughout different anatomical locations of the lung. However, our method did not allow the localization of PDCs with certainty. In conclusion, in the human lung MDCs were twice as numerous and expressed higher levels of costimulatory molecules than PDCs. Our data suggest that both lung DC subsets exert distinct immune modulatory functions.

Toxin-deficient mutants of Bacillus anthracis are lethal in a murine model for pulmonary anthrax.

Bacillus anthracis, the etiologic agent of anthrax, produces at least three primary virulence factors: lethal toxin, edema toxin, and a capsule. The capsule is absolutely required for dissemination and lethality in a murine model of inhalation anthrax, yet the roles for the toxins during infection are ill-defined. We show in a murine model that when spores of specific toxin-null mutants are introduced into the lung, dissemination and lethality are comparable to those of the parent strain. Mutants lacking one or more of the structural genes for the toxin proteins, i.e., protective antigen, lethal factor, and edema factor, disseminated from the lung to the spleen at rates similar to that of the virulent parental strain. The 50% lethal dose (LD50) and mean time to death (MTD) of the mutants did not differ significantly from those of the parent. The LD50s or MTDs were also unaffected relative to those of the parent strain when mice were inoculated intravenously with vegetative cells. Nonetheless, histopathological examination of tissues revealed subtle but distinct differences in infections by the parent compared to some toxin mutants, suggesting that the host response is affected by toxin proteins synthesized during infection.

Murine model of pulmonary anthrax: kinetics of dissemination, histopathology, and mouse strain susceptibility.

Bioweapons are most often designed for delivery to the lung, although this route is not the usual portal of entry for many of the pathogens in the natural environment. Vaccines and therapeutics that are efficacious for natural routes of infection may not be effective against the pulmonary route. Pulmonary models are needed to investigate the importance of specific bacterial genes in virulence, to identify components of the host immune system that are important in providing innate and acquired protection, and for testing diagnostic and therapeutic strategies. This report describes the characteristics of host and Bacillus anthracis interactions in a murine pulmonary-infection model. The infective dose varied depending on the route and method of inoculation. The germination process in the lung began within 1 h of inoculation into the lung, although growth within the lung was limited. B. anthracis was found in the lung-associated lymph nodes approximately 5 h after infection. Minimal pneumonitis was associated with the lung infection, but significant systemic pathology was noted after dissemination. Infected mice typically succumbed to infection approximately 3 to 4 days after inoculation. The 50% lethal doses differed among inbred strains of mice, but within a given mouse strain, neither the age nor the sex of the mice influenced susceptibility to B. anthracis.

Flt3 ligand preferentially increases the number of functionally active myeloid dendritic cells in the lungs of mice.

In the present study, we investigated the effects of in vivo Flt3L administration on the generation, phenotype, and function of lung dendritic cells (DCs) to evaluate whether Flt3L favors the expansion and maturation of a particular DC subset. Injection of Flt3L into mice resulted in an increased number of CD11c-expressing lung DCs, preferentially in the alveolar septa. FACS analysis allowed us to quantify a 19-fold increase in the absolute numbers of CD11c-positive, CD45R/B220 negative DCs in the lungs of Flt3L-treated mice over vehicle-treated mice. Further analysis revealed a 90-fold increase in the absolute number of myeloid DCs (CD11c positive, CD45R/B220 negative, and CD11b positive) and only a 3-fold increase of lymphoid DCs (CD11c positive, CD45R/B220 negative, and CD11b negative) from the lungs of Flt3L-treated mice over vehicle-treated mice. Flt3L-treated lung DCs were more mature than vehicle-treated lung DCs as demonstrated by a significantly higher percentage of cells expressing MHC class II, CD86, and CD40. Freshly isolated Flt3L lung DCs were not fully mature, because after an overnight culture they continued to increase accessory molecule expression. Functionally, Flt3L-treated lung DCs were more efficient than vehicle-treated DCs at stimulating naive T cell proliferation. Our data show that administration of Flt3L favors the expansion of myeloid lung DCs over lymphoid DCs and enhanced their ability to stimulate naive lymphocytes.

Complementation of a capsule deficient Cryptococcus neoformans with CAP64 restores virulence in a murine lung infection.

Cryptococcosis is a systemic infection in humans caused by the opportunistic fungal pathogen, Cryptococcus neoformans. The infection usually presents as chronic meningoencephalitis, but infects via the respiratory tract. A polysaccharide capsule is a major virulence factor, which allows the yeast to resist host defenses. However, the essential role of the capsule in allowing it to resist host defenses during the initial lung infection has not been clearly shown. A mutant acapsular C. neoformans strain 602 was complemented with the CAP64 gene to obtain an encapsulated strain, TYCC38-602. TYCC38-602 persisted in the lungs of C.B-17 mice after intratracheal inoculation and disseminated to the brain, whereas the mutant acapsular 602 and the plasmid control transformant CIP3-602 strains grew less readily in the lung and were infrequently detected in the brain. T cell-mediated immunity, developed to the encapsulated organism, was required to control growth within the lungs and had a significant impact on numbers of yeasts detected in the brain. The parent acapsular strain, but not the transformant control, also required T cells for optimal inhibition of growth within the lung, but not for maintaining control of the colony-forming units (cfu) in the brain. In summary, the cryptococcal capsule plays an important role in lung virulence and dissemination to the brain, and intact immunity is required to control lung growth of the encapsulated yeast.

Dendritic cells: immune regulators in health and disease.

Dendritic cells (DCs) are bone marrow-derived cells of both lymphoid and myeloid stem cell origin that populate all lymphoid organs including the thymus, spleen, and lymph nodes, as well as nearly all nonlymphoid tissues and organs. Although DCs are a moderately diverse set of cells, they all have potent antigen-presenting capacity for stimulating naive, memory, and effector T cells. DCs are members of the innate immune system in that they can respond to dangers in the host environment by immediately generating protective cytokines. Most important, immature DCs respond to danger signals in the microenvironment by maturing, i.e., differentiating, and acquiring the capacity to direct the development of primary immune responses appropriate to the type of danger perceived. The powerful adjuvant activity that DCs possess in stimulating specific CD4 and CD8 T cell responses has made them targets in vaccine development strategies for the prevention and treatment of infections, allograft reactions, allergic and autoimmune diseases, and cancer. This review addresses the origins and migration of DCs to their sites of activity, their basic biology as antigen-presenting cells, their roles in important human diseases and, finally, selected strategies being pursued to harness their potent antigen-stimulating activity.