Single-cell atlas of the small intestine throughout the human lifespan demonstrates unique features of fetal immune cells

Proper development of mucosal immunity is critical for human health. Over the past decade, it has become evident that in humans, this process begins in utero. However, there are limited data on the unique features and functions of fetal mucosal immune cells. To address this gap, we integrated several single-cell ribonucleic acid sequencing datasets of the human small intestine (SI) to create an SI transcriptional atlas throughout the human life span, ranging from the first trimester to adulthood, with a focus on immune cells. Fetal SI displayed a complex immune landscape comprising innate and adaptive immune cells that exhibited distinct transcriptional programs from postnatal samples, especially compared with pediatric and adult samples. We identified shifts in myeloid populations across gestation and progression of memory T-cell states throughout the human lifespan. In particular, there was a marked shift of memory T cells from those with stem-like properties in the fetal samples to fully differentiated cells with a high expression of activation and effector function genes in adult samples, with neonatal samples containing both features. Finally, we demonstrate that the SI developmental atlas can be used to elucidate improper trajectories linked to mucosal diseases by implicating developmental abnormalities underlying necrotizing enterocolitis, a severe intestinal complication of prematurity. Collectively, our data provide valuable resources and important insights into intestinal immunity that will facilitate regenerative medicine and disease understanding.

Immune dysregulation in Glycogen Storage Disease 1b - a CyTOF approach

Glycogen Storage Disease type 1b (GSD1b) is a rare disease manifesting as hypoglycemia, recurrent infections and neutropenia, resulting from deleterious mutations in the SLC37A4 gene encoding the glucose-6-phosphate transporter. The susceptibility to infections is thought to be attributed not only to the neutrophil defect, though extensive immunophenotyping characterization is currently missing. Here we apply a systems immunology approach utilizing Cytometry by Time Of Flight (CyTOF) to map the peripheral immune landscape of 6 GSD1b patients. When compared to control subjects, those with GSD1b had a significant reduction in anti-inflammatory macrophages, CD16+ macrophages, and Natural Killer cells. Additionally, there was a preference towards a central versus an effector memory phenotype in multiple T cell populations, which may suggest that these changes stem from an inability of activated immune cell populations to undergo the appropriate switch to glycolytic metabolism in the hypoglycemic conditions associated with GSD1b. Furthermore, we identified a global reduction of CD123, CD14, CCR4, CD24 and CD11b across several populations and a multi-cluster upregulation of CXCR3, hinting at a potential role of impaired immune cell trafficking in the context of GSD1b. Taken together, our data indicates that that the immune impairment observed in GSD1b patients extends far beyond neutropenia and encompasses innate and adaptive compartments, which may provide novel insights into the pathogenesis of this disorder.

Molecular epidemiology of HIV-1 infection in the Philippines, 1985 to 1997: transmission of subtypes B and E and potential emergence of subtypes C and F

The molecular epidemiology of HIV-1 infection in the Philippines from 1985 to 1997 was investigated following subtyping of 54 (33 women, 21 men) prospectively collected clinical specimens using the heteroduplex mobility assay (HMA). In contrast with other Asian countries, subtype B accounted for most (70%) of the infections in the population studied, among female commercial sex workers (CSWs, 18 of 28), overseas contract workers (OCWs, 7 of 10), and men who have sex with men (MSM, 8 of 10). However, although viral specimens from HIV-seropositive persons diagnosed before 1993 (n = 16) were all of subtype B, diagnoses in more recent years (1993-present, n = 38) indicate the existence of subtypes E (29%), F (8%), and C (5%) in the population. Since its estimated introduction in the early 1990s, subtype E has accounted for 60% of the infections among female CSWs diagnosed after 1992 (n = 15). This genotype distribution shift occurred in parallel with a shift in transmission focus from the U.S. military bases to the the Philippine national capital region. So far, both events appear to have had no significant effect on the stability of HIV-1 transmission in the country. The recent identification of non-B subtypes in the Philippines may present novel insights on the dynamics of HIV-1 transmission in a high-risk but low-HIV prevalence setting in Asia.

Effect of didactic teaching and experiential learning on nursing students' AIDS-related knowledge and attitudes

A total of 562 nursing students from Manila, the Philippines participated in a quasi-experimental design study which assessed the comparative effectiveness of didactic teaching and experiential learning. A 3-hour training session with identical content on AIDS epidemiology, infection control, socio-ethical issues related to HIV infection and nursing care of patients in the hospital and in the community was given by the same two teachers to the two groups, one using an experiential learning approach and the other a didactic teaching approach. Both groups had a person with HIV/AIDS narrating his/her life story and answering questions. A control group received no education. Significant differences were found in a 2 x 3 (pre-/post-test x teaching method) ANOVA. Knowledge post-test scores were significantly higher for the two teaching groups while there was no change in the control group. Students in the experiential group had significantly higher scores than the didactic group on the three knowledge post-tests. In the attitude tests, only the scale measuring fear of attracting HIV had significantly higher post-test scores than pre-test scores but there was no significant difference between the didactic teaching and experiential learning groups. The use of experiential learning is recommended in training situations where experienced facilitators are available.

Longitudinal studies of children born to HIV-1 antibody positive Filipino commercial sex workers (CSW): diagnostic dilemmas

Fifteen term babies born to 12 HIV-1 antibody positive Filipino CSW have been monitored for signs and symptoms of HIV-1 infection. Eleven babies were enrolled in the study within the first 6 months after birth; 4 others were enrolled at 4, 9, 11 and 21 months of age respectively. Every 3 months after enrolment, each baby received a physical examination, serum was tested for HIV-1 antibodies and p24 antigen and peripheral blood mononuclear cells were cultured for isolation of virus. After a mean follow-up period of 39.3 months (range 7-72 months), virus isolation and serum p24 antigen assays confirmed that 2 babies have been infected with HIV-1. If the 4 babies less than 18 months of age were excluded, the vertical transmission rate was 18.2%. Seven babies who have been monitored for a minimum of 25 months (range 31-60 months) lost their maternal antibodies but 6 of them subsequently developed indeterminant Western blots (WB); reactivity to p24 and/or gp120/ 160 but no reactivity to gp41. Of the remaining 6 babies, still less than 25 months of age (range 7-24 months), 2 lost their maternal antibodies within one year. The other 4 continued to recognize either p24 or gp120/160 well after the accepted 15-month period for loss of maternal antibody. Although a diagnosis could not be established upon the basis of these laboratory findings, clinical observations (failure to thrive, anergy, persistent generalized lymphadenopathy and recurrent pneumonias) mimicked HIV-1 infection. However, because these clinical features are common among many babies in the developing world, their usefulness in supporting a diagnosis of perinatal HIV-1 infection is limited.

Natural history of HIV infection in Filipino female commercial sex workers

A prospective follow-up study of the progression of HIV infection, from seroconversion to onset of opportunistic infections (OI) indicative of immune deficiency and to death, was performed in a cohort of 54 HIV-1 antibody positive Filipino female commercial sex workers (FCSW). The cumulative probability of having a CD4+ T cell count of < 200/mm3 and/or an OI indicative of severe immune deficiency was 52.9% within 5 years and 73.8% within 6 years after seroconversion. The cumulative probability of death was 52.1% within 6.5 years following seroconversion and 52.7% within 1.5 years after a depressed (< 200/mm3) CD4+ T cell or onset of an OI. Although several OI associated with immune impairment were observed, a CD4+ cell count of < 200/mm3 was the initial indicator of a failing immune system in more than 50% of the patients. Mycobacterium tuberculosis or unidentified acid fast bacilli (presumed to be M. tuberculosis) and Pneumocystis carinii pneumonia were the initial indicators of immune deficiency in the remaining patients.