Comparison of fine-needle aspiration techniques

BACKGROUND

Fine-needle aspiration (FNA) has been reported since 1912 beginning with the use of trocars and other specialized instruments that were impractical. Since then, FNA has proven to be a successful alternative technique to excisional biopsy for some assays despite a few limitations.

METHODS

In this study, we compared four different techniques for FNA in rhesus macaques by evaluating total live cells recovered and cell viability using a standard 6 mL syringe and 1.5-inch 22-gauge needle.

RESULTS

Technique B which was the only technique in which the needle was removed from the syringe after collection of the sample to allow forced air through the needle to expel the contents into media followed by flushing of the syringe and needle resulted in the highest total cell count and second highest cell viability in recovered cells.

CONCLUSION

Based on our results, Technique B appears to be the superior method.

A combined adjuvant approach primes robust germinal center responses and humoral immunity in non-human primates

Adjuvants and antigen delivery kinetics can profoundly influence B cell responses and should be critically considered in rational vaccine design, particularly for difficult neutralizing antibody targets such as human immunodeficiency virus (HIV). Antigen kinetics can change depending on the delivery method. To promote extended immunogen bioavailability and to present antigen in a multivalent form, native-HIV Env trimers are modified with short phosphoserine peptide linkers that promote tight binding to aluminum hydroxide (pSer:alum). Here we explore the use of a combined adjuvant approach that incorporates pSer:alum-mediated antigen delivery with potent adjuvants (SMNP, 3M-052) in an extensive head-to-head comparison study with conventional alum to assess germinal center (GC) and humoral immune responses. Priming with pSer:alum plus SMNP induces additive effects that enhance the magnitude and persistence of GCs, which correlate with better GC-TFH cell help. Autologous HIV-neutralizing antibody titers are improved in SMNP-immunized animals after two immunizations. Over 9 months after priming immunization of pSer:alum with either SMNP or 3M-052, robust Env-specific bone marrow plasma cells (BM BPC) are observed. Furthermore, pSer-modification of Env trimer reduce targeting towards immunodominant non-neutralizing epitopes. The study shows that a combined adjuvant approach can augment humoral immunity by modulating immunodominance and shows promise for clinical translation.

Long-primed germinal centres with enduring affinity maturation and clonal migration

Germinal centres are the engines of antibody evolution. Here, using human immunodeficiency virus (HIV) Env protein immunogen priming in rhesus monkeys followed by a long period without further immunization, we demonstrate germinal centre B (BGC) cells that last for at least 6 months. A 186-fold increase in BGC cells was present by week 10 compared with conventional immunization. Single-cell transcriptional profiling showed that both light- and dark-zone germinal centre states were sustained. Antibody somatic hypermutation of BGC cells continued to accumulate throughout the 29-week priming period, with evidence of selective pressure. Env-binding BGC cells were still 49-fold above baseline at 29 weeks, which suggests that they could remain active for even longer periods of time. High titres of HIV-neutralizing antibodies were generated after a single booster immunization. Fully glycosylated HIV trimer protein is a complex antigen, posing considerable immunodominance challenges for B cells1,2. Memory B cells generated under these long priming conditions had higher levels of antibody somatic hypermutation, and both memory B cells and antibodies were more likely to recognize non-immunodominant epitopes. Numerous BGC cell lineage phylogenies spanning more than the 6-month germinal centre period were identified, demonstrating continuous germinal centre activity and selection for at least 191 days with no further antigen exposure. A long-prime, slow-delivery (12 days) immunization approach holds promise for difficult vaccine targets and suggests that patience can have great value for tuning of germinal centres to maximize antibody responses.

Multi-site proficiency testing for validation and standardization of assays to detect specific pathogen-free viruses, coronaviruses, and other agents in nonhuman primates

In efforts to increase rigor and reproducibility, the USA National Primate Research Centers (NPRCs) have focused on qualification of reagents, cross-laboratory validations, and proficiency testing for methods to detect infectious agents and accompanying immune responses in nonhuman primates. The pathogen detection working group, comprised of laboratory scientists, colony managers, and leaders from the NPRCs, has championed the effort to produce testing that is reliable and consistent across laboratories. Through multi-year efforts with shared proficiency samples, testing percent agreement has increased from as low as 67.1% for SRV testing in 2010 to 92.1% in 2019. The 2019 average agreement for the four basic SPF agents improved to >96% (86.5% BV, 98.9 SIV, 92.1 SRV, and 97.0 STLV). As new pathogens such as SARS coronavirus type 2 emerge, these steps can now be quickly replicated to develop and implement new assays that ensure rigor, reproducibly, and quality for NHP pathogen detection.

Acute Respiratory Distress in Aged, SARS-CoV-2-Infected African Green Monkeys but Not Rhesus Macaques

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a wide range of disease severity, ranging from asymptomatic infection to a life-threating illness, particularly in the elderly population and individuals with comorbid conditions. Among individuals with serious coronavirus 2019 (COVID-19) disease, acute respiratory distress syndrome (ARDS) is a common and often fatal presentation. Animal models of SARS-CoV-2 infection that manifest severe disease are needed to investigate the pathogenesis of COVID-19-induced ARDS and evaluate therapeutic strategies. We report two cases of ARDS in two aged African green monkeys (AGMs) infected with SARS-CoV-2 that had pathological lesions and disease similar to severe COVID-19 in humans. We also report a comparatively mild COVID-19 phenotype characterized by minor clinical, radiographic, and histopathologic changes in the two surviving, aged AGMs and four rhesus macaques (RMs) infected with SARS-CoV-2. Notable increases in circulating cytokines were observed in three of four infected, aged AGMs but not in infected RMs. All the AGMs had increased levels of plasma IL-6 compared with baseline, a predictive marker and presumptive therapeutic target in humans infected with SARS-CoV-2. Together, our results indicate that both RMs and AGMs are capable of modeling SARS-CoV-2 infection and suggest that aged AGMs may be useful for modeling severe disease manifestations, including ARDS.

Acute Respiratory Distress in Aged, SARS-CoV-2-Infected African Green Monkeys but Not Rhesus Macaques

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a wide range of disease severity, ranging from asymptomatic infection to a life-threating illness, particularly in the elderly population and individuals with comorbid conditions. Among individuals with serious coronavirus 2019 (COVID-19) disease, acute respiratory distress syndrome (ARDS) is a common and often fatal presentation. Animal models of SARS-CoV-2 infection that manifest severe disease are needed to investigate the pathogenesis of COVID-19–induced ARDS and evaluate therapeutic strategies. We report two cases of ARDS in two aged African green monkeys (AGMs) infected with SARS-CoV-2 that had pathological lesions and disease similar to severe COVID-19 in humans. We also report a comparatively mild COVID-19 phenotype characterized by minor clinical, radiographic, and histopathologic changes in the two surviving, aged AGMs and four rhesus macaques (RMs) infected with SARS-CoV-2. Notable increases in circulating cytokines were observed in three of four infected, aged AGMs but not in infected RMs. All the AGMs had increased levels of plasma IL-6 compared with baseline, a predictive marker and presumptive therapeutic target in humans infected with SARS-CoV-2. Together, our results indicate that both RMs and AGMs are capable of modeling SARS-CoV-2 infection and suggest that aged AGMs may be useful for modeling severe disease manifestations, including ARDS.

Tuberculosis Exacerbates HIV-1 Infection through IL-10/STAT3-Dependent Tunneling Nanotube Formation in Macrophages

The tuberculosis (TB) bacillus, Mycobacterium tuberculosis (Mtb), and HIV-1 act synergistically; however, the mechanisms by which Mtb exacerbates HIV-1 pathogenesis are not well known. Using in vitro and ex vivo cell culture systems, we show that human M(IL-10) anti-inflammatory macrophages, present in TB-associated microenvironment, produce high levels of HIV-1. In vivo, M(IL-10) macrophages are expanded in lungs of co-infected non-human primates, which correlates with disease severity. Furthermore, HIV-1/Mtb co-infected patients display an accumulation of M(IL-10) macrophage markers (soluble CD163 and MerTK). These M(IL-10) macrophages form direct cell-to-cell bridges, which we identified as tunneling nanotubes (TNTs) involved in viral transfer. TNT formation requires the IL-10/STAT3 signaling pathway, and targeted inhibition of TNTs substantially reduces the enhancement of HIV-1 cell-to-cell transfer and overproduction in M(IL-10) macrophages. Our study reveals that TNTs facilitate viral transfer and amplification, thereby promoting TNT formation as a mechanism to be explored in TB/AIDS potential therapeutics.

Similar cardiovascular disease histopathology and macrophages in heart tissues of younger adult SIV-infected and uninfected aged rhesus macaques

Cardiovascular disease is a major cause of morbidity in aging and in HIV-infected individuals despite efficacy of cART, and furthermore, is associated with macrophage activation and inflammation. Nonhuman primates simulate human disease, and we previously reported that distinct macrophage populations play different roles in the pathogenesis of disease during SIV infection in rhesus macaques. For example, in the lung, short-lived macrophages were more readily destroyed by SIV and contributed to AIDS pathogenesis. Long-lived alveolar macrophages on the other hand were not easily destroyed by virus and thus may contribute to a long-term virus reservoir that also promotes chronic inflammation. The present studies extend this work to characterize macrophages in heart and skeletal muscles affecting cardiomyopathy observed during SIV/HIV infection as well as in heart tissues of uninfected younger and older macaques. The results demonstrated that macrophages are distributed uniformly throughout the heart tissues in animals of all age groups. Increased percentages of macrophages, however, were observed in hearts of aged macaques with similar increased percentages of macrophages in SIV-infected younger adult macaques. Interestingly, the increased macrophages of both aged uninfected and younger SIV-infected macaques was not due to increases in the absolute numbers of macrophages but rather to decreased heart muscle cellularity. This suggested that cardiovascular disease observed in aged as well as HIV-infected individuals may be due to similar mechanisms of decreased number of heart muscle cells and dysfunctional inflammatory long-lived macrophages of the heart.

Tuberculosis-associated IFN-I induces Siglec-1 on tunneling nanotubes and favors HIV-1 spread in macrophages

While tuberculosis (TB) is a risk factor in HIV-1-infected individuals, the mechanisms by which Mycobacterium tuberculosis (Mtb) worsens HIV-1 pathogenesis remain scarce. We showed that HIV-1 infection is exacerbated in macrophages exposed to TB-associated microenvironments due to tunneling nanotube (TNT) formation. To identify molecular factors associated with TNT function, we performed a transcriptomic analysis in these macrophages, and revealed the up-regulation of Siglec-1 receptor. Siglec-1 expression depends on Mtb-induced production of type I interferon (IFN-I). In co-infected non-human primates, Siglec-1 is highly expressed by alveolar macrophages, whose abundance correlates with pathology and activation of IFN-I/STAT1 pathway. Siglec-1 localizes mainly on microtubule-containing TNT that are long and carry HIV-1 cargo. Siglec-1 depletion decreases TNT length, diminishes HIV-1 capture and cell-to-cell transfer, and abrogates the exacerbation of HIV-1 infection induced by Mtb. Altogether, we uncover a deleterious role for Siglec-1 in TB-HIV-1 co-infection and open new avenues to understand TNT biology.

Lack of susceptibility in neonatally infected rhesus macaques to simian immunodeficiency virus-induced encephalitis

Despite combination antiretroviral therapies making HIV a chronic rather than terminal condition for many people, the prevalence of HIV-associated neurocognitive disorders (HAND) is increasing. This is especially problematic for children living with HIV. Children diagnosed HAND rarely display the hallmark pathology of HIV encephalitis in adults, namely infected macrophages and multinucleated giant cells in the brain. This finding has also been documented in rhesus macaques infected perinatally with simian immunodeficiency virus (SIV). However, the extent and mechanisms of lack of susceptibility to encephalitis in perinatally HIV-infected children remain unclear. In the current study, we compared brains of macaques infected with pathogenic strains of SIV at different ages to determine neuropathology, correlates of neuroinflammation, and potential underlying mechanisms. Encephalitis was not found in the macaques infected within 24 h of birth despite similar high plasma viral load and high monocyte turnover. Macaques developed encephalitis only when they were infected after 4 months of age. Lower numbers of CCR5-positive cells in the brain, combined with a less leaky blood-brain barrier, may be responsible for the decreased virus infection in the brain and consequently the absence of encephalitis in newborn macaques infected with SIV.

Characterization of heart macrophages in rhesus macaques as a model to study cardiovascular disease in humans

Rhesus macaques are physiologically similar to humans and, thus, have served as useful animal models of human diseases including cardiovascular disease. The purpose of this study was to characterize the distribution, composition, and phenotype of macrophages in heart tissues of very young (fetus: 0.5 years, n = 6), young adult (2-12 years, n = 12), and older adult (13-24 years, n = 9) rhesus macaques using histopathology and immunofluorescence microscopy. Results demonstrated that macrophages were uniformly distributed throughout the heart in animals of all age groups and were more prevalent than CD3-positve T-cells and CD20-positive B-cells. Macrophages comprised approximately 2% of heart tissue cells in the younger animals and increased to a mean of nearly 4% in the older adults. CD163-positive macrophages predominated over HAM56-positive and CD206-positive macrophages, and were detected at significantly higher percentage in the animals between 13 and 24 years of age, as well as in heart tissues exhibiting severe histopathology or inflammation in animals of all age groups. In vivo dextran labeling and retention indicated that approximately half of the macrophages were longer lived in healthy adult heart tissues and may comprise the tissue-resident population of macrophages. These results provide a basis for continued studies to examine the specific functional roles of macrophage subpopulations in heart tissues during homeostasis and in cardiovascular disease for then developing intervention strategies.

Overexpression and activation of colony-stimulating factor 1 receptor in the SIV/macaque model of HIV infection and neuroHIV

In the present study, we investigated whether colony-stimulating factor 1 receptor (CSF1R) is expressed on brain macrophages and microglia in the human and macaque brain and whether it is upregulated and activated after lentivirus infection in vivo and contributes to development of encephalitic lesions. We examined, using multi-label and semi-quantitative immunofluorescence microscopy, the protein expression level and cellular localization of CSF1R in brain tissues from uninfected controls and SIV-infected adult macaques with or without encephalitis and also from uninfected controls, HIV-infected encephalitic subjects and virally suppressed subjects. In the normal uninfected brain, CSF1R protein was detected only on microglia and brain macrophages but not on neurons, astrocytes or oligodendrocytes. Microglia constitutively expressed CSF1R at low levels, and its expression was largely unchanged in non-encephalitic and encephalitic animals. Brain macrophages, including perivascular macrophages (PVMs), expressed higher levels of CSF1R compared to microglia. Interestingly, we found significantly increased expression of CSF1R on the infected PVMs and lesional macrophages in the brains of encephalitic macaques. Moreover, the per cell expression of CSF1R determined by its mean pixel intensity (MPI) correlated positively with the MPI of SIV Gag p28 in SIV-infected PVMs. Using phosphorylated CSF1R at tyrosine residue 723 and phosphorylated signal transducer and activator of transcription 5 at tyrosine reside 694 as markers for CSF1R activation, we found selective activation of CSF1R signaling in infected brain macrophages in encephalitis. We also found colocalization of CSF1R and its ligand CSF1 in PVMs and lesional macrophages in the brains of encephalitic macaques and humans. Notably, elevated brain CSF1R expression was found in virally suppressed subjects. These findings point to opportunities for developing a specific approach targeting infected brain macrophages, with several brain-penetrant CSF1R inhibitors that are available now, in order to eliminate central nervous system macrophage reservoirs, while not affecting resting uninfected microglia and PVMs that show no CSF1R activation.

Tuberculosis boosts HIV-1 production by macrophages through IL-10/STAT3 dependent tunneling nanotube formation

The tuberculosis (TB) bacillus, Mycobacterium tuberculosis (Mtb) and HIV-1 are known to act synergistically, however, the mechanisms by which Mtb exacerbates HIV-1 pathogenesis are not well known. Using in vitro and ex vivo cell culture system, we show that human M(IL-10) anti-inflammatory macrophages, present in TB-associated microenvironments, produced high levels of HIV-1. In vivo, M(IL-10) macrophages were expanded in lungs of co-infected non-human primates, their number correlated with disease severity, and markers for these cells (soluble CD163 and MerTK) accumulated in the blood of co-infected patients. These M(IL-10) macrophages formed direct cell-to-cell bridges, which we identified as tunneling nanotubes (TNTs) involved in viral transfer. TNT formation required the IL-10/STAT3 signaling pathway, and targeted inhibition of TNTs substantially reduced the enhanced HIV-1 cell-to-cell transfer and overproduction in M(IL-10) macrophages. Our study reveals that TNTs facilitate viral transfer and amplification, promoting TNT formation as a mechanism to be explored in TB/AIDS potential therapeutics.

Shifting Dynamics of Intestinal Macrophages during Simian Immunodeficiency Virus Infection in Adult Rhesus Macaques

The intestinal tract is a primary barrier to invading pathogens and contains immune cells, including lymphocytes and macrophages. We previously reported that CD163⁺CD206^- (single-positive [SP]) interstitial macrophages of the lung are short-lived and succumb early to SIV infection. Conversely, CD163⁺CD206⁺ (double-positive [DP]) alveolar macrophages are long-lived, survive after SIV infection, and may contribute to the virus reservoir. This report characterizes analogous populations of macrophages in the intestinal tract of rhesus macaques (Macaca mulatta) with SIV/AIDS. By flow cytometry analysis, immunofluorescence staining, and confocal microscopy, CD163⁺CD206⁺ DP macrophages predominated in the lamina propria of uninfected animals, compared with CD163⁺CD206^- SP macrophages, which predominated in the lamina propria in animals with SIV infection that were exhibiting AIDS. In submucosal areas, CD163⁺CD206⁺ DP macrophages predominated in both SIV-infected and uninfected macaques. Furthermore, BrdU-labeled CD163⁺CD206⁺ DP and CD163⁺CD206^- SP macrophages recently arriving in the colon, which are both presumed to be shorter-lived, were observed to localize only in the lamina propria. Conversely, longer-lived CD163⁺CD206⁺ DP macrophages that retained dextran at least 2 mo after in vivo administration localized exclusively in the submucosa. This suggests that CD163⁺CD206⁺ DP intestinal macrophages of the lamina propria were destroyed after SIV infection and replaced by immature CD163⁺CD206^- SP macrophages, whereas longer-lived CD163⁺CD206⁺ DP macrophages remained in the submucosa, supporting their potential role as an SIV/HIV tissue reservoir. Moreover, the DP macrophages in the submucosa, which differ from lamina propria DP macrophages, may be missed from pinch biopsy sampling, which may preclude detecting virus reservoirs for monitoring HIV cure.

Rapid Turnover and High Production Rate of Myeloid Cells in Adult Rhesus Macaques with Compensations during Aging

Neutrophils, basophils, and monocytes are continuously produced in bone marrow via myelopoiesis, circulate in blood, and are eventually removed from circulation to maintain homeostasis. To quantitate the kinetics of myeloid cell movement during homeostasis, we applied 5-bromo-2'-deoxyuridine pulse labeling in healthy rhesus macaques (Macaca mulatta) followed by hematology and flow cytometry analyses. Results were applied to a mathematical model, and the blood circulating half-life and daily production, respectively, of each cell type from macaques aged 5-10 y old were calculated for neutrophils (1.63 ± 0.16 d, 1.42 × 10⁹ cells/l/d), basophils (1.78 ± 0.30 d, 5.89 × 10⁶ cells/l/d), and CD14⁺CD16^- classical monocytes (1.01 ± 0.15 d, 3.09 × 10⁸ cells/l/d). Classical monocytes were released into the blood circulation as early as 1 d after dividing, whereas neutrophils remained in bone marrow 4-5 d before being released. Among granulocytes, neutrophils and basophils exhibited distinct kinetics in bone marrow maturation time and blood circulation. With increasing chronological age, there was a significant decrease in daily production of neutrophils and basophils, but the half-life of these granulocytes remained unchanged between 3 and 19 y of age. In contrast, daily production of classical monocytes remained stable through 19 y of age but exhibited a significant decline in half-life. These results demonstrated relatively short half-lives and continuous replenishment of neutrophils, basophils, and classical monocytes during homeostasis in adult rhesus macaques with compensations observed during increasing chronological age.

Role of Monocyte/Macrophages during HIV/SIV Infection in Adult and Pediatric Acquired Immune Deficiency Syndrome

Monocytes/macrophages are a diverse group of cells that act as first responders in innate immunity and then as mediators for adaptive immunity to help clear infections. In performing these functions, however, the macrophage inflammatory responses can also contribute to pathogenesis. Various monocyte and tissue macrophage subsets have been associated with inflammatory disorders and tissue pathogeneses such as occur during HIV infection. Non-human primate research of simian immunodeficiency virus (SIV) has been invaluable in better understanding the pathogenesis of HIV infection. The question of HIV/SIV-infected macrophages serving as a viral reservoir has become significant for achieving a cure. In the rhesus macaque model, SIV-infected macrophages have been shown to promote pathogenesis in several tissues resulting in cardiovascular, metabolic, and neurological diseases. Results from human studies illustrated that alveolar macrophages could be an important HIV reservoir and humanized myeloid-only mice supported productive HIV infection and viral persistence in macrophages during ART treatment. Depletion of CD4+ T cells is considered the primary cause for terminal progression, but it was reported that increasing monocyte turnover was a significantly better predictor in SIV-infected adult macaques. Notably, pediatric cases of HIV/SIV exhibit faster and more severe disease progression than adults, yet neonates have fewer target T cells and generally lack the hallmark CD4+ T cell depletion typical of adult infections. Current data show that the baseline blood monocyte turnover rate was significantly higher in neonatal macaques compared to adults and this remained high with disease progression. In this review, we discuss recent data exploring the contribution of monocytes and macrophages to HIV/SIV infection and progression. Furthermore, we highlight the need to further investigate their role in pediatric cases of infection.

Kinetics modeling of myeloid cells in rhesus macaques with pulse-chase BrdU labeling

Myeloid cells are continuously produced via bone marrow hematopoiesis and then cleared from the circulation to maintain homeostasis. To better understand the kinetics of such cell movement, we applied in vivo BrdU pulse-chase labeling and flow cytometry analysis to follow the kinetics of cell division during homeostasis of each subset of myeloid cells in peripheral blood in rhesus macaques. Results were applied to a mathematical model to estimate the half-life and daily production of each subset as follows; neutrophils (1.63±0.16 days, 1.42×109cells/L/day), basophils (1.78±0.30 days, 5.89×106 cells/L/day), classical monocytes (1.01±0.15 days, 3.09×108 cells/L/day), intermediate monocytes (1.23±0.14 days, 2.90×107 cells/L/day), non-classical monocytes (3.45±0.93 days, 1.58×107 cells/L/day), CD1c+ myeloid dendritic cells (DCs) (1.11±0.16 days, 1.65×107 cells/L/day), CD123+ plasmacytoid DCs (2.69±0.38 days, 9.67×105 cells/L/day). Unlike monocytes which were released into the blood circulation as soon as 1 day after dividing, neutrophils required ~4–5 days in bone marrow before being released. Interestingly, even within the granulocyte population, neutrophils and basophils exhibited distinct kinetics in peripheral blood and different bone marrow maturation times. We also applied our model to healthy rhesus macaques ranging from 3 to 19 years of age and observed that while the half-life of neutrophils did not change with increasing age, the older animals produced fewer neutrophils per day. In addition to neutrophils and monocytes, the non-classical (inflammatory) monocytes, pDCs and mDCs, as well as basophils, were relatively shorter-lived cells that may contribute to protection and homeostasis at steady state.

Investigation of Macrophages Serving as a Viral Reservoir in Pediatric SAIDS

In SIV-infected adult Macaca mulatta, increases in monocyte turnover indicates death of short-lived tissue macrophages and predicts SAIDS. Increased turnover also correlates with infection, not death, of long-lived tissue macrophages. Higher baseline monocyte turnover is measured in neonates, and faster disease progression. Our data shows increase in monocyte turnover and tissue macrophage infection is associated with rapid SAIDS progression in infants. We hypothesize early and high infection of macrophages results in establishment of viral reservoir in long-lived subsets, in infants not controlling viral load despite antiretroviral therapy (ART). In rhesus infants infected with SIVmac251, cell turnover is measured using BrdU uptake. Flow cytometry and confocal imaging allow phenotypic characterization of cells in blood and tissues. PCR and in situ hybridization are used to quantify SIV. Plasma cytokine analysis is performed using Milliplex bead panel. Infant macaques euthanized post-infection (no ART) are used to quantify macrophage infection. Animals euthanized after various lengths of ART provide data on reservoir seeding, viral persistence and immune activation status. ART-treated infants with discordant viral loads are evaluated to identify the source of viral replication. In treated animals, regardless of viral load, no differences are observed in activation status, absolute number, or kinetics of CD4 and CD8 T cells. Confocal imaging and viral RNA and DNA analysis of tissues and sorted cells should confirm that viral replication during ART is due to infected macrophages. Ongoing works suggest magnitude of long-lived macrophage infection may dictate effectiveness of ART in pediatric SIV infection.

Mesenchymal stem cell therapy for the treatment of amyotrophic lateral sclerosis: signals for hope?

Based on the distinctive cellular, molecular and immunomodulatory traits of mesenchymal stem cells (MSC), it has been postulated that these cells may play a critical role in regenerative medicine. In addition to the participation of MSC in the repair of mesodermal-derived tissues (bone, cartilage), robust data have suggested that MSC may also play a reparative role in conditions involving damage of cells of ectodermal origin. The above content has been supported by the capability of MSC to differentiate into neuron-like cells as well as by a competence to generate a ‘neuroprotective’ environment. In turn, several preclinical studies have put forward the concept that MSC therapy may represent an option for the treatment of several neurological disorders and injuries, including amyotrophic lateral sclerosis. We expect that the above foundations, which have inspired this review, may result in the founding of an effective and/or palliative therapy for amyotrophic lateral sclerosis.

Presence of osteoclast precursor cells during ex vivo expansion of bone marrow-derived mesenchymal stem cells for autologous use in cell therapy

BACKGROUND AIMS

To obtain a cell product competent for clinical use in terms of cell dose and biologic properties, bone marrow-derived mesenchymal stem cells (MSCs) must be expanded ex vivo.

METHODS

A retrospective analysis was performed of records of 76 autologous MSC products used in phase I or II clinical studies performed in a cohort of cardiovascular patients. In all cases, native MSCs present in patient bone marrow aspirates were separated and expanded ex vivo.

RESULTS

The cell products were classified in two groups (A and B), according to biologic properties and expansion time (ex vivo passages) to reach the protocol-established cell dose. In group A, the population of adherent cells obtained during the expansion period (2 ± 1 passages) was composed entirely of MSCs and met the requirements of cell number and biologic features as established in the respective clinical protocol. In group B, in addition to MSCs, we observed during expansion a high proportion of ancillary cells, characterized as osteoclast precursor cells. In this case, although the biologic properties of the resulting MSC product were not affected, the yield of MSCs was significantly lower. The expansion cycles had to be increased (3 ± 1 passages).

CONCLUSIONS

These results suggest that the presence of osteoclast precursor cells in bone marrow aspirates may impose a limit for the proper clinical use of ex vivo expanded autologous bone marrow-derived MSCs.

Mesenchymal stem cells and the treatment of conditions and diseases: the less glittering side of a conspicuous stem cell for basic research

Not too long ago, several motivated and forward-looking articles were published describing the cellular and molecular properties of mesenchymal stem cells (MSCs), specially highlighting their potential for self-renewal, commitment, differentiation, and maturation into specific mesoderm-derived lineages. A very influential publication of that period entitled "Mesenchymal stem cells: No longer second class marrow citizens" [1] raised the point of view that "…challenges to harness MSC cell therapy to treat diseases … need to wait for the full comprehension that marrow is a rich source of mesenchyme-derived cells whose potential is still far from fully appreciated." Whether or not the prophecy of Gerson was fulfilled, in the last 8 years it has become evident that infusing MSCs into patients suffering a variety of disorders represents a viable option for medical treatment. Accordingly, a vast number of articles have explored the privileged cellular and molecular features of MSCs prepared from sources other than the canonical, represented by the bone marrow. This review will provide more information neither related to the biological attractiveness of MSCs nor to the success after their clinical use. Rather, we would like to underscore several "critical and tangential" issues, not always discussed in biomedical publications, but relevant to the clinical utilization of bone-marrow-derived MSCs.

Intravenous administration of multipotent stromal cells prevents the onset of non-alcoholic steatohepatitis in obese mice with metabolic syndrome

BACKGROUND & AIMS

Metabolic syndrome is secondary to obesity and characterized by dyslipidemia, insulin resistance, and hypertension. Non-alcoholic fatty liver disease is its hepatic manifestation, whose progression-limiting step is non-alcoholic steatohepatitis (NASH). The latter is characterized by lipid accumulation, hepatocyte damage, leukocyte infiltration, and fibrosis. NASH is a prodrome to cirrhosis and hepatocellular carcinoma. Multipotent stromal cells (MSCs) have been shown to be immunomodulatory and contribute to liver regeneration in acute failure conditions. Our aim was to evaluate whether MSC administration prevents the onset of NASH in obese mice with metabolic syndrome.

METHODS

C57BL/6 mice were chronically fed with high-fat diet. At week 33, mice received intravenously either the vehicle (obese untreated) or two doses of 0.5×10(6) syngeneic MSCs (obese MSC-treated). Four months later, liver function and structure, and metabolic syndrome markers were assessed. The persistence of donor MSCs(GFP) in obese mice was evaluated 17 weeks after their administration.

RESULTS

Obese untreated mice presented high plasma levels of hepatic enzyme, hepatomegaly, liver fibrosis, inflammatory cell infiltration, and hepatic triglyceride accumulation. Furthermore, they showed high expression levels of fibrosis markers and pro-inflammatory cytokines. By contrast, obese MSC-treated mice only presented steatosis. Mice kept obese, hypercholesterolemic, hyperglycemic, and insulin resistant irrespective of whether they received MSCs or not. Donor MSCs(GFP) were found in liver, bone marrow, heart, and kidney of obese mice.

CONCLUSIONS

MSC administration prevents the onset of NASH in obese mice. Observed hepatoprotection is not related to a reversion of the metabolic syndrome but to the preclusion of the inflammatory process.

Restriction of HIV-1 by APOBEC3G is cytidine deaminase-dependent

Cytidine deamination is the primary mechanism by which APOBEC3G restricts HIV-1; however, several studies have reported that APOBEC3G also inhibits virus replication via a mechanism that is independent of deamination. Using active site APOBEC3G mutants, we have re-evaluated the biological relevance of deaminase-independent APOBEC3G-mediated restriction of HIV-1. APOBEC3G proteins with Glu-->Ala mutations in AS1, AS2 or AS1 and AS2 were stably expressed at physiological levels in CEM-SS T cells and 293T cells and the ability of the cells to support Deltavif HIV-1 replication was then tested. The AS2 and AS1/AS2 mutants were packaged efficiently into virions but in single-cycle or multi-cycle HIV-1 replication assays, were found to lack antiviral activity. The AS1 mutant, which retained deaminase activity, maintained near wild-type antiviral function. To determine the potency of APOBEC3G antiviral activity, cell lines were established that that expressed low levels of wild-type APOBEC3G and generated virions that contained as few as 1-2 APOBEC3G molecules. Even at very low copy number, APOBEC3G caused a significant reduction in infectivity, suggesting that a single molecule of packaged APOBEC3G inactivates the virus. The high potency of APOBEC3G is consistent with a catalytic mechanism of restriction in which a single molecule can induce a string of mutations but difficult to reconcile with a deaminase-independent, non-catalytic mechanism. Analysis of the reverse transcript sequences showed that the G-->A mutations were clustered, likely reflecting the action of single APOBEC3G molecules acting processively. We conclude that cytidine deamination is the mechanism by which APOBEC3G restricts HIV-1.

Dynamic of distribution of human bone marrow-derived mesenchymal stem cells after transplantation into adult unconditioned mice

BACKGROUND

The use of mesenchymal stem cells (MSC) for cell therapy relies on their capacity to engraft and survive long-term in the appropriate target tissue(s). Animal models have demonstrated that the syngeneic or xenogeneic transplantation of MSC results in donor engraftment into the bone marrow and other tissues of conditioned recipients. However, there are no reliable data showing the fate of human MSC infused into conditioned or unconditioned adult recipients.

METHODS

In the present study, the authors investigated, by using imaging, polymerase chain reaction (PCR), and in situ hybridization, the biodistribution of human bone marrow-derived MSC after intravenous infusion into unconditioned adult nude mice.

RESULTS

As assessed by imaging (gamma camera), PCR, and in situ hybridization analysis, the authors' results demonstrate the presence of human MSC in bone marrow, spleen, and mesenchymal tissues of recipient mice.

CONCLUSIONS

These results suggest that human MSC transplantation into unconditioned recipients represents an option for providing cellular therapy and avoids the complications associated with drugs or radiation conditioning.

[44-year-old patient with fulminant liver failure]

The 44-year old female patient was admitted with acute hepatic failure and extensive haemolysis under the preliminary diagnosis of Wilson's disease. General characteristic criteria of Wilson's disease as Kayser-Fleischer ring, low serum copper and low ceruloplasmin levels were not observed. The preliminary diagnosis of acute Wilson's disease was established on the basis of the characteristic laboratory values with an AP/bilirubin ratio <2, an AST/ALT ratio >4, accompanying hemolysis and a highly elevated cupruresis. The definitive diagnosis of Wilson's disease was verified after orthotopic liver transplantation by quantitative copper evaluation in the explanted liver. The case represents the yet oldest patient reported with an acute manifestation of Wilson's disease.

Amount of co-transplanted donor-derived leukocytes determines in-vivo microchimerism and mixed lymphocyte culture changes post-liver transplantation

OBJECTIVE

To evaluate the impact of passenger leukocytes in liver grafts on the rate of microchimerism induction after liver transplantation and to evaluate immunological changes thereafter based on serial donor-specific MLC's in these patients.

METHODS

26 orthotopic liver transplant recipients were prospectively evaluated for immunological changes based on the co-transplantation of donor-derived leukocytes. Intraoperatively harvested liver biopsies and peripheral blood-lymphocytes of liver transplant recipients were sampled at various time points. Donor spleen cells were obtained during organ procurement.

RESULTS

HLA-PCR analysis demonstrated a stable pattern of microchimerism in 15 out of 26 patients. Microchimerism was detectable by PCR up to a mean of 7 weeks after transplantation, when chimerism in the peripheral blood became negative. Passenger donor leukocytes were present in all biopsies obtained during backtable preparation of the liver graft. For the 15 patients presenting microchimerism the rate of passenger leukocytes in the liver graft biopsies showed a mean of 155.8 leukocytes per mm 2 liver tissue (SD +/- 23.2 cells/mm2, range 121 to 217 cells per mm2 tissue). Otherwise patients without chimerism showed a mean of 90.4 passenger leukocytes per mm2 tissue (SD +/- 14.5 cells/mm2, range: 52 to 99 cells/mm2). Lymphocyte proliferation, determined by donor-specific "multiple" single-way- mixed-lymphocyte-cultures (dsmMLC) was reduced to a mean of 62.2 % of preoperative values (SD +/- 14.5 %, range 33 % to 88 %) in the 15 patients with stable microchimerism. Otherwise in the 11 patients without microchimerism dsmMLC results stayed at continuously higher levels with a mean of 106 % (SD +/- 13.4, range 92 % to 134 %).

CONCLUSIONS

The results from these studies of microchimerism and lymphocyte reactivity after liver transplantation suggest that the co-transplantation of donor leukocytes plays an important and active role in the modulation of the host-immune system.

Validation in mesenchymal progenitor cells of a mutation-independent ex vivo approach to gene therapy for osteogenesis imperfecta

Over 100 dominant-negative mutations within the COL1A1 gene have been identified in osteogenesis imperfecta (OI). In terms of human therapeutics, targeting each of these mutations independently is unlikely to be feasible. Here we show that the hammerhead ribozyme Rzpol1a1, targeting a common polymorphism within transcripts from the COL1A1 gene, downregulates COL1A1 transcript in human mesenchymal progenitor cells at a ribozyme to transcript ratio of only 1:1. Downregulation was confirmed at the protein level. Transducing stem cells with Rzpol1A1 ex vivo followed by autologous transplantation could provide a gene therapy for a large proportion of OI patients with gain-of-function mutations using a single therapeutic.

Identification of a discrete population of human bone marrow-derived mesenchymal cells exhibiting properties of uncommitted progenitors

Human bone marrow-derived mesenchymal progenitor cells (MPC) after ex vivo expansion give rise to a heterogeneous mixture of cells with distinct proliferative potential at various stages of differentiation. Here we show that when proliferative MPC were forced to metabolic death by exposure to 5-fluorouracil, the remaining subset (5-20%) contains a population of quiescent, uncommitted, and undifferentiated mesenchymal cells. The isolated cells self-renew and generate precursors committed at least to the adipogenic and osteogenic lineages. Taken together, these results demonstrate that within ex vivo-expanded bone marrow-derived MPC, there exist a discrete population of mesenchymal cells with properties of uncommitted progenitors. Because these cells are capable of engraftment into bone marrow, spleen, bone, and skeletal muscle after intravenous infusion and can be efficiently transduced with adenoviral vectors, they may represent an interesting option for cellular and gene therapies for a wide range of disorders of mesenchymal tissues.

Impact of cyclosporine and low-dose steroid therapy on insulin sensitivity and beta-cell function in patients with long-term liver grafts

To examine whether factors controlling glucose tolerance, i.e., insulin sensitivity (SI) and first-(phi1) and second-phase insulin secretion (phi2), are impaired in after orthotopic liver transplantation (OLT), they were assesssed in patients that had undergone OLT for cirrhosis (n = 10) with cyclosporin A and low-dose steroid therapy (5 mg prednisone per day) and were compared with those of healthy matched control subjects (n = 10). These factors were determined by means of computer-based analysis of frequently sampled intravenous glucose tolerance tests (FSIGTT). Glucose and insulin profiles (posthepatic insulin) did not differ between both groups, whereas C-peptide levels (prehepatic insulin) were elevated in the transplant group after the FSIGTT, indicating an increased hepatic insulin degradation. SI and (phi1 did not differ between both groups. phi2, however, was significantly enhanced (23.94 +/- 2.63 vs 13.88 +/- 1.25 min(-1), P < 0.05). These results indicate that cyclosporine and low-dose steroid therapy do not impair SI and phi1. However, enhanced phi2 compensates the increased hepatic insulin clearance.

Blutungskomplikationen in der Leberchirurgie und bei der Lebertransplantation

Nachdem über Leberresektionen und Lebertransplantationen erst in den 60er Jahren berichtet wurde, werden diese heutezutage häufig durchgeführt und stellen sichere Verfahren dar. Aufgrund der technischen Weiterentwicklung der Leberchirurgie sind lebensbedrohliche intraoperative Blutungen selten geworden. Durch entsprechende präoperative Vorbereitung und blutsparende Resektionsverfahren können Blutungen weitgehend vermieden werden. Bei der LTx hat sicherlich die Standardisierung der Transplantationstechnik zu dieser positiven Entwicklung beigetragen. In den Vordergrund sind in der Leberchirurgie Störungen der endogenen Hämostase durch den teilweisen oder kompletten Ausfall der Leberfunktion getreten. Durch den Abfall der in der Leber synthetisierten Gerinnungsfaktoren und Kofaktoren kann es zu erheblichen perioperativen Blutverlusten kommen. Einer präoperativ bestehenden Leberfunktionsstörung kommt hierbei große Bedeutung zu. Diese erfordert dann postoperativ ein engmaschiges Monitoring und eine adaptierte Therapie. Durch die Verbesserung der operativen Ergebnisse wurden die Indikationen zur Leberresektion und -transplantation ausgeweitet: es werden sowohl erweiterte Resektionen als auch Resektionen bei Patienten mit vorbestehendem Leberparenchymschaden durchgeführt, Lebertransplantationen werden zunehmend in einem früheren Erkrankungsstadium vorgenommen. Voraussetzung für diese Ausweitung von Indikation und Resektionsausmaß sind eine verbesserte perioperative Betreuung und ein exaktes Verständnis der perioperativen Veränderungen im Leberstoffwechsel. Nicht zuletzt wurden diese Kenntnisse im Rahmen der Lebertransplantation mit temporärem Ausfall der Lebersyntheseleistung gewonnen.

[Liver transplantation and splenectomy in idiopathic portal hypertension]

Idiopathic portal hypertension (IPH) was diagnosed in a 30-year-old man. Clinical signs were splenomegaly, leucothrombocytopenia, and esophageal varices of fourth degree. The histology of the liver biopsy showed portal fibrosis with no evidence of cirrhosis. No causing agent or known disease could be found for the histopathological and clinical features. Due to a severe deterioration of general condition and a decline of synthetic liver function, liver transplantation and splenectomy were performed. The histological examination of the explanted liver revealed features of IPH, demonstrating portal fibrosis and dilated vessels adjacent to portal tracts; no cirrhosis was found. The postoperative recovery was without any severe complications. The duration of hospitalization was 28 days. Following liver transplantation, the esophageal varices disappeared and leucocytes, platelets as well as parameters of hepatic synthesis reached normal values. Initially, the immunosuppression was composed of prednisolon, tacrolimus, and antibodies against IL-2 receptors (BT 563) and was later continued with prednisolon and tacrolimus. Within the follow-up observation of 26 months, there was no evidence for graft rejection, severe infection, or occurrence of portal hypertension. Up till now the patient is in good condition with normal graft function. Liver transplantation may be a curative therapy for patients with advanced disease of IPH but the long-term follow-up after transplantation has to show whether IPH can reoccur.

[Pneumococcal vaccination after heart and liver transplantation. Immune responses in immunosuppressed patients and in healthy controls]

BASIC PROBLEM AND OBJECTIVE OF STUDY

Among other effects, therapeutic immunosuppression after organ transplantation impairs antibody formation. But because of the increased risk of infection, the efficacy of prophylactic immunization is of particular importance in patients after transplantation. For this reason the immunogenicity after immunization against pneumococcus was investigated in transplanted patients.

PATIENTS AND METHODS

A 23-valent vaccine of capsular polysaccharides (Pneumovax 23) was administered to 31 patients 4-85 months after transplantation (16 hearts transplants, 15 liver transplants; age range 22-63 years). The same immunization was given to 23 healthy control subjects. The immune response was measured serologically in all groups.

RESULTS

Immunization was well tolerated by all participants, and there were no infectious or systemic side effects. Mean postvaccinal global pneumococcus-specific antibody titres were comparable in the healthy and transplanted subjects (controls: 5490 U/ml, heart transplanted: 5513 U/ml, liver transplanted: 4148 U/ml; differences not significant). Analysis of individual titres for the nine most important serotypes showed comparable results for six serotypes, reduced titres being found for serotypes 3 and 8 after heart transplantation, and for serotypes 8 and 23 after liver transplantation.

CONCLUSION

Safe antipneumococcal immunization is possible during therapeutic immunosuppression after heart or liver transplantation. The achieved immune response is comparable to that in healthy controls. The high efficacy of the pneumococcal vaccine, compared with other vaccines, in immunosuppressed patients may be due to T-cell dependent antibody production against polysaccharides.