Herpes Simplex Virus type 1 infects Langerhans cells and the novel epidermal dendritic cell, Epi-cDC2s, via different entry pathways.

Skin mononuclear phagocytes (MNPs) provide the first interactions of invading viruses with the immune system. In addition to Langerhans cells (LCs), we recently described a second epidermal MNP population, Epi-cDC2s, in human anogenital epidermis that is closely related to dermal conventional dendritic cells type 2 (cDC2) and can be preferentially infected by HIV. Here we show that in epidermal explants topically infected with herpes simplex virus (HSV-1), both LCs and Epi-cDC2s interact with HSV-1 particles and infected keratinocytes. Isolated Epi-cDC2s support higher levels of infection than LCs in vitro, inhibited by acyclovir, but both MNP subtypes express similar levels of the HSV entry receptors nectin-1 and HVEM, and show similar levels of initial uptake. Using inhibitors of endosomal acidification, actin and cholesterol, we found that HSV-1 utilises different entry pathways in each cell type. HSV-1 predominantly infects LCs, and monocyte-derived MNPs, via a pH-dependent pathway. In contrast, Epi-cDC2s are mainly infected via a pH-independent pathway which may contribute to the enhanced infection of Epi-cDC2s. Both cells underwent apoptosis suggesting that Epi-cDC2s may follow the same dermal migration and uptake by dermal MNPs that we have previously shown for LCs. Thus, we hypothesize that the uptake of HSV and infection of Epi-cDC2s will stimulate immune responses via a different pathway to LCs, which in future may help guide HSV vaccine development and adjuvant targeting.

Human anogenital monocyte-derived dendritic cells and langerin+cDC2 are major HIV target cells.

Tissue mononuclear phagocytes (MNP) are specialised in pathogen detection and antigen presentation. As such they deliver HIV to its primary target cells; CD4 T cells. Most MNP HIV transmission studies have focused on epithelial MNPs. However, as mucosal trauma and inflammation are now known to be strongly associated with HIV transmission, here we examine the role of sub-epithelial MNPs which are present in a diverse array of subsets. We show that HIV can penetrate the epithelial surface to interact with sub-epithelial resident MNPs in anogenital explants and define the full array of subsets that are present in the human anogenital and colorectal tissues that HIV may encounter during sexual transmission. In doing so we identify two subsets that preferentially take up HIV, become infected and transmit the virus to CD4 T cells; CD14+CD1c+ monocyte-derived dendritic cells and langerin-expressing conventional dendritic cells 2 (cDC2).

Identification of HIV transmitting CD11c+ human epidermal dendritic cells.

Langerhans cells (LC) are thought to be the only mononuclear phagocyte population in the epidermis where they detect pathogens. Here, we show that CD11c+ dendritic cells (DCs) are also present. These cells are transcriptionally similar to dermal cDC2 but are more efficient antigen-presenting cells. Compared to LCs, epidermal CD11c+ DCs are enriched in anogenital tissues where they preferentially interact with HIV, express the higher levels of HIV entry receptor CCR5, support the higher levels of HIV uptake and replication and are more efficient at transmitting the virus to CD4 T cells. Importantly, these findings are observed using both a lab-adapted and transmitted/founder strain of HIV. We also describe a CD33low cell population, which is transcriptionally similar to LCs but does not appear to function as antigen-presenting cells or acts as HIV target cells. Our findings reveal that epidermal DCs in anogenital tissues potentially play a key role in sexual transmission of HIV.

Phenotypic and functional consequences of different isolation protocols on skin mononuclear phagocytes.

Mononuclear phagocytes are present in skin and mucosa and represent one of the first lines of defense against invading pathogens, which they detect via an array of pathogen-binding receptors expressed on their surface. However, their extraction from tissue is difficult, and the isolation technique used has functional consequences on the cells obtained. Here, we compare mononuclear phagocytes isolated from human skin using either enzymatic digestion or spontaneous migration. Cells isolated via enzymatic digestion are in an immature state, and all subsets are easily defined. However, cells isolated by spontaneous migration are in a mature state, and CD141 cross-presenting DCs (cDC1) are more difficult to define. Different pathogen-binding receptors are susceptible to cleavage by blends of collagenase, demonstrating that great care must be taken in choosing the correct enzyme blend to digest tissue if carrying out pathogen-interaction assays. Finally, we have optimized mononuclear phagocyte culture conditions to enhance their survival after liberation from the tissue.

The primo vascular system as a new anatomical system.

Traditional Eastern medicine has had a successful existence for a long time and has provided functional paths for curing disease. However, some scientists do not accept acupuncture, primarily because the meridian system lacks a physical anatomical basis. To date, scientific theories have not been able to explain the functional paths used by traditional Eastern medicine to cure disease. According to Western medicine, no known anatomical foundation exists for the meridians and unknown nervous, circulatory, endocrine, and immune mechanisms mediate the effects of acupuncture. In the early 1960s, only one hypothesis was proposed to explain the anatomical basis of the meridians. By using different experimental approaches during the past 10 years, the number of scientific papers that report the discovery of different anatomical and physiological evidence confirming the existence of an anatomical basis for the meridian system has increased. Morphological science is greatly challenged to offer a new biomedical theory that explains the possible existence of new bodily systems such as the primo vascular system (PVS). The PVS is a previously unknown system that integrates the features of the cardiovascular, nervous, immune, and hormonal systems. It also provides a physical substrate for the acupuncture points and meridians. Announcements of the morphological architectonics and the function of the PVS fundamentally changed the basic understanding of biology and medicine because the PVS is involved in the development and the functions of living organisms. We propose a new vision of the anatomical basis for the PVS and the vital energy-called "Qi"-as an electromagnetic wave that is involved very closely with the DNA in the PVS. DNA provides genetic information and it functions as a store of information that can be obtained from the electromagnetic fields of the environment. The PVS is the communication system between living organisms and the environment, and it lies at the lowest level of life. The theory of the PVS could be a good basis for forming a new point of view of Darwin's evolutionary theory. Discoveries in morphological theory-such as discoveries with respect to the PVS-have not been made since the 18th century. For that reason, the PVS needs more attention.

Squamous cell carcinoma arising in an area of long-standing necrobiosis lipoidica.

BACKGROUND: Squamous cell carcinoma in an area of chronic ulceration is a well-documented phenomenon. However, its occurrence arising de novo in an area of necrobiosis lipoidica is rare. METHOD: We report a case in a 53-year-old female who presented with a 2 month history of an erythematous nodule occurring in a plaque of necrobiosis lipoidica on the medical aspect of the right lower leg. She had a background of poorly controlled Type 1 diabetes. RESULTS: Histopathological findings revealed a well-differentiated squamous cell carcinoma overlying an area of necrobiosis lipoidica. Treatment was by excision and split-thickness skin graft. CONCLUSION: Clinicians should be aware of malignant transformation within a plaque of necrobiosis lipoidica. Early detection will allow conservative treatment.