Question

Which part is histopathologically affected in spinal cord of HAM/TSP? a. Axon b. Myelin c. Axon and Myelin

Short answer

Answer: Axon and Myelin

Step-by-step solution

Identify HAM/TSP impact

HAM/TSP is a condition caused by the HTLV-1 virus, which affects the spinal cord. The infection usually results in the progressive demyelination of spinal nerves.

Eliminate incorrect choices

Knowing that HAM/TSP affects the spinal cord by causing demyelination, we can eliminate option a (Axon) as this is not primarily affected in HAM/TSP.

Choose the correct option

Given the information, the correct answer is option c (Axon and Myelin). While the primary pathology is demyelination, axons can also be affected in the process, resulting in the clinical symptoms observed in patients with HAM/TSP.

Key concepts

HTLV-1 Virus

The Human T-cell Lymphotropic Virus Type 1 (HTLV-1) is a retrovirus associated with several health conditions, one of the most notable being HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). This virus primarily targets the immune system's T-cells which can result in neurological complications. As a retrovirus, HTLV-1 inserts its genetic material into the host DNA, potentially disrupting normal cellular functions and promoting inflammation.

In the context of HAM/TSP, HTLV-1 induces an immune response that mistakenly attacks cells within the central nervous system, leading to neurodegeneration. People infected with HTLV-1 may develop HAM/TSP years after the initial viral infection, suggesting a complex interplay between virus persistence and host immune responses.

Spinal Cord Demyelination

Demyelination refers to the loss of myelin, the protective sheath around nerve fibers, known as axons, in the central nervous system. In the case of HAM/TSP, spinal cord demyelination is a significant pathologic feature. Myelin is vital for the rapid transmission of electrical impulses along nerve cells. When it is damaged or destroyed, nerve signal transmission slows down or stops altogether, leading to neurological symptoms such as muscle weakness, sensory loss, and impaired coordination.

As the step-by-step solution to the exercise indicates, both the axon and myelin are histopathologically affected in HAM/TSP, but demyelination is the primary change. Demyelination can also predispose axons to further damage, exacerbating the neurological decline in individuals with HAM/TSP.

Neuroimmune Pharmacology

Neuroimmune pharmacology is an interdisciplinary field that explores the interactions between the nervous and immune systems, and how drugs can modify these interactions to treat diseases. In HAM/TSP, the immune system's aberrant attack on the nervous system's components makes this field particularly relevant. The treatments considered in neuroimmune pharmacology aim to modulate the immune response, prevent further demyelination, protect neurons, or repair damaged myelin.

Understanding how HTLV-1 manipulates the immune system to cause neuropathology is essential in developing effective treatments for HAM/TSP. Drugs might target specific immune cells, signaling pathways involved in inflammation, or directly impact the mechanisms of demyelination and axonal degeneration. This complex approach is necessary given the multifaceted nature of virus-host interactions and the downstream consequences leading to HAM/TSP.